海上稠油油藏聚合物微球调驱适用性研究

Study of the Applicability of Polymer Microspheres in Offshore Heavy Oil Reservoirs

针对海上稠油油田开发中后期面临水窜严重、产量递减加大等问题,以渤海Q油田开发为例,利用室内实验和数学分析方法系统开展了新型聚合物微球调驱体系性能评价研究。结果表明:随着溶胀时间增加,聚合物微球粒径呈现出先增大后减少并趋于稳定,微观形态上,中前期形成均匀分布的网状球形结构,后期分子结构降解形成大规模“团聚”现象;微球体系对于高渗储层具有较强的封堵能力,影响封堵率大小为岩心渗透率>微球浓度>溶胀时间;微球体系能够大幅调整层间吸水剖面、实现液流转向和扩大微观驱油效率的作用。利用该方法进行了Q油田微球调驱现场试验,采用“高浓度前置段塞、低浓度主段塞”的组合配方,微球质量浓度为3 000~6 000 mg/L,注入段塞为0.02~0.03 PV。调驱的有效率达到100%,平均井组日增油20 m^(3)/d,含水率下降2.6%,累计增油8.5×10^(4) m^(3),控水增油效果明显。

Taking the development of Q oilfield in Bohai Sea as an example, the performance evaluation of the new polymer microsphere regulating and flooding system was systematically studied by conducting laboratory experiment and mathematical analysis to solve the problems of serious water channeling and curb the increasing production decline in the middle and late development of offshore heavy oil fields. Results show that with the increase of swelling time, the particle size of polymer microspheres increases first, then decreases and tends to be stable. In terms of microstructure, the spherical mesh structure with uniform distribution is formed in the middle and early stage, and the molecular structure degrades and forms a large-scale “agglomeration” phenomenon in the late stage. Microsphere system has strong plugging ability for high permeability reservoir, and the relationship affecting the plugging rate features that the core permeability is greater than the microsphere concentration and the swelling time. The microsphere system can greatly adjust the interlayer water absorption profile, realize the flow direction and expand the micro-oil displacement efficiency. The method was used to carry out the field test of microsphere control and flooding in Q oilfield. The combined formula of “high concentration front slug and low concentration main slug” was adopted. The mass concentration of microsphere was between 3 000 mg/L and 6 000 mg/L, and the injected slug volume was between 0.02 PV and 0.03 PV. The effective rate of regulating and flooding measures reached 100%,with the average daily oil increase of well group being 20 m^(3)/d, the water cut decreased by 2.6%, and the accumulative oil increase being 8.5×10^(4)m^(3). The effect of water control and oil increase was obvious.