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Transient Simulations (Restart/Shut-in) Using

CSMFlow

Govind Hegde

September 3rd, 2014

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Restart/Shut-in Simulations Plan

The ultimate goal is to simulate steady state simulations,followed by a shut-in, followed by a restart and then

attain steady state production again.

We are starting off with the simplest case of a restart

case Currently facing some problems designing the

simulations using the Hydrodynamic Slug Flow model.

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Restart Simulations

Previous simulations: We have an initial USG(initial), USL(initial)at the inlet of the flowline

UM= USG(initial)+ USL(initial)throughout the simulations

USG, USLchange during simulation, but UMis constant

throughout Hence, since gas-liquid slip US(HL) depends only on the UM, it is

a constant function of HL

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Restart Simulations

Restart quiescent system with UM= 3 m/s, USL= 2 m/s

At time t = 0, fluids in all cells have zero velocity

US(HL) = 0

Time = 0 (Initial Conditions)

x = 1 x = 2 x = 3 x = i x = n-2 x = n-1 x = nx = 0

UM

= 0

USL= 0

UM

= 0

USL= 0

UM

= 0

USL= 0

UM

= 0

USL= 0

UM

= 0

USL= 0

UM

= 0

USL= 0

UM= 0

USL= 0

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Restart Simulations

When we begin the restart simulation, the first cell has

UM= source UM

How do we determine the UMof the intermediate cells inorder to calculate slip velocity?

In other words, how does the fluid entering the first cell

travel along the flowline

First timestep (dt=1s), Time = 1s

x = 1 x = 2 x = 3 x = i x = n-2 x = n-1 x = nx = 0

UM= 3

USL= 2

UM= ?

USL

= ?

UM= ?

USL

= ?

UM= ?

USL= ?

UM= 0

USL= 0

UM= 0

USL= 0

UM= 0

USL= 0

Restart quiescent system with UM= 3 m/s, USL= 2 m/s

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Restart Simulations: Possible Solution

Is it fine to assume that the liquid travels with constant

velocity USL = 2 (or UM= 3?), such that the liquid travels

along the line with that velocity like a wave front, andhence updating the cell to UM = 3?

According to this, if the front is assumed to propagate at

liquid superficial velocity, the third and fourth cells will

have UM= 3 in the 2ndtime step.

Timestep = t, dt = 1 s

x = 1 x = 2 x = 3 x = i x = n-2 x = n-1 x = nx = 0

UM

= 3 UM= ? UM= ? UM= ? UM= 0 UM= 0 UM= 0

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Restart Simulations: Questions

Is it fine to assume a constant propagation of wave frontas in the previous slide?

If not, is there a better way of doing this in order to

represent the restart case in a better way?

What other considerations do we have to keep in mindwhile simulating restart cases (since we do not consider

pressure and temperature effect on flow) ?