碱酸复合解堵技术的研究与应用

Research and application of alkali-acid composite plug removal technology

针对卫城油田浅层区块低温、低压、低含水率、高黏度井采用常规土酸酸化效果不佳的情况,提出了碱酸复合解堵技术。该技术借鉴综合了三元复合驱和CO2驱的优点,采用前置驱油体系和后置酸液体系,前置驱油体系主要组分为瓜胶、交联剂、烷基苯磺酸钠、Na2CO3和NaHCO3,利用三元复合驱驱油原理,剥离驱替黏附于岩石孔隙表面的原油,避免生成酸渣;后置酸液体系为常规土酸酸液,主要作用是除污扩孔,以及与前置驱油体系反应放出热量、CO2气体降黏、促排。室内实验和现场应用结果表明,碱酸复合解堵技术前置驱油体系能为后置酸液体系解除地层污染创造良好条件,酸碱反应生成大量的CO2气体及放出的热量与酸液有效结合能很好解决低温、低能和低含水井的有机污染和无机污染问题。

In view of the fact that conventional mud acid acidizing effect is not satisfactory for wells with low temperature, lowpressure, low watercut and high viscosity in shallow blocks of Weicheng Oilfield, this paper presents this alkali-acid composite plugremoval technology, which integrates the advantages of ASP flooding and CO2 flooding, and uses the previa flooding system and postacid system. The previa flooding system is mainly composed of guar, crosslinking agent, sodium alkyl benzene sulfonate, Na2CO3 andNaHCO3, which adopts the principle of ASP flooding, stripping and displacing the crude oil attached to the surface of rocks pore to avoidresidues. The post acid system is conventional mud acid liquid, the function of which is to remove dirt, enlarge pores and also react withthe previa flooding system to give off heat and CO2 to reduce viscosity and enhance emission. Its plug removal effect was studied bymicro-model and physical model. The experiment and field application showed that, in the alkali-acid composite plug removal technology,the previa flooding system created favorable conditions for post acid system to remove formation pollution; the reaction betweenalkali and acid produced large amount of CO2 and heat, which combined with acid and effectively solved the problem of organic pollutionand inorganic pollution in wells of low temperature, low pressure and low watercut.