基于砾石-基质-裂缝三元素的砂砾岩岩相划分

近年来砂砾岩油气藏勘探不断获得重大发现，使得砂砾岩体成为油气勘探的新领域.当前，砂砾岩体侧重于沉积响应分析，针对其特征的岩相组合划分及差异性探讨较薄弱，缺乏统一划分标准，尤其是在渤海湾盆地渤南低凸起南侧断坡区古近系砂砾岩存在多砾石组分、复合成岩作用影响，极大制约优质砂砾岩储层的分布预测、评价.因为研究区内多物源供给，砾石组分、支撑类型和基质类型多样，基于区内典型钻井岩心、镜下综合观察及扫描电镜分析，提出“以沉积岩、变质岩及岩浆岩三种母岩类型为一级划分标准，支撑类型和基质类型作为二级划分标准”，将砂砾岩岩相划分为三大类、七小类，依次为:（1）以火山岩砾石为主的基质支撑-砂级基质-构造缝-砾岩相、颗粒支撑-砂级基质-砾缘缝-砾岩相、基质支撑-泥级基质-砾岩相，（2）以碳酸盐岩砾石为主的基质支撑-砂级基质-砾岩相、基质支撑-砂级基质-角砾岩相，（3）以变质岩砾石为主的胶结物支撑-砂级基质-含砾砂岩相及颗粒支撑-砂级基质-压实砾内缝-含砾砂岩相.不同砾石类型储层中，基质类型和裂缝发育程度具有明显的差异性，泥质含量高的储层渗透性很差，裂缝发育会改善其孔隙的连通性，并诱导形成砾内溶蚀和基质溶蚀，从而改善储集物性. 

Division of Glutenite Lithofacies Based on the Trielement of Gravel-Matrix-Fracture

In recent years, glutenite oil and gas reservoir exploration has continuously made major discoveries, making the conglomerate body a new field of oil and gas exploration. At present, the conglomerate body is focused on sedimentary response analysis, and its characteristics of lithofacies combination division and differences are relatively weak, and there is a lack of a unified division standard, especially in the Paleogene in the southern slope area of the Bonan low uplift in the Bohai Bay basin. There are multiple gravel components and composite diagenesis in the sandy conglomerate, which greatly restricts the distribution prediction and evaluation of high-quality sandy conglomerate reservoir. Due to the multiple sources of supply in the study area, the gravel composition, support type and matrix type are diverse. Based on the typical drilling core in the area, comprehensive observation under the microscope and scanning electron microscope analysis, it proposes the "three parent rocks of sedimentary rock, metamorphic rock and magmatic rock. The type is the first-level classification standard, and the support type and matrix type are the second-level classification standards." The sandstone and conglomerate lithofacies are divided into three major categories and seven subcategories, followed by (1) matrix support mainly based on volcanic matrix support-sand-level matrix-structural fracture-conglomerate facies, particle support-sand-level matrix-intra-gravel fracture-conglomerate facies, matrix support-mud-level matrix-conglomerate facies, (2) matrix support mainly composed of carbonate conglomerate-sand-level matrix-conglomerate facies (carbonate rock and gravel), matrix support-sand grade matrix-breccia facies, (3) cement support mainly composed of metamorphic rock and gravel-sand grade matrix-concrete sandstone facies, and particle support-sand grade matrix-gravel-edge fracture-concrete sandstone facies. In reservoirs of different gravel types, the matrix type and fracture development degree are obviously different. The reservoir with high mud content has poor permeability. The fracture development will improve the connectivity of its pores and induce the formation of intra-gravel dissolution and matrix dissolution to improve storage properties.