Acoustic emission-based numerical simulation of tectonic stress field for tectoclase prediction in shale reservoirs of the northern Guizhou area, China

Natural fractures,like tectoclases,are essential in the formation of shale gas reservoirs and have been the focus of study for shale gas development.Tectoclases provide most storage space for gas and are largely controlled by the paleo-tectonic stress field in shale reservoirs of the Niutitang Formation,northern Guizhou area,China.An accurate prediction of the development and distribution of tectoclases in the reservoirs is of great significance to exploring and developing shale gas sweet spots in the area.Based on geological structure evolution and fracture characterization,this study is focused on factors that control the fracture development in the Niutitang Formation shale reservoirs in northern Guizhou through characterization and modeling of geomechanisms and tectonic movements.A geomechanical model is formulated for the shale reservoirs against the geological background of the area.On this basis,the fractures are predicted by using the acoustic emission data.Numerical simulation results show that the development and distribution of tectoclase is controlled by fault zones,some of which have no obvious turning points with tectoclase in the middle sections being more developed and fragmented than those at the two ends.Some of these have obvious S-shaped turning points where tectoclases are the most developed and fragmented.