Technology Integration to Assess End-point Oil Saturation of the Relative Permeability Curves

Abstract

Quantification of the end-point oil saturation of the relative permeability curves is an essential part of building a reliable simulation model to better capture the flow dynamics. A key challenge is to reduce measurement uncertainties and overcome technology limitations. Particularly for water flooded heterogeneous reservoirs with mixed salinity environment, it is vital to combine multiple sources of oil saturation measurements to substantiate end-point results. In this paper, a new workflow is established to estimate the oil end-point oil saturation by integrating specialized logging and core analysis techniques. This workflow examines data collected from both ends of a reservoir's scale spectrum that represent macro and micro scales, ranging from field in-situ electrical logging to plug-size lab experiments. The dataset incorporates oil saturation data acquired from sponge coring, centrifuge test, dielectric log, and carbon-oxygen log. The oil saturation data are clustered based on a set of petrophysical hydraulic flow units. The data sufficiency and quality are evaluated from the statistical analysis of the distribution profiles. The high uncertainty measurements are filtered out for spurious points and also for the log results that are beyond the tools' threshold. The saturation data collected from different logging and coring methods are compared per rock type. Despite the variety of scale and techniques used, the workflow yields consistent results. The centrifuge test is used as the primary source of the end-point oil saturation. For hydraulic units with low reservoir quality, sponge core results are used to derive end-point oil saturation in the absence of centrifuge data. Additionally, in-situ saturation data derived from dielectric and carbon-oxygen logs are in a close agreement to sponge core data, which are used to corroborate the derived end-point oil saturations. The approach highlighted in this work can be used as a benchmark for future studies. There is no unique practice in the oil industry for the determination of the end-point oil saturation and there are very few comprehensive studies in the literature. The workflow presented here is validated by implementation to a diverse dataset, which is used to characterize relative permeability curves in the reservoir simulation model.