Process for measuring the formation water pressure within an oil layer in a dipping reservoir
AssigneeShell Oil Company
InventorsMichael Prats, Alexander S. Williamson
Life of this patent
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Abstract
A pressure substantially equalling the formation water pressure within an oil-productive portion of a subterranean reservoir can be directly measured by displacing a limited portion of water into a continuous water phase extending through a material having an oil entry pressure high enough to effectively prevent oil entry while maintaining a permeability to water, and fluid communication with the reservoir, allowing imbibition to reduce the pressure within the water phase, and subsequently measuring that pressure.
Claims7
A process for directly measuring a pressure substantially equalling the formation water pressure in an oil-productive portion of a subterranean reservoir comprising:
- displacing a limited volume of water into a continuous water-phase which (a) extends through a material which has an oil entry pressure which is high enough to effectively prevent oil entry while maintaining a permeability to water and thus to function as a selectively water-permeable capillary diaphragm and (b) extends into the oil-productive reservoir;
- allowing the pressure within said water-phase to be reduced by the imbibition of water into the reservoir;
- and,
- subsequently measuring the pressure within said water-phase.
A well logging process for measuring the formation water pressure in an oil-productive layer within a dipping reservoir which contains a water layer at a location different from the measuring location, comprising:
- mechanically displacing water within a logging tool at a selected depth within the well so that the displaced water forms a water column which has a relatively small volume, is continuous, extends through a permeable material having pores too small to pass a significant proportion of particles of a water-base mudcake, extends through material capable of functioning as a selectively water-permeable capillary diaphragm, and extends into said oil layer;
- maintaining the water within said water column substantially static until the rate at which its pressure decreases due to the imbibition of water into the oil layer becomes relatively insignificant;
- and,
- measuring the pressure of water in said water column.
Dependencies are inferred from the claim text.