This scientific work presents the design of combined acid fracturing in carbonate reservoirs of an oil field using mathematical modeling methods. An analysis of geological and technical actions was carried out, on the basis of which it was revealed that the previously used acid fracturing showed high efficiency, but at the same time there was a rapid rate of decline in production. In this regard, after studying various types of fracturing, combined acid fracturing is recommended to apply. It was found that the application of this method helps to increase the width of fracture and keeps it open, thereby compensating the lack of traditional acid fracturing.

Drilling mud has various functions, one of which is to carry cuttings to the surface. All other things being equal, the removal of cuttings is characterized by the upward velocity. This paper simulates the rheology of polymer-glycolic non-dispersing mud (in particular viscosity) to achieve the required upward velocity in the «Ansys CFX» software. The viscosity of the mud varies from 6 to 12 mPa·s, on production casing drilling in Arctic conditions. The results of the study showed that for such conditions, the viscosity should be in the range from 6 to 8 mPa·s.