Table 4.

The models of fracture interpretation.

Model type	Formula	Parameter description
Porosity	${\mathrm{\Phi }}_f=\sqrt[\mathit{mf}]{R_m(\frac{1}{K_r{R}_{\mathit{xo}}}-\frac{1}{R_T})}$	Φf——fracture porosity, % Rm——mud filtrate resistivity, Ω∙m RXO——shallow lateral resistivity, Ω∙m RT——deep lateral resistivity, Ω∙m Kr——the coefficient of fracture distortion, in the range of 1–1.3. Itis 1.3 for horizontal fractures and 1 for vertical fractures mf——fracture bond index, constant ε—— fracture width, μm Rb——matrix rock resistivity, Ω∙m Kf——fracture penetration rate
Fracture angle	logRb − logRT/logRb(> 0.15, high-angle fractures; 0.05 ~ 0.15, low-angle fractures)
High-angle unlocked fracture	ε = 10,000 × Rm × ($\frac{1}{R_T}-\frac{1}{R_b}$)/4
Low-angle unlocked fracture	ε = 1000 × Rm × ($\frac{1}{R_T}-\frac{1}{R_b}$)/1.2
Permeability	Kf = 8.50 × 10–4 × ε2 × Φf

For the value of the fracture cementation index m_f, the m_f of the large-scale fractures is 1.04, and the m_f of the structural fractures is 0.99 (derived from the rock data).