Mehmet Altunbay (Baker Atlas)

The presentation is about pore typing, permeability qualification and quantification and there from productivity analysis by integration of NMR and conventional log data via modified form of the Timur-Coates permeability model. The new model takes into account the pore-connectivity variations in carbonate reservoirs. The calibration of the permeability index from modified “p” model to in-situ permeability values from Wireline Formation Tester (WFT) qualifies and quantifies the pore-structure in the bulk-volume-movable portion of the porosity into types of “non-contributing” and “contributing” pores. With the help of this differentiation, the secondary porosity that is identified by the difference between acoustic and NMR porosity is further partitioned into “isolated-pores” and “networked-pores” yielding a detailed pore typing. These findings are consistent with that observed on the image logs. By qualifying porosity types, determining bulk volume irreducible and calibrating the NMR permeability to WFT permeability (for single phase fluid), absolute permeability profile is driven under in-situ conditions. Then, using well-established relative permeability correlations for the gas/brine system in carbonates and the resistivity-based water saturation profile, krg and krw profiles are generated. Absolute and relative permeability profiles make it possible to compute effective permeability to wetting and non-wetting phases. The above approach eliminates the urgent—and impossible to meet—requirement of having core data for calibrating NMR permeability at the well site; thus providing the valuable and reliable information at the stage of wireline data interpretation rather than waiting for core data to become available. In addition, the availability of effective mD-ft computations in selected intervals provides the input for production rate estimations that helps decision making for completion and/or perforating operations.