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Look ahead opportunity in geosteering operations: real time seismic calibration using ultra-deep azimuthal resistivity
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, Second EAGE/SPE Geosteering and Well Placement Workshop, Nov 2018, Volume 2018, p.1 - 5
Abstract
Ultradeep electromagnetic azimuthal LWD has reached a depth of investigation up to 100 feet from the well bore, providing a reservoir mapping in terms of resistivity variation, close to seismic resolution.
A new workflow was developed to predict the geological structure ahead of the bit. A 3D local model, generated in pre-drill stage, is updated by comparing in real time a synthetic seismic picture of the reservoir, generated from the LWD resistivity mapping. For each incremental drilling step, EM measurements are compared to real seismic data using non-rigid matching to quantify the depth mismatch. The estimated displacement is then applied to the pre-drill 3D geo-model repository (i.e. reservoir horizons, faults, and geobodies) to predict the structural setting of the reservoir ahead of the bit. The process is automatically iterated while drilling advances. The workflow improves Geosteering prediction capabilities, overcoming the current limitation of “looking around the wellbore” of the deep directional resistivity measurement; and it provides structural information in a robust way up to 150 m ahead of the bit. Case studies are presented, highlighting all the steps of the workflow, from prejob repository model generation to real time modelling while drilling.