酸化夹石膏油气储层时石膏沉淀的理论探讨

DISCUSSION ON THE PRECIPITATION THEORY OF GYPSUM IN ACIDIZING TREATMENT TO THE GYPSIFEROUS RESERVOIR

为了有效地防止酸化过程中出现的石膏沉淀，提高失石膏油气储层的酸化增产效果，本文运用化学热力学、化学平衡和电化学理论，对石膏溶解和沉淀的物理化学机理进行了较全面的分析和探讨。结果表明，石膏在酸化中的沉淀趋势与石膏在储层中的溶解程度有密切的关系。而石膏在储层中的溶解程度又取决于体系中温度效应、问离子效应、盐效应、欧效应及溶剂效应的相互作用大小。因此，要有效地防止石膏在购也中的沉淀，应首先对石膏在储层中溶解的影响诸因素进行综合研究。

In order to prevent effectively the precipitation of gypsum in acidizing treatment and to improvethe result of acidiring treatment to the gypsiferous reservoir, this paper analyses and discusses systematically the physical and chemical mechanism of dissolution and precipitation of gypsum aPP1ying thechemical thermodynamics, chemical equilibrium and electrochemical theory. The resu1ts indicate thatthe precipitation of gypsum in acidizing treatment relates to the solubility of gypsum in the reservoir,which depends on the interactions among the temperature effect, plasma effect, salt effect, acid effectand solvent effect. Therefore, in order to prevent effectively the precipitution of gypsum, the synthetical study on the factors to influence the dissolution of gypsum in the reservoir is the first thing