Drilling Torques Acoustic Logging an effective duo for calibrating near surface seismic data
Paper presented at the EAGE 2021 – Annual Technical Conference and Exhibition, Amsterdam, Netherland, November 2021, and co-written by J. L. Mari, K. Gestin & P. Gaudiani.
An experimental site, situated in the Cher region (central part of France), is located at the transition from the Triassic to the Jurassic. Recent superficial deposits overlay a carbonate formation with a thickness of about 200 m, covering the basement rock. The carbonate formation can be locally fractured. On the site, two boreholes have been drilled for field experiments. During the drilling, some parameters such as penetration rate and Torque have been continuously recorded. Field experiments include acoustic logging and seismic surveying such as refraction tomography and VSP acquisition.
After a review of seismic imaging of the site, the paper shows how drilling parameters, acoustic logging, and refraction tomography can be merged for obtaining a very high-resolution continuous velocity model from the surface up to the terminal depth of the borehole. We also show the benefit of combining of hybrid seismic methods (reflection seismic processing, refraction tomography), drilling parameters and acoustic logging to extend the previous velocity model, laterally in the vicinity of the borehole.