注聚井用SC-3型双季铵盐基复合防堵剂

Organic Diammonium Salt Based Compounded Reservoir Blokage Preventing Fluid SC-3 for Use in Polymer Injection Wells

大庆聚合物驱油田出现了注聚压力上升甚至注入困难问题。其原因是聚合物在地层孔隙中吸附滞留和沉淀及吸附油膜导致聚合物堵塞。采用井距150m的一注一采井组模型，在水驱至含水90％时注入1000mg／L的聚合物，用数值模拟方法计算出，沿程压力在0～40m区间出现上升快、峰尖锐、拖尾明显的高峰。而现用强氧化荆／复合酸／转向剂型解堵剂的作用半径仅有3m。为此研制了由能形成分子沉积膜的有机双季铵盐（5g／L）、有洗油作用的表面活性剂和高价阳离子螫合剂（各0．5g／L）组成的复合解堵剂SG-3。讨论了SC-3中各组分的作用。经SC-3处理的人造岩心（K=0．5μm^2）。在连续注入800mg／L的聚合物时，注入压力上升较慢且稳定值较低（0．55MPa，空白岩心为0．70MPa）。杏四区西部聚驱区块新投产的5口注入井．于10月8～10日注入800mg／L的SC3．平均单井注入300m^3，投入注水后的防堵井和4口对比井注入压力持续下降，防堵井下降更快，2005年3月底均下降4．1MPa，此后开始注聚，注入压力均迅速上升，5月底对比井注入压力升至11．0MPa，防堵井只升至9．7MPa。图3表1参3。

Raise in injection pressures and, in some cases, troubles with injectivity appear in lots of polymer injection wells in polymer flooding reservoirs in Daqing and are explained by blockage creation caused by adsorption/retention and precipitation of polymer molecules and existance of adosrbed oil film in formation pores. On a well group model composed of an injection and a production wells 150 m apart, the flowing pressure of 1000 mg/L polymer solution being injected at 90% water cut phase of water flooding is calculated by using a digital simulation method and a high pressure peak with sharp starting section and notable tail is obtained in 0-40 m from the injection well. The presently used blockage removing agent consisting of strong oxidizer, mixed acid, and diverting agent is effective in zones of 3 m radius only. A compounded reservoir blockage preventing agent, SC-3, is developed and composed of an organic diamrnonium salt capable of forming molecular deposition fiLm （5 g/L）, oil washing surfactant （0.5 g/L）, and chelating agent for high valence ions （0.5 g/L）. The functions of every components in SC-3 are discussed. When injecting 800 mg/L polymer solution into an artificial core of K = 0.5μm^2 treated by SC-3, the injection pressure increases slower and reaches lower steady value of 0.55 MPa in comparison with the blank core （0.70 MPa）. In the polymer flood program area of District West Xing-4,5 new injection wells are treated by squeezing 300 m3 of 800 mg/L SC-3 solution in average Oct 8-10, 2005 and the water injection pressure in the treated and 4 blank wells decreases continuously, more faster in the treated wells, and a pressure drop of 4.1 MPa is observed at the end of March 2005 ; when polymer injection starts, the injection pressure raises fast in both treated and blank wells but the pressure reached at the end of May 2005 is lower, 9.7 MPa, in the treated wells in comparison with that in the blank wells, 11.0 MPa.