富有机质泥页岩内滑脱层形成机理及其油气输导能力研究

The slip layer in organic-rich shale is a special kind of oil source fault. However, its horizontal transportation capacity for hydrocarbon often is ignored. In well HD-1, the shale gas flow is obtained at the slip layer in Wufeng formation, which is showing that the horizontal hydrocarbon transportation in Wufeng-Longmaxi formation is obviously controlled by the slip layer in Wufeng formation. The aim of this work is quantitatively evaluate the hydrocarbon transport capacity of the slip layer and the contribution of exogenous type shale gas. The object of this study is the successful areas of shale gas located in Sichuan basin and its surrounding area. It will study the spatial distribution characteristics, formation mechanism and the hydrocarbon transport capacity of the slip layer in Wufeng formation and the contribution of exogenous type shale gas for shale gas field, on the basis of outcrops, core samples, well log data and seismic data with the methods such as rock mechanics simulation, dating, seepage simulation, micro-CT scanning. This work will not only benefit to study the enrichment mechanism of shale gas in Wufeng-Longmaxi formation, promote low-cost and pollution development of shale gas, but also benefit to the study of dynamic reservoiring processes in complicated structural zones.

富有机质泥页岩内发育的滑脱层作为一种特殊的油源断裂，其对油气的侧向输导能力常被忽略。华地1井在五峰组内滑脱层钻获天然页岩气流，初步证实了五峰组内发育的该套滑脱层对五峰—龙马溪组内页岩气的侧向运移具有重要的控制作用。为深入研究该套滑脱层的油气输导能力，评估外源补给型页岩气的贡献率。本课题以四川盆地及周缘现有页岩气勘探实例为研究对象，在大量露头、岩心、测井和地震资料的基础上，通过岩石力学模拟、年代学测定、渗流模拟、微米CT等方法，对该套滑脱层的空间展布规律、形成机理、滑脱层油气输导能力进行研究，并定量评价外源补给型页岩气的贡献率。研究成果不仅有助于探索五峰—龙马溪组页岩气富集规律的认识，推动页岩气资源低成本、低环境压力开发，而且有助于复杂构造区的油气动态成藏机理研究。

随着页岩气开发的不断推进，水力压裂导致成本高昂、可能打破地应力平衡、污染地下水等行业瓶颈日益突出，同时，现有页岩气“自生自储”理论尚无法解释焦页1-HF井累计产气量大于其单井地质资源量；川南地区同一优质页岩相内高产井与低产井比邻等诸多实践问题。本项目以华地1井钻获天气页岩气流的五峰组滑脱层为研究对象，.（1）通过野外调查、地震构造解译、岩心观察和CT扫描等多种手段，发现五峰组滑脱层厚0.3~1.5m，稳定分布于中上扬子地区。其内泥页岩破碎，尽管部分孔缝为方解石和石英脉胶结，但大量微裂缝仍相互连接。胶结物内烃类包裹体丰富，证实其为五峰组—龙马溪组页岩气目标层内的一套油气输导层；.（2）通过薄片、矿物组分和力学测试、滑脱位移量的定量分析，发现五峰组内滑脱层的形成与宏观与微观尺度下均存在二厚能干层夹一薄软弱层的岩性组合和弯滑剪切应力作用密切相关。宏观上，宝塔组与龙马溪组为能干层，五峰组内板状硅质岩层段为软弱层；微观上，板状硅质岩层理面为软弱层，板状硅质岩为能干层；.（3）在实验测试基础上，建立了其渗透率与孔隙压和围压的二元非线性应力敏感函数，为定量预测输导能力提供了基础；.（4）以华蓥山背斜为例，运移本项目提出的外源补给型页岩气预测方法，推测该地区外源补给型页岩气贡献率约28.08%；.（5）根据滑脱层形成机理，在川东地区下陆相页岩内局部发现滑脱层发育，实现成果转化，为平安1井获得陆相页岩油气突破提供技术支撑；.（6）综合外源补给型页岩气富集理论、滑脱层野外识别、裂缝预测、渗透率应力敏感性定量分析、单井产能预测等技术，形成外源补给型页岩气勘探技术一套。将有助于探索页岩气免压裂开发潜力、促进四川盆地页岩油气勘探和丰富我国页岩气富集理论研究。.依托本项目，发表论文7篇，其中SCI（EI）收录4篇；形成专利3项；科普论文1篇；实现成果转化2项；形成建议报送中央有关部门2份；赴德国学术访问1人次。.