Difference between revisions of "Gilbert choke equation"

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<div style='text-align: right;'>By Mikhail Tuzovskiy on {{REVISIONTIMESTAMP}}</div>
 
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==Brief==
 
==Brief==
The most common formula used for multiphase flow through surface chokes by Gilbert <ref name=Gilbert/><ref name=KermitBrown1984/>.
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The most common formula used for multiphase flow through surface chokes developed by '''Gilbert''' in 1954<ref name=Gilbert/>.
  
Echometer is used to measure the fluid level in the wells.
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Gilbert developed his empirical equation from field data in California<ref name=KermitBrown1984/>.
 
 
Fluid level is used to calculate and monitor the bottom hole pressure of the wells.
 
  
 
==Math and Physics==
 
==Math and Physics==
 
:<math>P_{wh}=\frac{435 \times GLR^{0.546}}{D^{1.89}} \times q</math>
 
:<math>P_{wh}=\frac{435 \times GLR^{0.546}}{D^{1.89}} \times q</math>
  
===Flowing well fluids segregation===
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Note that the equation is independent of the downstream pressure and assumes that the downstream pressure is less than 70% of the upstream pressure, i.e. the flow is "critical" i.e. fluid reach sonic velocity in the throat of the choke<ref name=Economides/>.
When the well is flowing with the pump this is how fluids segregate in the well bore:
 
*Oil, gas and water are produced through the tubing from the reservoir to the surface 
 
*Gas is in the annulus from the surface to the fluid level, Hd
 
*Oil and gas are between the fluid level Hd, and the pump setting depth, Hd
 
*Water, oil and gas are between pump, Hd and the top of the perforations, Hperfs
 
*Water is in the rathole
 
  
===Equation to calculate the BHP from the fluid level===
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==Example==
:<math>P_{wf}=P_{ann}+\frac{(H_{perfs}-H_{pump})(SG_o(1-WCUT)+SG_w WCUT)+(H_{pump}-H_d)SG_o}{10.32}</math>
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===Given data===
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Oil rate = 600 bbl/d, GLR=400 scf/bbl, D=22/64 in, Line pressure = 180 psia
  
Note that for the deviated wells TVD depths should be used.
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Calculate the well head pressure?
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===Solution===
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:<math>P_{wh}=\frac{435 \times 0.4^{0.546}}{22^{1.89}} \times 600 = 460 psig = 460 +14.7 = 474.7 psia</math>
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Validity check 180/474.7=0.38 < 0.7 OK
  
 
==Nomenclature==
 
==Nomenclature==
:<math>g</math> = 9.81, m/s^2
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:<math>D</math> = choke beam diametr, 64th of an inch
:<math>h</math> = depth, m
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:<math>GLR</math> = gas liquid ratio, Mscf/bbl or 10^3 scf/bbl
:<math>H_d</math> = fluid level, m
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:<math>P_{wh}</math> = well head pressure, psig
:<math>H_{perfs}</math> = top of the perforations, m
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:<math>q</math> = liquid flow rate, bbl/d
:<math>H_{pump}</math> = pump setting depth, m
 
:<math>P</math> = pressure, atm
 
:<math>P_{ann}</math> = annulus presssure, atm
 
:<math>P_{wf}</math> = well flowing bottomhole pressure, atm
 
:<math>\rho</math> = density, kg/m^3
 
:<math>SG_o</math> = oil specific gravity, dimensionless
 
:<math>SG_w</math> = water specific gravity, dimensionless
 
:<math>WCUT</math> = well water cut, fraction
 
  
 
== References ==
 
== References ==
Line 53: Line 44:
 
  |place=Tulsa, Oklahoma
 
  |place=Tulsa, Oklahoma
 
}}</ref>
 
}}</ref>
 
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<ref name=Economides>{{cite book
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|last1= Economides |first1=M.J.
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|last2= Hill |first2=A.D.
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|last3= Economides |first3=C.E.
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|last4= Zhu |first4=D.
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|title=Petroleum Production Systems
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|edition=2
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|date=2013
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|publisher=Prentice Hall
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|place=Westford, Massachusetts
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|isbn=978-0-13-703158-0
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}}</ref>
 
</references>
 
</references>
  

Latest revision as of 19:10, 8 November 2024

By Mikhail Tuzovskiy on 20241108191031

Brief

The most common formula used for multiphase flow through surface chokes developed by Gilbert in 1954[1].

Gilbert developed his empirical equation from field data in California[2].

Math and Physics

P_{wh}=\frac{435 \times GLR^{0.546}}{D^{1.89}} \times q

Note that the equation is independent of the downstream pressure and assumes that the downstream pressure is less than 70% of the upstream pressure, i.e. the flow is "critical" i.e. fluid reach sonic velocity in the throat of the choke[3].

Example

Given data

Oil rate = 600 bbl/d, GLR=400 scf/bbl, D=22/64 in, Line pressure = 180 psia

Calculate the well head pressure?

Solution

P_{wh}=\frac{435 \times 0.4^{0.546}}{22^{1.89}} \times 600 = 460 psig = 460 +14.7 = 474.7 psia

Validity check 180/474.7=0.38 < 0.7 OK

Nomenclature

D = choke beam diametr, 64th of an inch
GLR = gas liquid ratio, Mscf/bbl or 10^3 scf/bbl
P_{wh} = well head pressure, psig
q = liquid flow rate, bbl/d

References

  1. Gilbert, W.E. (1954). Flowing and Gas-Lift Well Performance. Drilling and Production Practice API. p. 143. 
  2. Brown, Kermit (1984). The Technology of Artificial Lift Methods. Volume 4. Production Optimization of Oil and Gas Wells by Nodal System Analysis. Tulsa, Oklahoma: PennWellBookss. 
  3. Economides, M.J.; Hill, A.D.; Economides, C.E.; Zhu, D. (2013). Petroleum Production Systems (2 ed.). Westford, Massachusetts: Prentice Hall. ISBN 978-0-13-703158-0.