疏水聚合物微球制备及其缓膨和封堵效果评价

Preparation of Hydrophobic Polymer Microspheres and Evaluation of Its Slow Swelling and Plugging Effect

与聚合物溶液相比较,聚合物微球分散液为非连续相,并且微球粒径分布比较集中,可以做到"堵大不堵小",在一定程度上增加了水相波及体积,减缓了"剖面反转"现象。近年来,聚合物微球调驱技术研究和矿场试验受到广泛重视。为了适应海上油田调驱技术需求,本文采用反相乳液聚合方法合成一种疏水缔合聚合物微球,综合利用化学表征手段和岩心渗流实验,开展了聚合物微球粒径分布、缓膨性、封堵性和油藏适应性以及传输运移能力的一系列实验研究。结果表明,采用水溶性单体AMPS和疏水单体α-甲基苯乙烯可以与丙烯酰胺和丙烯酸钠等共聚形成无规分布疏水缔合共聚物即微球材料。在此基础上,采用四因素三水平正交试验法合成了9个微球样品(代号AMPS),来研究水溶性单体AMPS含量、乳化剂含量、引发剂含量以及温度对微球粒径的影响。其中,AMPS-8微球初始粒径在2μm左右,水化240h后,粒径稳定在18μm左右,膨胀倍数达到8至9倍。同时在岩心渗透率为1600×10^(-3)μm^2时的残余阻力系数最大,达到9.53,说明其渗透率极限为1600×10^(-3)μm^2,且在岩心中具有较强滞留封堵效果。在渤海油田注入水的条件下,AMPS疏水聚合物微球粒径中值差异不大,表明其具有良好抗盐性。采用膨胀效果较好的AMPS-8微球进行60cm长岩心的传输运移实验,结果表明,入口端附近的残余阻力系数高达19.417,岩心中部的残余阻力系数为6.6,岩心出口附近的残余阻力系数为2.8,说明AMPS-8微球具有较好的深部传输运移能力。

Compared with the polymer solution, the polymer microsphere solution is a discontinuous phase, and the particle size distribution of the microspheres is more concentrated. It can "plug large pores and not plug small pores", to a certain extent, the swept volume of water phase were increased, and the phenomenon of "profile inversion" was slowed down. In recent years, polymer microsphere flooding technology research and field test have received extensive attention. In order to meet the needs of profile control technology in offshore oilfield, a hydrophobically associating polymer microsphere was synthesized by inverse emulsion polymerization. Chemical characterization and core seepage experiments were used to study the particle size distribution, slow swelling, plugging, reservoir adaptabilityand transmission and migration capacity of polymer microspheres. The results show that the water-soluble monomer AMPS and the hydrophobic monomer alpha methylstyrene can be copolymerized with acrylamide and sodium acrylate to form a random distributed hydrophobically associating copolymer, that is microsphere material. On this basis, nine microsphere samples (AMPS) were synthesized by four-factor three-level orthogonal test to study the effects of AMPS content, emulsifier content, initiator content and temperature on microsphere particle size. The initial particle size of AMPS-8 microsphere is about 2μm, and the particle size is stable at about 18μm after the hydration of 240h. The expansion ratio reached 8 to 9 times, and the residual resistance coefficient is the largest when the core permeability is 1600×10^-3μm^2, reaching 9.53, indicating that the permeability limit is 1600×10^-3μm^2 and the microsphere has a strong retention and plugging effect in the core.Under the condition of injected water in Bohai oilfield, there is little difference in the median size of AMPS hydrophobic polymer microspheres, indicating that it has good salt resistance. The transport and migration experiments of 60cm long core were carried out by using AMPS-8 microspheres with better expansion effect. The results show that the residual resistance coefficient near the entrance is as high as 19.417, the residual resistance coefficient of the middle is 6.6, and the residual resistance coefficient near outlet is 2.8, indicating that AMPS-8 microspheres have good deep transport and migration ability.