The lithofacies characteristics of fine sedimentary rocks affect the hydrocarbon generation capacity and reservoir performance of tight oil and are closely related to the sedimentary environment. On the basis of field outcrops and core observations, combined with logging data, thin section identification, grain size analysis, organic carbon analysis and physical property tests, the fine sedimentary facies of the Chang 7 Member in the Ordos Basin are studied. Nine lithofacies types are identified in the study area, including planar and trough cross-bedding sandstone facies (Spt), massive bedding sandstone facies (Sm), slump deformation fine sandstone facies (Ssd), sand-mud interbedded facies (Sb), rippled siltstones facies (Fr), horizontal bedding mudstone facies (Mh), massive bedding mudstone facies (Mm), horizontal bedding shale facies (S) and tuff facies (T). Lithofacies types Spt, Ssd, Fr are developed in the gentle slope belt in the northeastern study area, which is a delta front-semi-deep lake sedimentary environment and mainly contains underwater distributary channel and estuary dam sedimentary microfacies types. Lithofacies types such as Sm, Sb, Mh and T are developed in the southwestern steep slope zone of the study area, which is a channel-type gravity flow sedimentary environment, and sedimentary microfacies types such as near-source channels, far-source channels and leading-edge dolomites are developed. In the vertical direction, during the Chang 7₃ sedimentation period, the lake surface area and water depth reached their maxima, and S and Mh lithofacies developed, which were conducive to the formation of high-quality hydrocarbon source rocks for tight oil. During the Chang 7₂-Chang 7₁ sedimentation period, the lake basin shrank, and the reducibility of the water body weakened. The delta front sand body composed of Spt lithofacies in the northeast and the sandy clastic flow sand body composed of Sm in the southwest constitute the main tight oil reservoirs. High-quality hydrocarbon-generating lithofacies and favourable reservoir lithofacies are spatially superposed and developed, forming two source-reservoir combinations in the Chang 7 tight oil source-reservoir formation and near source-reservoir formation.

精细沉积岩的岩相特征影响致密油的生烃能力和储层性能，与沉积环境密切相关。在野外露头和岩心观测的基础上，结合测井资料，薄片识别，粒度分析，有机碳分析和物性测试，研究了鄂尔多斯盆地长7段的精细沉积相。研究区共确定了9种岩相类型，包括平面和低谷交叉层状砂岩相（Spt），块状层状砂岩相（Sm），坍落变形细砂岩相（Ssd），砂泥交错层相（Sb），波纹状粉砂岩相（Fr），水平顺层泥岩相（Mh），块状顺层泥岩相（Mm），水平层理页岩相（S）和凝灰岩相（T）。岩相类型Spt，Ssd，Fr发育于东北研究区的缓坡带，是三角洲前半深的湖泊沉积环境，主要包含水下分布通道和河口大坝沉积微相类型。研究区西南陡坡带发育有Sm，Sb，Mh和T等岩相类型，为通道型重力流沉积环境，近源，远源通道为沉积微相类型。和先进的白云岩被开发出来。在垂直方向上，昌7 它是三角洲前半深湖的沉积环境，主要包含水下分布通道和河口大坝的沉积微相类型。研究区西南陡坡带发育有Sm，Sb，Mh和T等岩相类型，为通道型重力流沉积环境，近源，远源通道为沉积微相类型。和先进的白云岩被开发出来。在垂直方向上，昌7 它是三角洲前半深湖的沉积环境，主要包含水下分流河道和河口大坝的沉积微相类型。研究区西南陡坡带发育有Sm，Sb，Mh和T等岩相类型，为通道型重力流沉积环境，近源，远源通道为沉积微相类型。和先进的白云岩被开发出来。在垂直方向上，昌7 开发了远源渠道和前沿白云岩。在垂直方向上，昌7 开发了远源渠道和前沿白云岩。在垂直方向上，昌7_3个沉积期，湖泊表面积和水深达到最大值，形成S和Mh岩相，有利于致密油优质烃源岩的形成。在Chang 7 ₂ -Chang 7 ₁沉积期间，湖盆收缩，水体的还原性减弱。东北部由Spt岩相组成的三角洲前砂体和西南部由Sm组成的砂质碎屑流砂体是主要的致密油藏。高质量的生烃岩相和有利的储层岩相在空间上叠加和发育，在长7致密油源-储层和近源-储层中形成了两个源-储组合。