转向酸滤失基础理论研究

The novel self-diversion acid is characterized by the viscosity variation and diversion. Based on the leak-off characteristics of diversion acid, the theoretical research is focus on the propagation of wormholes, spatial distribution of complex wormholes and leak-off theory. The mechanism of acid diversion and effect of diversion can be obtained by the single core and parallel cores flow experiment, analysis the leak-off of wormholes and influential factors. Based on the result of experiment test, the extension model of single wormhole and complex wormhole network model can be established accounting the viscosity variation and the existence of supercritical carbon dioxide. The diversion acid leak-off model based on complex dynamic wormholes can be established in this research accounting the leak-off mechanism and influential factors of diversion acid. Through this work, the models and simulations can be used to characterize the growth and distribution of wormholes, and calculate the loss volume accurately, especially provide theoretical basis and technical support for the acidizing design of carbonate reservoir.

清洁转向酸是一种具有变粘、转向特征的新型酸液体系。针对转向酸滤失特点以及滤失过程中所产生的酸蚀蚓孔发育、复杂蚓孔空间分布等物理现象开展基础理论研究工作。采用单岩心及并联岩心流动实验，研究酸液转向机理和转向效果，分析蚓孔滤失量及影响因素。在实验测试基础上，考虑酸液变粘和超临界二氧化碳的影响，建立酸蚀单蚓孔发育模型和酸蚀复杂蚓孔网络数学模型。分析转向酸滤失机理及影响因素，建立基于复杂酸蚀蚓孔几何形态的滤失计算数学模型。研究成果能定量描述蚓孔发育规律和空间分布，准确计算转向酸滤失量，为碳酸盐岩储层酸化设计提供理论依据和技术支撑。

本项目进行了转向酸稠化剂、缓蚀剂、铁离子稳定剂等的优选评价，形成了耐高温转向酸配方。开展了转向酸液的流变性能、动态腐蚀、酸岩反应速度等实验评价，完成了并联岩心转向分流效果测试。提出了缝洞型储层蚓孔发育及滤失测试表征方法，进行了不同压差和不同浓度下的酸液滤失测试。建立了蚓孔内酸岩反应流动模型及酸蚀蚓孔发育模型，并进行了蚓孔孔径和蚓孔长度的计算分析。建立了考虑超临界CO2影响的酸液滤失模型，分析了CO2、排量、酸液粘度等对滤失量的影响。研发的转向酸在四川盆地某气井应用取得显著增产效果；项目授权发明专利1项，资助发表论文3篇，其中SCI收录1篇、EI收录1篇，与项目有关的硕士研究生论文2篇，支撑省部级成果一等奖1项。