页岩气藏压裂有效缝网反演方法研究

Multi-stage fracture horizontal well (MFHW) is widely used in shale gas reservoir development, which greatly increases the recovery efficiency of every single well. Inverse modeling with production data as well as determined the parameters of hydraulic fracture network are key issues during shale gas reservoir development. The traditional history –matching methods do not characterize the fracture network precisely enough and might frequently lead to multiple uncertainty of results. In this project, we proposed a new method to solve the issues of accuracy of automatic history-matching in shale gas reservoir development. In this method, plenty of techniques such as micro-seismic, proppant transportation simulation will be applied in order to reduce the uncertainty of history-matching. The content of this project is divided into three parts, which are (a) study on the reconstruction of effective fracture network; (b) study on flow simulation in complex multi-scale fracture network and (c) study on the automatic history-matching method which can be utilized to recognize the effective fracture network. All of the achievements of this project can be used to guide the development of shale gas reservoir in Weiyuan deep shale gas reservoir.

页岩气藏大多采用压裂水平井开发，准确拟合生产数据，反演复杂缝网，对气藏下一步开发部署意义重大。本项目针对目前页岩气开发工程实践中存在的压裂有效缝网刻画不精细，参数反演不确定性强的问题，综合运用微地震监测，支撑剂运移模拟，岩心实验等辅助手段，形成基于自动历史拟合，考虑支撑剂运移分布和裂缝动态闭合等过程，准确，高效的有效缝网反演方法。本项目的主要研究内容包括：（1）页岩气压裂有效缝网重构方法研究；（2）多尺度裂缝网络渗流模拟方法；（3）能够识别压裂有效缝网的生产数据自动历史拟合方法。本项目的研究成果将直接运用于中石化威远深层页岩气田指导生产，预测剩余气分布，优化井网井距。

本项目针对目前工程实践中存在的有效压裂缝网刻画不精细，参数反演不确定性强的问题，综合运用微地震监测，支撑剂运移模拟，岩心实验等辅助手段，形成考虑支撑剂运移分布和裂缝动态闭合等过程，准确，高效的压裂水平井生产数据自动历史拟合方法。本项目的研究成果如下：(1)开展了深层页岩气多尺度介质耦合流动规律研究。通过物理实验开展了对四川盆地深层页岩气岩心的吸附/解吸和应力敏感研究，通过实验结果分析确定了我国四川盆地典型深层页岩气吸附解吸、应力敏感等流动规律特征；(2)开展了基于嵌入式离散裂缝的页岩气压后缝网渗流模拟方法研究，实现了在真实三维地质模型中大量运用嵌入式离散裂缝开展压后页岩气开发数值模拟。形成了基于CFD-DEM的支撑剂在裂缝中运移规律的数值模拟方法，并在交叉裂缝等复杂情形下得到应用，进而依据支撑剂分布构建了有效支撑裂缝模型；(3)开展了能够识别有效缝网的生产数据自动历史拟合方法研究，提出了在有微地震约束情况下的压后有效缝网反演方法并在实际页岩气井中得到应用,缝网反演结果准确率达到85%以上。共发表论文7篇，其中SCI/EI论文6篇，申请国家发明专利1件。本项目相关成果已经集成至中国石化自主研发的数值模拟软件COMPASS中，该软件已经在中国石化所属页岩气田中得到大量应用，逐步实现了对国外同类产品的有效替代。