考虑树状次生裂缝的页岩气藏试井分析模型及其应用  

Shale Gas Well Test Analysis Model Considering the Characteristics of Tree-shaped Secondary Fractures and Its Application

作　　者：吴建发 常程 韩建[2] 王庆 赵勋 谢维扬 朱仲义 彭瑀[5,6] WU Jianfa;CHANG Cheng;HAN Jian;WANG Qing;ZHAO Xun;XIE Weiyang;ZHU Zhongyi;PENG Yu(Shale Gas Research Institute of PetroChina Southwest Oil&Gas Field Company,Chengdu,Sichuan 610051,China;Chongqing Gas Field of PetroChina Southwest Oil&Gas Field Company,Chongqing 400021,China;No.6 Gas Production Plant of Changqing Oil Field Company of Petrochina,xi′an,Shaanxi 710018,China;Suining Emergency Rescue and Maintenance Center of PetroChina Southwest Oil and Gas Field Company,Suining,Sichuan 629000,China;Southwest Petroleum University,Chengdu,Sichuan 610500,China;State Key Laboratory of Oil&Gas Reservoir Geology and Exploitation,Chengdu,Sichuan 610500,China)

机构地区：[1]中国石油西南油气田分公司页岩气研究院 [2]中国石油西南油气田分公司重庆气矿 [3]中国石油长庆油田分公司第六采气厂 [4]中国石油西南油气田分公司遂宁应急抢险维修中心 [5]西南石油大学 [6]油气藏地质及开发工程国家重点实验室

出　　处：《钻采工艺》2022年第3期84-88,共5页Drilling & Production Technology

基　　金：中国石油—西南石油大学创新联合体科技合作项目;国家自然科学基金区域创新发展联合基金“四川深层页岩气水平井缝网压裂填砂暂堵物理机制研究”(编号:U19A2043);国家自然科学基金“致密油储层压裂后关井渗吸—水化多物理场耦合作用机制研究”(编号:52174033)。

摘　　要：如何在试井分析模型中考虑体积压裂次生裂缝的分布特征,成为了制约其解释精度的重要技术难题。现有常规渗流理论一般不考虑页岩气藏的多重运移机制及次生裂缝的形态特征,为了有效诊断次生裂缝的复杂程度,文章考虑裂缝具有树状分支特征,耦合吸附、扩散等多重运移机制,建立了页岩气藏压裂水平井流动数学模型。通过点源函数、局部坐标变换、Laplace变换、Duhamel原理和Stehfest数值反演等方法对模型进行半解析求解并进行典型试井曲线绘制和流动阶段划分。提出利用拟压力导数的斜率曲线对次生裂缝发育情况进行诊断的方法,并分析了树状分支裂缝的流量分布特征,最后对一口实际页岩气井进行了解释分析应用。结果表明:通过裂缝干扰段的斜率特征能有效诊断次生裂缝的发育程度,其斜率值在裂缝干扰流动段的值越大、曲线上翘越高则次生裂缝越发育。该研究对于指导页岩气藏压力动态特征分析具有重要意义。How to consider the distribution characteristics of secondary fractures in the well test analysis model has become an important technical problem that restricts the interpretation accuracy.Aiming at the problem that the multiple migration mechanism and secondary fracture morphology are not considered in the conventional percolation theory for shale gas reservoir,a mathematical model of tree-like branching fractures was built with coupling adsorption,diffusion and other multiple migration mechanisms.By employing point source function,local coordinate transformation,Laplace transform,Duhamel principle and Stehfest numerical algorithm,the model was solved semi-analytically and the typical well test curves were drawn and the flow stages were divided.The slope curve of pseudo-pressure derivative was used to diagnose the development degree of secondary fractures,and the flow distribution characteristics of the tree-like branching fractures were analyzed.Finally,an actual shale gas well was interpreted and analyzed.Result shows that the development degree of secondary fractures can be effectively diagnosed through the slope characteristics of fracture interference stage.The larger the value of slope in fracture interference stage,the higher the curve goes up,the more developed the secondary fractures will be.Therefore,this study is of great significance for guiding the analysis of dynamic pressure characteristics in shale gas reservoirs.

关 键 词：页岩气 压裂水平井 树状分支 次生裂缝 井底压力动态特征 裂缝流量分布特征 斜率曲线 

分 类 号：TE27[石油与天然气工程—油气井工程]