皖南地区二叠系页岩储层微观孔隙特征及影响因素

皖南地区二叠系发育一定规模的富有机质泥页岩。为了深入研究该套泥页岩储层的微观孔隙特征，选取两口钻井岩芯样品进行了氮气吸附、压汞、氩离子抛光扫描电镜试验，结合泥页岩地球化学、有机岩石学和矿物组成特征探讨了微观孔隙发育的影响因素。结果表明:龙潭组和孤峰组泥页岩总体厚度大，总有机碳高，成熟度适中，矿物成分以石英、伊利石、长石和黄铁矿为主；龙潭组泥页岩有机质以固体沥青和镜质组为主，类型为Ⅱ Ⅲ型，其形态表现为片层状、条带状或块状，优势孔隙类型为晶间孔和微裂缝，有机孔发育较差，页岩比表面积和孔隙度分别介于6.80～41.62 m^2.g^-1和0.68%～4.44%，主要来自中孔；孤峰组泥页岩有机质以腐泥组和固体沥青为主，类型为Ⅱ型，其形态主要为薄膜状或填隙状，优势孔隙类型为有机孔，也发育一定的晶间孔和微裂缝，页岩比表面积介于3.12～49.45 m^2.g-¹，主要来自微孔，孔隙度介于0.86%～21.08%，主要来自中孔和大孔；总有机碳是这两套泥页岩比表面积的主要影响因素，但是对孔隙度起着明显的抑制作用；伊利石含量与比表面积之间存在一定的负相关性，与孔隙度之间无明显相关性。

Micro Pore Characteristics and Their Controlling Factors of Permian Shale Reservoir in Southern Anhui

Permian develops a certain scale of organic-rich shales in the southern Anhui. In order to study the pore structure characteristics of the shale reservoir, the core samples from two wells were collected to carry out low-pressure nitrogen adsorption, mercury intrusion, argon ion polishing and field emission scanning electron microscopy tests, and the controlling factors were also discussed combining with the geochemistry, organic petrology and mineral composition. The results show that shale reservoirs in Longtan and Gufeng Formations have great thickness, high total organic content (TOC) and moderate thermal maturity; the minerals are mainly consisted of quartz, illite, feldspar and pyrite; the organic matter of Longtan Formation is dominated by vitrinite and solid bitumen, and the kerogen is type Ⅲ which behaves as lamellar structure, stripped or block-shaped, and the dominated pore types are intergranular pores and fractures, but the organic pores are not developed; the specific surface area and porosity of shales in Longtan Formation are in the range of 6.80-41.62 m^2.g^-1 and 0.68%-4.44%, respectively, which are mainly contributed by mesopores; shales in Gufeng Formation have type Ⅱ kerogen which is composed of sapropel and solid bitumen with thin layer or interstitial shapes; shales in Gufeng Formation develop abundant organic pores and a certain number of intergranular pores and fractures, and have the specific surface area of 3.12-49.45 m^2.g^-1 which is mainly contributed by micropores, and the porosity of 0.86% 21.08% which is mainly contributed by mesopores and macropores; TOC is the controlling factor of the specific surface area of these Permian shales, but has a significant inhibitory effect on porosity; content of illite has an obvious negative relationship with the specific surface area, but has no relationship with porosity for these Permian shales.