# Thread: Clarification of term in Darcy's Law

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## Clarification of term in Darcy's Law

Hey guys,

In Reservoir Engineering Handbook by T.Ahmed at page 368 it say that velocity for radial flow is :

v=5.615*0.001127*k/mu*dp/dr.

What does "5.615 " mean? 0.001127 is the conversion factor from SI unit to Field units.

Thanks.

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Last edited by pet_spec; 04-24-2013 at 04:49 PM.

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## Re: Clarification of term in Darcy's Law

5.615 = conversion factor, cu ft/bbl.
0.001127 constant to convert darcy's unit to field units

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## Re: Clarification of term in Darcy's Law

5.615 = conversion factor, cu ft/bbl.
0.001127 constant to convert darcy's unit to field units

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## Re: Clarification of term in Darcy's Law

hi friend as stated earlier,
the first thing you have to pay attention is the system of units.

In US Oil field units

Flow Rate is n Bbl/day
Pressure in PSI
and velocity is in ft/sec

Initial darcy's law in field units has 1.127* 10^(-3) as constant for calculating q.
now this q is in bbl/day q=v.A
so to get v in ft/sec you need to multiply by 5.615 (since 1 bbl= 5.615 ft^3).