海上油田开发早期储层构型研究及应用——以渤中A油田X沉积体为例

渤海新近纪浅水三角洲沉积储层纵横向变化快、隔夹层发育,在少井条件下如何开展储层展布研究及水平井部署是海上油田开发早期亟待解决的问题。以渤中A油田浅水三角洲相X沉积体为例,据岩心、测井、地震等资料分析储层沉积特征,在高分辨率层序地层学指导下细分成因单元,分析单砂体对应测井、地震波形特征并刻画其展布。研究区储层类型以叠置分流河道、河口坝及河道间沉积为主,结合高分辨率地层学将目的层划分为1个短期旋回、4个超短期旋回,反映了一套基准面逐渐下降至暴露环境,后基准面上升至再次湖泛的过程。根据储层沉积特征、地震响应特征和复合砂体精细构型研究,识别出复合砂体的3种接触关系,同时对X沉积体进行了单河道识别和隔夹层分布规律研究,将X沉积体细分为3期单元砂体,并总结出3种储层结构类型,结合已有水平井的生产动态特征,提出X沉积体水平井部署的4种开发模式,有效指导了开发井实施。

FINE RESERVOIR CHARACTERIZATION AND ITS APPLICATION TO EARLY DEVELOPMENT OF AN OFFSHORE OILFIELD: A CASE STUDY FROM THE SAND BODY X OF BOZHONG A OILFIELD

The Neogene shallow-water deltaic reservoir, which bears many intercalations, changes quickly both vertically and horizontally in the Bohai Oilfield. Predicting the reservoir distribution and optimizing the location of horizontal wells need to be solved in the early stage of development in order to reduce the well number to the minimum. The shallow-water deltaic deposit in the Bozhong A oilfield is selected as an example in this case of study. According to the data of cores, logging and seismics, the deposits are divided into several genetic units under the guidance of high resolution sequence stratigraphy. In the study area, distributary channels, mouth bars and river sediments are well developed. The depositional sequence includes 1 short-term cycles and 4 ultra-short-term cycles, reflecting a progradational sequence as the sea-level decline to exposure, and then a retrogradational sequence as the sea level rising again to the flooding surface. According to the deposition pattern and sequence characteristics, 3 kinds of contact relationship of the composite sand body are identified. Moreover, single-channel sand body and distribution of interlayers are predicted. The sand body X is separated into three upon structures. Combining with the production characteristics of horizontal wells, suggestions are made for optimization of horizontal wells under the four development modes.