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Motivation


One of the key challenges in Pipe Flow Dynamics is to predict the pressure distribution along the pipe during the stationary fluid transport.

In many practical cases the stationary pressure distribution can be approximated by Isothermal or Quasi-isothermal homogenous fluid flow model.

Pipeline Flow Pressure Model is addressing this problem with account of the varying pipeline trajectory, gravity effects and fluid friction with pipeline walls.


Outputs


LaTeX Math Inline
bodyp(l)

Pressure distribution along the pipe

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bodyq(l)

Flowrate distribution along the pipe

LaTeX Math Inline
bodyu(l)

Flow velocity distribution along the pipe

Inputs


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bodyT_s

Intake temperature 

LaTeX Math Inline
bodyT(l)

Along-pipe temperature profile 

LaTeX Math Inline
bodyp_s

Intake pressure 

LaTeX Math Inline
body\rho(T, p)

Fluid density 

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bodyq_s

Intake flowrate 

LaTeX Math Inline
body\mu(T, p)

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bodyz(l)

Pipeline trajectory TVDss

LaTeX Math Inline
bodyA

Pipe cross-section area  
LaTeX Math Inline
body\theta (l)


Pipeline trajectory inclination,

LaTeX Math Inline
body--uriencoded--\displaystyle \cos \theta (l) = \frac%7Bdz%7D%7Bdl%7D

LaTeX Math Inline
body\epsilon

Inner pipe wall roughness

Assumptions


Stationary flowHomogenous flowIsothermal or Quasi-isothermal conditions

Constant cross-section pipe area

LaTeX Math Inline
bodyA
along hole


Equations



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anchorPP
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\bigg( 1 -  \frac{c(p) \, \rho_s^2 \, q_s^2}{A^2}   \bigg )  \frac{dp}{dl} = \rho \, g \, \frac{dz}{dl}  - \frac{\rho_s^2 \, q_s^2 }{2 A^2 d} \frac{f({\rm Re}, \, \epsilon)}{\rho}



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anchor1
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q(l) = \frac{\rho_s \cdot q_0}{\rho}



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u(l) = \frac{\rho_s \cdot q_s}{\rho \cdot A}



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anchorp0
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p(l=0) = p_s



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anchorp0
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q(l=0) = q_s



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anchorp0
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\rho(T_s, p_s) = \rho_s


where

LaTeX Math Inline
body--uriencoded--f(%7B\rm Re%7D, \, \epsilon)

Darcy friction factor

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body--uriencoded--\displaystyle %7B\rm Re%7D = \frac%7Bu(l) \cdot d%7D%7B\nu(l)%7D = \frac%7B4 \rho_s q_s%7D%7B\pi d%7D \frac%7B1%7D%7B\mu(T, p)%7D

Reynolds number

LaTeX Math Inline
body--uriencoded--\displaystyle d = \sqrt%7B \frac%7B4 A%7D%7B\pi%7D%7D

characteristic linear dimension of the pipe

(or exactly a pipe diameter in case of a circular pipe)


See Derivation of Pressure Profile in Stationary Isothermal Homogenous Pipe Flow @model.


Approximations



Incompressible pipe flow 
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body\rho(T, p) = \rho_s
with constant viscosity 
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body\mu(T, p) = \mu_s

Pressure Profile in Incompressible Isoviscous Stationary Quasi-Isothermal Pipe Flow @model


Pressure profilePressure gradient profileFluid velocityFluid rate


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anchorPPconst
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p(l) = p_s + \rho_s \, g \, z(l) - \frac{\rho_s \, q_s^2 }{2 A^2 d} \, f_s \, l



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anchorgradP
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\frac{dp}{dl} = \rho_s \, g \cos \theta(l) - \frac{\rho_s \, q_s^2 }{2 A^2 d} \, f_s



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anchor1
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q(l) =q_s = \rm const



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anchor1
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u(l) = u_s = \frac{q_s}{A} = \rm const




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titleDerivation


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See Pressure Profile in Incompressible Isoviscous Stationary Quasi-Isothermal Pipe Flow @model



The first term in the right side of 

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anchorgradP
defines the hydrostatic column of static fluid while the last term defines the friction losses under fluid movement:


In most practical applications in water producing or water injecting wells, water can be considered as incompressible and friction factor  can be assumed constant

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body f(l) = f_s = \rm const
 along-hole ( see  Darcy friction factor in water producing/injecting wells ).



References


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