ABSTRACT
A compositional model consisting of material balance (M-B) ‘equations and the Peng-Robinson (P-R) Equation of State (EOS), was developed starting with the work of Bergman, Tek, and Katz. The model simulates constant volume expansion (CVE) as obtained from experimental analyses of gas condensates.
The contributions of this paper include the following: (1) evaluation of the phase behavior and fluid properties for an arbitrary mixture of components (2) development of the material balance equations to compute depletion performance, (3) investigation of P-R EOS as a tool for reproducing measured PVT data, and (4) analysis of the effect of component property estimation on EOS predictions.
The North Field Khaff reservoir, which is situated offshore northwest of the northern top of Qatar, and the specific K-4 reservoir description was used as the example in this work.
Laboratory measurements for constant volume depletion and phase separations of a condensate fluid sample were obtained from well No. NWD 5 in the K-4 reservoir of the North Field in Qatar. This experimental data was used as a basis for comparing results from the proposed compositional model. The data analysis was carried out up to C20+ group hydrocarbons.
The experimental data used for comparison with the calculated results were volume percent liquid (retrograde condensation), cumulative produced volume, molecular weight of heavy components (C7+) produced, and compressibility factor. In addition to the values calculated above constant composition expansion at different temperatures, a partial phase diagram for K-4 gas condensate, and viscosity were calculated by the model.