四川盆地下志留统龙马溪组页岩纳米孔隙发育特征及主控因素

Characteristics and main controls of nano-pores in the Lower Silurian Longmaxi shale, Sichuan Basin

梁峰 邱峋晰 戴赟 张琴 卢斌 陈鹏 马超 漆麟 胡曦

LIANG Feng QIU Xunxi DAI Yun ZHANG Qin LU Bin CHEN Peng MA Chao QI Lin HU Xi

中国石油勘探开发研究院, 北京 100083 四川页岩气勘探开发有限责任公司, 成都 610051 中国石油集团 川庆钻探工程有限公司 地质勘探开发研究院, 成都 610051

PetroChina Research Institute of Petroleum Exploration and Development, Beijing 100083, China Sichuan Shale Gas Exploration and Development Co., Ltd., Chengdu, Sichuan 610051, China Geological Exploration and Development Research Institute, CNPC Chuanqing Drilling Engineering Company Ltd., Chengdu, Sichuan 610051, China

上奥陶统五峰组-下志留统龙马溪组页岩是我国目前实现页岩气商业开发的唯一层系，而在四川盆地及周边不同区域页岩气单井产量却存在明显差异。筛选位于不同构造位置、不同压力系数、相同层段[鲁丹阶早期（LM1-LM3）]5口典型井的36个页岩样品，应用岩石矿物学、构造地质学、储层地质学等手段系统分析了页岩孔隙特征，从储层微观结构方面分析不同地区产量差异的原因。页岩的储集空间主要以有机质孔为主，不同构造区域页岩小孔体积、中孔体积、大孔体积和总孔体积随有机碳含量的增大呈现出不同的趋势，反映不同的孔隙演化阶段。建立了页岩有机质孔隙发育模式，指出页岩孔隙在高压情况下可能被压实，其压实程度与有机质孔孔径、岩石矿物组成、有机质含量、区域构造条件和压力系数密切相关，指出受构造运动影响小且压力系数较高的区域为孔隙发育的有利区。

The Upper Ordovician Wufeng-Lower Silurian Longmaxi shale is the only yield layer of commercial deve-lopment of shale gas in China at present. However, there are significant differences in the production of individual shale gas wells in different areas of the Sichuan Basin and its periphery. This paper investigates those differences from the perspective of reservoir space. The pore development of 36 shale samples from the Lower Rhuddanian in 5 typical wells with different reservoir pressure in different tectonic areas in the Sichuan Basin was compared by applying, petromi-neralogical, structural geological and reservoir geological methods. The reservoir space in these shales is dominated by organic pores. With the increase of TOC content, the volumes of micropores (< 10 nm), mesopores (10~50 nm), macropores (>50 nm) and total pores in different structural regions show different trends, reflecting different stages of pore evolution. A preliminary organic pore development model of shale has been established. The extent of pore development in shale samples located in the overpressure area in the basin is obviously better than that in the structural transformation area of the basin margin. It is confirmed by experiments that the shale pores may be compacted under high pressure conditions, and the degree of compaction is closely related to the organic matter pore size, the rock mineral composition, the organic matter content, the domain structure conditions and the pressure coefficient. The areas affected by the weak tectonic movement and having a high pressure coefficient are favorable areas for pore development.

国家科技重大专项 2017ZX05035

https://doi.org/10.11781/sysydz202003451