Utilizing acoustic telemetry networks for potential Seismic-While-Drilling applications

Historically, Reverse-VSP Seismic While Drilling (SWD) technology, using the downhole drilling vibration signal as a seismic source, has suffered from the lack of a proper pilot signal signature recording. Most surveys use geophones clamped to the drilling device, at the surface, to record the drillstring vibrations. In recent years, seismic sensors have been included in the Bottom Hole Assembly (BHA). The downhole seismic pilot signal can then be recorded and used for processing. Total tested such a technology in an offshore well in 2018. The nodes recording the downhole signal were part of an acoustic telemetry network that was used for Managed Pressure Drilling purposes. Being an opportunity job, the surface acquisition system was not fully adequate for a complete SWD acquisition, but it was possible to record and analyze datasets for several days, both of drilling and non drilling periods. Although data included multiple types of signals, it was possible to filter them and to extract a coherent downhole signal propagating from downhole to surface over a period of several hours. Multiple challenges are still ahead for this technology, but these observations open the door to the possibility of a better understanding of the downhole drilling signal and its capture for processing purposes.