Influence of Drill Collar Wave on Multipolar Source Seismoelectric Logging While Drilling

An important factor that limits the acoustic logging while drilling is the existence of drill collar waves, which can even obscure the longitudinal wave information in the formation, making it impossible to extract effective information in the formation. The seismoelectric effect is only produced in the stratum, which excites the electromagnetic waves propagating with the acoustic field, reflecting the propagation characteristics of acoustic field. In this paper the frequency and velocity correlation characteristics of the field was done, and the propagation characteristics of seismoelectric field of different excitation sources in logging while drilling was studied. Comparative analysis of seismoelectric field with different excitation sources is done, and it’s revealed that measuring electromagnetic field signals in seismoelectric logging while drilling can effectively reduce the influence of the collar wave, and the electric field is basically not affected by the drill collar wave when excited by dipole source. This work provides theoretical guidance for the selection of excitation source of seismoelectric logging while drilling.