低渗透裂缝性油藏调剖物理模型研制及实验评价

Development and Experimental Evaluation of Profile Control Physical Model for Low Permeability Fractured Reservoir

为提高低渗透裂缝性油藏调剖剂评价物理模型的模拟程度,设计了一种裂缝宽度可调、基质和裂缝流量可分别计量的低渗透裂缝性油藏调剖物理模型。利用该模型开展了弱凝胶、预交联凝胶颗粒以及预交联凝胶颗粒-弱凝胶复合调剖体系对裂缝封堵能力评价实验以及复合调剖体系提高低渗透裂缝性岩心采收率驱油实验。研究结果表明,三种体系在裂缝中的封堵能力均随裂缝宽度的增加而减小,当裂缝宽度大于0.69 mm后,弱凝胶和预交联凝胶颗粒对裂缝基本不起有效封堵作用;随预交联凝胶颗粒浓度的降低,注入压力显著增加时对应的注入量增加、注入时间延长,最佳注入浓度为1000 mg/L;相同裂缝宽度下,复合调剖体系最高封堵压力值高于弱凝胶和预交联凝胶颗粒,且所需预交联凝胶颗粒的量相对较少。当复合调剖体系将裂缝完全封堵后,低渗透裂缝岩心的采收率由5.33%提高至45.58%,提高采收率的效果明显。

In order to improve the simulation of physical model for low permeability fractured reservoir,a physical model was designed,which could adjust the width of fracture and measure the flow rate of matrix and fracture. The plugging strength performance of weak gel,pre-gel particle and their composite profile control system was evaluated,respectively,by using the fracture physical model. What＇s more,low permeability fractured cores flooding experiment was developed by using composite profile control system. The results showed that the plugging strength performance of the three systems decreased with increasing fracture width. When the fracture width was greater than 0.69 mm,the weak gel and pre-gel particle could not effectively block.With decreasing concentration of pre-gel particle,the injection volume and injection time increased when the injection pressure increased significantly,and the optimum injection concentration of pre-gel particle was 1000 mg/L.However,the maximum sealing pressure of composite profile control system was higher than that of weak gel and pre-gel particle in the same fracture width,and the content of pre-gel particle was relatively small.When the composite profile control system completely blocked the fracture,the recovery rate of low permeability fractured core increased from 5.33%to 45.58%,showing significant effect for oil recovery.