智能转向酸化的机理及试验研究

Mechanism and Experimental Study of Intelligent Diversion of Acidification

为了解决在常规酸化中高渗透层的指进、酸液的穿透深度小和残余伤害严重等问题,提出了一种新型的智能转向酸化技术,该酸液体系以粘弹性表面活性剂(visco-elastic surfactants简称VES)和盐酸或土酸为主体外加各种添加剂,在酸化过程中主要依赖于粘弹性表面活性剂的特殊性能实现转向、破胶、缓速降滤的功能,同时具有控水调堵的作用。在酸化反应过程中,随着pH值的升高和钙镁离子的增多,胶束开始聚集,宏观上表现为酸液粘度的大幅度升高,酸液实现转向并能起到缓速降滤的作用,在返排过程中遇到油气实现自动破胶。酸液体系的变粘性能是关系酸化施工成败的关键,通过分析室内的岩心驱替试验可以看出,酸液的粘度受胶束的结构粘度和非结构粘度的共同影响,粘弹性表面活性剂的耐高温抗剪切性能对于酸液体系的变粘和转向性能有显著影响。

In order to solve the problems in conventional acidification,such as fingering,small penetration depth and serious damage in high permeability reservoirs,a new intelligent acidification technique was proposed through theoretical studies and laboratory experiments.The acid system was mainly composed of viscoelastic surfactant and hydrochloric acid as well as a variety of additives,depending on the special properties of viscoelastic surfactant used for particular diversion,gel breaking,fluid retarder,and at the same time it had the function of water control,plugging,adjustment in the acidification process.In the process of reaction,pH increased and calcium and magnesium ions grew,thus it caused micelles to be gathered,which controlled the substantial increase of viscosity,achieved steering and retarder,and gel breaking was automatically carried out when it encountered with oil and gas in the back flow.Viscosification of the fluid system was the key of success or failure of acidization.Viscosifying mechanism of the acid system was studied through laboratory core displacement test.The experimental results show that micelle's structural viscosity and non-structural viscosity determine the overall viscosity of the acid system,and it also suggests the importance of researching high temperature resistance and shear resistance viscoelastic surfactant.