Selection of Adequate Reservoir Models for EOR Laboratory Simulation

Abstract

Summary The publication reviews the influence of core samples on reliability of data collected during laboratory simulation of formation stimulation techniques depending on the type of reservoirs. The analysis has shown that, as opposed to composite models, a full-size core displays the interconnection of pore systems in complex reservoirs in the best possible way, and this makes it possible to draw more correct conclusions on the efficiency of techniques such as assessment of adsorption and mechanical destruction of polymer compounds, strength of the built waterproof barrier, pressure dynamics during injection, etc. When selecting full-size core samples, in order to increase reliability of the laboratory simulation data, it is necessary to consider rock anisotropy that is inherent to carbonate reservoirs and is generally associated with rock fracturing. Based on the obtained knowledge about improvement of EOR simulation efficiency under complex carbonate reservoir conditions, laboratory analyses have been carried out using core material and METКA thermoreversible polymer compound developed by the Institute of Petroleum Science, Russian Academy of Sciences, Siberian Branch. The usage of a full-size core made it possible to assess the efficiency of METКA technology in terms of involvement in the development of not only low-permeability layers, but also high-permeability formation zones which have not been covered before or lightly covered by water-flooding. The analyses carried out using composite models from a standard-size core showed that the obtained data in terms of assessment of water-flooding coverage had low informative value. Thus, it was found that core samples of the maximum diameter must be used for testing under complex carbonate reservoir conditions due to low representativity of standard samples. The obtained findings are of practical importance in terms of correct assessment of EOR parameters for wells during field development.