Laboratory Determination of Relative Permeability

Abstract

Abstract A detailed study of a number of methods of relative permeability measurementhas been made in a search for the technique most suited to routine analysis ofcores taken from reservoir rock. It has been found from tests run on the samesamples of core material by a number of techniques that the Penn State, Hassler, Hafford, and dispersed feed techniques all yield results which arefelt to be reliable. Conditions under which the faster single core dynamictechnique may be used are described. Further work on the calculation ofrelative permeabilities to oil from data obtained by the gas drive method isneeded before this latter rapid method can be utilized. Correlations between theoretical studies and experimental results have beenobtained in studies of the boundary effect, pressure distribution in two-phaseflow, and gas expansion effects. Previous conclusions that the effects of theoutflow boundary could be made negligibly small have been substantiated.Results of experimentally determined oil and gas pressure distributions along acore sample during flow are presented. Further studies of the effects of rateof flow in the measurement of relative permeability-saturation relations haveshown that results are independent of the rate of flow as long as the flow rateis below the point where inertial effects commence. An analysis of the effectsof a severalfold expansion of gas along the flow path indicates that whilesaturation gradients are induced in the test sample, the errors caused by thisphenomenon in relative permeability measurements are small. Introduction Many pages of literature have been devoted to pointing out the need forrelative permeability-saturation relations in reservoir engineering. One of themost attractive ways of obtaining this information is by the analysis ofsamples of core material taken from the formation in question, and againliterature has described many methods for obtaining these data. It is thepurpose of this paper to present the work that has been done in the study ofsome of these published methods together with some other methods that have beenrecently developed in this laboratory. Also, a study of some of the factorsthat influence the laboratory determination of relative permeability-saturationrelations is presented. T.P. 3375