北部湾盆地涠西南凹陷碳酸盐岩潜山储层特征与主控因素分析

北部湾盆地涠西南凹陷已发现多个碳酸盐岩潜山油田和含油构造，运用岩心、薄片、钻井、测井、地震等资料，对石炭系碳酸盐岩储层特征及主控因素进行了综合分析。研究认为涠西南凹陷碳酸盐潜山主要分布在一号断裂带至二号断裂带附近，其中一号断裂带碳酸盐岩潜山主要为上石炭统黄龙组，岩性为浅灰色灰岩、白云质灰岩、白云岩互层，沉积微相以碳酸盐台地-台缘生屑灰岩滩为主，发育裂缝、溶孔、溶洞等储集空间；二号断裂带碳酸盐岩潜山主要为下石炭统下部石磴子段、孟公拗段，岩性为灰色、深灰色灰岩，沉积微相以台内灰岩滩沉积和台缘生屑灰岩滩为主，发育良好的裂缝型储集层。碳酸盐岩潜山储层发育程度主要受碳酸盐岩沉积环境、地下水活动、古构造应力以及潜山上覆地层岩性等内因和外因诸多因素影响，在这些因素共同作用下，涠西南凹陷碳酸盐岩潜山发育孔隙、裂缝、溶洞等多种储集空间，具备良好的储集条件。

An analysis on the characteristics and main controlling factors of reservoir in carbonate buried hill in the Weixi'nan Sag, Beibuwan Basin

Several oil fields and oil-bearing structures had been found in carbonate buried hills in Weixi''nan Sag of the Beibuwan Basin during the last forty years. In this paper, a comprehensive analysis had been made to study the carbonate reservoir characteristics and its main controlling factors based on core and thin-section observation, drilling and logging information and seismic data. Carbonate buried hills were found distributed around the area between No.1 and No.2 Fault Belt. The carbonate strata in No.1 Fault Belt were mainly light grey limestone, dolomitic limestone and dolomitite interaction of Huanglong formation in upper Carboniferous, which deposited in the environment of bioclastic lime bank of carbonate platform and platform margin. Fissure, dissolved pore and cave constituted its main reservoir space. The carbonate strata in No.2 Fault Belt was mainly grey and dark grey limestone of Shidengzi member and Menggong''ao member in lower Carboniferous, which deposited in the environment of lime bank of intra-platform and bioclastic lime bank of platform margin. And fissure was its main reservoir type. The development degree of carbonate reservoir in buried hills was mainly controlled by sedimentary environment, groundwater activity, paleotectonic stress and overlying strata. Affected by these factors together, carbonate buried hills in Weixi''nan Sag developed good reservoir condition with multiple reservoir types of pore, fissure and karst cave.