四川盆地下寒武统龙王庙组沉积相与储层分布预测研究

寒武系龙王庙组白云岩已经成为四川盆地非常重要的天然气勘探领域，并在高石梯_磨溪地区发现了万亿方储量规模的大气藏，但对储层成因和分布规律认识不清已经成为制约龙王庙组白云岩勘探的瓶颈。基于露头地质调查、岩心和薄片观察、储层地球化学特征及储层模拟实验，对这套白云岩储层的特征、成因和分布规律做了深入的研究，取得2项认识:一是四川盆地寒武系龙王庙组可划分为上、下2段，编制了以段为单元的岩相古地理图2张，建立了碳酸盐岩缓坡沉积模式，颗粒滩主要分布于上段的浅缓坡；二是颗粒滩是龙王庙组白云岩储层发育的基础，同生溶蚀作用是龙王庙组颗粒滩储层孔隙发育的关键，受暴露面控制，埋藏期溶蚀孔洞不但有规模，而且主要沿同生期的孔隙带发育，具继承性，分布有规律可预测。龙王庙组白云岩储层成因地质认识揭示储层的发育不仅限于高石梯_磨溪构造表生岩溶发育区，全盆地广布的颗粒滩相沉积都是潜在的勘探对象。

The facies and porosity origin of reservoirs:Case studies from Longwangmiao Formation of Cambrian,Sichuan Basin,and their implications to reservoir prediction

The dolostone of Cambrian Longwangmiao Formation has been significant gas exploration area in Sichuan Basin.In Gaoshiti-Moxi regions,giant gas pool with thousands of billion cubic meters’ reserve has been discovered.But the origin of reservoir and the distribution patterns were still in dispute,which has constrained the dolostone exploration of Longwangmiao Formation.Based on the outcrop geological survey,cores and thin-sections observation,reservoir geochemical characteristics study and reservoir simulation experiments,this paper focuses on the characteristics,origin and distribution patterns of the dolostone reservoir in Longwangmiao Formation.Two achievements were acquired:①The Longwangmiao Formation of Cambrian could be divided into upper part and lower part in Sichuan Basin.Based on the two parts of Longwangmiao Formation,two ligthofacies paleogeographic maps were accomplished and the carbonate ramp sedimentary models were established.The grainstone shoals are mainly distributed in the shallow ramp of the upper part in Longwangmiao Formation.②The grainstone shoals are the developing basis of dolostone reservoir in Longwangmiao Formation and the contemporaneous dissolution was the key factors of the development of grainstone shoal reservoir in Longwangmiao Formation.Controlled by the exposure surface,the dissolution vugs are not only extensively distributed,but also successionally developed along the contemporaneous pore zones.The distribution patterns could be predicted.The geological understandings of the origin of dolostone reservoir in Longwangmiao Formation show that the reservoir distributed in the areas of karstification in Gaoshiti-Moxi regions,and the widespread grainstone shoals in the whole basin are the potential exploration targets.