一种抗剪切的新型改性弱凝胶调剖体系

摘要

In view of high water cut,low output and great mobility difference between oil and water of a low permeability reservoir of Chang 6 formation in Yan Chang oilfield Z region,a weak gel profile control system was prepared with polyacrylamide modified by copolymerization as host,low polymer phenolic resin as crosslinking agent and polyhydroxyphenol as fortifier. The salt tolerance, temperature resistance and gel strength in dynamic shearing state of the weak gel were evaluated by viscosity measurement. The results indicated that gelling time and gel strength of the weak gel could be controlled by regulating the contents of the polymer,crosslinking agent and fortifier. The optimum gelling system formula was 0.3%(w)modified polyacrylamide+0.4%(w)low polymer phenolic crosslinking agent+0.2%(w)fortifier. This weak gel system was characteristized by excellent salt tolerance,low temperature stability and shearing resistance as well as short gelling interim time. The average stemming ratio in a fracture-matrix core group was 82.4% while that of meso/macroporous-matrixcore group was 96.6%. Additionally,the flooding efficiency was increased by 24.3 percentage points in average in four core group experiments,and the oil recovery efficiency was effectively enhanced.%针对延长油田Z区长6低渗储层含水量高、产量低、油水流度差异大的特点,制备了以共聚改性聚丙烯酰胺为主剂、低聚酚醛树脂为交联剂、多羟 基酚为促进增强剂的弱凝胶调剖体系.通过黏度测试评价了弱凝胶的耐盐性、耐温性和动态剪切下的成胶性能.实验结果表明,弱凝胶的成胶时间、成胶强度可以通过调节聚合物、交联剂和促进增强剂的含量来控制.最佳成胶体系配方为:0.3%(w)改性聚丙烯酰胺+0.4%(w)低聚酚醛交联剂+0.2%(w)促进增强剂.该弱凝胶体系具有良好的耐盐性、低温稳定性、抗剪切性和成胶过渡时间短的特点,裂缝-基质岩心组合平均封堵率为82.4%,中大孔-基质岩心平均封堵率为96.6%,4组岩心组合实验驱油效率平均提高了24.3百分点,有效地提高了采收率.