中国海相页岩气开发评价关键技术进展

Progress in key technologies for evaluating marine shale gas development in China

以四川盆地及其周缘下古生界龙马溪组和筇竹寺组页岩为对象,总结中国海相页岩的地质和储集层特征,结合"十二五"期间页岩气开发取得的理论和技术成果,建立了中国页岩气开发评价关键技术指标体系和静动态参数及经济指标相结合的页岩气井综合分类标准。针对页岩气井压裂后形成的复杂缝网特征,联合分形介质和连续介质理论刻画复杂裂缝系统,建立页岩气全过程渗流生产模型,并根据输入参数特征构建概率分布模型,利用蒙特卡洛随机模拟方法,预测不同概率下的气井生产动态指标;同时提出水平井段及主裂缝参数、开发井距和生产制度等关键开发参数优化的具体思路和方法。中国页岩气大规模效益开发在地质理论、渗流机理及产能评价方法、开发技术政策及经济效益方面仍然面临许多亟待解决的难题。

The Lower Paleozoic Longmaxi and Qiongzhusi Formatiion shale plays were taken as research objects to summarize the geologic and reservoir characteristics of marine shale gas in China. Based on the theory and technology achievements made during the twelfth five-year plan, a key index system was established to evaluate shale gas well production effect in China, and a comprehensive classification was consequently presented by integrating geological statistical indexes and economic evaluation indexes; to characterize the complex fracture network formed by fracturing, a generalized analytical model was established by incorporating fractal and continuum geometry theory to capture the transient behavior of such fractured horizontal well throughout production life. An associated probabilistic analysis, based on the Monte Carlo simulation was presented by linking a probabilistic worksheet with the analytical model, and then used to determine a range of possible outcomes（i.e., EUR, decline rate and production time）. Meanwhile, an optimization approach for development parameters, including fractured horizontal segment, fracture geometry（i.e., fracture length, conductivity, number）, well spacing and drawdown management was advanced. There are still many unresolved problems on geologic theory, flow mechanism and productivity evaluation method, development technical policy and economic benefits, which limit large-scale and high-efficiency exploitation of shale gas resource in China.