北部湾盆地涠西南凹陷南坡古近系流二段滩坝砂体分布规律

涠西南凹陷南坡H 1井区流二段发育了一定规模的滨浅湖滩坝砂体。在滩坝砂体沉积特征分析的基础上，利用地震沉积学分析方法和技术，对滩坝砂体分布规律及演化特征进行了研究。在沉积模型控制和钻井资料标定的基础上，地层切片属性分析能够较好的反映滩坝砂体的分布范围，并且能够较好的对坝砂和滩砂沉积进行区分和识别。地层切片分析表明MC1旋回内滩坝砂体早中期表现为进积特征，滩砂和坝砂沉积范围均明显扩大和迁移，中晚期表现为加积特征，坝砂厚度和范围明显增加；MC2旋回内滩坝砂体沉积过程中分布范围变化不大，滩砂和坝砂均呈明显的垂向加积特征。两个旋回内坝砂沉积主要呈相互平行的条带状分布在研究区东南部及中部。为了增加钻井成功率和探明滩坝砂体主体发育特征，建议目前的勘探重点应放在研究区东南部及中部坝砂沉积发育区。

Distribution of Beach-bar Sandbodies of the Second Member of Liushagang Formation of Paleogene of South Slope in Weixinan Depression, Beibuwan Basin

During the period of the second member of Liushagang Formation, there developed a certain scale  of beach bar sandbodies. Based on the analysis of sedimentary characteristics of beach bar sandbodies, the distribution and evolution characteristics of beach bar sandbodies were studied by using the method and technology of seismic sedimentology. According to the controlling of sedimentary model and the demarcation of drilling data, the analysis of seismic property of stratal slice could image the distribution area of beach bar sandbodies well and could also recognize and distinguish the beach sands and bar sands effectively. The analysis of statal slices indicates that the sandbodies were progradation at the early and middle stage of MC1 cycle and the sedimentary areas of beach sands and bar sands were extended and migratory obviously, while the sandbodies were vertical aggradation at the middle and late stage of MC1 cycle and the thickness and area of bar sands increased obviously. The distribution area of sandbodies was comparatively stable and the beach sands and bar sands were vertical aggradation during the process of beach bar development at the period of MC2 cycle. The bar sands of the two cycles were, parallel to each other as strips, mainly distribution at the southeast and centre parts of studying area. In the interest of increasing the successful rate of wells and prove up the development characteristics of main bodies of beach bar sandbodies, the exploration should be emphasis on the bar sands development area in southeast and centre parts of studying area.