Acoustic Velocity Measurements and Interpretation for Challenging Fluid Systems

Abstract

Abstract Acoustic velocity can be measured with a high degree of accuracy making it an attractive method for extracting related thermodynamic properties. Technical improvements were made to measure acoustic wave velocities in fluid samples over a range of temperatures, pressures, and fluid properties. The simplicity of this technique relative to conventional PVT measurements makes it a fast and reliable means for obtaining some of the data needed in petroleum engineering calculations. The primary objective in this study is to determine whether the designed apparatus is suitable for measuring compressional wave velocities in fluids commonly encountered in oil and gas operations. Additionally, the potential of the device to be used as a QC tool to accompany conventionally determined PVT properties was also studied. A robust experimental design allows for the determination of acoustic wave velocities at elevated pressures and temperatures and includes the ability to homogenize and recondition samples. For experiments involving heavy, viscous oils - especially those containing dissolved gas - this capability is particularly important. The following main points will be the focus of this study that also includes new data interpretation:Ultrasonic p-wave velocities in two heavy oil samples were measured up to 10,000 psig: A live fluid was diluted with solvent and the acoustic response was measured for two solvent dilution levels (8 and 20 percent by mass). Velocity decreased with increasing solvent concentration. A light hydrocarbon mixture was blended with a bitumen sample in a dilution range of 10 - 60% by mass. Velocity again decreased with increasing solvent concentration.