Sedimentary and reservoir characterization of wandering braided river: a case of the Xiashihezi Formation 1 member in Shilijiakhan west zone, Hangjinqi, Northern Ordos Basin

Hongtao Li; Tao Liu; Qingbin Liu

doi:10.1371/journal.pone.0329942

. 2025 Sep 8;20(9):e0329942. doi: 10.1371/journal.pone.0329942

Sedimentary and reservoir characterization of wandering braided river: a case of the Xiashihezi Formation 1 member in Shilijiakhan west zone, Hangjinqi, Northern Ordos Basin

Hongtao Li ^1,^*, Tao Liu ¹, Qingbin Liu ¹

Editor: Bappa Mukherjee²

PMCID: PMC12416704 PMID: 40920845

Abstract

The Ordos Basin’s Hangjinqi Shiligahan west zone Xiashihezi Formation 1 Member gas reservoir exhibits significant exploration and development potential. However, its sedimentation and reservoir characteristics are poorly understood. To address this, geological, seismic, macroscopic, and microscopic methods are combined. The available data includes core observation, thin sections, physical property analysis, mercury injection curve interpretation, seismic attribute predictions, and so on. The results show that the target stratum lithology and sedimentary structure are complex and diverse. They are dominated by gravelly coarse sandstone facies with strong hydrodynamic conditions, intercalated with thin mudstone and siltstone. The vertical meter-scale cycle sedimentation characteristics are distinct, representing a typical shallow braided river deposition. Through the mutual calibration and verification of lithology, logging, and seismic facies, the braided channel and its internal microfacies boundaries were accurately delineated. The reservoir primarily consists of gravel-bearing coarse sandstone, featuring intergranular and intragranular dissolved pores as the primary types of reservoir space. The pore types are predominantly mesopores and small pores, with pore-throat combinations favoring mesopores and medium throats, as well as medium to small pores and fine throats. The reservoirs average porosity and permibility are 7.6% and 0.53mD, respectively. This defines a typical reservoir with low to ultra-low porosity and low to ultra-low permeability. The sedimentary microfacies and their associated hydrodynamic conditions are crucial for the development of the reservoir in the Xiashihezi Formation 1 Member. This leads to variations in reservoir properties and pore structures. Thus, the reservoirs are predominantly located in the channel bar microfacies, clearly demonstrating characteristics of facies-controlled reservoir development.

Introduction

There are many sets of sandtone bodies developed in Permian in Ordos Basin. Among them, the reservoir sandstone bodies of the Xiashihezi Formation 1 Member are the most developed, which are vertically overlapped and horizontally combined, and have the characteristics of wide coverage spatial distribution [1]. This set of sandstone body reservoir has a controlled reserve of more than 100 billion m³ in the west zone of Shiligahan, Hangjinqi, with great exploration and development potential [1–6], and is one of the main target areas for increasing reserves and production in the future. However, low porosity and permeability and poor physical properties lead to low production degree of the gas reservoir. In order to further explore and develop the tight and low-permeability gas reservoirs in Ordos Basin, it is urgent to understand the sedimentary and reservoir characteristics of such gas reservoirs, clarify the impact of sedimentation on reservoir development, and provide the basis for further macro distribution analysis of reservoirs. Previous studies have shown that the gas reservoir type of the Xiashihezi Formation 1 Member in Shiligahan west zone, Hangjinqi, northern Ordos Basin was dominated by lithologic gas reservoirs [6,7]. Therefore, sedimentary microfacies was one of the important controlling factors for the development of reservoirs and gas reservoirs. However, there ws a great controversy on the understanding of the sedimentary characteristics of the western Shiligahan west zone by predecessors. Some scholars believed that it was alluvial fan sedimentation, while others believed that it was braided river sedimentation [8–10], and the understanding of sedimentation was not unified. In terms of sedimentary microfacies boundary delineation, predecessors used logging data to carry out single well sedimentary microfacies division, and used the difference method between wells to speculate sedimentary microfacies [3]. However, the study area is large, the degree of well control is low, and the deposition of the Xiashihezi Formation 1 Member is complex. The predecessors did not fully use seismic data to depict the microfacies boundary [3,11], and the plane distribution of sedimentary microfacies often has a large error with the actual production, that is, its predictability is poor. Although some scholars have preliminarily determined the distribution of sandstone bodies by using the geophysical arc length attribute, and have inversed the thickness of sandstone bodies in the Xiashihezi Formation 1 Member through geophysics, and compiled the sandstone strata ratio map [12], they have not really effectively depicted the sedimentary microfacies boundary. The sedimentary microfacies in this area change rapidly laterally. Facing the research object with such complex sedimentary laws, it is obviously difficult to accurately describe the plane distribution of sedimentary microfacies by using only limited wells data or sandstone strata ratio data. More importantly, the Xiashihezi Formation 1 Member in the west zone of Shiligahan area has diverse lithological assemblages, compact reservoir structure, complex reservoir space types and strong heterogeneity. The previous analysis of reservoir characteristics in the study area is relatively few, usually only the lithological and physical characteristics are analyzed, and the analysis of reservoir space type and pore structure is basically not carried out [12,13]. Therefore, the understanding of reservoir also has certain limitations. The pore structure and its combination characteristics can reflect the reservoir and seepage ability to control the occurrence state and seepage characteristics of reservoir fluid, and thus is one of the key contents of tight sandstone reservoir evaluation [14,15].

In summary, there is a need to enhance understanding of sedimentation and reservoir characteristics in this area, along with further research into how sedimentation influences and controls reservoir development, which in turn poses a challenge for exploration and development. Clearly, precisely delineating the favorable sedimentary facies of the gas reservoir, defining the boundaries of the favorable reservoir, and conducting research on fundamental reservoir characteristics such as basic petrology, physical properties, reservoir space types, and pore structure within these boundaries are fundamental to evaluating and predicting oil and gas reservoirs. These efforts are central to quantitative reservoir characterization and are essential prerequisites for understanding the gas reservoir. They provide a basis for precise and detailed description and evaluation of the gas reservoir and are key to its further effective development.

In this study, based on detailed observations of drilling coring and a range of data including geological, logging, and seismic information, the well and seismic data was closely integrated, and multidisciplinary combination research was carried out. Through integrated geological, logging, and seismic research, we investigated reservoir sedimentary characteristics, optimized geophysical sensitive attribute parameters, and precisely delineated microfacies boundaries to ascertain the reservoir’s macro distribution. Further analyses, including thin section observations, physical property measurements, and mercury injection curve evaluations, described reservoir lithology and space types, quantified physical properties, analyzed pore structure and other microscopic characteristics, and summarized the impact of sedimentation on reservoir development. The research results not only offer insights for the analysis of similar braided river tight sandstone reservoirs but also serve as a basis for further reservoir studies in this area, thus bearing significant theoretical and practical implications.

Regional geological background

The Hangjinqi area and its adjacent area are located in the northern Ordos Basin and in the west of Inner Mongolia Autonomous Region and the northwest of Ordos City, in the Ordos Plateau and Hetao Plain. The current tectonic position is located in the junction of Yimeng uplift and Yishan slope in the northern Ordos Basin. This area has been in a high position of the basin structure for a long time and is a favorable direction for natural gas migration. In general, the structure is monoclinic, inclined to the southwest, and a nosing structure with low amplitude trending to the northeast was developed locally. The north side of the Shilijiahan west zone is bordered by the Boerjianghaizi fault, and the west side is adjacent to the Wulanjilinmiao fault. The strike of the two faults is nearly east-west (Fig 1).

In the Late Carboniferous period, the southern area of Otogqi and Ejinhoroqi in the Hangjinqi region deposited the Carboniferous Taiyuan Formation as a result of weathering and erosion of the lower Ordovician carbonate rocks. In the early Permian, the transgression reached a climax, and the sedimentary range gradually expanded to the area of the Boerjianghaizi fault, depositing the Permian Shanxi Formation, the Xiashihezi Formation, the Shangshihezi Formation, and the Shiqianfeng Formation [2]. The Xiashihezi Formation was composed of (sandy) conglomerate, gravelly coarse sandstone, grayish green medium fine sandstone, silty mudstone and grayish green, brown mudstone. The middle and lower part of Xiashihezi Formation 1 Member was mainly composed of (sandy) conglomerate, gravelly lithic coarse sandstone, lithic quartz sandstone, which was an important reservoir development layer. The Shangshihezi Formation and Shiqianfeng Formation mainly deposited fine-grained sedimentary rocks.

Comprehensive analysis of sedimentary facies and its distribution characteristics

Sedimentary facies analysis and logging response characteristics.

The detailed core observation revealed that the lithology of the sandstone body of Xiashihezi Formation 1 Member was complex and diverse in the research area. Variegated (sandy) conglomerate was developed at the bottom of some channel sedimentary sequences, which was mainly composed of medium conglomerate and mostly composed of multi-component lithic conglomerate and mud gravel was rare. The gravel was poorly sorted but relatively well rounded. Gravel was slightly imbricated in some places, and calcite cementation and filling could be seen a small amount of gravel, showing the characteristics of traction current. The conglomerate and the underlying strata were mostly bounded by the scouring and filling structure plane, and the erosion cutting phenomenon was common, indicating that the conglomerate was mostly formed in the strong hydrodynamic environment. Its formation was attributed to the braided channel lag deposition (Figs 2.a-b). Additionally, a small amount of graded bedding could also be observed, which was mainly formed by the gradual weakening of water flow after rapid paroxysmal sedimentation events. Sandstone deposits, including gravelly coarse sandstone, coarse sandstone, medium sandstone, and medium fine sandstone, had been formed on the thin layer of conglomerate and glutenite. Among the various sandstone deposits, gravelly coarse sandstone and coarse sandstone were the most prevalent, exhibiting relatively poor sorting and rounding. Among them, gravelly coarse sandstone and coarse sandstone were developed with trough cross bedding, plate cross bedding and massive bedding (Figs 2.c-d), while medium sandstone and fine sandstone were usually developed with small flowing sand ripple bedding and parallel bedding (Figs 2.e-f). From the bottom to the top, there were obvious vertical facies sequence combinations with coarse-to-fine, such as conglomerate, (gravelly) coarse sandstone, medium sandstone and fine sandstone. There were also 4–10 cm low-energy deposits in falling silt layers or gullies with argillaceous bands between sandstone bodies, exhibiting the characteristics of multi-stage superimposed typical braided river channel bar configuration units. On the sandstone bodies, brown, greyish-green, and variegated floodplain muddy sediments were developed, with rare plant carbon debris, indicating an overall arid climate during that period (Figs 2.g-h). Based on the observations of the entire core section, the channel sediments in the Xiashihezi Formation 1 Member primarily consisted of normal cyclic sediments with meter-scale and grain size becoming finer upward, reflecting that the sedimentary water body decreases upward. The riverbed was dominated by coarse-grained sediments in middle-lower part, supplemented by fine-grained sediments such as the upper embankment and overtopping. The multi-stage cutting and overlapping characteristics of the channel bar were obvious, indicating that the river channel was wide, shallow and rapid, without a fixed embankment and easy to divert (Figs 2.i-j). Based on the above analysis of lithofacies characteristics, it could be posited that the Xiashihezi Formation 1 Member in this area represented a relatively typical shallow braided river deposit in the absence of a fixed river channel under relatively dry conditions [16,17].

The above description of core sedimentary characteristics, detailed correlation with logging curves, and lithology and vertical combination characteristics, as well as the amplitude and shape displayed by the corresponding logging curves, indicated that braided river sediments could be subdivided into three microfacies in a single well.

Channel bar microfacies were primarily developed in the lower portion of the sandstone body sedimentary cycle. In the channel bar microfacies, trough cross bedding (gravel-bearing) coarse sandstone facies, tabular cross bedding (gravel-bearing) coarse sandstone facies, and massive bedding (gravel-bearing) coarse sandstone facies were developed, indicating robust hydrodynamic sedimentary conditions. Typical channel scouring surfaces and channel lag gravel deposits could be observed at the base. Due to the relatively thin lag deposits observed in the Xiashihezi Formation 1 Member, it could be challenging to differentiate the logging curve characteristics between the thin lag deposits and the channel bar microfacies. Therefore, this paper didn’t further subdivide them. The logging curves corresponding to the channel bar microfacies could be classified into two types, with high amplitude tooth box type as the main type and a few smooth box types (Fig 3).

The channel sandy filling microfacies were typically developed at the upper or top of the sedimentary cycle of the sandstone body. The lithology was predominantly grayish green medium-fine sandstone, exhibiting parallel bedding and small sand-ripple bedding. The cores revealed the enrichment of bright flake mica, indicating that the hydrodynamic conditions were relatively weak. The logging curve was primarily a combination of medium-high amplitude toothed box and medium amplitude toothed bell (Fig 3).

Floodplain microfacies: The lithology was predominantly composed of mudstone facies and silty mudstone facies, which were generally developed on the deposition of sandstone body. Occasionally, mudstone drainage structures were observed, and the natural gamma curve (GR) was markedly elevated (Fig 3).

Description of sedimentary microfacies distribution based on well seismic combination.

The distribution of sedimentary microfacies was determined by analyzing the synthetic seismic records of the drilled wells and the seismic profile of the single well sedimentary microfacies. A comprehensive model of the sedimentary microfacies with logging and seismic response characteristics of the Xiashihezi Formation 1 Member was established (Fig 4), and the vertical and horizontal distribution of sedimentary microfacies was studied [18,19]. The seismic facies response characteristics of the three main sedimentary microfacies of the target layer were as follows.

In the channel bar microfacies, due to the strong acoustic impedance difference between the thick sandstone body and the surrounding rock (mudstone), it mainly presented the short axis reflection of low-frequency strong wave trough (Fig 4 and Fig 5.a). The channel sandy filling microfacies exhibited low-frequency, medium to weak trough reflections. The acoustic impedance difference between the medium-fine sandstone deposited under relatively weak hydrodynamic conditions and the surrounding rock was relatively small, and the reflection coefficient at the reflection interface was relatively small (Fig 4 and Fig 5.a), resulting in relatively medium-weak trough seismic reflection. The floodplain microfacies, with weak amplitude reflection, were primarily low-energy sedimentary assemblages of fine sandstone and mudstone, with thin interbedded deposition (Fig 4 and Fig 5.a). This served as the basis for microfacies correlation, and enabled the lateral thickness change of the sandstone body to be explored by using the value amplitude change of the amplitude attribute. Ultimately, this facilitated the completion of the microfacies analysis of the connection wells correlation section (Fig 5.b).

The detailed calibration results of sedimentary microfacies and seismic profile demonstrated that the greater the thickness of the sandstone, the stronger the trough amplitude. When the sandstone thickness was constant, the greater the proportion of coarse-grained sandstone, and the greater the absolute value of the trough amplitude attribute, that was, the absolute value of the maximum trough amplitude of flood plain, channel filling, and channel bar microfacies, there was a gradually increasing trend. Accordingly, the research findings on the relationship between sandstone body thickness and amplitude demonstrated that the channel boundary could be effectively described by the maximum trough amplitude attribute [20,21]. Furthermore, the morphological characteristics of different sedimentary microfacies could be effectively described by employing the corresponding relationship between the maximum trough amplitude range and different microfacies. The results of the above analysis of single well sedimentary microfacies and connected well sedimentary microfacies indicated that the amplitude of weak trough amplitude was primarily associated with floodplain deposits, while the medium trough amplitude was predominantly linked to channel filling microfacies. The most important channel bar microfacies had the characteristics of the strong trough amplitude (Fig 4, Fig 5). The maximum trough amplitude attribute plane for the main target layer was extracted (Fig 6.a), which showed a north-south strip (Fig 6.a). The plane distribution of sedimentary microfacies in the Xiashihezi Formation 1 Member was finally obtained by mutual calibration and constraint between the attribute of maximum trough amplitude and the single well sedimentary microfacies, the connected well sedimentary microfacies [21,22]. The study showed that there were 5 braided channels distributed in the Xiashihezi Formation 1 Member in the Shiligahan west zone, which were named Ch1, Ch2, Ch3, Ch4 and Ch5 respectively from west to East, with a north-south strip distribution. The scale of Ch3, Ch4 and Ch5 channels in the Middle East was larger than that of Ch1 and Ch2 channels in the West (Fig 6.b).

Reservoir microstructure and pore structure characteristics

Reservoir microscopic characteristics description.

According to the statistical analysis of thin section data in the study area, the reservoir lithology of Xiashihezi Formation 1 Member in the area was mainly lithic (gravel-containing) coarse sandstone and lithic quartz (gravel-containing) coarse sandstone (Figs 7.a-c), with a small amount of fine glutenite and medium sandstone. The rock clastic was mainly composed of quartz and rock debris, with less feldspar. The lithology in the Xiashihezi Formation 1 Member was predominantly coarse sandstone and gravelly coarse sandstone. In addition to using thin section observation, Bappa Mukherjee et al. (2021) proposed the use of hierarchical clustering analysis (HCA) in lithology identification, which can achieve lithology identification using conventional logging curves. This is also a highly recommended method that can identify lithology throughout the entire wellbore [23]. The average content of quartz in clastic rocks from the Xiashihezi Formation 1 Member was 69.9%, with the particle size primarily comprising coarse grains and gravelly coarse grains. The interstitial materials were primarily composed of argillaceous matrix and authigenic calcite, kaolinite, chlorite, and other cements. The sorting of sandstone particles was predominantly medium to poor, with a sub-angular roundness, followed by sub-circular, and the overall textural maturity was low. Clastic grains were supported with the ways of point line contact, and concave convex contact (Fig 7). The cementation type was mainly pore cementation. From the perspective of the main rock types of the reservoir, it was matched with the sedimentary types with variable braided river dynamic conditions in the region.

The statistical results of porosity and permeability from different types of lithology showed that the physical properties of gravel-bearing coarse sandstone and coarse sandstone lithology reservoirs were significantly better than those of sandy conglomerate, medium sandstone, fine sandstone, and other lithology (Fig 8.a). This suggested that the reservoir development in this area was controlled by sedimentary microfacies. The correlation between porosity and permeability of samples from the Xiashihezi Formation 1 Member in this area was good, indicating that the reservoir space type is mainly pore type (Fig 8.b). The porosity value ranged from 0.4% to 18.7%, with an average of 7.6% (Fig 9.a). The majority of samples exhibited porosity values below 15%. Permeability values ranged from 0.007mD to 15.1mD, with an average of 0.53mD. The permeability of 87% of the samples was less than 1mD (Fig 9.b). Therefore, the Xiashihezi Formation 1 Member in the study area was generally a low-porosity, ultra-low-porosity, ultra-low-permeability (tight) reservoir.

The experimental results of injecting thin section identification and image analysis indicated that the reservoir space type of the reservoir in the study area was primarily intergranular dissolved pores, intragranular dissolved pores, and primary intergranular pores. Additionally, mold pores and intergranular micropores were also relatively developed, with a small amount of microfractures. The content of intergranular dissolved pores was the highest in the secondary dissolved pores, followed by intragranular dissolved pores and mold pores. The specific characteristics of pore types, such as dissolution intergranular pores, whose dissolution phenomena were evident at the edges of pores, and some of them were in the shape of dissolution harbors (Fig 7.d-e). Mold pores and intragranular dissolution pores, the majority of these were formed by complete or partial dissolution of feldspar and soluble rock fragments (Fig 7.f). The primary intergranular pores were triangular and multilateral in shape, and the pore edges were mostly straight, without obvious dissolution (Fig 7.g). Intergranular micropores were primarily formed between the grains of bookworm-like kaolinite after the filling of authigenic kaolinite distributed between clastic particles (Fig 7. h). Microfractures were typically developed in relatively tight reservoirs, along grain boundaries or cutting clastic particles (Fig 7.i). A detailed analysis of the reservoir space indicated that intergranular dissolved pores contained some primary pores, which were the result of further dissolution on the basis of primary pores. In summary, the reservoir space type in this area was mainly pore type, including intergranular dissolved pores, intragranular dissolved pores, primary intergranular pores, mold pores, and intergranular micropores, with a small amount of microfractures developed.

Analysis of reservoir pore structure characteristics.

Pore structure research is a fundamental aspect of reservoir microscopic analysis. In particular, low-permeability tight sandstone reservoirs exhibit distinctive microscopic pore structure characteristics and seepage mechanisms that regulate the migration and accumulation of oil and gas, as well as the productivity of gas wells [24,25]. The size, distribution, uniformity, and other characteristics of pore throats can be reflected by the throat radius, skewness, sorting coefficient, and other parameters of the mercury injection capillary pressure curve [24,26,27]. Mercury injection data from a variety of reservoir samples from the Xiashihezi Formation 1 Member of the Shilijiahan west zone were sorted and analyzed. The resulting data were used to calculate the mercury injection parameters (Table 1), which were then used to create a mercury injection curve (Fig 10). This curve was used to study the microscopic pore structure of low-permeability tight sandstone reservoirs.

Table 1. Statistical table of reservoir pore throat characteristic parameters in Shilijiahan west zone.

Curve type	Lithologic type	Microfacies type	Porosity (%)	Permeability (mD)	Displacement pressure (MPa)	Median pressure (MPa)	Average throat radius (μm)	Maximum mercury saturation (%)	Sorting coefficient
class I	gravelly coarse sandstone, coarse sandstone	Channel bar	13.8	1.35	0.29	2.42	0.37	91.5	0.35
class II	coarse sandstone, gravelly coarse sandstone	Channel bar	9.3	0.91	0.52	8.27	0.16	88.1	0.39
class III	medium sandstone, medium coarse sandstone	Channel filling	5.5	0.3	1.2	20.2	0.08	67.6	0.09
class IV	medium fine sandstone, siltstone	Channel filling, floodplain	3.6	0. 15	4.6	/	0.02	41.2	0.02

Open in a new tab

The inclination of the mercury injection curve to the lower left indicated that the coarser throat skewness is associated with greater reservoir permeability. The wider the mercury injection curve platform is, the better the sorting performance of the throat is. The results of the study indicated that the mercury intrusion curves of the samples in the study area could be divided into four categories (Fig 10), with the corresponding mercury intrusion parameters enumerated in Table 1. The class I curve of capillary pressure was generally concave to the bottom left of the map, with a slight coarse skewness (Fig 10.a). The average displacement pressure was 0.29 MPa, and the average median pressure was 2.42 MPa. The average throat radius was 0.37 μm, and the maximum mercury saturation was 91.5% (Table 1). The class II curve was a steep slope type with medium skewness (Fig 10.a). The capillary pressure curve of the rock samples was steeper than that of the Class I samples, indicating poor sorting. The average displacement pressure was 0.52 MPa, and the average median pressure was 8.27 MPa (Table 1). The average throat radius was 0.16 μm, and the maximum mercury saturation was 88.1%. The Class III capillary pressure curve of the rock samples was slightly smoother than that of the Class II samples, with a slight fine skewness (Fig 10.a). The average displacement pressure was 1.2 MPa, and the average median pressure was 20.2 MPa. The average throat radius was 0.08 μm, and the maximum mercury saturation was 67.6% (Table 1). The skewness of the capillary pressure curve of the class IV type of rock samples was the smallest (Fig 10.a), indicating that the pore throat was very small and generally non-reservoir. The above indicated that the Class II curve of mercury intrusion was not only controlled by the original sedimentation, but also by the dissolution effect of later diagenesis, which led to the generation of uneven pores. Therefore, it was also an important reason for the complex pore structure of the reservoir in this area.

The pore throat distribution standard for clastic rock reservoir evaluation defines the pore throat greater than 1 μm as coarse throat, the pore throat of 0.25 μm ~ 1 μm as middle throat, the pore throat of 0.025 μm ~ 0.25 μm as fine throat, and the pore throat of less than 0.025 μm as micro throat. A mapping of the pore throat radius of the four kinds of rock sample types was presented in Fig 10.b. The characteristics of the pore throat radius distribution curve of the class I of samples were as follows. The curve was typical of a coarse middle throat type, with the majority of samples throat radius distributed at 0.25 μm to 2.5 μm (Fig 10.b). The middle throat and coarse throat are developed. The class II type of sample was the middle throat multi-peak type, with a wide peak. The range of throat radius was mostly at 0.025 μm to 1.6 μm, indicating that the fine throat and middle throat were relatively developed (Fig 10.b). The class III type of samples was medium fine throat single peak type, and the throat radius of the class III type of samples ranged from 0.01 μm to 0.25 μm. The IV type of samples was a fine-micro throat single-peak type. The throat radius distribution was mostly between 0.004 μm and 0.4 μm (Fig 10.b), exhibiting clear micro throat characteristics and a small amount of fine throat.

A review of the pore and throat characteristics in the study area, as analyzed in the context of reservoir space types, revealed that the pore sizes were primarily medium and small (micro) pores, with the presence of locally developed large pores. The throat radius, as reflected by mercury injection curves of different types of reservoirs, indicated that the throat as a whole was dominated by medium and fine throats (Fig 11.a). The pore throat combination included predominantly medium pore with medium throat type and medium-small pore with fine throat type (Fig 11.b), which was relatively poor.

Effect of sedimentation on reservoir development.

The sedimentary environment and facies exerted a profound influence on the formation and distribution of reservoirs. The water dynamic conditions of sedimentary in clastic rocks in different facies zones were markedly distinct. There were notable differences in mineral composition, grain size, and interstitial materials of reservoir rocks, which profoundly impacted the physical properties, pore structure, and percolation characteristics of sandstone reservoirs, resulting in significant alterations in reservoir performance in different facies zones [28–31]. Consequently, the sedimentary facies represented a pivotal factor in controlling reservoir performance.

The distribution characteristics of porosity and permeability of different samples in the study area (see Fig 8.a) were closely related to the sedimentary microfacies. The average porosity of gravelly coarse sandstone and coarse sandstone in braided river channel bars was 10.8%, with a permeability of 0.79 mD. The average porosity of sandstone and fine sandstone in channel filling was 5.45%, with a permeability of 0.34 mD. The porosity of siltstone in floodplain was 3%, with a permeability of 0.2 mD. The physical properties of braided river channel bar were the most favorable, while those of channel filling sandstone and floodplain sandstone were relatively poor (Fig 8). The braided river channel bar, subject to a strong hydrodynamic effect, was scoured by high-energy, stable water flow, resulting in the formation of a thick sandstone body, a large sandstone grain size, a small content of rock debris and matrix, and a relatively good sorting. Furthermore, it was susceptible to dissolution during diagenesis [32,33], which resulted in the development of intergranular and intragranular dissolved pores (Fig 7.d-f). This process facilitated the formation of sandstone reservoirs with desirable physical properties. Channel filling and floodplain sandstones were relatively fine in grain size and thin in thickness, rendering them more susceptible to the strong influence of the content of argillaceous and carbonate cements (Fig 2.e-f). The content of plastic particles and matrix, such as argillaceous rock debris and mica, in the reservoir was high (Fig 2.e-f, Fig 7.i), resulting in poor reservoir physical properties. It was evident that the braided river channel bar microfacies represented a favorable reservoir microfacies for exploration and development.

The aforementioned research demonstrated that the physical properties of sandstone bodies in diffirent sedimentary microfacies were distinct. However, even within the same sedimentary microfacies, the changes of sediment composition with hydrodynamic conditions would also be different, resulting in the observed differences in physical properties [32]. In the central and eastern part of the study area, the river channels designated Ch3, Ch4 and Ch5 exhibited a pronounced hydrodynamic force, low clay matrix content, an advanced pattern of sandstone body inheritance, a considerable width and thickness of the river channel, the presence of coarse sandstone particles, a higher original porosity and permeability. These conditions were also conducive to the occurrence of dissolution during the diagenetic stage, ultimately forming high-quality reservoirs with favourable physical properties, particularly in Jin32 well block at the intersection of multiple rivers in the south of the Ch3 river channel. The braided river channel was characterized by a wide, expansive channel bar, which was densely developed and conducive to reservoir development (Fig 6.b). While the sandstone bodies in the channel bar of the Ch1 and Ch2 river channels in the west were situated in relatively weaker hydrodynamic conditions than those in the middle and east, the river channel size and the grain size of sedimentary rocks were smaller than those in the Middle East, so the final reservoir physical properties were poor (Fig 6.b).

The microscopic pore structure of reservoir rock exerted a significant influence on the fluid reservoir and percolation capacity [34], which represented a pivotal factor in the evaluation of reservoir effectiveness. The porosity of braided river channel bar sandstone reservoirs was predominantly greater than 9% (Fig 8.a), with a maximum mercury saturation of over 80% and a displacement pressure of less than 0.6 MPa. Additionally, the average throat radius was typically greater than 0.16 μm, indicating that the pore throat structure was relatively good. Although the braided river channel bar sandstones were poorly sorted relative to other microfacies sandstones, the reservoir heterogeneity was enhanced due to the development of dissolution (Fig 7.d-f). Consequently, the number of large throats also increased, reflecting that the reservoir percolation ability was enhanced and the physical properties were improved. Although the channel filling sandstones were relatively well sorted, the majority of the sediments were medium sandstones with a small grain size, which were prone to form small pores and fine throats. These included residual intergranular pores, feldspar intragranular dissolved pores, and intergranular filling kaolinite intergranular micropores (Fig 7.g-i). Consequently, the reservoir pore structure was poor.

Conclusions

(1)
Based on an analysis of the lithology of cores, sedimentary facies marks, vertical sedimentary variation characteristics, sandstone body combination morphology and three-dimensional distribution, it can be concluded that the sedimentary type of the Xiashihezi Formation 1 Member in the Shiligahan west zone belongs to the wandering shallow braided river category. This is evidenced by the presence of approximately five braided river channels developed on a north-south long strip distribution plane. The river channels in the middle and east are larger than those in the west, and the channel bar is the best favorable sedimentary microfacies for reservoir development. An effective method for plane analysis of sedimentary microfacies is to establish the relationship among lithofacies, logging facies and seismic facies, and to select geophysical attributes with high correlation with sedimentary microfacies to constrain the characterisation of braided channel and its internal microfacies boundary.
(2)
The primary reservoir rock of the Xiashihezi Formation 1 Member is gravelly coarse sandstone, and the reservoir space types are primarily intergranular dissolved pores and intragranular dissolved pores, predominantly medium pores and small pores. The throat radius as reflected by mercury injection curves of varying reservoir types demonstrates the throat is dominated by medium and fine throats. The pore throat combination is of the medium pore medium throat type and the medium to small pore fine throat type. The seepage ability is medium to poor. This is a typical ultra-low porosity, low porosity, low permeability, tight porous reservoir. The sedimentary microfacies and their hydrodynamic conditions are of paramount importance in controlling the development of the Xiashihezi Formation 1 Member reservoir, as well as the reservoir thickness, lithologic grain size and filling material composition. This, in turn, gives rise to differences in reservoir macro distribution, reservoir physical properties and pore structure. This understanding provides a basis for facies-controlled reservoir geophysical prediction.

Supporting information

S1 Fig 8. Distribution characteristics and correlation relationship analysis data of porosity and peamibility analysis data of different lithology samples from Xiashihezi Formation 1 Member in Shilijiahan west zone.

(XLSX)

pone.0329942.s001.xlsx^{(55.1KB, xlsx)}

S2 Fig 9. Distribution characteristics analysis data of porosity and peamibility of samples from Xiashihezi Formation 1 Member in Shilijiahan west zone.

(XLSX)

pone.0329942.s002.xlsx^{(48.1KB, xlsx)}

S3 Fig 10. Capillary pressure curve and throat radius distribution analysis data of sandstone from the Xiashihezi Formation 1 Member in the shilijiahan west zone.

(XLSX)

pone.0329942.s003.xlsx^{(30.4KB, xlsx)}

S4 Fig 11. Different levels pore throats and pore combination analysis data from Xiashihezi Formation 1 Member in Shilijiahan west zone.

(XLSX)

pone.0329942.s004.xlsx^{(27KB, xlsx)}

Data Availability

All relevant data are within the manuscript and its Supporting Information files.

Funding Statement

Fund projects: "Research on the Development Potential of Dense and High Water-bearing Gas Reservoirs in Dongsheng Gas Field" (P23133) by the Ministry of Science and Technology of Sinopec and National Major Special Project "Development of Large Oil and Gas Fields and Coalbed Methane" (No. 2016ZX05002-006).

References

1.Zhao J, Fu J, Yao J. Reservoir formation model for large gas fields of quasi-continuous compact sandstone in Ordos Basin. Acta Petrolei Sinica. 2012;33(Suppl 1):37–52. doi: 10.1111/1755-6724.12305_2 [DOI] [Google Scholar]
2.Zhu Z, Li W, Li K. The characteristic of sequence stratigraphy and sedimentary systems of Taiyuan-Xiashihezi formation in Hangjinqi area. Journal of Northwest University (Natural Science Edition). 2010;40(6):1050–4. [Google Scholar]
3.Cao T. Depositional characteristics of Shihezi 1 member, Jin 72 well block of Hangjinqi area, Ordos basin. Natural Gas Technology and Economy. 2019;13(4):8–16. [Google Scholar]
4.Yang H, Liu X, Yan X. The relationship between tectonic sedimentary evolution and tight sandstone gas reservoir since the Paleozoic in Ordos basin. Earth Science Frontiers. 2015;22(3):175–83. [Google Scholar]
5.Li HT, Chen D, Zhang ZY. Sub-layer division and correlation based on well-seismic combination and step-by-step interface constraint: A case study of the Taiyuan-Lower Shihezi Formation in the Shilijiahan of the Hangjinqi area. Sedimentary Geology and Tethyan Geology. 2024;44(2):1–15. [Google Scholar]
6.Zhang W, Cao Q, Lu Y. Sealing model of tight gas reservoirs in the edge of Claraton Basin: A case study from the First Member of Lower Shihezi Formation in Hangjinqi area of the northern margin of the Ordos Basin. Bulletin of Geological Science and Technology. 2022;41(3):122–31. [Google Scholar]
7.Qi R, Li L, Qin X. Sand body configuration and gas-bearing properties of near source sand-gravel braided river on the northern margin of Ordos Basin. Petroleum Geology & Experiment. 2019;41(5):682–90. [Google Scholar]
8.Fu S, Shi X, Nan J. Characteristics of clastic reservoir of the Upper Paleozoic Taiyuan and Xiashihezi formations in northeastern Ordos Basin. Journal of Palaeogeography. 2010;12(5):609–17. [Google Scholar]
9.Zhang Y, Tian J, Zhang X. The sand body distribution law controlled by tectonic-sedimentary pattern: a case study of Permian in Hangjinqi area. Fault-Block Oil & Gas Field. 2021;28(2):187–93, 229. [Google Scholar]
10.Liu R, Xiao H, Fan L. A depositional mode of flood-induced braided river delta in Permian of Ordos basin. Acta Petrolei Sinica. 2013;34(supplement 1):120–7. [Google Scholar]
11.Zhang G, Jia C, Chen S. Study on sedimentary facies of the southern region of hangjinqi. Petrochemical Industry Technology. 2017;24(2):128–9. [Google Scholar]
12.Deng D. Reservoir Characteristics and Comprehensive Evaluation of He1 Member of J72 Well Area in Hangjinqi, Northern Ordos Basin. Northwest University. 2019. [Google Scholar]
13.Cao T. Discussion on the formation process of the lower Shihezi formation reservoir in the Hangjinqi area, northern Ordos basin. Complex Hydrocarbon Reservoirs. 2023;16(1):19–25. [Google Scholar]
14.Hao L, Wang Q, Tang J. Research progress of reservoir microscopic pore structure. Lithologic Reservoirs. 2013;25(5):123–8. [Google Scholar]
15.Zhu H. Pore structure characterization of low permeability sandstone reservoir and application. Chengdu: Southwest Petroleum University. 2014. [Google Scholar]
16.Wang M, Mu L, Zhao G. Architecture analysis of reservoirs in branching-and wandering-based braided rivers: taking FN field, Sudan as an example. Earth Science Frontiers. 2017;24(2):246–56. doi: 10.1155/2022/4822714 [DOI] [Google Scholar]
17.Eaton B, Millar R, Davidson S. Channel pattern: braided, anabranching, and single-thread. Geomorphology. 2010;120(3/4):353–64. [Google Scholar]
18.Zhu X, Dong Y, Zeng H. Research status and thoughts on the development of seismic sedimentology in China. Journal of Palaeogeography (Chinese Edition). 2020;22(3):397–411. [Google Scholar]
19.Chen C, Qi Y, Yu Z. Seismic identification of superposition relationship of the shallow water delta channel sandbodies: Case study of Linxing S area in eastern Ordos Basin. Natural Gas Geoscience. 2021;32(5):772–9. [Google Scholar]
20.Wei H. Characterization of the underwater distributary channel sandbodies by integrating the well log and seismology. Petroleum Geology and Oilfield Development in Daqing. 2018;37(6):132–9. doi: 10.3390/en17010115 [DOI] [Google Scholar]
21.Ling Y, Xi X, Sun D. Analysis on affecting factors of post-stack intersion and seismic attribute interpretation of thin reservoir. Geophysical Prospecting for Petroleum. 2008;47(6):531–58. doi: 10.1007/s12594-017-0661-4 [DOI] [Google Scholar]
22.Li H, Ma L, Shi Y. Distribution and evaluation of underwater distributary channel sandstone reservoir based on wellseismic combination: A case study of Jp35 sand group in Shifa gas reservoir. Lithologic Reservoirs. 2020;32(2):78–89. [Google Scholar]
23.Mukherjee B, Sain K. Vertical lithological proxy using statistical and artificial intelligence approach: a case study from Krishna‑Godavari Basin, offshore India. Marine Geophysical Research. 2021;42(3):3–23. doi: 10.1007/s11001-024-09546-3 [DOI] [Google Scholar]
24.Dou W, Liu L, Wu K, Xu Z. Pore structure characteristics and its effect on permeability by mercury injection measurement: An example from Triassic Chang-7 reservoir, Southwest Ordos Basin. Geological Review. 2016;62(2):502–11. doi: 10.1007/s12583-020-1057-8 [DOI] [Google Scholar]
25.He W, Yang L, Ma C, Guo W. Effect of MicroPore Structure Parameter on Seepage Characteristics in Ultra-Low Permeability Reservoir: A Case from Chang6 Reservoir of Ordos Basin. Natural Gas Geoscience. 2011;22(3):477–81. doi: 10.1007/s11053-020-09709-0 [DOI] [Google Scholar]
26.Nabawy B, Géraud Y, Rochette P, Nicolas B. Pore-throat characterization in highly porous and permeable sandstones. AAPG Bulletin. 2009;93(6):719–39. doi: 10.1306/03160908131 [DOI] [Google Scholar]
27.Zhang C, Sun W, Yang J, Gao H. Pore and pore-throat size distributions of low permeability sandstone reservoir and their differential origin. Acta Geologica Sinica. 2012;86(2):335–48. doi: 10.1111/1755-6724.14288 [DOI] [Google Scholar]
28.Hoy R, Ridgway K. Sedimentology and sequence stratigraphy of fan-delta and river-delta depo-systems, Pennsylvanian Minturn Formation, Colorado. AAPG Bulletin. 2003;87(7):1169–91. doi: 10.1007/s12517-019-4928-5 [DOI] [Google Scholar]
29.Li Y, Zhao Y, Yang R. Detailed sedimentary facies of a sandstone reservoir in the eastern zone of the Sulige gas field, Ordos Basin. Mining Science and Technology (China). 2010;20(11):891–7, 903. doi: 10.1016/S1674-5264(09)60302-1 [DOI] [Google Scholar]
30.Ma J, Huang Z, Wu H. Characteristics of reservoir microscopic pores and throats and their influence on reservoir physical properties in Huangliu Formation of DF Area, Yinggehai Basin. Acta Sedimentologica Sinica. 2015;33(5):983–90. [Google Scholar]
31.Luo J, Wei X, Yao J. Provenance and depositional facies controlling on the Upper Paleozoic excellent natural gas-reservoir in northern Ordos basin, China. Geological Bulletin of China. 2010;29(6):811–20. [Google Scholar]
32.Yang Y, Liu L, Xv Z. Diagenesis and diagenetic facies of the Lower Cretaceous Yingcheng Formation sandstones in the Dehui fault depression in the southern Songliao basin, China. Journal of Northeast Petroleum University. 2017;41(3):52–62, 72. doi: 10.1111/jpg.12600 [DOI] [Google Scholar]
33.Li H, Hu X, Shi Y. Sequence division and controlling factors of reservoir development of the 4th Member of Leikoupo Formation in foreland of Longmen Mountains in the Western Sichuan Depression, Sichuan Basin. Oil & Gas Geology. 2017;38(4):753–63. 36759629 [Google Scholar]
34.Zhou X, He S, Liu P. Characteristics and classification of tight oil pore structure in reservoir Chang 6 of Daijiaping area, Ordos Basin. Earth Science Frontiers. 2016;23(3):253–65. doi: 10.1016/S2096-2495(17)30028-5 [DOI] [Google Scholar]

PLoS One. doi: 10.1371/journal.pone.0329942.r001

Decision Letter 0

Vittorio Scisciani

2 Dec 2024

PONE-D-24-37259Sedimentary and reservoir characterization of wandering braided river: a case of the Xiashihezi Formation 1 Member in Shilijiakhan west zone, Hangjinqi, Northern Ordos BasinPLOS ONE

Dear Dr. Li,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit but does not fully meet PLOS ONE’s publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

We have now received two reports on the manuscript "Sedimentary and reservoir characterization of wandering braided river: a case of the Xiashihezi Formation 1 Member in Shilijiakhan west zone, Hangjinqi, Northern Ordos Basin" by Hongtao Li et alii, which was submitted to Plos One. Based on these reports, minor revision is required before the manuscript can be reconsidered for publication. Depending on the revision, the manuscript may need to be re-reviewed. Both referees suggest ways in which the paper and figures need to be revised, and one of them suggests that the English needs a careful checking. I agree with this and warm the authors that if they resubmit a revised version with poor quality English, the article will be automatically rejected. Please make sure also that you deal with the scientific criticisms and try to make the article a little bit more accessible to the general reader and to a broader audience (add new international references and expand the discussion by comparing the case study with others elsewhere).

Please submit your revised manuscript by Jan 16 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

If you would like to make changes to your financial disclosure, please include your updated statement in your cover letter. Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: https://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols . Additionally, PLOS ONE offers an option for publishing peer-reviewed Lab Protocol articles, which describe protocols hosted on protocols.io. Read more information on sharing protocols at https://plos.org/protocols?utm_medium=editorial-email&utm_source=authorletters&utm_campaign=protocols .

We look forward to receiving your revised manuscript.

Kind regards,

Vittorio Scisciani

Academic Editor

PLOS ONE

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1. Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at https://journals.plos.org/plosone/s/file?id=wjVg/PLOSOne_formatting_sample_main_body.pdf and https://journals.plos.org/plosone/s/file?id=ba62/PLOSOne_formatting_sample_title_authors_affiliations.pdf

2. In your Methods section, please provide additional information regarding the permits you obtained for the work. Please ensure you have included the full name of the authority that approved the field site access and, if no permits were required, a brief statement explaining why.

3. Thank you for stating the following financial disclosure: “Fund projects: "Research on the Development Potential of Dense and High Water-bearing Gas Reservoirs in Dongsheng Gas Field" (P23133) by the Ministry of Science and Technology of Sinopec and National Major Special Project "Development of Large Oil and Gas Fields and Coalbed Methane" (No. 2016ZX05002-006)”

Please state what role the funders took in the study. If the funders had no role, please state: "The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript." If this statement is not correct you must amend it as needed. Please include this amended Role of Funder statement in your cover letter; we will change the online submission form on your behalf.

4. We note that your Data Availability Statement is currently as follows: “All relevant data are within the manuscript and in Supporting Information files.”

Please confirm at this time whether or not your submission contains all raw data required to replicate the results of your study. Authors must share the “minimal data set” for their submission. PLOS defines the minimal data set to consist of the data required to replicate all study findings reported in the article, as well as related metadata and methods (https://journals.plos.org/plosone/s/data-availability#loc-minimal-data-set-definition). For example, authors should submit the following data: - The values behind the means, standard deviations and other measures reported; - The values used to build graphs; - The points extracted from images for analysis. Authors do not need to submit their entire data set if only a portion of the data was used in the reported study. If your submission does not contain these data, please either upload them as Supporting Information files or deposit them to a stable, public repository and provide us with the relevant URLs, DOIs, or accession numbers. For a list of recommended repositories, please see https://journals.plos.org/plosone/s/recommended-repositories. If there are ethical or legal restrictions on sharing a de-identified data set, please explain them in detail (e.g., data contain potentially sensitive information, data are owned by a third-party organization, etc.) and who has imposed them (e.g., an ethics committee). Please also provide contact information for a data access committee, ethics committee, or other institutional body to which data requests may be sent. If data are owned by a third party, please indicate how others may request data access.

5. We note that Figure 1 in your submission contain map/satellite images which may be copyrighted. All PLOS content is published under the Creative Commons Attribution License (CC BY 4.0), which means that the manuscript, images, and Supporting Information files will be freely available online, and any third party is permitted to access, download, copy, distribute, and use these materials in any way, even commercially, with proper attribution. For these reasons, we cannot publish previously copyrighted maps or satellite images created using proprietary data, such as Google software (Google Maps, Street View, and Earth). For more information, see our copyright guidelines: http://journals.plos.org/plosone/s/licenses-and-copyright. We require you to either (a) present written permission from the copyright holder to publish these figures specifically under the CC BY 4.0 license, or (b) remove the figures from your submission:

a. You may seek permission from the original copyright holder of Figure 1 to publish the content specifically under the CC BY 4.0 license. We recommend that you contact the original copyright holder with the Content Permission Form (http://journals.plos.org/plosone/s/file?id=7c09/content-permission-form.pdf) and the following text: “I request permission for the open-access journal PLOS ONE to publish XXX under the Creative Commons Attribution License (CCAL) CC BY 4.0 (http://creativecommons.org/licenses/by/4.0/). Please be aware that this license allows unrestricted use and distribution, even commercially, by third parties. Please reply and provide explicit written permission to publish XXX under a CC BY license and complete the attached form.” Please upload the completed Content Permission Form or other proof of granted permissions as an "Other" file with your submission. In the figure caption of the copyrighted figure, please include the following text: “Reprinted from [ref] under a CC BY license, with permission from [name of publisher], original copyright [original copyright year].”

b. If you are unable to obtain permission from the original copyright holder to publish these figures under the CC BY 4.0 license or if the copyright holder’s requirements are incompatible with the CC BY 4.0 license, please either i) remove the figure or ii) supply a replacement figure that complies with the CC BY 4.0 license. Please check copyright information on all replacement figures and update the figure caption with source information. If applicable, please specify in the figure caption text when a figure is similar but not identical to the original image and is therefore for illustrative purposes only. The following resources for replacing copyrighted map figures may be helpful: USGS National Map Viewer (public domain): http://viewer.nationalmap.gov/viewer/ The Gateway to Astronaut Photography of Earth (public domain): http://eol.jsc.nasa.gov/sseop/clickmap/ Maps at the CIA (public domain): https://www.cia.gov/library/publications/the-world-factbook/index.html and https://www.cia.gov/library/publications/cia-maps-publications/index.html NASA Earth Observatory (public domain): http://earthobservatory.nasa.gov/ Landsat: http://landsat.visibleearth.nasa.gov/ USGS EROS (Earth Resources Observatory and Science (EROS) Center) (public domain): http://eros.usgs.gov/# Natural Earth (public domain): http://www.naturalearthdata.com/

6. Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Comments:

Specific comments by reviewers are listed below:

Reviewer 1

1. The grammar/English writing of the manuscript can be further improved.

2. The geographic location and other information description of the area should be added in the "geological background" section.

3. In Section 2.2, "The plane distribution of sedimentary microfacies in the Xiashihezi Formation 1 Member was finally obtained by mutual calibration and constraint between the attribute of maximum trough amplitude and the single well sedimentary microfacies, the connected well sedimentary microfacies [21]." And " These conditions were also conducive to the occurrence of dissolution during the diagenetic stage, ultimately forming high-quality reservoirs with favourable physical properties”, Additional basis is needed, such as more references.

4. The legend text in Figure 1 of the paper needs to be adjusted, some fonts need to be enlarged, and some layouts are not standardized enough.

5.The amplitude attribute in figure 6.a of the paper lacks color legend.

6. Only layer and sublayer information appears in Figure 3. It is recommended to complete the complete System, Formation and other information.

7. The corresponding well number can be marked in the sedimentary microfacies type, logging mode and seismic response characteristics in Figure 4.

8.The reference format is not standardized and consistent. Please revise carefully according to the requirements of the journal.

Reviewer 2

1. In the part of “Regional geological background”, the last part of “Taiyuan Formation and Shanxi formation were the main source rock series, While Shanxi Formation and Xiashihezi formation were important reservoir rock series, and Shangshihezi formation and Shiqianfeng Formation were regional caprocks, which together formed the upper Paleozoic oil system of lower generation, upper reservoir and top sealing [17]” can be deleted because it has no great connection with the sedimentation and reservoir discussed in the article.

2. The article discusses that "based on the above analysis of lithofacies characteristics, it is considered that the HE1 Member in this area is a relatively typical wandering shallow braided river deposit without fixed river channel under partial drought conditions", and it is necessary to add necessary evidence and references to support the viewpoint of the article.

3. Fig. 2 is mainly based on core observation photos. It is not clear how to extend and change laterally with the view of a hole. It is suggested to add field outcrop photos and elaborate on the vertical and horizontal overlap characteristics of sedimentary microfacies in detail based on these photos.

4. Some of the references are relatively old, so a small number of older documents can be appropriately deleted, and references of nearly three years can be added to make the article more convincing.

[Note: HTML markup is below. Please do not edit.]

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: This paper presents a study of the sedimentary microfacies of the Xiashihezi Formation 1 Member in the Shiligahan area, situated in the northern Ordos Basin. By using core, logging, and 3D seismic data, the sedimentary environment and sedimentary microfacies were successfully identified. The study area was thus determined to be a wandering, shallow braided river sedimentary system. Through calibration and verification among lithofacies, logging facies, and seismic facies, a comprehensive characterization of the plane distribution of braided channels and their internal microfacies in the Xiashihezi Formation 1 Member was achieved. Further analysis of core observation, thin sections, physical properties, and mercury injection curves, particularly through the study and evaluation of pore structure, identified the microscopic characteristics of the reservoir. By integrating macro- and micro-level perspectives, this study elucidates the influence of sedimentation on reservoir development. The article's theme is evident, its structure is logical, and its findings are both novel and practically applicable. After minor revisions, it can be published.

Reviewer #2: This manuscript analyzes the sedimentary characteristics of shallow braided river in He 1 Member of northern Ordos Basin by using the integrated research of geology, logging and seismic, and summarizes the response modes of logging facies and seismic facies of different sedimentary microfacies. Through the research idea of single well sedimentary microfacies analysis, sedimentary connected wells microfacies correlation and plane sedimentary microfacies , combining the sedimentary microfacies from wells and seismic facies response modes, the sedimentary microfacies boundary is accurately delineated, which provides the basis for the macro distribution analysis of reservoir. The microscopic characteristics of reservoir lithology, physical property, reservoir space type and pore structure characteristics are analyzed in detail. Through the combination of macro and micro, the controlling factors of sedimentation on reservoir development are analyzed. The paper has rigorous structure, strong logic and sufficient evidence, and has certain innovation and application value, which provides technical support for further fine description and selection evaluation of gas reservoirs.

I suggest that this article can be published, but there are also some problems that need to be further modified and improved:

4. Some of the references are relatively old, so a small number of older documents can be appropriately deleted, and references of nearly three years can be added to make the article more convincing.

**********

6. PLOS authors have the option to publish the peer review history of their article (what does this mean? ). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy .

Reviewer #1: Yes: Wang Jian

Reviewer #2: No

**********

[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/ . PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org . Please note that Supporting Information files do not need this step.

Attachment

Submitted filename: comments.docx

pone.0329942.s005.docx^{(12.9KB, docx)}

PLoS One. 2025 Sep 8;20(9):e0329942. doi: 10.1371/journal.pone.0329942.r002

Author response to Decision Letter 1

20 Jan 2025

�2�Reply to reviewer 1

1. The grammar/English writing of the manuscript can be further improved.

Reply: The reviewer's comments are very good, and the author has made some modifications to the article to avoid grammar and language errors as much as possible. However, considering the author's relatively limited English proficiency, please the expert reviewers forgive us.

2. The geographic location and other information description of the area should be added in the "geological background" section.

Reply: According to the suggestions of the review experts, the geographical location and other information description of the area have been added in the "Geological Background" section.

Reply: According to the suggestions of the reviewing experts, references have been added in both sections to support the viewpoint of the article.

4. The legend text in Figure 1 of the paper needs to be adjusted, some fonts need to be enlarged, and some layouts are not standardized enough.

Reply: According to the suggestions of the review experts, the legend text in Figure 1 has been adjusted, and some fonts have been enlarged. Please refer to the revised draft for details.

5.The amplitude attribute in figure 6.a of the paper lacks color legend.

Reply: According to the suggestions of the review experts, a color legend for the amplitude attribute in Figure 6.a has been added.

6. Only layer and sublayer information appears in Figure 3. It is recommended to complete the complete System, Formation and other information.

Reply: According to the suggestions of the review experts, information such as Formation and Member has been added to Figure 3.

7. The corresponding well number can be marked in the sedimentary microfacies type, logging mode and seismic response characteristics in Figure 4.

Reply: According to the suggestions of the review experts, corresponding well numbers have been added to Figure 4.

8.The reference format is not standardized and consistent. Please revise carefully according to the requirements of the journal.

Reply: According to the suggestions of the reviewing experts, the reference format has been carefully revised according to the requirements of the journal.

(3) Response to reviewer 2:

Reply: According to expert advice, "Taiyuan Formation and Shanxi Formation were the main source rock series, while Shanxi Formation and Xiashihezi Formation were important reservoir rock series, and Shangshihezi Formation and Shiqianfeng Formation were regional capstones, which together formed the upper Paleozoic oil system of lower generation, upper reservoir and top sealing [17]" has been deleted.

Reply: According to expert advice, two additional references have been added to support the viewpoints and understanding of this paper.

Reply: According to expert advice, field outcrop photos have been added to further elucidate the vertical and horizontal stacking characteristics of sedimentary microfacies.

4. Some of the references are relatively old, so a small number of older documents can be appropriately deleted, and references of nearly three years can be added to make the article more convincing.

Reply: According to expert advice, 4 relatively old references have been deleted and 4 relatively new references have been added.

Finally, thank you again for the suggestions from the experts in your editorial department. The author has made every effort to revise and improve the original manuscript. If there are any shortcomings, we kindly ask the reviewers to criticize, correct and forgive us!

Attachment

Submitted filename: reply to plos one.docx

pone.0329942.s007.docx^{(251.4KB, docx)}

PLoS One. doi: 10.1371/journal.pone.0329942.r003

Decision Letter 1

Bappa Mukherjee

5 Mar 2025

PONE-D-24-37259R1Sedimentary and reservoir characterization of wandering braided river: a case of the Xiashihezi Formation 1 Member in Shilijiakhan west zone, Hangjinqi, Northern Ordos BasinPLOS ONE

Dear Dr. Li,

Please submit your revised manuscript by Apr 19 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org . When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

A rebuttal letter that responds to each point raised by the academic editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

We look forward to receiving your revised manuscript.

Kind regards,

Bappa Mukherjee

Academic Editor

PLOS ONE

Journal Requirements:

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article’s retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Comments:

Editorial comments to improve the quality and presentation:

1. Please incorporate the range of the petrophysical parameters in the abstract.

2. The sentences presented in the abstract is too long, break them and make a simple representation.

3. Please add suitable keywords.

4. In Fig. 6a please mention the name of the parameter presented with a color scale.

5. Please check the axis title of Fig. 10a.

6. If possible, kindly add a dendrogram analysis based on the hierarchical cluster analysis. You may follow the article "Mukherjee, B., Sain, K. Vertical lithological proxy using statistical and artificial intelligence approach: a case study from Krishna-Godavari Basin, offshore India. Mar Geophys Res 42, 3 (2021). https://doi.org/10.1007/s11001-020-09424-8." Otherwise in the discussion section you can add a few lines and make a recommendation for future researchers to consider this analysis.

[Note: HTML markup is below. Please do not edit.]

PLoS One. 2025 Sep 8;20(9):e0329942. doi: 10.1371/journal.pone.0329942.r004

Author response to Decision Letter 2

21 Jul 2025

Journal Requirements:

Reply: the references are complete and correct, and an additional reference has been added.

Additional Editor Comments:

Editorial comments to improve the quality and presentation:

1. Please incorporate the range of the petrophysical parameters in the abstract.

Reply�According to the requirements, add petrophysical parameters such as reservoir porosity and average permeability in the abstract.

2. The sentences presented in the abstract is too long, break them and make a simple representation.

Reply�Following the suggestion, the long sentence has been revised to be as short as possible.

3. Please add suitable keywords.

Reply�Added 6 keywords.

4. In Fig. 6a please mention the name of the parameter presented with a color.

Reply�In Figure 6.a, the names of geophysical attributes have been added to the color scale.

5. Please check the axis title of Fig. 10a.

Reply�Modified the vertical axis title in Figure 10a

Reply�In the discussion section, we add a few lines and make a recommendation for future researchers to consider hierarchical clustering analysis (HCA) analysis. an additional reference of Mukherjee has been added.

Attachment

Submitted filename: reply to Journal Requirements .docx

pone.0329942.s008.docx^{(17.7KB, docx)}

PLoS One. doi: 10.1371/journal.pone.0329942.r005

Decision Letter 2

Bappa Mukherjee

24 Jul 2025

Sedimentary and reservoir characterization of wandering braided river: a case of the Xiashihezi Formation 1 Member in Shilijiakhan west zone, Hangjinqi, Northern Ordos Basin

PONE-D-24-37259R2

Dear Dr. Li,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

An invoice will be generated when your article is formally accepted. Please note, if your institution has a publishing partnership with PLOS and your article meets the relevant criteria, all or part of your publication costs will be covered. Please make sure your user information is up-to-date by logging into Editorial Manager at Editorial Manager® and clicking the ‘Update My Information' link at the top of the page. For questions related to billing, please contact billing support .

If your institution or institutions have a press office, please notify them about your upcoming paper to help maximize its impact. If they’ll be preparing press materials, please inform our press team as soon as possible -- no later than 48 hours after receiving the formal acceptance. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

Kind regards,

Bappa Mukherjee

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

PLoS One. doi: 10.1371/journal.pone.0329942.r006

Acceptance letter

Bappa Mukherjee

PONE-D-24-37259R2

PLOS ONE

Dear Dr. Li,

I'm pleased to inform you that your manuscript has been deemed suitable for publication in PLOS ONE. Congratulations! Your manuscript is now being handed over to our production team.

At this stage, our production department will prepare your paper for publication. This includes ensuring the following:

* All references, tables, and figures are properly cited

* All relevant supporting information is included in the manuscript submission,

* There are no issues that prevent the paper from being properly typeset

You will receive further instructions from the production team, including instructions on how to review your proof when it is ready. Please keep in mind that we are working through a large volume of accepted articles, so please give us a few days to review your paper and let you know the next and final steps.

Lastly, if your institution or institutions have a press office, please let them know about your upcoming paper now to help maximize its impact. If they'll be preparing press materials, please inform our press team within the next 48 hours. Your manuscript will remain under strict press embargo until 2 pm Eastern Time on the date of publication. For more information, please contact onepress@plos.org.

You will receive an invoice from PLOS for your publication fee after your manuscript has reached the completed accept phase. If you receive an email requesting payment before acceptance or for any other service, this may be a phishing scheme. Learn how to identify phishing emails and protect your accounts at https://explore.plos.org/phishing.

If we can help with anything else, please email us at customercare@plos.org.

Thank you for submitting your work to PLOS ONE and supporting open access.

Kind regards,

PLOS ONE Editorial Office Staff

on behalf of

Dr. Bappa Mukherjee

Academic Editor

PLOS ONE

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

(XLSX)

pone.0329942.s001.xlsx^{(55.1KB, xlsx)}

S2 Fig 9. Distribution characteristics analysis data of porosity and peamibility of samples from Xiashihezi Formation 1 Member in Shilijiahan west zone.

(XLSX)

pone.0329942.s002.xlsx^{(48.1KB, xlsx)}

S3 Fig 10. Capillary pressure curve and throat radius distribution analysis data of sandstone from the Xiashihezi Formation 1 Member in the shilijiahan west zone.

(XLSX)

pone.0329942.s003.xlsx^{(30.4KB, xlsx)}

S4 Fig 11. Different levels pore throats and pore combination analysis data from Xiashihezi Formation 1 Member in Shilijiahan west zone.

(XLSX)

pone.0329942.s004.xlsx^{(27KB, xlsx)}

Attachment

Submitted filename: comments.docx

pone.0329942.s005.docx^{(12.9KB, docx)}

Attachment

Submitted filename: reply to plos one.docx

pone.0329942.s007.docx^{(251.4KB, docx)}

Attachment

Submitted filename: reply to Journal Requirements .docx

pone.0329942.s008.docx^{(17.7KB, docx)}

Data Availability Statement

All relevant data are within the manuscript and its Supporting Information files.

[pone.0329942.ref001] 1.Zhao J, Fu J, Yao J. Reservoir formation model for large gas fields of quasi-continuous compact sandstone in Ordos Basin. Acta Petrolei Sinica. 2012;33(Suppl 1):37–52. doi: 10.1111/1755-6724.12305_2 [DOI] [Google Scholar]

[pone.0329942.ref002] 2.Zhu Z, Li W, Li K. The characteristic of sequence stratigraphy and sedimentary systems of Taiyuan-Xiashihezi formation in Hangjinqi area. Journal of Northwest University (Natural Science Edition). 2010;40(6):1050–4. [Google Scholar]

[pone.0329942.ref003] 3.Cao T. Depositional characteristics of Shihezi 1 member, Jin 72 well block of Hangjinqi area, Ordos basin. Natural Gas Technology and Economy. 2019;13(4):8–16. [Google Scholar]

[pone.0329942.ref004] 4.Yang H, Liu X, Yan X. The relationship between tectonic sedimentary evolution and tight sandstone gas reservoir since the Paleozoic in Ordos basin. Earth Science Frontiers. 2015;22(3):175–83. [Google Scholar]

[pone.0329942.ref005] 5.Li HT, Chen D, Zhang ZY. Sub-layer division and correlation based on well-seismic combination and step-by-step interface constraint: A case study of the Taiyuan-Lower Shihezi Formation in the Shilijiahan of the Hangjinqi area. Sedimentary Geology and Tethyan Geology. 2024;44(2):1–15. [Google Scholar]

[pone.0329942.ref006] 6.Zhang W, Cao Q, Lu Y. Sealing model of tight gas reservoirs in the edge of Claraton Basin: A case study from the First Member of Lower Shihezi Formation in Hangjinqi area of the northern margin of the Ordos Basin. Bulletin of Geological Science and Technology. 2022;41(3):122–31. [Google Scholar]

[pone.0329942.ref007] 7.Qi R, Li L, Qin X. Sand body configuration and gas-bearing properties of near source sand-gravel braided river on the northern margin of Ordos Basin. Petroleum Geology & Experiment. 2019;41(5):682–90. [Google Scholar]

[pone.0329942.ref008] 8.Fu S, Shi X, Nan J. Characteristics of clastic reservoir of the Upper Paleozoic Taiyuan and Xiashihezi formations in northeastern Ordos Basin. Journal of Palaeogeography. 2010;12(5):609–17. [Google Scholar]

[pone.0329942.ref009] 9.Zhang Y, Tian J, Zhang X. The sand body distribution law controlled by tectonic-sedimentary pattern: a case study of Permian in Hangjinqi area. Fault-Block Oil & Gas Field. 2021;28(2):187–93, 229. [Google Scholar]

[pone.0329942.ref010] 10.Liu R, Xiao H, Fan L. A depositional mode of flood-induced braided river delta in Permian of Ordos basin. Acta Petrolei Sinica. 2013;34(supplement 1):120–7. [Google Scholar]

[pone.0329942.ref011] 11.Zhang G, Jia C, Chen S. Study on sedimentary facies of the southern region of hangjinqi. Petrochemical Industry Technology. 2017;24(2):128–9. [Google Scholar]

[pone.0329942.ref012] 12.Deng D. Reservoir Characteristics and Comprehensive Evaluation of He1 Member of J72 Well Area in Hangjinqi, Northern Ordos Basin. Northwest University. 2019. [Google Scholar]

[pone.0329942.ref013] 13.Cao T. Discussion on the formation process of the lower Shihezi formation reservoir in the Hangjinqi area, northern Ordos basin. Complex Hydrocarbon Reservoirs. 2023;16(1):19–25. [Google Scholar]

[pone.0329942.ref014] 14.Hao L, Wang Q, Tang J. Research progress of reservoir microscopic pore structure. Lithologic Reservoirs. 2013;25(5):123–8. [Google Scholar]

[pone.0329942.ref015] 15.Zhu H. Pore structure characterization of low permeability sandstone reservoir and application. Chengdu: Southwest Petroleum University. 2014. [Google Scholar]

[pone.0329942.ref016] 16.Wang M, Mu L, Zhao G. Architecture analysis of reservoirs in branching-and wandering-based braided rivers: taking FN field, Sudan as an example. Earth Science Frontiers. 2017;24(2):246–56. doi: 10.1155/2022/4822714 [DOI] [Google Scholar]

[pone.0329942.ref017] 17.Eaton B, Millar R, Davidson S. Channel pattern: braided, anabranching, and single-thread. Geomorphology. 2010;120(3/4):353–64. [Google Scholar]

[pone.0329942.ref018] 18.Zhu X, Dong Y, Zeng H. Research status and thoughts on the development of seismic sedimentology in China. Journal of Palaeogeography (Chinese Edition). 2020;22(3):397–411. [Google Scholar]

[pone.0329942.ref019] 19.Chen C, Qi Y, Yu Z. Seismic identification of superposition relationship of the shallow water delta channel sandbodies: Case study of Linxing S area in eastern Ordos Basin. Natural Gas Geoscience. 2021;32(5):772–9. [Google Scholar]

[pone.0329942.ref020] 20.Wei H. Characterization of the underwater distributary channel sandbodies by integrating the well log and seismology. Petroleum Geology and Oilfield Development in Daqing. 2018;37(6):132–9. doi: 10.3390/en17010115 [DOI] [Google Scholar]

[pone.0329942.ref021] 21.Ling Y, Xi X, Sun D. Analysis on affecting factors of post-stack intersion and seismic attribute interpretation of thin reservoir. Geophysical Prospecting for Petroleum. 2008;47(6):531–58. doi: 10.1007/s12594-017-0661-4 [DOI] [Google Scholar]

[pone.0329942.ref022] 22.Li H, Ma L, Shi Y. Distribution and evaluation of underwater distributary channel sandstone reservoir based on wellseismic combination: A case study of Jp35 sand group in Shifa gas reservoir. Lithologic Reservoirs. 2020;32(2):78–89. [Google Scholar]

[pone.0329942.ref023] 23.Mukherjee B, Sain K. Vertical lithological proxy using statistical and artificial intelligence approach: a case study from Krishna‑Godavari Basin, offshore India. Marine Geophysical Research. 2021;42(3):3–23. doi: 10.1007/s11001-024-09546-3 [DOI] [Google Scholar]

[pone.0329942.ref024] 24.Dou W, Liu L, Wu K, Xu Z. Pore structure characteristics and its effect on permeability by mercury injection measurement: An example from Triassic Chang-7 reservoir, Southwest Ordos Basin. Geological Review. 2016;62(2):502–11. doi: 10.1007/s12583-020-1057-8 [DOI] [Google Scholar]

[pone.0329942.ref025] 25.He W, Yang L, Ma C, Guo W. Effect of MicroPore Structure Parameter on Seepage Characteristics in Ultra-Low Permeability Reservoir: A Case from Chang6 Reservoir of Ordos Basin. Natural Gas Geoscience. 2011;22(3):477–81. doi: 10.1007/s11053-020-09709-0 [DOI] [Google Scholar]

[pone.0329942.ref026] 26.Nabawy B, Géraud Y, Rochette P, Nicolas B. Pore-throat characterization in highly porous and permeable sandstones. AAPG Bulletin. 2009;93(6):719–39. doi: 10.1306/03160908131 [DOI] [Google Scholar]

[pone.0329942.ref027] 27.Zhang C, Sun W, Yang J, Gao H. Pore and pore-throat size distributions of low permeability sandstone reservoir and their differential origin. Acta Geologica Sinica. 2012;86(2):335–48. doi: 10.1111/1755-6724.14288 [DOI] [Google Scholar]

[pone.0329942.ref028] 28.Hoy R, Ridgway K. Sedimentology and sequence stratigraphy of fan-delta and river-delta depo-systems, Pennsylvanian Minturn Formation, Colorado. AAPG Bulletin. 2003;87(7):1169–91. doi: 10.1007/s12517-019-4928-5 [DOI] [Google Scholar]

[pone.0329942.ref029] 29.Li Y, Zhao Y, Yang R. Detailed sedimentary facies of a sandstone reservoir in the eastern zone of the Sulige gas field, Ordos Basin. Mining Science and Technology (China). 2010;20(11):891–7, 903. doi: 10.1016/S1674-5264(09)60302-1 [DOI] [Google Scholar]

[pone.0329942.ref030] 30.Ma J, Huang Z, Wu H. Characteristics of reservoir microscopic pores and throats and their influence on reservoir physical properties in Huangliu Formation of DF Area, Yinggehai Basin. Acta Sedimentologica Sinica. 2015;33(5):983–90. [Google Scholar]

[pone.0329942.ref031] 31.Luo J, Wei X, Yao J. Provenance and depositional facies controlling on the Upper Paleozoic excellent natural gas-reservoir in northern Ordos basin, China. Geological Bulletin of China. 2010;29(6):811–20. [Google Scholar]

[pone.0329942.ref032] 32.Yang Y, Liu L, Xv Z. Diagenesis and diagenetic facies of the Lower Cretaceous Yingcheng Formation sandstones in the Dehui fault depression in the southern Songliao basin, China. Journal of Northeast Petroleum University. 2017;41(3):52–62, 72. doi: 10.1111/jpg.12600 [DOI] [Google Scholar]

[pone.0329942.ref033] 33.Li H, Hu X, Shi Y. Sequence division and controlling factors of reservoir development of the 4th Member of Leikoupo Formation in foreland of Longmen Mountains in the Western Sichuan Depression, Sichuan Basin. Oil & Gas Geology. 2017;38(4):753–63. 36759629 [Google Scholar]

[pone.0329942.ref034] 34.Zhou X, He S, Liu P. Characteristics and classification of tight oil pore structure in reservoir Chang 6 of Daijiaping area, Ordos Basin. Earth Science Frontiers. 2016;23(3):253–65. doi: 10.1016/S2096-2495(17)30028-5 [DOI] [Google Scholar]

PERMALINK

Sedimentary and reservoir characterization of wandering braided river: a case of the Xiashihezi Formation 1 member in Shilijiakhan west zone, Hangjinqi, Northern Ordos Basin

Hongtao Li

Tao Liu

Qingbin Liu

Roles

Abstract

Introduction

Regional geological background

Fig 1. Map showing tectonic unit division in Ordos Basin and loction of Shilijiahan west zone, Hangjinqi area.

Comprehensive analysis of sedimentary facies and its distribution characteristics

Sedimentary facies analysis and logging response characteristics.

Fig 2. Typical sedimentary structures of braided river from Xiashihezi Formation in Shilijiahan west zone.

Fig 3. Lithofacies and sedimentary microfacies division of the Jin93 well from Xiashihezi Formation 1Member.

Description of sedimentary microfacies distribution based on well seismic combination.

Fig 4. Logging facies and seismic facies characteristics of the Xiashihezi Formation 1 Member.

Fig 5. Seismic profile and sedimentary microfacies of the Xiashihezi Formation 1 Member in the Shilijiahan west zone.

Fig 6. Seismic attributes and sedimentary facies of the Xiashihezi Formation 1 Member from the Shilijiahan west zone in Hangjinqi area, Ordos basin.

Reservoir microstructure and pore structure characteristics

Reservoir microscopic characteristics description.

Fig 7. Photos showing pore type from He1 Member gas pool in Jin72 well block, Shilijiahan aera.

Fig 8. Distribution characteristics and correlation relationship of porosity and peamibility of different lithology samples from Xiashihezi Formation 1 Member in Shilijiahan west zone.

Fig 9. Distribution characteristics of porosity and peamibility of samples from Xiashihezi Formation 1 Member in Shilijiahan west zone.

Analysis of reservoir pore structure characteristics.

Table 1. Statistical table of reservoir pore throat characteristic parameters in Shilijiahan west zone.

Fig 10. characteristics of capillary pressure curve and throat radius distribution of sandstone from the Xiashihezi Formation 1 Member in the shilijiahan west zone.

Fig 11. Percentage of different levels pore throats and pore combination Xiashihezi Formation 1 Member in Shilijiahan west zone.

Effect of sedimentation on reservoir development.

Conclusions

Supporting information

Data Availability

Funding Statement

References

Decision Letter 0

Vittorio Scisciani

Roles

Author response to Decision Letter 1

Decision Letter 1

Bappa Mukherjee

Roles

Author response to Decision Letter 2

Decision Letter 2

Bappa Mukherjee

Roles

Acceptance letter

Bappa Mukherjee

Roles

Associated Data

Supplementary Materials

Data Availability Statement

ACTIONS

PERMALINK

RESOURCES

Similar articles

Cited by other articles

Links to NCBI Databases