A SYSTEMATIC INVESTIGATION INTO THE MOST SUITABLE DATA FOR THE DEVELOPMENT OF EQUATIONS OF STATE FOR PETROLEUM RESERVOIR FLUIDS

Equations of state (EoS), particularly cubic equations of state, are o ften used to describe the phase behaviour and fluid properties of petr oleum reservoir fluids. This paper does not dwell on the ''how'' of tu ning an equation of state; rather it addresses the often overlooked qu estion of what data should be used in the tuning process. Often the tu ning process is necessarily constrained because the best data for the determination of equation of state parameters were not collected throu gh reasons of economy (laboratory data is expensive), time pressures, or simple oversight. We demonstrate that by addressing this issue earl y in the data collection process later uncertainties can be avoided. W e consider the relative merits of various types of black oil PVT data and the role they play in the development of and equation of state for enhanced oil recovery and surface processing design. We conclude that with the judicious choice of initial experiments one can develop a fl exible equation of state which can then provide a cost-effective means of testing reservoir depletion strategies.