Characterization of Oil and Water Sound Speeds and Densities for Ultrasonic Water Cut Meters

Abstract

Abstract This paper presents produced water and heavy oil density and speed of sound (SOS) data for an extended range of temperatures and pressures. The data were obtained from laboratory measurements of samples collected from selected heavy oil wells and and from tests conducted at a specially designed flow loop. The paper also presents recommended methods for establishing oil and water density and SOS reference values required for ultrasonic water cut measurement. The laboratory tests were designed to evaluate short-term measurement repeatability, equipment reproducibility and long-term stability of oil and water samples at 101.3 kPa (14.7 psia) pressure and temperatures ranging from 20 to 70 °C (68 to 158 °F). Additional tests were conducted at a flow loop constructed by Chevron to evaluate two-phase and three-phase metering equipment over a range of temperatures, pressures, flow rates, water cuts and gas volume fractions. Water only and oil only flow loop density and SOS tests were conducted under steady-state conditions with pressures ranging from 377 to 653 kPa (54.7 to 94.7 psia) and temperatures ranging from 60 to 122 °C (140 to 250 °F). This is the first time that laboratory and flow loop data have been used to conduct an in-depth assessment of published tables and empirical equations for oil and water SOS and density. As a result, this effort has produced improved methods for creating reference density and SOS values for oil and water over an extended range of temperatures and pressures, an important breakthrough in the effort to utilize ultrasonic SOS methods to measure water cut.