新型无固相压井液的研制及性能评价

DEVELOPMENT OF NOVEL SOLID-FREE WELL CONTROL FLUID AND ITS BEHAVIOR EVALUATION

修井作业过程中,不合理的压井液对储层造成不同程度的损害,导致油气井产能降低。大量的研究表明,压井液对油气层的损害主要是固相堵塞岩石孔道及造成岩石的性质发生改变。针对修井作业中无固相压井液对地层伤害小,利于油气层保护的要求,对压井液中所需要的增粘剂、降滤失剂、无机盐结晶抑制剂等进行了优选,并分别考察了加量对压井液性能的影响,室内研制了利于储层保护,具有较好抑制性与低固相损害的无固相压井液,合理的压井液配方:1%YJ1+0.1%YJ2+0.8%粘土稳定剂+0.12%其它添加剂+10% CaCl2,该体系具有密度可调、无固相、滤失量低、流变性、热稳定性好,抗温可达110 ℃等优点,室内岩心流动实验表明,该压井液体系对高低渗透率岩心伤害程度小,对油气层具有很好的保护作用。

In the process of workover job, an improper well control fluid will cause the reservoir to be damaged to a certain extent, thus making oil/gas well productivity decrease. A great number of research results indicated that the damage of well control fluid to oil reservoir was mainly the plug-of rock pores by solid grains and the variation in rock property. In consideration of the solid-free well control fluid's demands for reducing the damage to formation and being favorable to oil reservoir protection in workover job, the viscosifying agent, fluid loss additive and inorganic salt crystalline inhibitor, which are needed by the well control fluid, were optimized and the influences of their added-in quantities were examined respectively. A reasonable formulation of solid-free well control fluid: 1% YJ, + 0.1% YJ2+ 0.8% clay stabilizer + 0.12% the other additive + 10% CaCl2, which is beneficial to reservoir protection and has good inhibition and low solid grain damage, was developed in laboratory. Such a well control fluid system is of the following advantages: adjustable density, solid free, low filtration, good rheologjcal property and good thermal stability (with a heat resistance of 110 °C), etc. Through the core flowing test in laboratory, it was shown that the system had good protection effect on oil reservoir, the degree of its damage to the cores with both high and low permeabilities being poor.