低渗透油田酸化降压增注技术研究与应用

Research and application of the acidizing technology of low-permeability reservoirs for increasing water injection

针对低渗透油藏低孔、低渗的储层特征导致注水过程中注水压力上升较快、欠注严重的问题,开展了酸化降压增注的应用研究,并优选出了一种水井降压增注的酸液体系.首先根据地层特征对酸液的要求和岩心溶蚀实验选出有机缓速酸和盐酸作为主体液,在此基础上根据实验优选了防水锁剂、黏土稳定剂、缓蚀剂、铁离子稳定剂等酸液添加剂及其体积分数,从而确定该酸液配方为"8%HCl+8%有机缓速酸+1%H3BF4+2%聚合醇+(1%～2%)缓蚀剂HSJ-1+(0.5%～1%)黏土稳定剂QJ-Ⅱ+2%EDTA".通过酸化流动模拟实验对该酸液体系进行了评价并与土酸进行了对比,结果表明该酸液体系具有很好的缓速性能,能够达到深部酸化的目的.矿场试验取得了很好的效果,注水压力从16 MPa降到6.0～9.8 MPa,日注水量从2～8 m3达到40 m3.

Aiming at the problem of water injection pressure rising rapidly and insufficient water injection in low permeability reservoirs,the acidizing technology for low permeability reservoirs is studied,and an acidizing fluid system for water injection wells is developed.Firstly,an organic retarded acid is developed.And then,an acidizing liquid system is optimized according to the formation characteristics and core corrosion experiments.Finally,the additives in acidizing liquid system are optimized on the basis of experiments,including anti-water-blocking agent,clay stabilizer,corrosion inhibitor and ferric ion stabilizer,and their volume fractions are determined.The formulation of the acidizing liquid system is 8% HCl+8% organic retarded acid +1% H3BF4+2% polyalcohol +(1%~2%)corrosion inhibitor HSJ-1+(0.5%~1%)clay inhibitor QJ-Ⅱ+2% EDTA.The acidizing result of the acidizing fluid system is evaluated through core acidizing simulation experiments,and compared with that of mud acid,it is shown that the acidizing system has better retarding performance and deep acidizing ability.Field test results show that the acidizing system can reduce water injection pressure from 16 MPa to 6.0~9.8 MPa,and it can correspondingly increase daily water injection rate from 2~8 m3/d to 40 m3/d.