Prediction of technological indicators of gas-condensate field with oil rim under the scheme of simultaneous-joint development

The article proposes a three-phase multi-component calculation model of filtration, which allows estimating the technological indicators of the process of oil and gas condensate field exploitation with gas return to the gas condensate cap, and water – to the oil rim after condensate separation by separating gas and water from the extracted products when exploiting gas, water and oil by the same well. The joint combination of the equation of isothermal flow of a threephase multicomponent mixture, the continuity equation for each component of the three phases, the generalized Darcy’s law and the relationship of thermodynamic nonequilibrium of the phases was chosen as a basis (the use of the relationship of thermodynamic nonequilibrium is considered necessary when developing a suitable technological solution to maintain the pressure of the gas condensate cap). Dynamics of change of parameters characterizing physical properties of phases included in the calculation model (density and viscosity parameters), in accordance with the change of thermobaric conditions is determined by the relations describing thermodynamic non-equilibrium state of fugacity of components of gas-liquid and gas-water phases, and the joint solution of balance equations of gas-liquid-water system as a system. In this case, the intensity of the interphase flow of a component entering the system is expressed by the difference of its chemical potentials in the phases. On the basis of the computational model the indicators of development of techno-logical approach for a specific reservoir model were calculated – oil recovery of oil rim and condensate recovery coefficient of gascondensate cap were calculated, and to assess its effectiveness an approximate comparison with the results of the depletion mode of oil rim and other existing conventional development options was made. Based on the results of comparison, it was found that it is possible to increase the oil recovery factor by about 7–12 % and the condensate recovery factor by 15– 20 %. The proposed technological approach to recovery of oil and condensate reserves when more than 98 % of well production is watered out proved to be cost-effective, allowed to maintain oil and condensate flow rates at an acceptable level, and it was found that the condensate recovery factor recovered from the gas condensate cap can reach approximately half of its condensate reserve.