非均质储层水驱剩余油分布及其挖潜室内模拟研究

为了挖潜长期注水开发油田水淹层内的剩余油,通过分析储层孔隙结构和孔喉大小,研制了可视化非均质模型,以录像的方法室内观察水驱剩余油形成过程,分析其分布特征及挖潜技术思路。基于弹性颗粒在孔喉结构中的材料性能,提出与储层孔喉相匹配的弹性颗粒粒径筛选原则,并通过非均质岩心水驱后颗粒调剖实验,评价该弹性颗粒的动态封堵能力和调剖效果。结果表明:油田储层普遍存在非均质性,该性质影响水驱剩余油的分布;水淹层内剩余油以非均质剩余油为主,多数存在于层内局部低渗部位,分布较为分散,其挖潜应以提高微观波及效率为主;弹性颗粒对喉道的封堵强度随粒径的增大先增大后趋于恒定,当颗粒粒径与喉道直径之比超过3时,颗粒在孔喉结构中发生破碎;封堵水淹层水流通道、挖潜层内剩余油时,选择粒径为3倍大孔喉尺寸的弹性颗粒,其效果明显。

Distribution of remaining oil by water flooding in heterogeneous reservoirs and indoor simulation study for its potential tapping

In order to tap the potentiality of the remaining oil from water flooded layer of the long-term water flooding oil fields, a visualized heterogeneous model was developed through analyses of the pore structure and the size of pore throats of the reservoirs, which was used to carry out indoor observation of the formation process of water flooding remaining oil by way of video and analysis was conducted of its distribution characteristics and way of thinking of potential tapping techniques. Based on the material properties of elastic particles in throat structure, the screening principle for the diameter of this elastic particle which was in match with reservoir throat was presented. And through test of profile control of particles after water flooding in heterogeneous cores, evaluation was made on the dynamic plugging capacity and profile control effectiveness of this elastic particle. The results show that heterogeneity occurs commonly in oilfield reservoirs, which affects the distribution of water flooding remaining oil; the remaining oil in flooded layers is mainly heterogeneous remaining oil, mostly found in local low-permeability zones of the layers and distributed dispersedly, so its potential tapping will be mainly by improving the microscopic sweep efficiency; the plugging strength of elastic particles on throat increases first and then keeps constant with the enlarging of elastic particle diameter-when the ratio of particle diameter with throat diameter is over 3, the particles will be broken in throat structure; when plugging the water channel in water flooded layer and tapping the remaining oil, the elastic particle works effectively whose diameter is three times of the size of throat.