北部湾盆地涠西南凹陷灰岩潜山储层特征及分布规律

北部湾盆地涠西南凹陷经过多年勘探，常规碎屑岩领域勘探潜力越来越小，灰岩潜山勘探程度低，剩余资源潜力大，1，2号断裂带周缘已发现多个潜山油田或含油构造，展示了其良好的勘探前景。综合利用岩心观察、薄片分析、测井分析、测试分析等，结合区域构造演化及海平面波动研究灰岩潜山储层特征，深入剖析灰岩潜山有利储层控制因素及展布规律，研究表明，涠西南凹陷1号断裂带灰岩潜山主要为碳酸盐岩台地边缘滩相储层，发育颗粒灰岩，为后期构造破裂作用和岩溶作用提供了良好的物质基础，储层储集空间为孔隙+缝、洞型，强烈白云岩化明显改善孔隙型储层，同时，1号断裂带周缘（廉江-信宜断裂向海延伸）经历中生代早期左旋压扭及晚期右旋张扭的复杂构造演变，晚期的张扭型裂缝可为岩溶提供良好的渗流通道，加速了风化淋滤的进程，形成沟通良好的溶蚀孔洞。指出涠洲E近似于涠洲A区，位于强应力的构造裂缝发育区，白云化及溶蚀作用发育，为有利勘探方向，为涠西南凹陷灰岩潜山勘探提供地质依据。

Characteristics of limestone buried-hills and their distribution in the Weixinan Depression of the Beibu Gulf Basin

After years of exploration in the Weixinan Depression of the Beibu Gulf Basin, the oil fields in conventional clastic rocks become rare with time. However, the degree of exploration in the limestone buried-hill is low, and the remaining resources are great in amount. A number of buried-hill oil fields and/or oil-bearing structures have been found in the surrounding areas of the fault zones 1and 2, and show good prospects for exploration. By means of core observation, thin section determination, well logging analysis and other laboratory testings, combined with a thorough review of regional tectonics and sea level fluctuations, the controlling factors and the distribution of high-quality reservoirs are studied in this paper. The following understandings are obtained. The types of pore and fracture-cave reservoir space are widely distributed in grain limestone which is well developed in the border of carbonate beaches of carbonate platforms, and may provide a high quality material basis for the later fracturing and karstification. Strong dolomitization obviously improves the pore type reservoir. Besides, The fault zone 1, which is the extension of the Lianjiang-Xinyi fault offshore have experienced complex tectonic evolution from sinistral rotation and compressive shearing to the dextral transtensional later in the Mesozoic Era. The later transtensional fault may provide percolation path for karst structures, which accelerated the process of weathering and eluviation to form holes and pores of good communication. It is further pointed out that the Weizhou E is a favorable exploration target similar to the Weizhou A, located in the zone of strong stress where structural fractures accelerated dolomitization and dissolution. The research results provide a geological guidance for the exploration of limestone buried-hill in the Weixinan Depression.