Equation of state of crude oil through temperature dependent ultrasonic measurements

Abstract

Ultrasound interferometery has been used to determine the velocity of propagation of compressional waves in two different samples of crude oil over a wide range of temperatures. The corresponding bulk density of the samples at similar conditions has also been measured using an Anton Paar density meter. These experimentally measured quantities form the basis for the thermo-physical characterization of crude oil through thermodynamic relations. This facilitated the evaluation of the acoustic impedance, compressibility and the coefficient of thermal expansion as a function of temperature. Simple analytical relations are suggested to describe the temperature dependence of thermo-physical functions. The equation of state for the crude oil has been set up by using these data. Our study yields a very close agreement to the reservoir conditions of the respective oil fields and to other empirical relations.