页岩气开采阶段及剩余资源量预测实验方法研究

China has abundant shale gas resources and has successfully achieved commercial development. However, how to more efficiently develop and accurately evaluate the remaining resources potential is a hot topic at home and abroad, and it is also a difficult issue faced by our country in the process of shale gas industrial exploitation. At present, there is no effective method for determining the stage of shale gas extraction and evaluating the remaining resources. This project intends to use the Wufeng-Longmaxi Formation shale in the Jiaoshiba region as the research object, and using an independently designed gas injection-desorption instrument to simulate the entire production cycle of shale under actual geology temperature and pressure conditions. The carbon isotope composition of methane (δ13C1), the ratio of adsorbed gas and free gas (Qa/Qf) and the velocity of desorption gas (Vn) during the entire production cycle will be stagely detected and calculated, and then to summarize the relationship among the δ13C1, Qa/Qf, Vn, shale gas exploitation stage and remaining production potential. Then, combing the coupling relationship between the desorption gas in geology and laboratory. Finally, it provides a theoretical basis to determine the shale gas production stage, to predict the remaining resources potential of shale gas, and to propose optimized production plan.

我国具有丰富的页岩气资源，并已经成功实现商业开发，而如何高效的开发与准确的预测剩余开采潜量是国内外研究的热点，也是我国页岩气工业化开采过程中面临的难点。目前，尚无有效的确定页岩气开采阶段和评价剩余资源量的方法。本项目拟以焦石坝地区五峰-龙马溪组页岩为研究对象，利用自主设计的页岩人工注气-解吸仪，模拟实际地层温压条件下不同长度岩心页岩气的全生产周期。通过对不同定量解析阶段甲烷碳同位素值、吸附气量与游离气量比值（Q吸/Q游）、解析效率（Vn）等进行检测与计算，建立甲烷碳同位素、Q吸/Q游、Vn的变化特征与页岩气开采阶段及剩余开采潜量之间的响应模型。进一步结合现场解析数据与不同长度岩心人工注气-解析实验结果的耦合关系，为判断页岩气的开采阶段、预测页岩气剩余开采潜力以及可采取的优化开采方案提供理论依据与技术支撑。

我国具有丰富的页岩气资源，并已经成功实现商业开发，而如何高效的开发与准确的预测剩余开采潜量是国内外研究的热点，也是我国页岩气工业化开采过程中面临的难点。目前，尚无有效的确定页岩气开采阶段和评价剩余资源量的方法。本项目拟以焦石坝地区五峰-龙马溪组页岩为研究对象，分析影响页岩气吸附性能的关键因素，利用等温吸附实验获取的实验数据，建立页岩吸附气含量计算模型；利用自主设计的页岩人工注气-解吸仪，以样品初始游离气含量、剩余总含气量的5%、10%、15%、20%、25%、30%、35%、40%、45%、50%、60%、70%和近似100%等13个定量取气节点进行解析实验，读取每个取气节点的地层压力数据，结合已建立的吸附气含量计算模型，计算相应的吸附气含量，并进一步获取吸附气量与游离气量比值（Q吸/Q游）；通过对每个取气节点的甲烷气进行碳同位素值测定，明确页岩气解析过程中的碳同位素分馏特征，进一步建立碳同位素分馏特征同Q吸/Q游等页岩气全生产周期过程中含气量变化特征等的相关关系。从而进一步为页岩气不同开采阶段的判定、剩余资源量的预测提供一定程度的理论依据与技术支撑。从而为页岩气有效开采、高效开发、节能减支等的优化开发方案提供一定的参考价值。