多氢酸酸液体系酸度特性实验分析

一般砂岩的主要成分含有大量的硅质（包括石英和硅酸盐），由于氢氟酸能与石英和硅酸盐反应，迄今为止对于砂岩酸化都是用含有HF的酸液体系。但是，氢氟酸会快速的与黏土反应，同时产生二次、三次沉淀，这不利于保护岩矿的胶结和防止酸化过程中的储层伤害。为了减少这些负面效应的产生，提高油气藏酸化效果，国内外一直致力于酸液体系和酸化工艺改进研究。为此，对多氢酸酸液体系的特性进行了进一步的实验研究，结果表明：多氢酸酸液体系是一种多元弱酸，在酸化过程中能逐渐释放H⁺，可以保持溶液的pH值变化较小，即保持酸液的HF浓度变化较小；多氢酸酸液体系的初始pH值较高，可减少缓蚀剂的用量；多氢酸酸液体系是一种缓冲酸液体系；对于砂岩酸化，多氢酸比传统的含HF酸液体系更好；对于高温砂岩地层油气藏酸化，使用多氢酸酸液体系可延长酸液有效作用范围。

EXPERIMENTAL ANALYSIS ON ACIDITY CHARACTERISTICS OF MULTI HYDRO ACID FLUID SYSTEM

As the main component of common sandstone is a large number of siliceous, including quartz and silicate, and the hydrofluoric acid can react with quartz and silicate, the acidification of sandstone has been achieved by using the acid fluid system containing HF acid until now. However, hydrofluoric acid can react with clay quickly, and the reaction will cause secondary and tertiary precipitation simultaneously, which is not conducive to protecting the cementation of rock and mineral and preventing reservoirs' damage in the process of acidification. In order to reduce these adverse influences and enhance reservoirs' acidification effect, experts, both at home and abroad, have been dedicating to the study of improving the acid fluid system and acidification technology. Therefore, further experimental study on the characteristics of multi hydro acid fluid system has been conducted. The study showed some results as follows: the multi hydro acid fluid system is a kind of polybasic weak acid, which can gradually release H+ during the acidizing process to maintain relatively slight change of solution's pH value, i.e., to keep the change of HF concentration within a small range; the initial pH value of the multi hydro acid fluid system is relatively high, so the usage of the corrosion inhibitor can be reduced; the multi hydro acid fluid system is a kind of buffer acid system; for the sandstone acidification, the multi hydro acid fluid system is a better choice, compared with the traditional HF acid fluid system; for the acidification of sandstone stratigraphic hydrocarbon reservoirs at high temperature, the effective range of acidizing fluid can be extended by using the multi hydro acid fluid system.