Heads Up Coring Guided by a Seismically Derived Vclay Volume

We introduce a methodology for pre-drill lithology prediction combining detailed stratigraphy and a seismically derived lithology volume. The methodology was successfully applied for planning and execution of heads up coring operations during recently drilled appraisal wells, with remarkably accurate results that conduced to the acquisition of more than 100 m of core, sand proportion greater than 70%, excellent reservoir quality facies, and 100% core recovery.

The methodology required: (1) having a robust seismic interpretation from a pre-stack depth volume obtained using reverse time migration: PSDM RTM; (2) a robust structural and stratigraphic seismic interpretation across the overburden, particularly in the section above the reservoir; (3) establishing a stratigraphic framework integrating the seismic interpretation and well log data; (4) generating a seismically derived volume predicting clay content and lithology, obtained from AVO inversion; (5) using neural networks to derive a predicted GR curve combining seismic, well logs and well tops; and (6) defining a clear protocol establishing the key criteria to call the coring points.