稠化剂提高低渗油藏CO_(2)驱油效果适应性评价

Adaptability Evaluation of Using Thickener to Improve CO_(2)Flooding Effect in Low-permeability Reservoirs

针对CO_(2)驱油过程中易发生黏性指进,造成CO_(2)驱油效果严重受限的问题,开展了一种线型嵌段共聚物稠化剂对CO_(2)的增黏性能和对非均质岩心CO_(2)窜流的调控作用评价实验,同时,建立了稠化剂对CO_(2)流度控制和非均质性调控作用定量评价方法,分析了稠化剂提高CO_(2)驱油效果作用机制,并利用三维径向流模型对稠化剂提高低渗油藏CO_(2)驱油效果进行了模型模拟。结果表明:油藏条件下,稠化剂可增大CO_(2)黏度18倍;对渗透率级差为5和10的低渗非均质岩心,注入稠化剂-CO_(2)体系1.0 PV后CO_(2)驱,可分别提高CO_(2)驱油效果13.75和11.98个百分点;稠化剂改善黏性指进作用对两类非均质岩心提高驱油效率的贡献分别为79.6%和72.5%;利用稠化剂提高CO_(2)驱油效果的方法在低渗油藏的适应性较好。

During CO_(2)flooding,viscous fingering is prone to occur,which severely limits the effectiveness of CO_(2)flooding.To address this issue,an experiment for evaluating the viscosity increasing performance of a linear block copolymer thickener on CO_(2)and its control effect on CO_(2)channeling of heterogeneous cores was carried out.A quantitative method was established to evaluate the control and regulation effect of the thickener on CO_(2)viscosity and core heterogeneity,the mechanism of the thickener improving CO_(2)oil displacement efficiency was analyzed,and the effect of the thickener increasing CO_(2)oil displacement efficiency in low permeability reservoirs is simulated using a three-dimensional radial flow model.The experimental results show that,under reservoir conditions,the thickening agent can increase the viscosity of CO_(2)by 18 times;Injecting thickening agent-CO_(2)system 1.0 PV into two types of low permeability heterogeneous cores with the permeability difference of 5 and 10,and then performing CO_(2)flooding,can increase the CO_(2)flooding efficiency of the cores by 13.75 and 11.98 percentage points,respectively;The main mechanism of the thickener improving CO_(2)flooding efficiency in low permeability reservoirs is to increase CO_(2)viscosity,which contributes 79.6%and 72.5%to improving the oil displacement efficiency of two types of heterogeneous cores,respectively;The method of using thickeners to improve CO_(2)flooding efficiency has good adaptability to low permeability reservoirs.