高温碳酸盐岩储层双重缓速酸的制备与性能评价

Preparation and Performance Evaluation of Dual Retarding Acid for High-temperature Carbonate Reservoir

针对高温碳酸盐岩储层酸化中缓速酸缓速效果不佳、注入困难等问题,以二甲基二烯丙基氯化铵、丙烯酰胺、K_(2)S_(2)O_(8)和NaHSO_(3)为原料制备了缓速稠化剂(CPAM)。将CPAM、缓速剂(十二烷基三丁基溴化膦)、缓速分散剂(尿素)复配制得双重缓速酸体系。研究了双重缓速酸在高温下的缓速效果和酸蚀裂缝导流能力,通过扫描电镜和接触角的测定分析了缓速机理。结果表明,双重缓速酸主要依靠CPAM和尿素提高缓速剂在岩石表面的附膜效果来实现缓速。优选的双重缓速酸体系为1%~2%缓速剂+0.1%~0.3%CPAM+1.5%尿素。在90℃、170 s^(-1)的条件下,该双重缓速酸对应的鲜酸和残酸剪切后的黏度均小于10 mPa·s。在90℃下,双重缓速酸的缓速效率高达97%,缓速效率明显优于稠化酸;在180℃高温环境下,其导流能力保持率高,抗压能力强。该双重缓速酸具有易注入、抗高温、缓速效果好的优点,适用于180℃以上深层超深层碳酸盐岩储层的酸化改造。

Aiming at the problems of poor retarding effect and difficult injection of retarding acid during the acidizing in high-temperature carbonate reservoir,a retarding thickener(CPAM)was prepared by using dimethyldiallylammonium chloride,acrylamide,K_(2)S_(2)O_(8) and NaHSO_(3) as raw materials.A dual retarding acid system was prepared by compounding CPAM,retarding agent(dodecyltributylphosphine bromide),and retarding dispersant(urea).The retarding effect and acid etching fracture conductivity of the dual retarding acid at high temperature were studied.The retarding mechanism was analyzed by scanning electron microscopy and contact angle measurement.The results showed that the retarding acid mainly depended on CPAM and urea to improve the film adhesion effect of retarder on the rock surface,and then achieve the purpose of retarding.The optimum formula of dual retarding acid system was obtained as follows:1%-2% retarder,0.1%-0.3%CPAM,1.5%urea.At a temperature of 90℃ and a shear rate of 170 s^(-1),the viscosity of fresh acid and residual acid corresponding to dual retarding acid system after shearing was less than 10 mPa·s.The retarding efficiency was up to 97%at 90℃,which was obviously superior to that of gelling acid.In the high temperature environment of 180℃,it had high conductivity retention rate and high-pressure resistance.The dual retarding acid had the advantages of easy injection,high temperature resistance and excellent retarding performance,which was suitable for the acidizing transformation of deep and ultra-deep carbonate reservoir above 180℃.