螯合解堵液体系在涠洲低渗储层的研究与应用

THE STUDY AND APPLICATION OF CHELATE ACID IN WEIZHOU LOW-PERMEABILITY RESERVOIR

涠洲油田L1Ⅳ油组储层为中孔、低渗储层,存在中等偏强的水敏、酸敏,地层水矿化度高(15998 mg/L)、成垢离子含量高,在油井生产和修井作业过程中易受到水锁、水敏、结垢伤害。为解除油井污染、提高油井产能,通过大量的室内实验,构建了一套针对涠洲油田L1Ⅳ油组低渗储层解堵的螯合解堵液体系。该体系能有效解除修井液对低渗储层造成的伤害,改善储层渗透率。实验结果表明:低渗透率岩心经螯合解堵液体系处理后,渗透率增大至原始渗透率的150%,水锁伤害岩芯的渗透率恢复率达124.3%,体系阻垢率大于93%。体系在矿场应用后,取得了日增油24 m3/d、产能提高1.6倍的良好效果,在同类储层具有较大推广价值。

L1 Ⅳ of LiuShaGang in Weizhou is low-porosity and low-permeability reservoir with large thickness,which has strong water sensitivity,strong acid sensitivity,highly mineralized formation brines,and highly scale ion.L1Ⅳ is easy to be polluted by water block,water sensitivity,and scale.In order to remove the pollution of L1 Ⅳ,chelate acid was developed through numbers of laboratory experiments.Experiments results show that chelate acid could remove the pollution caused by workover fluid efficiently and the permeability of polluted core could be promoted to 1.5 times than be acidized before.Also,the chelate acid could increase the permeability of water-block core by 24.3%.The scale inhibition rate of chelate acid is greater than 93%.In the field application,the oil production of A5 is increased by 24 m^3/d with water content almost unchanged.