چكيده به لاتين
The phase behavior prediction of gas condensate reservoir and prediction the viscosity of petroleum fluids are from the important problems in petroleum engineering. One of the challenging problems in gas condensate reservoirs is the prediction of dew point pressure and liquid drop out, in which the binary interaction coefficients are the important factors in these predictions.
In this work a proper equation is presented for the determination of the binary interaction coefficients, for a statistical equation of state (EOS) from SAFT EOS family, PC-SAFT. The modeling results correspondeng to dew point pressure are presented for PC-SAFT in comparison to the experimental data and Peng-Robinson (PR) equations of state (with a common interaction coefficients estimation procedure).
The results demonstrate improved predictions by PC-SAFT with the new set of binary interaction coefficients. The average absolute deviations for the dew point pressure prediction by Peng Robinson (with common estimated values for interaction coefficients) and PC-SAFT with the proposed interaction coefficients estimation model were found to be 19.6 and 9.6 percent respectively when the two EOSs are used in prediction mode. Beside this, the prediction of the liquid dropout is relatively improved in the case of PC-SAFT relative to Peng Robinson EOS.
Also for the viscosity the free volume theory in combination with PC-SAFT is implanted for viscosity prediction of the petroleum reservoir fluids. FV has three adjustable parameters for viscosity calculation for each component. These three viscosity parameters for main pure components are available in literature but their value for petroleum fractions is still a challenge. In this work an equation as a function of molecular weight and specific gravity for determination of these parameters for plus fractions is presented. The procedure is applied for differential liberation tests for several reservoir fluid samples. Finally the presented model is used for 6 real samples in evaluation and the results are compared with available experimental data (experimental data in differential liberation test) and Lohrenz-Bray-Clark (LBC) method for viscosity calculation. The absolute average deviation was 9.70118% for free volume theory method and was 36.4219% for LBC correlation.
Keywords: gas condensate, binary interaction coefficient, liquid drop out, viscosity, free volume theory
