储层流动单元划分方法评价及优选

Evaluation and optimization of flow unit division methods

开展储层流动单元研究对于定量刻画储层非均质性、提高测井解释精度及认识剩余油分布具有重要意义,但其识别方法较多,且适用性存在差异。以珠江口盆地W油田为例,对比了4种不同的流动单元定量划分方法,并探索了其适用性。研究认为:修改的地层Lorenz图法和流动分层指标法均基于孔渗比值关系,难以识别致密层;孔喉几何形状法虽能识别致密层,但对质量较好的储层区分作用不明显,而对质量较差的储层划分又过细;非均质综合指数法同时考虑了控制储层平面非均质性的定性参数和表征流体渗流特征的定量参数,将致密层单独划分为一类流动单元,有效区别于其他油水层,划分结果避免了异常点或过渡类型的影响,能够全面、合理地反映储层非均质性。

Research on flow units is significant for the studies of reservoir heterogeneity and remaining oil distribution, as well as improving accuracy of well log interpretation models. Methods of flow unit identification are various, and their applicability is also different. Taking W oilfield in the Pearl River Mouth Basin as an example, this paper respectively used four methods to identify flow units, including modified stratigraphic Lorenz plot, flow zone indicator, integrated index of reservoir heterogeneity and pore throat aperture. Both modified stratigraphic Lorenz plot method and flow zone indicator method are based on permeability and porosity ratio, so it is difficult to identify tight reservoir. Pore throat aperture method can be used to identify tight reservoir, but it is difficult to differentiate high quality reservoir and metieulous to divide low quality reservoirs. Integrated index of reservoir heterogeneity synthesizes various qualitative and quantitative parameters, it divides tight reservoir as a separate kind of flow unit which can be effectively distinguished from other oil layer, and the division result can reflect reservoir heterogeneity reasonably, so it is the best method for flow unit division in the study area.