Use of chelators and hydrofluoric acid for the improvement of well productivity

Abstract

Abstract The paper presents the results of microscopic analysis of the content of elements on the surface of clay samples after treatment with an acidic mixture of HV:HF. The analysis showed that as a result of the dissolution of clay and quartz, quartz dissolves faster, the Si/Al ratio on the sample surface decreased, which indicated the formation of a protective film of aluminum phosphate silicate. The studies of the ability of chemical reagents to dissolve clay by the method of weight loss showed that in the HV:HF system, the dissolution rate of clays is much lower due to the formation of a coating layer. The stage of the increase in the rate of dissolution occurs when a part of this layer is dissolved. The studies of the ability of the HV:HF chemical reagent system to dissolve silicon showed that the amount of dissolved silicon varied linearly with the exposure time and the rate of silicon dissolution was proportional to the HF concentration in the system. The dissolution rate of silicon in the HV:HF system is much higher than in the HCl:HF system at the same HF concentration. This is a significant advantage of the proposed system of chemical reagents HV: HF in comparison with the traditional HCl:HF system. HV: HF system dissolves calcium carbonate much more efficiently than traditional hydrochloric or acetic acid systems.