Evaluation of terrestrial shale gas resource potential is a hot issue in unconventional oil and gas exploration. Organic-rich shales are widely developed in the Jurassic strata of Tarim Basin, but their shale gas potential has not been described well. In the study, the Lower-Middle Jurassic fine-grained sedimentary rocks (Kangsu and Yangye Formations) in northern Kashi Sag, northwestern Tarim Basin, were taken as the study object. The comprehensive studies include petrology, mineralogy, organic geochemistry, and physical properties, which were used to characterize the organic matter and reservoir characteristics. Results show that the Jurassic terrestrial shale in the northern Kashi Sag was mainly deposited in lakes, rivers, and deltas. The thickness of black lacustrine shale developed in the Early-Middle Jurassic in the study area is generally over 100 m. The total organic carbon (TOC) content is rich, averaging 2.77%. The vitrinite reflectance () values indicate that the Lower Jurassic shale organic matter is in the early mature–mature stage, while the Middle Jurassic is in the mature stage. Besides, organic matter is primarily II and III in kerogen types. The whole shale contains a large number of clay minerals, especially illite. The average brittle minerals such as quartz and feldspar are 28.67%, and the average brittleness index is 38.63%. Nanoscale pores containing intergranular pores, dissolution pores, and organic pores, coupled with microcracks, are well developed in Jurassic shale. The sample’s average pore volume is 0.017 cm³/g, and the specific surface area is 9.36 m²/g. Mesoporous contribute the most to pore volume, while the number of microporous is the largest. Both of them provide most of the surface area for the shale. Combined with regional geologic settings, we propose that the Jurassic terrestrial shale has good-excellent shale gas exploration potential and development prospects.

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塔里木盆地北部喀什凹陷侏罗系陆相页岩气潜力

陆相页岩气资源潜力评价是非常规油气勘探的热点问题。塔里木盆地侏罗系广泛发育富有机质页岩，但其页岩气潜力尚未得到很好的描述。本次研究以塔里木盆地西北部喀什凹陷北部的下中侏罗统细粒沉积岩（康苏组和羊野组）为研究对象。综合研究包括岩石学、矿物学、有机地球化学和物理性质，用于表征有机质和储层特征。结果表明，喀什凹陷北部侏罗系陆相页岩主要沉积于湖泊、河流和三角洲。研究区早-中侏罗世发育黑色湖相页岩厚度一般在100 m以上。总有机碳（TOC）含量丰富，平均为2.77%。镜质反射率（)值表明下侏罗统页岩有机质处于早期成熟-成熟阶段，中侏罗统处于成熟阶段。此外，干酪根类型中有机质主要为Ⅱ和Ⅲ。整个页岩含有大量粘土矿物，尤其是伊利石。石英、长石等脆性矿物平均含量为28.67%，脆性指数平均为38.63%。侏罗系页岩发育含有粒间孔、溶蚀孔和有机质孔的纳米级孔隙，并伴有微裂缝。样品的平均孔体积为0.017 cm ³ /g，比表面积为9.36 m ²/G。介孔对孔体积的贡献最大，而微孔的数量最多。它们都为页岩提供了大部分表面积。结合区域地质背景，认为侏罗系陆相页岩具有良好的页岩气勘探潜力和开发前景。