北部湾盆地涠西南凹陷D洼新近系稠油成因及资源潜力分析

Genesis and Resource Potential Analysis of Neogene Heavy Oil in D Sub-sag,Weixinan Sag,Beibuwan Basin

北部湾盆地涠西南凹陷自开展油气勘探活动以来,在主洼先后发现多个油田,而D洼勘探直到近几年才取得突破性进展。针对D洼的研究尤其是对新近系浅层首次发现的稠油油藏缺乏认识的问题,该文利用新井资料及周边区域地质资料,运用地球化学及成藏等综合分析方法,对涠西南凹陷D洼稠油特征、成因机制及主要成藏条件进行了系统的研究分析,取得了一系列的研究成果。研究发现D洼稠油为生物降解形成的高密度、高黏度、高沥青质、低含硫含蜡次生稠油。同时利用其成藏机理预测了整个D洼新近系浅层可能存在的含油气圈闭,研究成果对今后在涠西南凹陷D洼浅层勘探具有重要的理论指导意义。

Since the oil and gas exploration activities were carried out in Weixinan Sag of Beibu Gulf Basin,several oilfields have been found in the main depression,while the exploration of D Sub-sag has not made a breakthrough until recent years.The research on D Sub-sag,especially the first discovery of the heavy oil reservoir in Neogene,is lack of knowledge.In view of this problem,the characteristics,genetic mechanism and main reservoir forming conditions of the heavy oil in D Sub-sag of Weixinan Sag are systematically studied and analyzed by using new well data and regional geological data,geochemical and reservoir forming methods,and a series of research results are obtained.It is found that the heavy oil in D Sub-sag is the secondary heavy oil with high density,high viscosity,high asphaltene,low sulfur and wax content.At the same time,potential hydrocarbon traps of the whole D Sub-sag in Neogene are predicted by using the reservoir forming mechanism.The research results have important theoretical guiding significance for the future shallow exploration in D Sub-sag of Weixinan Sag.