Measuring relative permeability to steam in cores of water and oil containing reservoir formations

Claim 1

A process for determining permeability properties of at least one fluid of the group consisting of steam, water and oil in a sample of reservoir rock formation containing fluid phases inclusive of at least oil and water phases, comprising: providing a core of the reservoir formation containing oil and water; mounting the core within a flexible walled, impermeable, tubular sheath means arranged for flowing fluid through the core; mounting the flexible walled core-containing means within a relatively rigid walled container having fluid impermeable walls which are permeable to X-rays and pressurizing the core within the rigid walled container to a pressure approximating that of the reservoir formation; arranging the heat loss properties of the rigid walled chamber so that the rate of heat loss from the core is sufficient to condense some, but not all, steam flowing through the core while limiting the heat loss near the steam inlet into the chamber so that the temperature and steam quality can be controlled at the inlet and at least substantially throughout the core; flowing at least one fluid of the group consisting of steam, water and oil through the core at a selected rate and temperature until an equilibrium is attained at which the rate at which oil is produced becomes substantially constant; sealing the rigid walled container while it contains the fluid and fluid pressure that was present when said equilibrium was attained; X-ray scanning the sealed chamber to determine the bulk density all along the core; and determining said permeability properties from the properties of the fluids flowed into and out of the core and the pressure drop across the core.