海上复杂断块油田储层流动单元研究与应用——以北部湾A油田A1/A5断块为例

The study and application of reservoir flow unit in complex faulted block in offshore oilfield:Taking A1/A5 faulted block of A oilfield in Beibu Gulf as an example

开展海上复杂断块油田储层流动单元研究对刻画储层连通程度、剩余油的分布情况有着十分重要的实际意义。以北部湾A油田A1/A5断块为例,首先对复合砂体内单砂体的识别来建立流动单元研究的精细地质格架,然后结合断层封闭性、隔夹层分布、砂体接触关系所形成的渗流屏障进行流动单元划分。利用主成分分析和相关性分析的方法进行参数优选,确定孔隙度、泥质含量、渗流系数作为研究区流动单元分类的主要参数,并通过神经网络聚类分析将流动单元分为3类。在单井、剖面、平面流动单元展布研究的基础上,运用截断高斯模拟方法建立流动单元三维地质模型。结果表明:Ⅰ类流动单元具有最好的储渗能力,所钻油井累计产量比较高,但分布范围局限,成土豆状分布于水下分流河道中心部分;Ⅱ类分布范围最广,储渗能力较好,分布在水下分流河道微相中,剩余油分布较多,通过调整挖潜可以开发其生产潜力;Ⅲ类大多成条带状分布,主要位于水下溢岸砂沉积部位,储渗能力最差,产量很低,其开发潜力也比较差。

Research on reservoir flow units in complex faulted block in offshore oilfield has very important practical significance for the studies of reservoir connectivity degree and remaining oil distribution. Taking A1/A5 faulted block of A oilfield in Beibu Gulf as an example, firstly the fine geological framework of flow unit was established through identification of the single sand body in the compound sand bodies. Then the flow unit was divided through impermeable shields formed by fault sealing, interlayers/interlining distribution and the contact relationship of sand body. We conducted parameter optimization through component analysis and correlation analysis and deter- mined porosity, shale content and seepage coefficient as the main parameters for flow unit classification in the study area. Through neural network clustering analysis the flow unit was divided into three types. Based on the study of flow unit in single well, profile, and plane distribution, three-dimensional geological model of flow unit was estab- lished by making use of Truncated Gaussian Simulation method. The results show that type I has the best reservoir seepage ability and provides a high cumulative production, however its distribution is limited to a potato shape in the central part of underwater distributary channels. Type Ⅱ distribution is most widely distributed in the underwa- ter distributary channels microfacies with preferably reservoir seepage ability and much remaining oil distribution and its productive potential can be improved through adjustment and exploitation. Type Ⅲ has a banded distribu tion mainly in the underwater bank sand deposition area with wrost reservoir seepage capacity , low production and poor development potential.