Shale oil resources for exploration in the Xingouzui Formation,the Jianghan Basin were geologically assessed to be 3.6 X 108 t,and oil flow was obtained at several well sites from argillaceous dolomites in the lower Xingouzui Formation,the Chentuokou sag which was evaluated to be Grade-Ⅰ promising prospect.Economic shale oil production is usually achieved using horizontal well drilling+staged fracturing;thus stress information is important to fracturing stimulation of horizontal wells.A crucial issue in 3D stress modeling is how to improve cross-well prediction.The finite element method routinely used cannot yield good results due to its own limitations;thus our efforts focus on seismic inversion to improve cross-well prediction.In view of the problems related to multi-mineral,local sulfate rocks,and complicated stress conditions in the area of interest,log data-based evaluation is performed under the constraints of lab data for Xingouzui shale beds,and the results are validated using core measurements of X-ray diffrac-tion.Rock physical modeling is achieved using self-consistent approximation to calculate elastic parameters of shale beds;modeled results agree with measured curves.Based on formation pressure,rock mechanical properties measured in the lab,logging interpre-tation,and dynamic-static relations of different lithologies,effective stress ratio and tectonic strain methods are employed to calcu-late in-situ stress parameters at well sites.The final 3D stress model of Xingouzui shale beds is established using prestack seismic inversion results and the correlation and parameter constraints equal to those used in 1D geomechanical modeling.By comparison,pseudo-curves extracted from the 3D model are basically consistent with 1D modeled results at most well sites in the area,which demonstrates the feasibility and credibility of this method in stress evaluation for Xingouzui shale beds.
Chentuokou sagshale oilseismic rock physics1D-MEMsprestack seismic inversion3D stress modeling
维普
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