基于裂缝特征的高阶煤剩余资源分布预测

Prediction of residual resource distribution of high-order coal based on fracture characteristics

高阶煤剩余资源分布预测是气田开发中后期井位调整部署重要组成部分,合理选择井型和井距可促进井组间面积降压、提高产气效果。而目前精确预测剩余资源分布的关键问题是如何确定已开发井的采动影响范围。针对这一问题,以沁水盆地南部区块为依托,系统分析100余口井的地质参数、压裂监测数据和开发动态数据,剖析了影响煤层气井采动影响范围关键因素。研究结果表明:煤层气井的采动影响范围是由煤层的压裂裂缝控制的近似椭圆状分布;而压裂裂缝受构造影响较大,构造类型影响了压裂裂缝方向,单斜构造、背斜翼部、向斜翼部裂缝方向与最大主应力保持一致,背斜轴部裂缝方向与轴向方向一致,向斜轴部裂缝方向与轴向垂直;构造曲率与压裂主裂缝长度呈负相关关系,曲率越大主裂缝长度越短。基于以上研究结果,建立了剩余资源分布预测方法,其方法的核心内容是依据构造相似性原理,利用聚类统计法,根据已开发井构造特征,推测采动影响分布规律,确定剩余资源分布。运用该方法在樊庄北部实施调整后效果明显,为高阶煤中后期开发调整方案编制提供依据。

Predicting the distribution of remaining high-order coal resources is an important part of well position adjustment and deployment in the middle and later stage of gas field development.Reasonable selection of well type and spacing can promote the depressurization of the area between well groups and improve gas production effect.However,the key problem in accurately predicting the distribution of remaining resources is how to determine the impact range of the wells that have been developed.In view of this problem,based on the southern block of the Qinshui Basin,the geological parameters,fracturing monitoring date and dynamic data of more than 100 wells were systematically analyzed,and the key factors affecting the production range of coalbed methane wells were analyzed.The results show that the mining influence range of coalbed methane wells is an approximate elliptical distribution controlled by the fracturing fractures in the coal seam;the fractures are greatly affected by the structure,and the type of structure affects the direction of the fracturing fractures,such as monoclinic structure,anticline wing,and direction.The crack direction of single-angle structure,anticline wing and synclinal wing are consistent with the maximum principal stress.The crack direction of the axis of the anticline is consistent with the axial direction,and the crack direction of the axis of the syncline is perpendicular to the axis.The structural curvature has a negative correlation with the main crack length,and the greater the curvature,the shorter the length of the main fracture.Based on the above research results,a method for predicting the distribution of remaining resources was established.The core content of the method is based on the principle of structural similarity,using the clustering statistical method,according to the structural characteristics of the developed wells,inferring the distribution law of mining influence,and determining the distribution of remaining resources.Using this method to implement adjustment in the northern part of Fanzhuang has obvious effect,which provides a basis for the preparation of the adjustment plan for the development of high-order coal in the middle and later stages.