Stress Field Simulation And Fracture Prediction Of The Longmaxi Formation In Fushun-Yongchuan,Sichuan Basin

Sichuan Basin is the key area of shale gas exploration in China,but the stress characteristics are variable and the fracture development is not clear in the shale gas reservoirs because of the complex tectonic activities in the geological history.And those increase the difficulty of shale gas exploration and development.Aiming at this important influencing factor of shale gas exploration and development,the core observation were used to summarize the fracture development characteristics,fracture genetic type and rock mechanics parameter distribution characteristics;finite element simulation were used to simulate the stress field distribution characteristics;structural curvature calculation were used to calculate the curvature distribution and predict the fracture development;and all three were used to provide theoretical support for the design of further drilling,fracturing and trial production in shale gas development and engineering.The core observation and rock mechanics parameter analysis results show that natural fractures including high-angle and paralleled fractures are developed,with their spacing is small and their filling is common;the natural fractures are mainly caused by tectonic movement and hydrocarbon generation,the distribution of rock mechanical parameters is concentrated,and it's partly affected by structural morphology.The simulating and analyzing of the stress field and structural curvature method results show that the high stress areas are distributed along the anticline,and the anticline stress values in the eastern and southwestern area of the block are higher than other areas;the high curvature areas are distributed along the anticline,the curvature of the anticline in the east and southwest area of the block is higher than other areas.According to the comprehensive analysis,the fracture is more developed in the anticline of the block than in the syncline,at the same time it is more developed in the anticline of the eastern and southwestern area of the block than in other anticlines,and the high fracture development has some negative influence to the shale gas preservation.The next-step exploration and development can focus on the low fracture development area.