Application of Ultrasonic Wavesfor Degassing of Drilling Fluids and Crude OilsApplication of Ultrasonic Waves for Degassing of Drilling Fluids and Crude Oils

Abstract

In the oil and gas industry, both the produced oil and the drilling fluids used while drilling will contain gases that are entrapped within their liquid systems. These gases are removed, or degassed, using several methods such as separator tanks (for crude oil) and vacuum degassers (for drilling mud). This project, however, proposes a novel, environment friendly and cheap method of degassing that uses ultrasonic waves to remove gas bubbles from liquid systems. This method could be incorporated with already existing degassing technologies to increase their efficiency.
The objective of this work, therefore, is to investigate the feasibility of using ultrasonic waves as a method of degassing drilling fluids and crude oil samples. The basic idea of this new method is based on the effect that ultrasonic waves generate when in contact with a liquid medium as they create repeated compressions (high-pressure cycles) and rarefactions (low-pressure cycles) in which small vacuum bubbles (voids) are formed in the liquid. Dissolved gases will migrate into these small voids which will coalesce and then rapidly grow into large size bubbles that are easily removed out of the liquid.
Hence, this method insures more effective removal of dissolved gases that are entrapped within the liquid. Also, as this whole process happens rapidly, gas bubbles will have shorter time in contact with the liquid particles which reduces the possibility of gas redissolving; especially in the case of highly viscous liquids such as oil. This further adds to the advantages of using this new method.
For the purpose of this project, several testing methods such as sonication, density, pH, Particle Size Distribution (PSD), Fourier Transform Infra-Red (FTIR), and corrosion testing were conducted. These tests aimed to evaluate the physical and chemical impacts that ultrasonic waves have on the tested systems.
The results of these tests prove, to a great extent, the effectiveness of ultrasonic waves in removing gases from water based mud and crude oil samples. The impact of ultrasonic waves on the physical and chemical properties of the tested fluid systems, however, requires further investigation.