Heat capacity of two-phase systems according to the law of additivity

Practice shows that the temperature around drilling and production wells is of great interest in terms of design choices and preventing the precipitation of heavy fractions (paraffins, resins, asphaltenes). A literature analysis has demonstrated that the temperature of the elements of drilling and production wells can be determined with sufficient reliability using the method of successive changes in the stationary state. To select downhole equipment, both during drilling and operation, it is necessary to determine the temperature values for the wells. The performed calculations indicate that the change in the temperature of hydrocarbons along the wellbore during flow operation is considered in three cases of annulus filling. To refine the temperature calculations, they must be conducted step by step, dividing the length of the lift into specific intervals. Similar temperature calculations are also carried out for injection wells when hot water is injected into the reservoir. In such cases, it is important to maintain the temperature of the injected water above the formation temperature. The temperature of the water injected into the reservoir from the wellhead to the bottom of the well is determined by solving the equations of thermodynamics and heat transfer jointly. Literature analysis shows that, to calculate the temperature of produced or injected water, it is necessary to know the thermophysical properties of well production, reservoir fluids, cement stone, and surrounding rocks. In a particular case, a water-gas-oil mixture moves through a production well, with the concentration of its phases and components changing as it moves upwards to the wellhead. A similar mixture system is also present in the annular space between the pipe strings and within the pores of the rock.