基于改进Delaunay三角剖分算法的微地震数据SRV估算与应用  

Estimation and application of micro-seismic data SRV based on improved Delaunay triangulation algorithm

作　　者：王旭林 李玉海 王鹏 王晓阳[4] 吕明慧 WANG XuLin;LI YuHai;WANG Peng;WANG XiaoYang;Lü MingHui(Hubei Cooperative Innovation Center of Unconventional Oil and Gas,Wuhan 430100,China;Key Laboratory of Exploration Technologies for Oil and Gas Resources(Yangtze University),Ministry of Education,Wuhan 430100,China;Dongfang Geophysical Research Institute Dagang Branch,CNPC,Tianjin 300280,China;Southwest Geophysical Prospecting Branch of PetroChina Eastern Geophysical Exploration Company,Chengdu 610213,China)

机构地区：[1]非常规油气湖北省协同创新中心,武汉430100 [2]油气资源与勘探技术教育部重点实验室(长江大学),武汉430100 [3]东方地球物理公司研究院大港分院,天津300280 [4]中国石油集团东方地球物理勘探有限责任公司西南物探分公司,成都610213

出　　处：《地球物理学进展》2021年第2期689-695,共7页Progress in Geophysics

基　　金：国家自然科学基金项目(41604099);中国石油天然气股份有限公司科学研究与技术开发项目“大港油区效益增储稳产关键技术研究与应用”(2018E-11)联合资助.

摘　　要：影响页岩气藏改造效果的核心参数是储层的压裂改造体积(Stimulated Reservoir Volume,SRV),有效准确估算压裂改造体积有助于评估压裂效果.水力压裂过程中微地震事件点分布状态不规则,传统的SRV计算方法通过外接规则几何体进行计算,相应结果误差明显,进而采用Delaunay三角剖分算法来降低结果误差,但Delaunay三角剖分方法更适合处理凸数据集.若压裂裂缝网络比较分散,即存在一些非产能区域,该算法不能剔除该区域的影响,造成压裂改造体积估值偏大.针对该问题,本文提出了一种基于三维不规则包络体的SRV计算方法,首先使用DBSCAN算法对微震事件点进行聚类处理,排除微震事件的异常定位点的干扰,然后使用本文提出的边界凹陷算法,对裂缝网络内部非产能区域进行剔除,得出一个由多个四面体组成的封闭的三维包络体,通过计算其内部所有四面体的体积之和可估算出整体压裂改造体积.通过实测数据对本文方法进行检验,相应结果表明:计算获得的不规则包络体和微震事件空间展布特征具有较好的一致性,可明显消除非产能区域的影响,本文方法具有很好的可行性与准确性.The core parameter that affects the shale gas reservoir reconstruction effect is Stimulated Reservoir Volume(SRV).Effective and accurate estimation of the fracturing reconstruction volume is necessary to evaluate the fracturing effect.In the process of hydraulic fracturing,the distribution of micro-seismic event points is irregular.So,the traditional SRV calculation methods may cause obvious error.The Delaunay triangulation algorithm is generally used to improve the SRV.However,the Delaunay triangulation algorithm is more suitable for the convex data sets.If the hydraulic fracture network is scattered,there are some nonproductive areas.The exsiting Delaunay triangulation algorithm cannot exclude the effect of the non-productive areas,which will lead to overestimate the SRV of the hydraulic fracturing.For handling with the above problems,one SRV calculation method based three-dimensional irregular envelope is proposed in this article.First,the DBSCAN algorithm is applied to exclude the abnormal location points in the microseismic events.Then,the initial convex hull of the microseismic event points is generated by using the Delaunay triangulation algorithm.Next,one boundary sag algorithm proposed in this article is to find these non-effective productivity regions and remove them.The final result is regarded as the accumulation of multiple tetrahedrons volume closed in the three-dimensional envelope.In this article,one field data is used to validate the proposed method.The corresponding processing result shows that the proposed method can obtain better model of the irregular envelope and overcome the interference of the nonproductive areas.

关 键 词：体积压裂 微震监测 压裂改造体积 DELAUNAY三角剖分 边界凹陷算法 

分 类 号：P631[天文地球—地质矿产勘探]