稠油油藏聚合物驱微观波及实验及数值模拟研究

发布时间：2018-07-29 08:44

【摘要】：我国海上稠油资源储量丰富,但目前动用水平和已投入开发的稠油油田采收率都较低。聚合物驱作为一种提高海上稠油油藏采收率的重要战略手段,其应用潜力巨大。长期以来,在石油工程领域内普遍认为,聚合物驱提高原油采收率的机理是改善流度比、提高宏观波及效率,但对聚合物溶液在多孔介质中的微观驱替规律研究较少,特别是在油藏温度下对聚合物驱稠油微观波及认识不足。因此,有必要开展稠油聚合物驱微观波及规律研究。本文在分析稠油油藏孔喉特征的基础上,利用光刻技术制作出具有一定几何形状的二维玻璃仿真模型,开展了水驱/聚驱微观可视化流动性实验,利用采集到的图像分析了非均质性、注聚时机、聚合物溶液浓度和注入速度对聚驱稠油微观波及的影响,同时验证了微观模型的可靠性。在实验基础上,建立微观驱油数学模型,通过模拟结果和实验现象对照,分析数学模型的可靠性,在此基础上,探索微观孔喉结构对聚合物驱微观波及的影响。非均质模型的水驱前缘突进现象更加明显,突破时机提前,水驱通道形成之后横向波及速度明显减慢,水驱后形成大量网络状剩余油;水驱后转注聚能有效减小纵向波及速度扩大横向波及程度从而增大波及效率;非均质模型中聚驱后网络状残余油占38%,孤粒、孤滴状残余油占36%,差别不大,而均质模型中聚驱后网络状占了一半以上,说明非均质性愈强,聚合物驱后剩余油分布愈趋分散、复杂和多样化;水窜前转注聚最终波及效率最大,为85.69%,直接注聚次之,水窜后转注聚最终波及效率最低,为60.4%;水窜前转注聚指进通道短而宽,聚驱后残余油数量更少,分布更分散;随着聚合物溶液浓度增加,横向流道逐渐增多,纵横比逐渐降低,并趋于一个较小值。从较大尺度上看,驱替前缘趋于稳定。因此,波及效率和采收率均得到较大幅度提高;聚合物优先进入大孔隙,随着驱替速度增加,小孔隙也逐渐充满聚合物,表现为波及系数先增加后趋于平稳;随着孔喉比的增大,聚驱波及效率减小;随着配位数的增大,剩余油的形成机会减少,分布更分散,聚驱波及面积逐渐增大。因此,通过微观可视化驱油实验,结合数值模拟手段,为多角度、深层次认识聚合物微波及提供了行之有效的方法,也为进一步提高聚合物驱稠油油藏波及效率提供了一定的理论参考和现实价值。
[Abstract]:China is rich in heavy oil resources, but the production level and recovery factor of developed heavy oil fields are low. Polymer flooding as an important strategic means to improve oil recovery in offshore heavy oil reservoirs has great application potential. For a long time, in the field of petroleum engineering, it is generally believed that the mechanism of polymer flooding to improve oil recovery is to improve mobility ratio and macro sweep efficiency, but there is little research on the microscopic displacement of polymer solution in porous media. Especially at reservoir temperature, the microcosmic sweep of polymer flooding heavy oil is not well understood. Therefore, it is necessary to study the microcosmic sweep law of heavy oil polymer flooding. Based on the analysis of pore throat characteristics of heavy oil reservoir, a two-dimensional glass simulation model with certain geometry was made by lithography, and the microscopic visualization flow experiment of water flooding / polymer flooding was carried out. The effects of heterogeneity, timing of polymer injection, concentration of polymer solution and injection rate on microcosmic sweep of polymer flooding heavy oil were analyzed by using the collected images, and the reliability of the microscopic model was verified. On the basis of experiments, the mathematical model of micro-displacement is established. The reliability of the mathematical model is analyzed by comparing the simulation results with experimental phenomena. On this basis, the influence of microcosmic pore throat structure on microcosmic sweep of polymer flooding is explored. The phenomenon of water drive leading edge protruding in heterogeneous model is more obvious, the breakthrough time is ahead of schedule, the transverse sweep velocity after the formation of water drive channel is obviously slowed down, and a large number of network remaining oil is formed after water flooding. In the heterogeneous model, the network residual oil accounts for 38% of the residual oil, the fraction of the net residual oil is 38%, and the fraction of the solitary and droplet residual oil is 36%, the difference is not significant. In the homogeneous model, the network shape after polymer flooding accounts for more than half, which indicates that the stronger heterogeneity, the more dispersed, complex and diversified the remaining oil distribution after polymer flooding, the maximum sweep efficiency of water channeling is 85.69g, and the second is direct polymer injection. The final sweep efficiency of polymer transfer after water channeling is the lowest, which is 60.4. Before water channeling, the number of residual oil after polymer flooding is smaller and the distribution of residual oil is more dispersed, and the cross channel gradually increases and the aspect ratio decreases with the increase of polymer solution concentration. And tend to a smaller value. On a large scale, the front edge of displacement tends to be stable. Therefore, the sweep efficiency and oil recovery have been greatly improved, polymer preferential into the macropores, with the increase of displacement speed, small pores are gradually filled with polymers, showing that the sweep coefficient increases first and then tends to steady; With the increase of pore throat ratio, the sweep efficiency of polymer flooding decreases, and with the increase of coordination number, the formation opportunity of remaining oil decreases and the distribution becomes more dispersed, and the sweep area of polymer flooding increases gradually. Therefore, through the microscopic visualization oil displacement experiment and the numerical simulation method, it provides an effective method for the multi-angle and deep-level understanding of polymer microwave. It also provides a theoretical reference and practical value for further improving the sweep efficiency of polymer flooding heavy oil reservoirs.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE357.46

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