Experimental investigation and molecular-based modeling of crude oil density at pressures to 270 MPa and temperatures to 524 K

Abstract

A predictive crude oil density model reliable over a wide range of temperature and pressure conditions is increasingly important for the safe production of oil and accurate estimation of oil reserves. While hydrocarbon density data at low-to-moderate temperatures and pressures are plentiful, data and validated models that have reasonable predictive capability for crude oil at extreme temperatures and pressures are limited. In this investigation, we present new experimental density data for crude oil sample obtained from the Gulf of Mexico region. Density data are measured at pressures to 270 MPa and temperatures to 524 K. These conditions simulate those encountered from ultra-deep formations to platforms. These density data points are then used to validate both empirical-based and molecular-based equations of state models. Results show that the molecular-based perturbed-chain statistical associating fluid theory (PC-SAFT) models, without the use of any fitting parameters, predict the crude oil density within 1% of the experimental data. These results are superior to the density predictions obtained with the high-temperature, high-pressure, volume-translated cubic equations of state.