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低渗透非均质油藏通常具有气驱效率低、气窜严重等特点,气水交替注入(WAG)能够在一定程度上改善气驱的驱油效果。本文借助室内实验明确了WAG驱在低渗透非均质油藏的适应性,并从流度控制能力的角度分析了WAG驱提高采收率的作用机理。相对于均质油藏,WAG驱在渗透率级差较小的低渗透非均质油藏中具有更好的适应性。对于非均质程度较弱的低渗/特低渗透油藏,WAG驱可充分发挥其流度控制作用,启动低渗层中的原油,扩大注入气的波及体积,改善注入气的驱油效果。WAG驱注入参数优化结果表明,在注气速度为0.3 mL/min、段塞尺寸为0.1 PV和气水比为l:1的注入参数条件下,WAG驱可在水驱的基础上使低渗透非均质模型的采收率提高20.96个百分点。
Low permeability heterogeneous reservoirs usually have the characteristics of low gas drive efficiency and serious gas channeling, and the alternating gas and water injection (WAG) can improve the flooding effect of gas flooding to a certain extent. In this paper, the feasibility of WAG flooding in low-permeability heterogeneous reservoirs is clarified through laboratory experiments. The mechanism of WAG flooding recovery is analyzed from the perspective of fluid-flow control. Compared with homogeneous reservoirs, WAG flooding has better adaptability in low-permeability heterogeneous reservoirs with smaller permeability differences. For low permeability / low permeability reservoirs with weaker heterogeneity, WAG flooding can fully exert its flow control effect, start the crude oil in the low permeability layer, expand the volume of injected gas and improve the flooding effect of injected gas . The WAG flood injection parameters optimization results show that the WAG flooding can make low-permeability non-flooding water infiltration based on water flooding under the condition of injection rate of 0.3 mL / min, slug size of 0.1 PV and gas-water ratio of 1: 1 Homogenization model recovery rate increased by 20.96 percentage points.