针对辽河油田欢喜岭采油厂地区注水压力高、地层堵塞严重,常规土酸体系解堵效果差且有效期短等问题,用三氯化磷、有机酸和丙酮合成了一种酸化用无氟缓速酸。此缓速酸属有机磷酸类,单独使用不需复配其他HF酸或氟盐即可达到良好的降压增注效果。室内研究表明,60℃下反应48h时,20%缓速酸溶液的溶蚀~为23.25%,缓速效果好于土酸和氟硼酸。酸液产生沉淀时的pH值为7~8,络合能力为500~600g/L,可有效防止Fe(OH)3、A(lOH)3等二次沉淀的产生。天然岩心经20%缓速酸处理后的渗透~恢复值为173%,抗压强度损失为22.7%,是土酸处理的0.56倍。将缓速酸体系(20%缓速酸+3%黏土稳定剂BSA-101+0.1%缓蚀剂BSA-602+0.5%助排剂EL-11+0.1%破乳剂YBP-1)在辽河欢喜岭采油厂欢北区块现场应用两口井,注水压力降低5MPa以上,日注水量增加10m3以上。图3表4参12
Conventional acidizing treatment with HC1-HF system had bad efficiency of removing plugs and short effective period. For the above considerations and aiming at solving the problem of high water injection pressure and sever formation pore blockage in Huanxiling oil extraction factory of Liaohe oilfleld, a non-HF retarded acid was synthesized with phosphorus trichloride, organic acid and acetone. This organic phosphate' s capability of reducing injection pressure and enhancing injection was well when used alone without HF or fluoride salt. Indoor experiment results showed that the corrosion capacity of 20% retarded acid in aqueous solution to rock was 23.25% at 60~C after 48 hrs treatment, which had a better retarding effect than HC1-HF and HBF,. The pH value of acid solution when the scale formed was between 7 and8, and the complexing ability of that was 500-600 g/L, which could effectively prevent forming of secondary precipitations, such as Fe (OH) 3 and AI (OH) 3. Core flow test results showed that the permeability recovery could reach up to 173%. After retarded acidizing process, the core strength loss rate was 22.7%, which was 0.56 times that of mud acid treatment at the same condition. The retarded acid system, composed of 20% retarded acid, 3% clay stabilizer B SA- 101, 0.1% corrosion inhibitor BSA-602, 0.5% discharge aiding agent EL- 11, 0.1% demulsifier YBP- 1, was applied in 2 wells on Liaohe oilfield. The water injection pressure was reduced by more than 5 MP and daily water injection volume was increased above 10 m3.