陆丰A油田恩平组上段辫状河三角洲沉积特征及油气控制

Sedimentary Characteristics and Hydrocarbon Control of Braided River Delta in the Upper Enping Formation of Lufeng A Oilfield

基于对陆丰A油田恩平组上段储层岩性、岩石成分、岩石结构、岩石粒度、沉积构造、测井相及砂体分布特征的综合分析,认为恩平组上段是较强水动力条件下牵引流沉积的产物,其沉积环境为辫状河三角洲,发育三角洲前缘的水下分流河道、河道侧缘、分流河道间、席状砂、河口坝5种沉积微相。恩平组上段整体上表现为一个海进的过程,早期,海平面低,以发育厚层宽条带状水下分流河道为主;中期,随着海平面上升,波浪改造作用增强,研究区东南部河口坝、席状砂分布增多;晚期,海平面达到最高,分流河道分叉增多,前端河道呈窄条带状,河口坝、席状砂分布连片。沉积微相对储层物性、含油气性的控制作用明显,水下分流河道、河口坝物性最好,是油气聚集的主要相带,下一步井网部署应优先考虑。

Based on the comprehensive analysis of reservoir lithology,rock composition,rock structure,rock grain size,sedimentary structure,logging facies and sand body distribution characteristics of the upper member of Enping formation in Lufeng A oilfield,it is considered that the upper member of Enping formation is the product of tractive flow deposition under strong hydrodynamic conditions,and its sedimentary environment is braided river delta.There are five sedimentary microfacies in the delta front,including underwater distributary channel,lateral edge of channel,inter distributary channel,sheet sand and mouth bar.The upper member of Enping formation is a transgressive process.In the early stage,the sea level was low,and the thick layer and wide strip underwater distributary channel was relatively developed;in the middle stage,with the rise of sea level and the enhancement of wave transformation,the distribution of estuarine bar and sheet sand in the southeast of the study area increased;in the late stage,the sea level reached the highest;the distributary channel bifurcated more;the front channel was narrow strip,and the estuarine bar and sheet sand were widely distributed.The physical properties of underwater distributary channel and mouth bar are the best,which are the main facies belt of oil and gas accumulation,so the next well pattern deployment should be given priority.