准噶尔盆地阜康断裂带二叠系芦草沟组页岩油成藏条件

Shale oil accumulation conditions of Permian Lucaogou Formation in Fukang fault zone,Junggar Basin

准噶尔盆地阜康断裂带地处盆地前陆冲断带,构造复杂,勘探开发潜力大。通过烃源岩有机地球化学测试、铸体薄片鉴定、扫描电镜分析等对准噶尔盆地阜康断裂带二叠系芦草沟组页岩油成藏条件进行了分析。研究结果表明:①阜康断裂带二叠系芦草沟组烃源岩有机质丰度高,TOC质量分数平均为3.65%,有机质类型主要为Ⅱ_(1)型,R_(o)值为0.76%~1.41%,多处于成熟—高成熟阶段,为一套好—优质烃源岩。②研究区芦草沟组储层孔隙度平均值为5.12%,渗透率为0.02~2.69 mD,为一套低孔—特低孔、特低渗储层;储层岩石类型复杂,是以泥页岩、粉砂岩、碳酸盐岩为主的一套混积岩,脆性矿物质量分数平均为82.96%;储集空间类型包括粒间孔、晶间孔、溶蚀孔、有机质孔和微裂缝。③广覆式烃源岩、大面积连续分布的优势岩相以及有利的源储组合控制了研究区芦草沟组页岩油的富集成藏,形成了“源储紧邻的夹层型”与“源储一体的基质型”共存的页岩油富集模式,大龙口地区、小龙口—奇1井地区可作为下一步勘探开发的重点区域。

Fukang fault zone is located in the foreland thrust belt of Junggar Basin,with complex structure and great exploration and development potential.The shale oil accumulation conditions of Permian Lucaogou Formation in Fukang fault zone were analyzed through organic geochemical testing of source rocks,cast thin section identification and scanning electron microscope analysis.The results show that:(1)The source rocks of Permian Lucaogou Formation in Fukang fault zone have high organic matter abundance,with an average TOC mass fraction of 3.65%,and the organic matters are mainly type Ⅱ_(1) with R_(o) values of 0.76-1.41,mostly in the mature to high mature stage,which is a set of good to high-quality hydrocarbon source rocks.(2)The average porosity of the reservoirs of Lucaogou Formation in the study area is 5.12%,and the permeability ranges from 0.02 mD to 2.69 mD,which is a set of reservoirs with low to extra-low porosity and extra-low permeability.The reservoir rock type is complex,and it is a set of hybrid sedimentary rocks dominated by mud shale,siltstone and carbonate rocks,with an average brittle mineral mass fraction of 82.96%.The reservoir space includes intergranular pores,intercrystalline pores,dissolved pores,organic matter pores and microfractures.(3)The widely overlying hydrocarbon source rocks,the dominant lithofacies distributed continuously in a large area and the favorable sourcereservoir configuration control the shale oil enrichment and accumulation of Lucaogou Formation in the study area,forming a shale oil accumulation model of“source-reservoir adjacent interval type”and“source-reservoir integrated matrix type”coexistence.Dalongkou area and Xiaolongkou to Qi 1 well area are the key areas for the next exploration and development.