Leverett J-function
Encyclopedia
In petroleum engineering
, the Leverett J-function is a dimensionless function of water saturation describing the capillary pressure,
where
is the water saturation measured as a fraction, 
is the capillary pressure (in pascal
),
is the permeability
(measured in m²
),
is the porosity
(0-1),
is the surface tension
and
is the contact angle
. The function is important in that it is constant for a given saturation within a reservoir, thus relating reservoir properties for neighboring beds.
The Leverett J-function is an attempt at extrapolating capillary pressure data for a given rock to rocks that are similar but with differing permeability, porosity and wetting properties. It assumes that the porous rock can be modelled as a bundle of non-connecting capillary tubes, where the factor
is a characteristic length of the capillaries' radii.
Petroleum engineering
Petroleum engineering is an engineering discipline concerned with the activities related to the production of hydrocarbons, which can be either crude oil or natural gas. Subsurface activities are deemed to fall within the upstream sector of the oil and gas industry, which are the activities of...
, the Leverett J-function is a dimensionless function of water saturation describing the capillary pressure,
where
is the water saturation measured as a fraction, is the capillary pressure (in pascalPascal (unit)
The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
),
is the permeabilityPermeability (fluid)
Permeability in fluid mechanics and the earth sciences is a measure of the ability of a porous material to allow fluids to pass through it.- Units :...
(measured in m²
Square metre
The square metre or square meter is the SI derived unit of area, with symbol m2 . It is defined as the area of a square whose sides measure exactly one metre...
),
is the porosityPorosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...
(0-1),
is the surface tensionSurface tension
Surface tension is a property of the surface of a liquid that allows it to resist an external force. It is revealed, for example, in floating of some objects on the surface of water, even though they are denser than water, and in the ability of some insects to run on the water surface...
and
is the contact angleContact angle
The contact angle is the angle at which a liquid/vapor interface meets a solid surface. The contact angle is specific for any given system and is determined by the interactions across the three interfaces. Most often the concept is illustrated with a small liquid droplet resting on a flat...
. The function is important in that it is constant for a given saturation within a reservoir, thus relating reservoir properties for neighboring beds.
The Leverett J-function is an attempt at extrapolating capillary pressure data for a given rock to rocks that are similar but with differing permeability, porosity and wetting properties. It assumes that the porous rock can be modelled as a bundle of non-connecting capillary tubes, where the factor
is a characteristic length of the capillaries' radii.External links
- http://www.ux.uis.no/~s-skj/ResTek1-v03/Notater/Tamu.Lecture.Notes/Capillary.Pressure/Lecture_16.ppt