马朗凹陷芦草沟组泥页岩储层含油性特征与评价

The Oil-bearing Property Characteristics and Evaluation of Lucaogou Formation Shale Reservoirs in Malang Sag

通过泥页岩常规岩芯与密闭取芯的地球化学分析、物性分析、压汞实验分析等,评价马朗凹陷二叠系芦草沟组泥页岩储层的含油性,结合试油情况,研究其富油机制以及有利储层分布特征。结果表明,芦草沟组泥页岩储层含油性受有机质丰度和孔隙度影响,有利层段总有机碳要大于4%,孔隙度大于3%。体积含油率比含油饱和度更能准确表征泥页岩的含油性,油层要求含油率大于1%。压汞分析显示,泥页岩的储层富油机制与常规砂岩不同,包括未运移烃类的就地滞留富集和经历短距离初次运移在与优质源岩临近的次源岩层系中富集两个过程。芦草沟组页岩油的富集受岩性组合类型的影响,以泥岩为主,夹(薄层)泥质灰岩、泥质白云岩或者以灰质泥岩、白云质泥岩为主,为该区最有利岩性组合,含油性最好,对应于深湖—半深湖的沉积环境。

Through geochemical analysis, physical analysis and mercury intrusion analysis of conventional shale core and sealing drilling shale core, combining with the production oil test, this paper discussed the oil-bearing property of Lucaogou Formation shale oil reservoirs in Malang sag. It also studied the accumulation mechanism of shale oil, and the characteristics favorable reservoir development and distribution. The results show that the oil-bearing property of Lucaogou Formation shale is under the control of the richness of organic matter and porosity of the shale reservoirs. The TOC （ % ） of the shale reservoirs enriched oil should be more than 4%, and the porosity should be more than 3%. Volume- oil-beating rate （Po, % ） Can reflect the oil-bearing property of the shale reservoirs more accurate than the oil saturation. For shale reservoir enrichment in oil, the volume- oil-bearing rate should be more than 1%. Mercury in- jection data indicate that oil enrichment mechanism of shale reservoir is different from conventional sandstone reser- voirs. Oil entering the shale reservoirs includes two processes, one is that hydrocarbon was stranded in source rock without migration, the other is that oil moved into poor-source rock system near high quality source rock by short dis- tance primary migration. Beneficial lithologic association is the main influence factor for shale oil enrichment. The con- figuration relation of mudstone interbedded by argillaceous limestone, argillaceous dolomite or in calcareous mudstone and dolomitic mudstone is primarily the optimal lithologic association, and has the best oil-bearing property, which is deposited in sedimentary environment of deep lake and semi-deep lake.