四川盆地下寒武统筇竹寺组页岩储层特征及发育控制因素

Shale Reservoir Characteristics and Development Control Factors of Lower Cambrian Qiongzhusi Formation in Sichuan Basin

摘要: 近期川北陆内坳陷型的SZY1井和川中、川西南地区“拉张槽”型Z201井、JS103井皆获得突破，展示四川盆地下寒武统筇竹寺组页岩具有较好的勘探潜力，但不同类型页岩储层差异性及发育主控因素仍不清楚，亟需开展储层特征对比研究。文章基于三口井资料，对四川盆地下寒武统筇竹寺组不同类型页岩储层的岩石学、地球化学、储集性及可压性等特征进行系统对比分析。研究结果表明：川北地区陆内坳陷型寒武系页岩TOC及粘土矿物含量较高，以有机质孔和片状粘土矿物孔为主，比表面积与孔径较大，孔隙发育主要受有机质丰度和成岩作用控制；川中地区拉张槽深水陆棚相黑色页岩TOC与含气量较高，以有机孔为主，孔隙度与有机质丰度呈良好正相关性；川西南拉张槽浅水陆棚相粉砂质页岩TOC较低，含气量低，片状粘土矿物孔、粒间孔和微裂缝为主要孔隙类型，孔隙发育主要受成岩作用控制。川北陆内坳陷与川中拉张槽深水陆棚相沉积的筇竹寺组富有机质页岩具有一定相似性，TOC较高，优质页岩段以有机孔为主；川西南拉张槽浅水陆棚相粉砂质页岩TOC较低，以无机孔为主，但孔隙度较高、可压性较好，具备一定勘探潜力。

Abstract: Recently, breakthroughs have been made in the down warping region SZY1 well, the “intracratonic sag” type Z201 well and the JS103 well in central Sichuan and southwest Sichuan, showing that the Lower Cambrian Qiongzhusi Formation in the Sichuan Basin has good exploration potential, but the differences and main controlling factors of different types of shale reservoirs are still unclear, and it is urgent to carry out comparative research on reservoir characteristics. Based on the data of three wells, this paper systematically compares and analyzes the petrology, geochemistry, reservoir prosperities and crushability of different types of shale reservoirs in the Lower Cambrian Qiongzhusi Formation in the Sichuan Basin. The results show that the content of TOC and clay minerals in Cambrian shale of continent down warping region in northern Sichuan is higher, mainly organic matter pores and flaky clay mineral pores, the specific surface area and pore size are larger, and the pore development is mainly controlled by organic matter abundance and diagenesi. The black shale in the deep-water shelf facies of the intracratonic sag in central Sichuan basin had high TOC and gas content, mainly organic matter pores, and there was a good positive correlation between porosity and organic matter abundance. The intracratonic sag shallow shelf facies sandy shale in southwest Sichuan has low TOC and low gas content, ntergranular pores, tiny crackand flaky clay minerals pores are the main pore types. The pore development is mainly controlled by diagenesis. The organic-rich shale of the Qiongzhusi Formation deposited in the deep-water shelf facies of the northern Sichuan basin and central Sichuan basin has certain similarities, with high TOC and high-quality shale sections dominated by organic pores. The intracratonic sag shallow shelf facies sandy shale in southwest Sichuan has low TOC, mainly inorganic pores, higher porosity and good crushability, and has certain exploration potential.