羌塘盆地捷来白云岩古油藏特征及油气地质意义  

Characteristics of Jielai paleo-oil reservoir dolomites in Qiangtang basin and its petroleum geological significance

作　　者：孙逍晓 梁鹰 韩中鹏[1] 张栩 张烨 李亚林[1] SUN XiaoXiao;LIANG Ying;HAN ZhongPeng;ZHANG Xu;ZHANG Ye;LI YaLin(School of Earth Science and Resources,China University of Geosciences(Beijing),Beijing 100083,China)

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083

出　　处：《岩石学报》2025年第3期1084-1100,共17页Acta Petrologica Sinica

基　　金：第二次青藏高原综合科学考察研究(2019QZKK0803)资助.

摘　　要：中侏罗统布曲组白云岩是青藏高原南羌塘坳陷(盆地)古油藏带最为重要的储集岩,然而对古油藏的空间展布、储集物性和油源还存在争议,也制约了对盆地油气成藏条件和资源潜力的认识。根据岩石薄片、铸体薄片、储层物性、生物标志物等分析,本文探讨了南羌塘盆地古油藏带东段捷来地区新发现的含油白云岩的岩石学、储集物性和油源特征。研究结果表明捷来古油藏白云岩具中-粗晶结构,储集空间类型丰富,包括晶间溶孔、构造裂缝和溶蚀缝,白云岩孔隙度为1.75%~13.91%,平均为8.78%;渗透率为0.34×10^(-3)~35.31×10^(-3)μm^(2),平均29.53×10^(-3)μm^(2),储层类型为中孔中渗-低孔中渗型。捷来古油藏白云岩与南羌塘隆鄂尼、达卓玛地区古油藏白云岩具有相似的特点,生油母质主要为低等水生生物,同时包含高等陆生植物,其沉积环境具有还原、淡水-微咸水的特征。生物标志化合物等分析显示含油白云岩油源主要来源于曲色组油页岩,同时曲色组-色哇组泥岩也有少量贡献,表现出混合来源的特点。白云岩储层物性以及油源分析结果表明,以曲色组和色哇组为烃源岩、布曲组白云岩为储层、夏里组泥岩和膏盐岩为盖层组成的生储盖组合为南羌塘坳陷主力成藏组合。The dolomite of Middle Jurassic Buqu Formation is the most important reservoir of the South Qiangtang depression(basin)paleo-oil reservoir.However,the distribution,physical properties and oil source of the dolomites are still controversial,bringing an obstacle for understanding the hydrocarbon accumulation and resource potential of the Qiangtang basin.Based on the analysis of rock thin section,cast thin section,reservoir physical properties,and biomarker of the newly discovered Jielai paleo-oil dolomite in the eastern section in the South Qiangtang,we discuss the petrology,physical properties,and oil sources of the paleo-oil reservoir.The results show that the dolomite is mainly medium to coarse-crystalline texture with abundant reservoir space types,including intercrystalline dissolution pores,tectonic fractures and dissolution fractures.The dolomite porosity is 1.75%to 13.91%,with an average value of 8.78%.The permeability range is 0.34×10^(-3) to 35.31×10^(-3)μm^(2),with an average of 29.53×10^(-3)μm^(2).The reservoir types show medium porosity and medium permeability to low porosity and medium permeability,which is similar to the dolomites of the Longeni and Dazhuoma paleo-oil reservoirs of South Qiangtang.The oil source rocks of dolomites mainly come from lower aquatic organisms and partial higher terrestrial plants.The sedimentary environment of the dolomites shows the characteristics of reduction,fresh-brackish water.The biomarker compounds indicates that the oil source of the dolomite is mainly from the Quse Formation oil shale,while the Quse Formation and Sewa Formation mudstone also provides some contribution,thus the paleo-oil reservoir is characterized by mixed sources.The above results indicate that the source-reservoir-cap rock assemblage of the South Qiangtang Depression is mainly consists of Quse Formation and Sewa Formation as source rock,Buqu Formation dolomite as reservoir,Xiali Formation mudstone and salt-rock as cover.

关 键 词：羌塘盆地 古油藏 白云岩 储集层 油源对比 

分 类 号：P531[天文地球—古生物学与地层学] P588.245[天文地球—地质学] P618.13