Changes

[[file:subsurface-maps_fig6.png|thumb|{{figure number|6}}Porosity thickness (ϕH) maps for the B and C zones from the San Andres Formation reservoir, Jordan field, Ector and Crane Counties, Texas. Contours in PV fraction-feet. (After <ref name=pt06r81>Major, R. P., Holtz, M. H., 1989, Effects of geologic heterogeneity on waterflood efficiency at Jordan field, University Lands, Ector and Crane counties, Texas: 64th Annual Technology Conference of the Society of Petroleum Engineers, San Antonio, TX, Oct., SPE 19874, p. 633–640.</ref>.)]]

[[file:subsurface-maps_fig6.png|thumb|{{figure number|6}}Porosity thickness (ϕH) maps for the B and C zones from the San Andres Formation reservoir, Jordan field, Ector and Crane Counties, Texas. Contours in PV fraction-feet. (After <ref name=pt06r81>Major, R. P., Holtz, M. H., 1989, Effects of geologic heterogeneity on waterflood efficiency at Jordan field, University Lands, Ector and Crane counties, Texas: 64th Annual Technology Conference of the Society of Petroleum Engineers, San Antonio, TX, Oct., SPE 19874, p. 633–640.</ref>.)]]

===[[Permeability]]===

===Permeability===

Permeability (''k'') can also be mapped and contoured (see [[Core-log transformations and porosity-permeability relationships]]). As for [[Water saturation|saturation]] values, some care must be exercised in mapping permeability because values must be derived from indirect measurements. Typically, permeabilities are derived from wireline log [[Porosity|porosities]] transformed on the basis of core permeability versus porosity cross plots. Permeabilities can be reported at ambient laboratory conditions of pressure or adjusted to reservoir conditions of [[confining pressure]]. Similarly, permeabilities can be [[Absolute permeability|absolute permeabilities]] to air (nitrogen) or liquid or [[Effective permeability|effective permeabilities]] to oil in the presence of [[irreducible water]]. Permeability values in an individual well are thickness weighted and typically [[Averaging|averaged harmonically, arithmetically, or geometrically]], depending on [[flow geometry]]. Alternatively, [[flow capacity]] (''kH'') values derived from [[pressure transient testing]] can be divided by net pay thickness (''H'') to yield a liquid permeability value for a well.

[[Permeability]] (''k'') can also be mapped and contoured (see [[Core-log transformations and porosity-permeability relationships]]). As for [[Water saturation|saturation]] values, some care must be exercised in mapping permeability because values must be derived from indirect measurements. Typically, permeabilities are derived from wireline log [[Porosity|porosities]] transformed on the basis of core permeability versus porosity cross plots. Permeabilities can be reported at ambient laboratory conditions of pressure or adjusted to reservoir conditions of [[confining pressure]]. Similarly, permeabilities can be [[Absolute permeability|absolute permeabilities]] to air (nitrogen) or liquid or [[Effective permeability|effective permeabilities]] to oil in the presence of [[irreducible water]]. Permeability values in an individual well are thickness weighted and typically [[Averaging|averaged harmonically, arithmetically, or geometrically]], depending on [[flow geometry]]. Alternatively, [[flow capacity]] (''kH'') values derived from [[pressure transient testing]] can be divided by net pay thickness (''H'') to yield a liquid permeability value for a well.

===Porosity thickness===

===Porosity thickness===