Further Developments in the Laboratory Determination of Relative Permeability

Abstract

An earlier publication has discussed three methods for obtaining relativepermeability data on small core samples and the apparatus and technique for thecapillary pressure displacement method. This paper describes the apparatus andtechnique for the solution gas and the dynamic displacement methods andpresents a routine procedure for obtaining oil-gas and water-oil relativepermeability data. Theoretical and experimental considerations are presented to show that theend effect commonly associated with the dynamic flow mechanism is extremelysmall where constant rates are employed in the flowing phase. An effect of flowrate on relative permeabilities obtained by the dynamic system is found onlywhen gas is one of the flowing phases and this effect is ascribed to a form ofchanneling in the capillary system. The apparatus and procedures used to obtain relative permeability data withthree phases flowing are described and some preliminary results of the use ofthis method are shown. Introduction In a previous publication from this laboratory there appeared a briefdiscussion of the concepts behind three basic methods for obtaining relativepermeability data. These three methods were called the capillary pressuredisplacement method, the solution gas displacement method, and the dynamicdisplacement method - the names being suggestive of the type of process usedfor obtaining the desired saturation prior to making the permeabilitymeasurements. In the same publication, the apparatus and technique for thecapillary pressure displacement method were described and some typical resultsobtained by this method were presented. This paper will present:The routine procedure used to obtain permeability data on small coresamples flowing;The experimental techniques for the solution gas and dynamic displacementmethods for obtaining relative permeability data;The results of some studies on the mechanism of fluid flow throughconsolidated porous media; and,The preliminary results on the determination of relative permeability for asystem in which three phases are flowing. T.P. 3056

Accurate determination of characteristic relative permeability curves

“…However work by Botset (1940) showed saturation gradients exist along the core, caused by a capillary discontinuity that exists at the outlet boundary of the core (Leverett 1941;Hassler et al 1944; Richardson et al 1952). As relative permeability is a nonlinear function of saturation, spatially varying relative permeability values and associated nonlinear phase pressure gradients are evident, and are generically referred to as the end effect (Caudle et al 1951). The importance of these effects was apparent to early investigators who related the flowrate dependency of effective relative permeability to the end effect (Leas et al 1950; Caudle et al 1951;Geffen et al 1951; Osoba et al 1951; Richardson et al 1952; Rapoport and Leas 1953;Richardson 1957; Kyte and Leas 1958).…”

“…Investigators often recommend high viscous pressure gradients when using steady-state core flooding experiments to calculate effective relative permeability as a means to reduce the saturation gradients caused by capillary end effects(Leas et al 1950;Caudle et al 1951;Geffen et al 1951;Osoba et al 1951;Richardson et al 1952; …”

Realistic Assessment of Proppant Pack Conductivity for Material Selection

“…The impact of the high wetting phase saturation and its generation is described by several authors. [11][12][13] While these end-effects are usually only considered important in laboratory systems, they are important in any cases where capillary forces are large and pressure gradients are small. Holditch noted that the combination of relative permeability and capillary forces in a low permeability reservoir system, with small pore-size distribution, can result in a severe reduction in post-frac deliverability.…”

Literature review and recommendation of methods for measuring relative permeability of anhydrite from the Salado Formation at the Waste Isolation Pilot Plant

“…Caudle, Slobod, Brownscombe (1951) Rock is confined by a rubber sleeve. Inlet and outlet ends of rock sample extend beyond pressure taps.…”