Accurate Tool for IOR/EOR Screening and Estimating Target Recovery Factors

Abstract

Abstract A semi-analytical method to calculate recovery factors is presented which is valid for recovery technologies that are based on flooding the reservoir with a liquid, such as Water, Polymer, Alkaline Surfactant Polymer and solvents including MGI and WAG. The method is based on describing the total Recovery Factor (RF) as the net result of a macroscopic displacement efficiency, essentially capturing the fraction of the reservoir that can be contacted by the injectant, and a microscopic displacement efficiency, capturing the extent to which the contacted rock can be swept clean. Given specific reservoir and fluid characteristics such as reservoir permeability distribution and relative permeability relations, these two components can each be described analytically and then merged together in the so-called PDO Tubes Model. A comprehensive analysis of about 50 real IOR and EOR field cases with different geologies was done to validate the method. The PDO Tubes Model predictions of RF as a function of injected water in pore volumes were compared to full field simulation models showing a discrepancy of less than 5%. In this paper the tool and its validation will be discussed in detail and an example will be shown of an application of the tool for testing IOR and EOR implementation strategies for a very diverse set of fields. Application of the PDO Tubes Model has resulted in a good understanding of the contributions of various EOR technologies to unlocking remaining oil in the Sultanate of Oman. Among others the tool can be used in any company for: IOR and EOR selection and target recovery factor setting, QC of simulation results, steering geological model building and analysis of a company's portfolio of fields for IOR and EOR potential and their implementation strategies including the resource requirements imposed by a specific strategy.