Extended Brigham Model for Residual oil Saturation Measurement by Partitioning Tracer Tests

Abstract

Summary Brigham's model has been used extensively in the petroleum industry for thedesign and interpretation of interwell tracer tests. The model is based oncorrelation and has included physical dispersion as an input parameter. Inspite of its limitations, the model is useful in estimating layerheterogeneity, layer distribution, permeability contrast, and dispersion in thereservoir. However, the model can only handle nonpartitioning tracers thathave no solubility in oil. With the advancement in partitioning tracertechnology and interpretation technique, interwell partitioning tracer testinghas gained its popularity, especially in China,1 for determining residual oilsaturation, Sorw, between wells. Partitioning tracer testing also findsits application in environmental protection, where tests are routinely run todetermine the amount of nonaqueous liquid phase nonaqueous phase liquid (NAPL)trapped underground due to spill or seepage. While sophisticated streamline orfinite difference simulators have been increasingly used to determine Sorw distribution from the tracer production data, the simple semiquantitative modelstill has its merits in providing a direct, unambiguous estimate of average Sorw along the tracer flow path. This paper broadens the scope of theoriginal Brigham's model by incorporating partitioning tracers into the modelusing a chromatographic transformation technique. By matching the partitioningand nonpartitioning tracer curves, Sorw can be determined by layers. The extended Brigham model was applied to the Ranger oilfield multiple tracer test, and the residual oil saturation determined compared favorably with thoseobtained by chromatographic transformation method and numerical simulation.