Problem-To-Solution Approach to Characterization and Differentiation of Pore Types in Carbonate Reservoirs

Abstract

SUMMARYThe paper reviews the problems of differentiation of reservoirs with mixed types of voids including fractures, vugs and moldic pores for heterogeneous Lower Devonian and Upper Silurian carbonates of R. Trebsa oilfield (NAO) and Tournaisian-Frasnian carbonates of Tabynskoe oilfield (Bashkortostan) using core, wireline logs and production tests. The algorithms are presented to obtain additional information on textural features of the reservoir facies from integration of core data with results of extended logging suite. The study results in the reservoir flow model based on the ratio of connected pores, secondary voids, clay content by volume and to a greater extent relative shaliness. Matching of permeabilities measured on samples in the laboratory both on wholesized core and plugs to permeabilities estimated from well logs and flow tests revealed their different combinations in high-productivity and low-productivity wells producing from complex carbonates ranging in age from Upper Silurian to Lower Devonian on R. Trebsa oilfield and Upper Devonian to Lower Carboniferous on Tabynskoe oilfield. The integrated reservoir characterization from core data, special and standard methods of well logging, flow tests and production tests results in a new classification of reservoir facies and estimation of the range of the poroperm properties for the identified classes.