海上D油田注水井长效解堵体系研究及应用

Research and application of long-term plugging removal system for water injection wells in offshore D oilfield

针对海上D油田注水井注入压力高和储层欠注的问题,在分析储层污染机理的基础上,采用3种主剂及相关添加剂复配研制出一种长效酸体系。在地层温度下,开展了该长效酸系列评价实验。结果表明,长效酸对现场岩屑2h溶蚀率为25.11%,对石英2h溶蚀率仅为0.26%;长效酸体系与岩屑反应1~3h,溶蚀率由15.45%增至30.76%;长效酸对氟化钙、氟硅酸盐和氢氧化物的抑制率分别为51.65%、75.38%和77.90%;分别加入占长效酸质量分数1%和2%的表面活性剂后,长效酸表面张力分别为22.07mN/m和20.85mN/m^(2)长效酸对N80钢片的腐蚀速率为4.11g/(m^(2)·h);长效酸所用防膨剂的防膨率为91.21%;长效酸处理后的填砂模型渗透率由540.71mD增至742.63mD,渗透率增大为原来的1.37倍。长效酸现场应用6井次,增注效果显著。

Aiming at the problems of high injection pressure and reservoir underinjection in offshore D oilfield,based on the analysis of reservoir pollution mechanism,a long-term acid system was developed by using three main agents and related additives.A series of long-acting acid evaluation experiments were carried out at formation temperature.The experimental results show that the dissolution rate of long-acting acid to on-site rock cuttings in 2 h is 25.11%,and that to quartz in 2 h is only 0.26%;the long-acting acid system reacts with rock cuttings for 1 to 3 h,and the corrosion rate increases from 15.45%to 30.76%;the inhibition rates of long-acting acid on calcium fluoride,fluosilicate and hydroxide were 51.65%,75.38%and 77.90%respectively;after adding surfactants accounting for 1%and 2%of the mass fraction of long-acting acid,the surface tensions of long-acting acid were 22.07 mN/m and 20.85 mN/m respectively;the corrosion rate of N80 steel sheet by long-acting acid was 4.11 g/(m^(2)·h);the anti swelling rate of anti swelling agent used in long-acting acid was 91.21%;the permeability of the sand filling model after long-term acid treatment increased from 540.71 md to 742.63 mD,and the permeability increased by 1.37 times.The long-acting acid was applied in 6 wells,and the injection increase effect was remarkable.