The Effects of Ultrasonic Waves on Drilling Fluid Foaming
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abstract
Foam is a formation of small bubbles caused by dispersion of gas in a continuous liquid phase, stabilized by surfactant. Foam has been widely studied by researchers in the oil and gas industry, from issues and opportunities it can bring to the drilling operations. Depending on how it is handled, it could increase or reduce oil and gas production and may have an adverse effect on the environment and safety of personnel. Foam technology has been meticulously investigated as it plays a major role in many drilling operations particularly in shale gas drilling. Its popularity over classical conventional drilling fluids is due to its capability to decrease formation damage, fluid loss and differential sticking on low pressure drilling and reservoirs that are highly fractured and mature. Another benefit of foam is its capability to regulate the mud effective circulation density that aids in maintaining the expected bottom hole pressure. Foam is also used to mitigate the productivity reduction of shale gas drilling due to formation damage. Thus, a careful investigation on its characteristics can be a viable tool in order to mitigate any issues and plan ahead on any activity involving foam. Variables such as foam stability, rheology, hydrodynamic behavior towards high temperature and pressure are some of the characteristics that needs to be looked at in order to have a better understanding of the technology. On the other hand, in conventional drilling, due to components used in the drilling fluid related to the formation, foam is produced which can be detrimental to the operation. These issues are solved by adding defoamer or surfactants. In this project, we incorporate the use of ultrasonic energy, as a new method, to study the actual foam characteristics. The process of ultrasonication is the propagation of sound waves into a substance for agitation purposes. Ultrasonication uses the frequency of sound waves starting from 20 kHz. The mechanism of ultrasonication involves: a. Cavitation due to application of 20 kHz waves at high intensity and amplitude, b. Followed by rapid fluctuation of pressure, c. Formation of large masses of vacuous and small bubbles d. Rapid bubble growth towards critical size, e. Implosion of bubbles and generation intense shock waves that causes temperature to rise and liquid micro streaming, f. Increase in shear gradient that leads to weakening of interfacial films in the fluid. Having such mechanism in place for foam, would greatly affect its characteristic. This project will revolve around having the foam drilling fluid being subjected with the ultrasonic equipment, Heilscher UIP1500hd, which is placed inside a cabinet. The fluid will be placed in a beaker with a stirrer so as to simulate drilling while applying ultrasonic waves simultaneously. This will then enable us to check the level of foam formation and disappearance. Foam is having an increasingly important role in the oil and gas industry. As such a thorough study on the effects and the application of ultrasonic energy on the properties of foam may prove to be providing a great insight into the foam characteristics, and not much work has been done in this area. A major focus of this study will be on the stability of foam as well as rheological properties of foam when subjected to ultrasonic irradiation. Such knowledge can later on be useful for researchers in this field as well as engineers involved in underbalanced drilling operations. In order to get meaningful results, a matrix of various laboratory experiments will be designed and conducted. Prior to the start of the experimental work, the participating students will go thru an extensive laboratory safety training program.
