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  | isbn    = 0-89181-602-X

  | isbn    = 0-89181-602-X

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The rate of migration for oil or gas can be estimated using [[Fluid flow fundamentals|Darcy's law]], the principal formula for calculating [[permeability]]. Darcy's law generally holds for rocks with tube-shaped pore systems; however, it is only an approximation for flow in rocks with high percentages of clays, like shales, due to the platey grain shape of the clays. The [[Wikipedia:Kozeny–Carman equation |Kozeny–Carman correction]] estimates the permeability of rocks with high percentages of clays.

The rate of [[Hydrocarbon migration|migration]] for [[oil]] or [[gas]] can be estimated using [[Fluid flow fundamentals|Darcy's law]], the principal formula for calculating [[permeability]]. Darcy's law generally holds for rocks with tube-shaped pore systems; however, it is only an approximation for flow in rocks with high percentages of [[clay]]s, like [[shale]]s, due to the platey grain shape of the clays. The [[Wikipedia:Kozeny–Carman equation |Kozeny–Carman correction]] estimates the [[permeability]] of rocks with high percentages of clays.

==Procedure==

==Procedure==

The procedure for calculating the migration rate of oil or gas is outlined in the table below.

The procedure for calculating the [[Hydrocarbon migration|migration]] rate of oil or gas is outlined in the table below.

# Gather data, including [[permeability]] of carrier beds, [[Wikipedia:Viscosity|viscosity]] of oil, fluid density, and [http://www.glossary.oilfield.slb.com/en/Terms/p/pore_pressure.aspx pore pressure] gradient.

# Gather data, including [[permeability]] of carrier beds, [[Wikipedia:Viscosity|viscosity]] of oil, fluid density, and [http://www.glossary.oilfield.slb.com/en/Terms/p/pore_pressure.aspx pore pressure] gradient.

==Minimum buoyancy pressure for migration==

==Minimum buoyancy pressure for migration==

Migration upslope under a seal occurs when buoyancy is greater than capillary pressure, or

[[Hydrocarbon migration|migration]] [[upslope]] under a seal occurs when buoyancy is greater than capillary pressure, or

:<math>\mbox{g} \times \mbox{l} \times \sin \mbox{Q} \times (\rho_{\rm w} - \rho_{\rm hc}) > 2\gamma</math>

:<math>\mbox{g} \times \mbox{l} \times \sin \mbox{Q} \times (\rho_{\rm w} - \rho_{\rm hc}) > 2\gamma</math>