构造演化过程中泥页岩层变形作用及其富气机理研究

"Shale gas revolution" occurred in USA has grealty contributed to the worldwide research boom of shale gas, the preliminary geological evaluatioin and the pilot test of shale gas exploration and development is showing its effectiveness in several countries. The shale gas resource in China is huge, but most organic-rich shale experienced multi-stage, multi-genetic tectonic events and consequently caused the common development of deformation structures, restricting the accumulation, occurrence and development methods of shale gas in China. In order to solve this critical problem, more attentions should be placed on the aspects at the macro, micro and ultra-micro scale, including: (1) under the conditions of complex tectonic evolution, folding motion, bedding sliding, cutting-layer fault, uplifting and eroding led to various features of deformation; (2) structural deformation affects not only the structure of organic matters and clay minerals, but also significantly alter the structure of its micro-/nano-pores and fractures, and possibly cause complex interfaces effect and molecular internal defects, thereby affect the adsorption characteristics of shale gas. On the basis of the shale deformation characteristics of shale samples under natural conditions and after rheological experiments, this study attempts to recognize its micro-and nano-structural deformation evolution, establish the micro-nano pore structure model， and clarify the shale deformation mechanisms in complex tectonic evolution area, finally identify the occurrence and enrichment mod of shale gas by the adsorption experiment simulation and quantum chemical calculations and other big data analysis of deformed shale. This study will provide the scientific basis for the development of shale gas industrialization.

美国“页岩气革命”引发了世界范围的页岩气研究热潮，多国前期地质评价和勘探开发先导试验初具成效。中国页岩气资源量巨大，但富有机质泥页岩层大多经历了多期次、多成因的构造活动，构造变形普遍发育，制约着我国页岩气聚集、赋存与开发方式。从宏-微-超微尺度，主要涉及两个方面：（1）复杂构造演化条件下褶皱作用、顺层滑动、切层断层以及抬升剥蚀导致了泥页岩层不同的变形特征；（2）构造变形不仅影响泥页岩有机质和粘土矿物结构，而且显著改变其微纳米孔隙结构，造成复杂的界面效应或分子内部缺陷，进而影响页岩气吸附特征。本项目以天然条件和流变实验后泥页岩变形的宏微观特征研究为基础，认识其微纳米结构变形及演化过程，建立泥页岩微纳米孔隙结构模型，阐明多期构造变形区泥页岩变形机制；结合变形泥页岩吸附实验模拟与量子化学大数据计算，查明页岩气富集机理与富集模式，为我国页岩气大规模产业化开发提供科学依据。

中国南方海相页岩气资源量巨大，但富有机质页岩层系大多经历了多期次、多成因的构造活动，构造变形普遍发育，制约着页岩气的保存富集与勘探开发方式。该项目以我国南方四川盆地及其周缘为主要研究区域，以具有典型意义的上奥陶统五峰组-下志留统龙马溪组和下寒武统筇竹寺组含气泥页岩（页岩）层为研究对象，以构造演化与变形作用为主线，基于多学科交叉的研究思路，采用宏观、微观和超微观相结合的观测手段，深入剖析并阐明了多期构造演化过程中页岩层系的变形作用及其对页岩气富集保存的制约。该报告系统总结了项目执行期间的科研工作，取得的主要成果如下：（1）从天然条件下和高温高压变形实验后页岩变形的多尺度结构特征入手，研究了宏微观尺度的脆性变形和韧性变形以及超微观尺度的纳米结构变形，阐明了页岩层变形条件、变形机制及结构演化模式；（2）综合运用高分辨率电镜技术、页岩吸附实验模拟与量子化学计算等研究方法，分别从微-纳米尺度或分子尺度探讨了构造变形作用对页岩矿物结构和有机质结构演化及页岩气赋存的影响，建立了变形页岩的吸附/解吸模式和方程；（3）通过综合研究揭示了变形页岩层的页岩气富集和保存机理，提出了与页岩层变形有关的页岩气富集模式。由此，通过探索研究，该项目在富有机质页岩层系广泛分布且强烈结构变形的复杂构造区阐明了页岩气储层多尺度结构变形特征以及含气量的变化特点，厘清了页岩气富集和保存的地质条件，揭示了不同地质条件下页岩层系的变形过程及其机制，建立并完善了我国南方复杂构造区海相页岩气富集地质理论；从构造演化和有机岩结构变形角度入手，也是研究中国南方页岩气赋存与富集理论的一条新思路。该项目圆满地完成了研究计划，取得了一系列代表性研究成果和创新性认识，并为我国多期构造叠加变形区页岩气的大规模产业化开发提供了科学依据。