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Classification of Formation Resistivity Factor Data Based on Electrical Tortuosity
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 81st EAGE Conference and Exhibition 2019, Jun 2019, Volume 2019, p.1 - 5
Abstract
Complicated pore network of carbonate rocks and existence of different porosity types in them, generate many problems in petrophysical evaluation of carbonate reservoirs. Heterogeneous pore system of carbonate rocks causes unreliable estimation of Archie's parameters such as cementation factor (m) in calculation of water saturation. Traditional method for determination of m is log-log plot of formation resistivity factor (F) versus porosity. This technique gives undesirable results in carbonate rocks, because F data versus porosity significantly deviate from a straight line.
In this study, electrical tortuosity is introduced as a new classification parameter for categorizing F data to enhance the prediction accuracy of m value. In other words, rocks with similar values of electrical tortuosity constitute a distinct class which has its own linear equation of F versus porosity in log-log plot. Indeed, tortuosity is applied to divide F data into different electrical rock types. To verify this approach, an electrical dataset from one of the Middle East carbonate oilfield was used. Results showed that electrical tortuosity technique is a suitable approach for reduction of F data scattering and therefore improvement of estimation accuracy of m.