马朗凹陷二叠系芦草沟组致密油源储特征

利用岩石取心、薄片、物性、有机质地化等资料,采用镜下观察、岩石热解分析、地化参数交会等方法,对三塘湖盆地马朗凹陷二叠系芦草沟组混积岩的源储特征和生烃潜力开展了分析,并讨论其成藏条件。结果显示,芦草沟组储层岩性分为泥岩、泥质灰岩、泥质白云岩和凝灰岩4类,储集空间以粒间孔—粒内孔、晶间孔、火山灰脱玻孔以及长英质溶蚀孔、溶蚀缝为主,物性特征为低孔、特低渗。烃源岩的优势岩性为白云质泥岩和泥岩,TOC平均值为4.41%,有机质类型主要为Ⅰ型和Ⅱ₂型, 成熟度以低成熟—成熟为主,源岩为有机质丰度高、有机质类型好、生烃演化处于生油阶段的优质烃源岩。综合分析认为, 芦草沟组浅—半深湖相混积岩源储一体,生烃潜力大,是一套具备“物资基础好、基本条件够、油气高效聚集”有利成藏条件的“自生自储、高效聚集、他源供给”云质岩致密油藏。

Tight oil source reservoir characteristics of Permian Lucaogou Formation in Malang Sag

Based on the data of rock coring, thin sections, physical properties and organic texture, the source reservoir characteristics and hydrocarbon generation potential of the Permian Lucaogou Formation migmatite in Malang sag, Santanghu basin are analyzed by means of microscopic observation, rock pyrolysis analysis and geochemical parameter intersection, and the reservoir forming conditions are discussed. The results show that the reservoir lithology of Lucaogou Formation is divided into mudstone, argillaceous limestone, argillaceous dolomite and tuff. The reservoir space is mainly intergranular pore intergranular pore, intergranular pore, volcanic ash devitrification pore, felsic dissolution pore and dissolution fracture, and the physical properties are low porosity and ultra-low permeability. The dominant lithology of the source rock is dolomitic mudstone and mudstone, with an average TOC of 4.41%. The organic matter types are mainly type I and type II 2, and the maturity is mainly low maturity maturity. The source rock is characterized by high organic matter abundance, good organic matter type and hydrocarbon generation evolution in the oil generation stage. The comprehensive analysis shows that the shallow semi deep lacustrine mixed sedimentary rock source reservoir of Lucaogou Formation is integrated, with great hydrocarbon generation potential. It is a set of "self generation, self storage, high-efficiency accumulation and other source supply" tight dolomitic oil reservoir with favorable reservoir forming conditions of "good material foundation, sufficient basic conditions and efficient accumulation of oil and gas".