Development of an automated phase behaviour measurement system for lean hydrocarbon fluid mixtures, using re-entrant rf/microwave resonant cavities

A re-entrant resonator has been developed and tested, specifically tailored for automated phase boundary measurements in the natural gas fluids of the north west shelf of Western Australia. The resonator is based on a constan t volume, rf re-entrant resonant cavity capable of detecting phase boundari es in binary mixtures [1]. Our resonator is capable of isothermal and isoba ric measurements in addition to isochoric measurements. The vacuum characteristics of the resonator have been studied using extensi ve models, and measured in experiments with helium. The resonator was then employed to study phase transitions in pure carbon dioxide and a binary mix ture of propane and carbon dioxide. The suitability of the resonator for de w point detection in lean hydrocarbon mixtures was also tested. The results indicate that microwave resonators are not just limited to phase boundary measurements, rather they can measure phase volumes and potentially determi ne the compositions of the two-phases. However, further development is need ed to achieve a system in which accurate measurements can be made for gas c ondensate type fluids. (C) 2001 Elsevier Science B.V. All rights reserved.