Analysis Of Development Characteristics And Main Controlling Factors In Mud-shale Reservoirs In The Gulong Area

Tectonic fractures in the mud shale reservoir of Qingshankou Formation in the Gulong area, Songliao Basin are well developed. The study of fracture development characteristics is of great significance to the shale oil exploration and development in this area. Based on data of outcrops, cores, thin sections, the development types of mud shale fractures are divided and the development characteristics, formation mechanism and main controlling factors of shale fractures are analyzed. By using the finite element numerical simulation technology and the results of previous studies, core fracture linear density and other parameters as the main basis,combining fractal geometry forecasting method based on fault distribution, the mud shale reservoir fracture distribution is predicted comprehensively. There exists four types of fractures in the study area, including structural fracture, overpressure fracture, diagenetic fracture and slip fracture. Among them, tectonic fractures formed by overpressure are dominated. The trend is NNW-SSE direction, NE-SW direction, NEE-SWW direction. The formation and distribution of tectonic fractures are affected by organic carbon content, rock brittle index, abnormal pressure and fault. The analysis of regional tectonic evolution and fault activities indicate that the area has experienced three stages of tectonic stress field.Combining the inclusion test results with the analysis data of burial-thermal history, it indicates that tectonic fractures are mainly formed in the late Qingshankou-Yaojia formation,Nenyi and Nener section, and late Mingshui formation sedimentation. Based on the comparison of oil and gas accumulation stage and fraction forming time in this area, the tectonic fractures are important oil and gas reservoir space and seepage channels. The comprehensive prediction results of tectonic fractures show that reservoir fractures can be divided into four development units. Level ? and level ? are fracture development zones, and the high yield wells are located in them. When the fracture density is less than 0.8 m/m~2, the yield is relatively low.