Numerical modeling of borehole acoustics : parallel implementation of a loggin-while-drilling (LWD) model

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2000.Includes bibliographical references (p. 41-42).A finite difference code is used to investigate acoustic waves in a borehole environment. The wave response to a logging-while-drilling (LWD) geometry is modeled in a fast formation. Helical waves circling the tool are shown to asymptote to the Stoneley wave velocity, giving confirmation of the fluid velocity in the borehole. Parameter studies for simpler borehole geometries show that the Stoneley wave, in soft formations where no shear arrival is present, can be used to invert for the shear velocity of the rock. A Beowulf parallel computer is used to implement the finite difference code showing the efficiency of cluster computing in a discretized space.by Victoria Alice Briggs.S.M