珠江口盆地惠州凹陷HZ25-7构造古近系成像测井沉积学研究

Imaging Logging Sedimentology Study on Paleogene System in HZ25-7 Structure of Huizhou Depression in Pearl River Mouth Basin

珠江口盆地惠州凹陷HZ25-7构造是近年来发现的一个重要的深层古近系含油岩系,因岩性复杂,致使物源、沉积环境及有利储层分布等认识不清,给进一步勘探开发带来很大难度。以古近系文昌组和恩平组为研究对象,利用高分辨率成像测井资料,结合岩心分析资料和常规测井资料,精细分析了该区地层的岩性特征和沉积构造特征,认为目的层段为辫状河三角洲沉积,并建立了陆上辫状河道、水下分流河道及河口坝3类关键微相砂体的测井响应特征;通过对井点处古水流方向及物源方向分析,认为物源主要来自南部,并长期持续存在。最后,结合区域地质背景及综合研究,建立了文昌组关键砂体的沉积微相平面展布,指出了研究区有利储层的分布方向。

The HZ25-7 structure is one of the very important oil-bearing series find in deep Paleogene of Huizhou depression in Pearl River Mouth Basin in recent years,but because the lithology,source direction and depositional environment of this structure are complicate,it is difficult for further exploration and development. Focused on the Wenchang Formation and Enping Formation,this paper detailedly analyzes the characteristics of lithology and sedimentary structure of the study area using the high-resolution electric imaging data together with core data and conventional logging data.The result indicates that the objective interval is of braided river delta. The logging response characteristics of three sedimentary microfacies,i.e.braided channel,subaqueous dis-tributary channel and mouth bar are established.The analysis of palaeocurrent direction shows that the source is migrated from south to north for a long time.Then the regional distribution of microfacies of the key sandbody is mapped based on the above results and the regional geological background,indicating the distribution direction of the favorable reservoir in the study area.