Azimuthal shear-wave anisotropy measurement in a borehole: Physical modeling and dipole acoustic verification.

An anisotropic physical model is constructed to evaluate the anisotropy measurement. The model consists of a series of equally spaced thin limestone slab sheets cemented with concrete, resulting in a transversely isotropic medium. For the anisotropy measurement evaluation, the borehole model is tested by a standard multipole acoustic tool.

Acoustic source characterization for a logging while drilling tool: Theoretical and experimental modeling.

The development of acoustic source technology has been an important task for acoustic logging while drilling (LWD) and various source designs have been implemented. Using a multipole wave expansion theory, this study demonstrates that a LWD acoustic source can be represented as a combination of monopole, dipole, and quadrupole constituents and characterized by the contribution of each constituent. The theoretical analysis is experimentally demonstrated with a cylindrical pipe simulating the LWD collar.

Extensional-wave stopband broadening across the joint of pipes of different thickness.

The stopband of pipe extensional waves is an interesting natural phenomenon. This study demonstrates an important extension of this phenomenon. That is, the stopband can be effectively broadened by transmitting the waves across the joint of pipes of different thickness.