Reservoir Rock-types Determination Based on Wire-line Logs and 3D Petrophysical Modeling in Ahnet Basin Field

Abstract

The vertical and lateral reservoir properties distribution over field scale is a critical factor that requires investigation for the appraisal wells drilling success. This paper provides an approach based on a technical classification of rock-group, the so-called rocktyping technique. Each rock-type has specific sedimentological characteristic and homogeneous petrophysical properties. These rock-types are used in a 3D Static geocellular modeling. This technique is used advantageously in Ahnet field uncored wells, where the interval studied is a layercake reservoir type and in which the lower part is generally producing gas. An electrofacies characterization is performed for all wells with complete logs suites. The cores porosity (PHIE) and permeability (KH) are generally used in addition to the logs, to give a petrophysical sense. Because of the low permeability values, these properties are not used and the core porosities are replaced by estimated porosities (PIGE). Six (6) electrofacies are defined, simultaneously calibrated with estimated porosities PIGE and ranked progressively from clean sandstone (Rock-Type 1) with the best porosities to shale rock type (Rock-Type 6).