新型低氯根螯合酸液体系研究及性能评价

New Low Chlorine Chelating Acid System and Performance Evaluation

目前库车山前储层酸化大多数是以土酸为主的酸液体系,该类酸液体系存在反应速度快,二次伤害严重,酸化后残酸中Cl-质量浓度高,对钢材设备腐蚀严重,尤其容易造成超级13Cr局部腐蚀而导致高压气井出现井筒完整性失效等问题。为确保储层增产改造的有效性,减少残酸中Cl-对完井管柱造成的腐蚀伤害,降低高压气井出现井筒完整性失效的几率,需要研发新的低Cl-质量浓度、低伤害、高溶蚀率的酸液体系。研究并提出了一种复合磷酸盐与酯、醚复配的螯合酸液体系,该酸液体系基本配方为:5%甲酸+8%大分子酸+2%氢氟酸(配方中的百分数为质量分数),使用高温高压腐蚀仪研究该酸液体系对13Cr腐蚀性能的影响,同时结合岩粉溶蚀试验与岩心酸化流动仪考察该酸液体系性能,试验结果表明该酸液体系对13Cr腐蚀速率低,同时具有高效、缓速、缓蚀等特点。研究的酸液体系对于高温、酸性气藏储层进行酸化改造具有很强的参考价值。

Mud acid system was widely used in acidizing treatment in Kuqa Piedmont reservoirs,however,many problems were associated with the system,such as fast reaction rate,potential damage,high Cl-concentration after treatment,and corrosion,especially the local corrosion brought by super 13Cr,which always resulted in integrity failure of wellbore of high pressure wells.In order to ensure the effective reservoir reconstruction,reduce the damage of casing strings in well completion caused by high Cl-concentration and low down the probability of integrity failure in wellbore of high pressure gas wells,a novel acid system with low Cl-concentration,less damage and high dissolution rate was needed to be researched and developed.In this paper,a complex phosphate ester,ether compound chelating acid system was studied and proposed,its basic formula was 5%formic acid+8%polymer acid+2% hydrofluoric acid.The corrosion behavior of this system on corrosion rate of 13Cr wasevaluated with HTHP corrosion analyzer,and combined withthe test results of rock powder dissolution test and core flooding experiment,performance of the novel acid system was investigated.Laboratory tests indicate that this novel acid system has low corrosion rate on the acid system,it has the characters of high dissolution rate,retard and corrosion inhibition.It provides reference for the reconstruction of reservoirs with high temperature and acidic gas.