油藏内部阻渗屏障等效表征方法探讨——以渤海A油田新近系为例

Discussion on equivalent characterization method of reservoir permeability barrier,taking Neogene of Bohai oilfield A as an example

海上油气田受平台规模约束,开发井距大,地质不确定性贯穿开发全寿命历程,对于油藏内部影响开发效果、但无法精确刻画的小尺度(厚度小于5 m、展布范围小于500 m)阻渗屏障体,等效表征是主要解决方案。本文以渤海A油田为例,探讨了小尺度阻渗屏障体的等效表征方法。具体为:首先,基于新近系浅水三角洲地质知识库,从储层构型角度入手,总结了构成潜在渗流屏障的地质界线,包括沙坝-沙坝、沙坝-河道、河道-河道三种界线类型;然后,通过简化界线几何形态模式,开展机理建模,包括两套模型:小尺度网格精细原型模型、大尺度网格粗化等效模型;最后,设定无水采油期、采收率(30年)、剩余油分布规模作为检验条件,开展数值模拟等效实验,落实最优网格方案及渗透性参数,并基于实验结果,建立了A油田典型单元的渗流屏障等效地质模型。

The offshore oil and gas fields are constrained by the platform scale,with large development well spacing.The geological uncertainty runs through the whole development life cycle.For the small scale permeability barriers(thickness lower than 5 m,distribution range less than 500 m)which affect the development effect but can not be accurately characterized in the reservoir,equivalent characterization method is the main solution.Taking Bohai oilfield A as an example,in this paper,the equivalent characterization method is discussed for small scale permeability barrier.Firstly,based on the geology knowledge database of Neogene shallow water delta,from the perspective of reservoir configuration,the geological boundaries that constitute potential permeability barriers are summarized,including 3 types of boundaries,bar-bar,bar-channel and channel-channel.Secondly,by simplifying the boundary geometry model,the mechanism modeling is carried out,including 2 sets of models,small grid fine prototype model and large grid coarsening equivalent model.Finally,setting water-free production period,recovery factor(30 years)and remaining oil distribution as test criteria,numerical simulation equivalent test is carried out,and the optimal grid scheme and permeability parameters are implemented.Based on the test results,the equivalent geological model of permeability barrier of typical unit in oilfield A is established.