低渗透油田选择性酸化解堵剂研制

Research on the Mechanism of Selective Conventional Acidization in Low-permeability Reservoir

针对无机垢、有机垢和微生物细菌3种主要的造成地层堵塞因素,研制出一种适用于水敏性地层和低渗透油层的多功能水包油型乳状酸液(油为外相、酸为内相)。室内对无机垢解堵酸液、有机垢解堵剂及乳化剂进行了优选,得出:对于石灰岩乙酸为最佳解堵酸,对于硅质砂岩氟硼酸为最佳解堵酸;对于以沥青质、胶质为主要成分的有机垢堵塞,确定以粗苯-柴油(9∶1)复配体系为有机解堵剂;选择了具有耐酸能力、且具适宜HLB值的OP-10和Span80混合体系作为乳化剂,OP-10和Span80的最佳质量分数分别为0.4%和0.2%。考察了油和酸的乳化状况以及配成的乳状液随温度变化的稳定性,实验结果表明,无机垢解堵酸液和有机垢解堵剂的最佳配比为7∶3,该乳状液在室温下稳定,高温下自动破乳,释放出酸和高性能油,达到恢复和提高地层渗透率、提高原油产量的目的。

A multi-functional oil-in-water acid emulsion is developed in the treatment of inorganic scales, organic scales and microorganisms in water sensitive formations and low permeability reservoirs. Laboratory experiments have been done on the optimization of the acidization liquid for inorganic scales, the plug remover for organic scales and the emulsifiers. It is concluded that, acetic acid is the optimum acidization fluid for limestones (mainly carbonates), fluoro-boric acid is the best acidization fluid for silica sandstones. For the organic scales mainly composed of asphaltene and gum, an organic scale remover containing benzol and diesel (9:1) is selected. OP-10 and Span-80, mixed together with mass fractions of 0.4% and 0.2%, respectively, forms the required emulsifier, which has acid tolerance and an appropriate HLB value. Experiments have been done investigating the emulsification of oil and acids, and temperature stability of the emulsion prepared, and show that the optimum ratio between the acidization liquid for inorganic scale and that for organic scale is 7:3, an emulsion formed in this ratio is table at room temperature and will automatically break at elevated temperatures. Thus, when injected into the formations, the prepared emulsion will automatically break at the high temperatures in the formations, releasing acid and oil to recover the impaired permeability of the formations and enhance oil production.