页岩孔缝结构及海相与陆相储层特征差异研究

为了深入分析海、陆相页岩微观孔隙的特征差异和含气潜力，采用FEI Quanta 200F场发射环境扫描电镜对页岩岩样进行了高真空扫描，建立了微观储层孔隙结构体系。以扫描电镜观测的微观孔隙孔径大小、形态及连通性结果为基础，参考前人对页岩吸附气、游离气研究成果及吸附气、游离气特征差异，对不同孔隙的储气能力和对页岩气的渗滤扩散的控制作用进行了研究，将陆相页岩和海相页岩的微观孔隙进行对比分析，总结海、陆相页岩微观孔隙的特征差异和含气潜力。研究结果表明，页岩气6类储层孔隙中，有机质纳米孔、黏土矿物粒间孔富集海、陆相页岩吸附气，古生物化石孔、岩石骨架矿物孔、黄铁矿晶间溶蚀孔、微裂缝富集游离气，改造后的岩石骨架矿物孔和微裂缝在页岩气的渗滤扩散方面起到主要作用。海相页岩中有机质和有机质纳米孔的含量远高于陆相页岩，而纳米孔富集吸附气；海相包含较多石英、长石及碳酸盐岩矿物，使海相页岩脆性矿物的含量高于陆相页岩，更易压裂，以上两个因素导致海相页岩的开发潜力大于陆相。

Studies on the structures of pores and fractures in shale reservoirs and the characteristic differences between marine and continental shale reservoirs

In order to analyze deeply the characteristic differences and gas bearing potential of microscopic pores in marine and continental shale, high vacuum scanning was carried out on shale samples by using FEI Quanta 200F field emission environmental scanning electron microscope (FE-ESEM), and the structural systems of microscopic reservoirs pores were established. Then, the gas storage capacity of different pores and the their controlling effect on the seepage and diffusion of shale gas were investigated based on the size, morphology and connectivity of microscopic pores observed through SEM, combined with the former research results of shale adsorbed gas and free gas and the characteristic differences between adsorbed gas and free gas. The microscopic pores in marine and continental shale were compared. And finally, the characteristic differences and gas bearing potential of microscopic pores in marine and continen-tal shale were summarized. It is indicated that among 6 types of pores in shale gas reservoirs, adsorbed gas is enriched in the organic nanopores and the intergranular pores in clay minerals, and free gas is enriched in the pores in paleontologic fossils, mineral pores in rock skeletons, the intercrystalline dissolved pores in pyrite and the microfractures. The reworked mineral pores in rock skeletons and microfractures play an important role in the seepage and diffusion of shale gas. The content of organic matters and organic nanopores in marine shale is much higher than that in continental shale, and nanopores are enriched with adsorbed gas. There is more quartz, feldspar and carbonate minerals in marine shale, so the content of fragile minerals in marine shale is higher than in continental shale, and consequently marine shale can be fractured easily. Based on above-mentioned two factors, therefore, the development potential of marine shale is higher than that of continental shale.