Abstract: Seismic prediction of fractures with small scale and low dip in shale is difficult.Taking the shale gas reservoir of the Wufeng Fm-1^st member of Longmaxi Fm in the Jiaoshiba area of Fuling shale gas field as an example, we explored post-stack seismic fracture prediction method under constraint of stress field.Firstly, the post-stack seismic data were processed to enhance the structure response, so as to improve the ability of identifying faults and fractures, then the high precision seismic curvature volume was tracked to describe the level of fracture development.Secondly, the distribution characteristics of present stress field was simulated to reveal the orientation and strain strength of fractures.Finally, the seismic curvature and stress field attributes were normalized to build a fracture prediction model for accurate identification of orientation and intensity of fracture in the shale reservoirs.The results show that NE-trending fractures with moderate to weak intensity dominate the shale reservoir in the Wufeng Fm-1^st member of Longmaxi Fm in the major part of the Jiaoshiba box anticline structure and NE-trending and NW-trending fractures with moderate to strong intensity occur locally on the flanks of structure and fault (fold) belt.The prediction results are in accordance with the geologic understandings.Well-to-seismic calibration reveals that the fracture prediction results correlate well with the fracture leakage zones identified during drilling, further validating the effectiveness and applicability of the method.It can be used to guide the comprehensive evaluation of shale gas reservoirs and drilling engineering.

Key words: stress field constraint, post-stack seismic, fracture prediction, shale, Longmaxi Formation, Jiaoshiba area, Fuling shale gas field