川东北地区二叠系大隆组页岩储层特征及其主控因素  

Characteristics and determinants of shale reservoir development in the Permian Dalong Formation,northeastern Sichuan Basin

作　　者：王威[1,2,3] 刘珠江 魏富彬[1,2,3] 李飞 WANG Wei;LIU Zhujiang;WEI Fubin;LI Fei(Exploration Company,SINOPEC,Chengdu,Sichuan 610041,China;SINOPEC Key Laboratory of Shale Oil/Gas Exploration&Production Technology,Beijing 102206;State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Efficient Development,Beijing 102206)

机构地区：[1]中国石化勘探分公司,四川成都610041 [2]中国石化深部地质与资源重点实验室,北京102206 [3]页岩油气富集机理与高效开发全国重点实验室,北京102206

出　　处：《石油与天然气地质》2024年第5期1355-1367,共13页Oil & Gas Geology

基　　金：中国石油化工股份有限公司科技攻关项目(P23070,P23221,P22136)。

摘　　要：川东北地区二叠系大隆组发育一套海相优质页岩,页岩储层控制了页岩气的富集。以大隆组深水陆棚相页岩为研究对象,利用氩离子抛光扫描电镜、低温氮气吸附脱附法和高压压汞等测试资料,通过地球化学和矿物组成特征研究,与志留系龙马溪组、二叠系茅口组三段和吴家坪组二段等海相页岩储层进行差异性对比分析,提出了大隆组储层发育主控因素。研究结果表明:①深水陆棚相和盆地相区优质页岩发育,沿开江-梁平陆棚呈环带状分布,厚度介于20~35 m。川东北地区大隆组深水陆棚相页岩发育混合硅质页岩相和含灰硅质页岩相。南江地区深水陆棚相页岩厚度介于20~30 m,以混合硅质页岩相为主;在普光地区深水陆棚相页岩厚度相对较大,介于30~35 m,以含灰硅质页岩相为主;而靠近陆棚中间位置深水陆棚相页岩厚度略有减薄,在20 m左右,以硅质页岩相为主。②大隆组页岩储层具有“高碳、高脆、高孔、高含气”的“四高”特征。页岩为有机质发育的孔隙型储层,总体具有高孔-特低渗、微孔占比高和孔隙连通性较好的特征。③沉积环境控制了大隆组页岩储层孔隙发育程度及类型,流体超压使孔隙后期得以保存。④相比其他层系,海相页岩储层大隆组岩性组合以灰黑色硅质页岩夹薄层泥质灰岩为主,纵向灰岩夹层多,岩性非均质性强。不同层系页岩主要储集空间总体相似,均以有机质孔为主,但大隆组储层龙马溪组页岩储层孔隙度较其他层系页岩总体偏低。The Permian Dalong Formation in the northeastern Sichuan Basin contains a suite of high-quality marine shales,with shale reservoirs governing shale gas enrichment.In this study,we investigate the deep-shelf shales in this formation using data from scanning electron microscopy(SEM)of argon-ion milled shale samples,low-temperature nitrogen adsorption and desorption method,and mercury injection capillary pressure(MICP)technique.The geochemistry and mineralogy of shales in the Dalong Formation reveal the dominant factors controlling the occurrence of shale reservoirs in the Formation while comparing with those of other marine shale reservoirs in the Sichuan Basin,including the Silurian Longmaxi Formation,the 3rd member of the Permian Maokou Formation(also referred to as the Mao 3 Member),and the 2nd member of the Permian Wujiaping Formation(also referred to as the Wu 2 Member).The results indicate that high-quality shales occur in deep-shelf and basin facies in the northeastern Sichuan Basin.These shales show a ring-shaped distribution along the Kaijiang-Liangping shelf,with a thickness ranging from 20 to 35 m.The deep-shelf shales in the Dalong Formation comprise mixed siliceous and calcareous siliceous shales.In the Nanjiang area,the shales measure 20 to 30 m in thickness and are dominated by mixed siliceous shales.In the Puguang area,they exhibit greater thicknesses ranging from 30 to 35 m and consist primarily of calcareous siliceous shales.In contrast,near the central part of the Kaijiang-Liangping shelf,the shales are slightly thinner,around 20 m,and predominately comprise siliceous shales.The shale reservoirs in the Dalong Formation feature high total organic carbon(TOC)content,brittleness index,porosity,and gas content.As porous reservoirs dominated by organic pores,these reservoirs typically exhibit high porosity combined with ultra-low permeability,a large proportion of micropores,and excellent pore connectivity.The developmental degree and types of pores in the Dalong Formation shale reservoirs are determi

关 键 词：有机质孔 储层特征 页岩 大隆组 二叠系 川东北地区 四川盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]