153 / 2022-02-27 15:40:45

渝东南川地区古构造应力场模拟与裂缝预测

Longmaxi Formation shale;Numerical simulation;Fracture distribution;Palaeotectonic stress field

Abstract: As the main reservoir space of Longmaxi Formation shale gas in Sichuan and southeast of Chongqing,tectonic fractures is controlled by tectonic stress of its development. Thus , it’s of great significance to study the distribution of paleotectonic stress field for shale gas development , Through the field survey of and peripheral region conjugate shear joints and back, the trend of the syncline axis trace geological data, combined with chronology information,We learned that Nanchuan has been affected by multiphase tectonic stress action since Mesozoic-Cenozoic, its main structure formed in mid of Middle Yanshanian period, with the compressive stress of SE – NW direction, and influenced by the tectonic superimposition in late Middle Yanshanian period, with the compressive stress of EW direction. Based on seismic data, rock triaxial mechanical and rock acoustic emission experimental data, the geological, mechanical and mathematical models are established by ANSYS software to predict the distribution of tectonic stress field. Based on Mohr - Coulomb fracture criterion, the distribution of structural fractures is predicted.In mid of Middle Yanshanian period, stress field direction was 145°-155°, and the maximum principal stress distributed from 135Mpa to 166Mpa. This period is the main development period of tectonic fractures, and the trend of development is NE-SW. At the end of the Middle Yanshan Period, the stress field direction changed to 85°-95°, and the maximum principal stressdistributed from 116Mpa to 147Mpa. This period is the secondary development period of tectonic fractures, and the trend of tectonic fractures was nearly north to south.Tectonic fractures mainly occur in develop faults and their surrounding areas, as well as their inflection points, endpoints and junctions.