摘要
针对聚合物驱过程中吸液剖面返转现象，通过模拟渤海某油藏的地质条件，从不同黏度的同质聚合物溶液在低渗透层的分流率出发，研究了聚合物溶液黏度对注聚过程中吸液剖面返转的影响规律，并开展了浓度为1500 mg/L的剪切后黏度分别为30.5 mPa·s和130.8 mPa·s的异质聚合物（HPAM和HAPAM）溶液段塞组合的驱油实验。结果表明，聚合物溶液黏度增加，聚合物驱时吸液剖面返转时机将提前，低渗透层分流率先升后降，并且分流率的峰值会增大，注入聚合物溶液黏度过低或者过高都不利于提高采收率。对于渤海某油田，过炮眼后聚合物溶液黏度控制在15~30 mPa·s范围之内较为合适。高黏度HAPAM溶液对非均质油藏改善效果要强于低黏度HPAM溶液，但其相应的注入压力也更高，对于海上正在实施聚合物驱的某多层非均质油藏，采用高黏-低黏异质聚合物溶液交替注入方式对非均质油藏改善效果更加明显。
Abstract
Aiming at profile reversal during polymer flooding, in this paper, based on the geological conditions of a reservoir in the Bohai oilfield, the law of profile reversal during polymer injection with polymer viscosity was researched by investigating the diversion rate in low permeability layers with homogeneous polymer solution with different viscosity, furthermore, the oil-displacement experiments of slug combination were conducted with two heterogeneous polymers HPAM and HAPAM solutions with the concentration of 1500 mg/L and the viscosity of 30.5 mPa·s and130.8 mPa·s, respectively. The results showed that, with the increase of the polymer viscosity, the opportunity of profile reversal during polymer flooding became ahead of time, the diversion rate rose first and then fell, the peak value of the diversion rate in low permeability layers enhanced. Too high or too low viscosity was detrimental to enhancement of oil recovery. As for the Bohai oilfield, it was suitable to control the viscosity of the polymer solutions after across the embrasure within the range of 15—30 mPa·s. The profile improvement effect of the HAPAM solution with higher viscosity to multilayer heterogeneity reservoir was better than that of the HPAM solution with lower viscosity polymer; however, the injection pressure of the HAPAM solution was much higher than that of the HPAM solution. The alternating injection of high-low viscosity heterogeneous polymers had a more pronounced profile improvement effect for the multilayer heterogeneity reservoir offshore which was being implemented polymer flooding.
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