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建立了砂岩基质酸化时酸液沿井筒径向流动以及关井反应的数学模型,考虑温度对反应速度的影响,进行了数值求解,研究了酸岩反应规律,可以对酸化效果进行预测.计算结果表明:沿井筒径向HF酸浓度下降很快,其作用范围只有0.4m左右;次生H2SiF6与HF的溶解能力相当,并且是HF的有益补充,0.4～0.9m范围内快速反应矿物的消耗主要是由H2SiF6溶解,增加了土酸的穿透深度;硅胶Si(OH)4沉淀随着反应时间的增长而逐渐增加,酸化结束后一定时间内残酸必须彻底返排,否则容易形成2次沉淀,影响酸化效果;地层温度越高HF酸消耗越快,有效作用距离越短,生成的硅胶Si(OH)4浓度越大;提高注酸速度有利于提高酸化穿透距离,解除地层深部伤害.
The mathematic model of the acid flow along the wellbore and the well shut-in reaction during the acidification of the sandstone was established. The effect of temperature on the reaction rate was numerically solved, and the acid-rock reaction rule was studied to predict the acidification effect. The results show that the HF acid concentration decreases rapidly along the wellbore, and the range of its action is only about 0.4m. The dissolubility of secondary H2SiF6 and HF is equivalent and is a beneficial supplement of HF. The consumption of rapidly reacting minerals in the range of 0.4-0.9m is mainly Is dissolved by H2SiF6, increasing the penetration depth of earth acid; Silica gel Si (OH) 4 precipitation gradually increases with the increase of reaction time, after a certain period of acidification, the residual acid must be completely back row, otherwise easy to form secondary precipitate , Which affected the acidification effect. The higher the temperature of formation was, the faster the HF acid consumption was. The shorter the effective distance was, the higher the concentration of Si (OH) 4 was generated. Increasing the acid injection rate was beneficial to increase the acidification penetration and relieve the deep damage of the formation.