(101a) Dynamic Ultrasound Phase Separation Measurements: From Liquid/Liquid to Gas/Liquid Separation

The performance of separators is crucial to oil field operation. Multiphase flow occurs in separators at low velocity compared to pipes and gravity forces cannot be neglected. To understand the behavior of such system, we have developed a technique based on ultrasound applied for liquid/liquid separation. The main advantage of this technique vs. well known bottle test is to provide more parameters than the conventional evolution of settled water volume such as the height and location of the dense pack zone, water droplet sedimentation kinetic or the evolution of water fraction in the separated oil. Experimental set-up equipped with dynamic ultrasound scanners of different scale and operating modes were used to develop a methodology to select processes, determine operating conditions and chemical treatment strategy to meet the BS&W specification for several projects.

The systems generated in the presence of gas and liquids in separators can also lead to complex interfaces that require advanced measurement technology, especially for foaming which is a well known problem in oil & gas separation.

After an introduction on the use of the ultrasound methods on liquid/liquid separation, the purpose of this work is to present the results of ultrasound methods applied to gas/liquid separation and to compare with standard foaming test based on visual observations and image analysis. Preliminary results have shown that foam decay and degassing from liquid occurring simultaneously are adequately captured on a system where air is dispersed in a stock tank oil. Results from real hydrocarbon system after depressurization of a cell equipped with dynamic ultrasound scanner will also be presented. Similarly to liquid/liquid separation, the perspectives of using ultrasonic tools to improve gas/liquid separation processes and chemical treatment requirement will also be also detailed.