Table 2. The locations and characteristics of injection and production wells from the four oil fields in China used in this study.

Oil Field	Location	Oil Reservior	Wells	Waterfloodig Date	Sampling Date	Depth (m)	In situ Temperature
Xinjiang	Junggar basin	No. 6	T6186	1974	10/09/2009	800	25°C
			T6073
Changqing	Ordos Basin	Yan 9	L28-45	1999	03/05/2010	1289	40°C
			L28-46
Dagang	Bohai Sea coast	Kong 2	1098-8	1979	06/08/2004	1400	55°C
			1017-7
Henan	Henan Province	V4	V187	1977	05/09/2010	1355	70°C
			V149