"Dipole Shear Anisotropy Using Logging While Drilling Tools"
Matthew Blyth (Schlumberger)
This paper describes new modeling capabilities and processing workflows to output dipole shear anisotropy answers, such as the fast and slow dipole shear slownesses and azimuths from LWD sonic tools. A major objective is to model the coupling between the drill-collar and formation flexural modes that has been the root cause of measurement problems with LWD dipole in the past and invert either of these two modes for the formation dipole-shear slowness. A new dispersion extraction algorithm isolates and identifies both of these dispersive arrivals in the recorded wave train. This is followed by a model based inversion of either the drill-collar flexural or formation flexural dispersions to obtain the dipole shear slownesses either in a fast or slow formations. The method offers a robust and reliable dipole shear answer and opens the door to formation anisotropy characterization in all formations with LWD.
Matthew Blyth is the LWD Geophysics, Acoustics and Geomechanics Domain Head with Schlumberger Drilling and Measurements. Since joining Schlumberger in 1997 he has filled a variety of roles, all within the field of logging while drilling. He is currently involved in the long term technical development plan for LWD acoustic and seismic technology and their applications within Schlumberger. He has authored and coauthored multiple papers on LWD technology and its uses. Matthew graduated in 1996 from Cambridge University with a Bachelors and a Masters in Engineering. He is a member of the SPWLA, SPE, SEG and ASA and has served as both a VP and as President of the Houston SPWLA chapter. He is currently the secretary of the SPWLA Sonic SIG and is a 2016/2017 SPWLA Distinguished Speaker.