地质科学2024，Vol.59Issue(4)：1003-1017,15.DOI:10.12017/dzkx.2024.071
四川盆地龙马溪组与大安寨段页岩储层特征对比研究:海相与湖相的差异分析
Comparative study of shale reservoir characteristics between the Longmaxi Formation and the Da'anzhai Member in the Sichuan Basin:Highlighting facies differences between marine and lacustrine depositional environments
摘要
Abstract
Reservoir characteristic is the key focus and challenge in lacustrine shale research.To provide a theoretical basis and reference for future exploration and development of lacustrine shale gas,this study compared and analyzed the differences between marine and lacustrine shale reservoirs.Organic geochemistry experiments,whole-rock X-ray diffraction(XRD)analysis,scanning electron microscopy(SEM)with argon ion polishing,and low-temperature nitrogen adsorption experiments were conducted on lacustrine shale from the 1st Member of the Longmaxi Formation in Southeast Sichuan and the 2nd sub-member of the Da'anzhai Member in North Sichuan.This research aims to compare and analyze the organic geochemistry,reservoir characteristics,pore structure differences,and controlling factors between lacustrine and marine shales.The results show that,compared to the Longmaxi Formation shale,the Da'anzhai shale exhibits lower organic matter content.The organic matter kerogen in Da'anzhai shale is primarily type Ⅱ,with a small amount of type Ⅲ,and is in a high-over mature stage.Mineral composition in the Da'anzhai shale is characterized by lower siliceous minerals and higher clay mineral content,primarily illite and mixed-layer illite.The presence of shell fossils contributes to a higher calcium content.In terms of pore composition,the Longmaxi Formation is dominated by organic pores.In contrast,the Da'anzhai shale is primarily characterized by clay mineral interpore,accounting for over 70％of the total pores,followed by organic pores.Micro-fractures are mainly clay interlayer fractures and mineral edge fractures.The pore size distribution is dominated by mesopores ranging from 2 to 50 nm,forming a"double peak"at intervals of 4 nm and 20 nm,respectively.The dominant reservoir space in the Da'anzhai shale is primarily controlled by clay mineral and organic matter content.The effective spatial coupling of organic matter and clay mineral composition facilitates the formation of pores between oil and gas-bearing clays,creating favorable conditions for reservoir development.The striated zone of the lacustrine shale exhibits high porosity,high total organic carbon(TOC)content,high gas content,and well-developed micro-fractures,making it conducive to fracturing and fracture formation.This zone represents a high-quality reservoir development interval,conducive to oil and gas accumulation.关键词
龙马溪组/大安寨段/海相页岩/湖相页岩/孔隙结构/控制因素Key words
Longmaxi Formation/Da'anzhai member/Marine shale/Lacustrine shale/Pore structure/Control factor分类
能源科技引用本文复制引用
辛利伟,李虎,王晓蕾,张芝龙,侯守康,何顺..四川盆地龙马溪组与大安寨段页岩储层特征对比研究:海相与湖相的差异分析[J].地质科学,2024,59(4):1003-1017,15.基金项目
山西省基础研究计划自由探索项目(编号:202203021212503)、山西省高等学校科技创新项目(编号:2021L569)、吕梁市重点研发项目(编号:2022GXYF09)、页岩油气富集机理与有效开发国家重点实验室开放基金项目(编号:G5800-20-ZS-KFZY002)、油气藏地质及开发工程全国重点实验室开放基金项目(编号:PLN2023-31)和页岩气评价与开采四川省重点实验室开发基金项目(编号:YSK2023001,YSK2022002)资助 （编号:202203021212503）
