有效降解PRD钻井液的低温破胶剂JPC室内研究

Low Temperature Gel Breaker JPC for Breakdown of Gelled PRD Polymer Drilling-in Fluid in Borehole Bottom

用PRD聚合物钻井液钻井完钻后，须对井筒内余留的钻井液实施破胶处理，以免钻井液污染地层。常用的氧化荆破胶法低温破胶效果差。本文报道低温破胶刑JPC的实验研究结果。实验钻井液（胶液）为0．65％PF-VIS增粘的PRD钻井液。用破胶率即以空白处理胶液为基准的破胶剂处理胶液表观粘度降低率表示破胶效果。在包括强氧化性酸、盐、碱的9种化学（生化）刑中，JPC的50℃、4h破胶率最高，为95．2％（加量1．0％），α-葡糖酶次之,为72．1％（加量1．5％），其余均低于50％。JPC的破胶率随加量增大而增大，加量≥1．5％时趋于恒定，适宜加量为2．0％；破胶温度升高（21-95℃）或破胶时间延长（0.5～5．0h）时破胶率增大，加量2．0％、50℃、3h破胶率超过90％，破胶液21℃表现粘度为4．0mPa·s。JPC对储层无伤害，注入2．0％的JPC海水溶液4．5PV时，南海西江23—1油藏岩心渗透率不降低，油相渗透率在注入煤油7．0PV时完全恢复。图3表3参2。

When a well drilling job is completed, the residual gelled PRD polymer drilling-in fluid in the bottom must be treated by a proper gel breaker （GB） to prevent from reservoir formation damage. The oxidants comonly used as GBs are less effective at low ternperatures. The laboratory results of low temperature GB JPC are presented. The experimental PRD fluid is one with 0.65% polymer viscosifier PF-VIS added. The function of GBs is appraised according to gel breakdown rate （GBR）, that is, percent reduction in apparent viscosity of the test PRD fluid. Of 9 chemicals （biochemicals） including strong oxidative acids, salts, and alkaline, the GBR at 50℃ in 4 h is the largest for JPC, 95.2% at dosage 1.0%, followed by α-glucosidase, 72.1% at dosage 1.5%, and is 〈50% for others. The GBR of JPC increases with increasing dosage and is close to a constant at dosage 91.5% ; the optimum dosage of JPC is of 2.0%. The GBR of JPC increases with increasing treating temperature （21-95℃） and time （0.5-5.0 h） and exceeds 90% at 50℃ in 3 h with 2.0% JPC added while the broken fluid has AV = 4.0 mPa· s at 21℃. JPC is not damaging to reservoir formations, the permeability of a test core of reservoir Xijiang-23-1, South China Sea, is not reduced during injecting 4.5 PV of 2% JPC solution in sea water and its oil permeability is completely recovered after 7.0 PV of kerosene injected.