Characterization of Ultrasonic Waves in various Drilling Fluids

Abstract

The aim of this master thesis is to characterize ultrasonic wave propagation in different mud samples with respect to propagation distance using three different transducers frequency, this is expected to be an introduction to utilizing ultrasonic Doppler measurements for determining mud flow rate in the test rig at USN. The experiments were carried out to determine the amplitude attenuation coefficient of the different fluid samples while comparing it to their acoustic properties at different frequencies. The transducers were operated in through transmission mode while taking apart along an axial propagation distances. A pulser device was employed to drive the transducers at their various designed frequencies, and the amplitude decay from the ultrasonic beam were observed and recorded at several points within the distances between the emitter and the receiver. Results were obtained by estimating the exponential function that described the attenuation coefficient of the fluid sample and multivariate data analysis was used in analyzing the correlations between the fluid samples. The sound speed of the materials was also calculated but the obtained values for sound speed in water did not completely show concordance with the one defined by literature. This could be due to errors related to the discrepancies associated with the frequencies involved but they have not been completely identified. Nevertheless, experiments yielded successively better results. It was observed that highly viscous fluid samples with particle composition attenuations more than denser fluid with soluble salt contents.