丁山五峰龙马溪组页岩储层物质点法地应力差预测

地应力预测是长期困扰页岩气勘探研究的难题之一,目前针对地应力预测缺乏有效的方法技术。物质点法地应力差异性预测能够求取代表应力梯度初始分布的相对地应力差。结合丁山构造背景应力场条件和天然裂缝发育情况,利用反演计算获得的弹性参数构建物质点,模拟该地区龙马溪组地应力差分布情况。实际应用结果的对比分析表明,物质点法具备对局部地应力差预测的能力,能够预测局部地应力差。丁山地区受多期次构造运动影响,构造主体地应力差相对较低,主体内部北东和北西两个方向地应力差异较大。同时由于地应力释放程度存在差异,因而平行断裂走向且距离断裂相对较远的位置更有利于水平井轨迹设计及后期进行压裂改造。

In-situ stress prediction for shale gas exploration and research is difficult.Effective methods and technologies for in-situ stress prediction are few.The prediction of in-situ stress difference via the material point method can yield the relative in-situ stress difference,representing the initial distribution of the stress gradient.Elastic parameters are obtained in this study by considering the background stress-field conditions of the Dingshan structure and the development of natural fractures and by performing an inversion calculation to construct material points for simulating the distribution of in-situ stress differences of the Longmaxi formation in the Dingshan area.Comparative analysis results of practical applications show that the material point method can accurately predict the local in-situ stress difference.In the Dingshan area,multiple tectonic movements occur,and the in situ stress difference of the main structure is relatively small,and the in situ stress difference in the northeast and northwest directions within the main body is significant.Considering the different degrees of in situ stress release,the location parallel and distant from the fault is conducive to the trajectory design of horizontal wells and the reconstruction of fracturing in the later stage.