Creation of high-conductive filtration channels in core samples when simulating acid exposure at a filtering unit

Abstract

Background. Hydrochloric acid treatment is currently one of the main methods used for recovering and improving the reservoir properties of bottom-hole formation zones. In the process of acid treatment, during the reaction of the acid composition and the rock, highly conductive filtration channels are formed. The structure and shape of such channels characterise the treatment efficiency. As a result, much research attention is currently paid to predicting the formation of filtration channels and changes in the filtration characteristics of reservoirs with different properties and types of pore space.Aim. To study the factors that directly affect the formation of dissolution channels in core samples when simulating hydrochloric acid treatment of the bottom-hole zone of carbonate reservoirs on a filtration unit. The main objectives are to determine the significance of these factors and to establish dependencies reflecting their effect on the efficiency of technologies aimed at stimulating oil inflow.Materials and methods. We used the results of filtration and X-ray tomographic studies on core samples taken from the scientific base of the “Geology and Development of Oil and Gas Fields” Scientific and Educational Centre. The collection of rock samples is represented by various deposits confined to the oil and gas complexes of the Perm Territory.Results. The conducted analysis allowed us to identify the effect of various factors on the formation of highly conductive filtration channels during acid treatment. These factors were found to include the lithological and mineralogical composition and initial filtration parameters of core samples, as well as the type of pore structure. Dependences that characterise the efficiency of acid treatment were determined.Conclusions. The obtained results can be used when developing measures for the intensification of oil production, taking into account the revealed factors.