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以钻井资料为基础,依据笔石生物地层、地球化学特征、岩石矿物组成、储集层微观特征、构造条件等数据,研究渝东北地区巫溪2井页岩气富集模式。巫溪2井上奥陶统五峰组—下志留统龙马溪组富有机质页岩厚达89.8 m,笔石带发育齐全,富有机质页岩段从奥陶系凯迪阶上部上延到下志留统特列奇阶下部,沉积厚度及时间远超四川盆地其他区域。页岩最高实测含气量超8 m3/t,含气性主要受TOC大小控制,有机质纳米孔为主要储集空间,无机矿物对储集空间的贡献较小;其中孔径大于50 nm的有机质孔隙较常见,小于10 nm的有机质孔为吸附气的主要赋存场所。巫溪2井目的层段处于挤压型背斜(田坝背斜)核部中性面以下,在脆性较强层段形成了2个垂向裂缝(劈理)发育带,利于页岩气的储集及后期压裂改造形成复杂缝网;田坝背斜两翼断层属挤压性断层,断层两侧为非渗透性的页岩,且预测断层面有泥岩涂抹现象,具有良好的封堵性,有利于页岩气的保存。上述诸多有利条件的良好匹配最终形成了研究区“构造型甜点”。
Based on the drilling data, the shale gas enrichment model of the Wuxi 2 well in northeastern Chongqing is studied based on the data of biota, geochemical characteristics, rock mineral composition, reservoir micro-characteristics and structural conditions. The Wujiang-2 Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation organic-rich shale is 89.8 m thick. The pen-stone belt is well developed. The organic-rich shale extends from the upper part of the Ordovician Kaidi step to the next In the lower part of the Autonomous series, the sedimentary thickness and time are much longer than other parts of the Sichuan Basin. The highest measured gas content of shale is over 8 m3 / t. The gas content is mainly controlled by TOC size. Organic matter nanopores are the main reservoir space. The contribution of inorganic minerals to reservoir space is small. The porosity of organic matter with pore size greater than 50 nm Common organic pores less than 10 nm are the main sites for adsorbed gas. The purpose layer of the Wuxi 2 well is below the neutral part of the crustal anticline (Tianba anticline), and two vertical fractures (cleavage) development zones are formed in the more brittle layers, which is favorable for shale gas The fractures of the two wings of the Tianba anticline belong to the extrusion faults and the two sides of the fault are impermeable shales, and mudstone smear is predicted on the fault plane with a good blockage It is good for shale gas preservation. The good match of many of the above conditions eventually led to the study area of “structured desserts.”