聚合物浓度对溶液渗流特性的影响及合理浓度上限

Effect of Polymer Concentration on Solution Seepage Characteristics and Reasonable Concentration Limit

王荣健 韩大伟 卢祥国 郭琦 杨怀军 张杰

WANG Rongjian HAN Dawei LU Xiangguo GUO Qi YANG Huaijun ZHANG Jie

以大港油田港西三区储层和流体为实验对象，开展了聚合物浓度对聚合物溶液渗流特性的影响研究及其作用机理分析。结果表明，在聚合物浓度相同时，随岩心渗透率增加，阻力系数（FR）和残余阻力系数（FRR）减小；在岩心渗透率一定时，随聚合物浓度增加，FR和FRR增大。当聚合物质量浓度从400 增至1600 mg/L 时，FR和FRR增幅降低；当聚合物浓度从1600 增至2500 mg/L时，FR和FRR增幅增大；当聚合物浓度超过2500 mg/L后，FR和FRR增幅再次降低。推荐港西三区高浓度聚合物驱聚合物浓度上限为2500 mg/L。剪切作用导致聚合物溶液中部分聚合物分子链发生断裂，网状结构遭到损坏，包裹水分子能力下降，宏观上表现出增黏能力降低和渗流阻力减小。聚合物质量浓度由50 增至400 mg/L，分子线团尺寸（d）先降低后增加，在200 mg/L时达到最低值245.3 nm；聚合物分子线团尺寸分布也呈现先发散后集中的变化趋势。图10 表3 参16

Based on the reservoir and fluid in Gangxi Block3 area of Dagang oilfield，the effect of polymer concentration on solution seepage characteristics was carried out and the mechanism was analyzed. The results showed that resistance factors（FR）and residual resistance factors（FRR）decreased with increasing core permeability at same polymer concentration，while FR and FRR increased with increasing polymer concentration at same core permeability. The increment rate of FR and FRR reduced when the mass concentration of polymer increased from 400 to 1600 mg/L，and that increased with 1600—2500 mg/L，at last，reduced again after 2500 mg/L. So it was recommended that 2500 mg/L was the upper limit concentration of high concentration polymer flooding. Themolecule chains in polymer solution broke under the shearing action of core pore，and the network structure was destroyed，the parcel ability of water molecule decreased，which showed the increasing viscosity ability and percolation resistance of polymer solution decreased in macroscopic scale. Polymer molecular clew size increased first and then decreased when the concentration of polymer increased from 50 to 400 mg/L，and 245.3 nm was the lowest value at 200 mg/L. The distribution of molecular clew size had the trend of being divergent first and then concentrated.