Wellclean* Module: * Mark Of Schlumberger

WELLCLEAN* Module

* Mark of Schlumberger

Ranges For Flow

Friction Pressure

Laminar flow

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lastic P m a h g Bin Model

-

Turbulent flow

ode l Power Law M del o M n nia Newto

Flow Rate Q

Types of Flow V=0 Laminar Flow Velocity Profile (Sliding motion)

V=2 x Vav

Turbulent Flow Velocity Profile (Swirling motion)

Laminar and Turbulent Flow regimes are found anywhere (pipe, concentric or eccentric annuli)

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REYNOLDS NUMBER  Dimensionless number used to predict the flow regime turbulent or

laminar – For a Newtonian fluid of density flowing in a pipe of diameter D, at an average velocity V :  Reynolds

number

Re =

 VD/



– For non-Newtonian fluids, formula can be adapted using the apparent viscosity :  Reynolds

number

Re =

VD/  a critical Reynolds  Turbulent flow is achieved when Re exceeds number Rec-

 Calculated critical flow for turbulence may vary according to the

formulae used to calculate R e the definition of Re (3000,…).

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The Effects of Casing Standoff The effect of the Casing Standoff on the Annular Flow is qualitatively equivalent to the following flow pattern

Q D1 V1

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

D2

p 

V2

Q

Newtonian Laminar Flow VELOCITY :

V1   = 32 I D12

= 32 

D2 = D1 V1 V2

Re =

 V2 D2   =

= 8

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V1 D1



D22

2

if D2 = 2D1

REYNOLDS NUMBER

V2

V2 = 4V1

4 V1 2D1



Re2 = 8 Re1

Newtonian Turbulent Flow Velocity

P

=

L

=

0.241 x  0.75 x µ0.25 x V1 1.75 D11.25 0.241 x  0.75 x µ0.25 x V2 D21.25 V1 V2

if D2 = 2D1

1.75

=

(

D1 D2

0.714

)

V2 = 1.64V1 (For 67%)

Reynolds Number Re2

=

V2 D2 µ

=

1.64V12D1 µ

Re2 = 3.28Re1 (For 67%)

12

=

3.28V1D1 µ

Newtonian Flow Possibilities nt e l uulent Tubrb Tur

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ar n i Lam

Tu rbu

arr n i a min Laam L

l en

t

Turbulen t

w o l F g in s ea r Inc

te a R

Influence of Pipe Eccentricity Laminar

c Turbulent

Concentric Pipes at critical flow rate for turbulence Qc 14

Eccentric Pipes at same rate QC

c = Critical Angle

Correction Table for Turbulent Flow

FLOW-RATE RATIO

10 9 8 7 6 5 4 3 2 1

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0 10 20 30 40 50 60 70 80 90 100 API STANDOFF (%)

Turbulent Flow Displacement  Turbulent flow of the preflush(es) all round the

pipe.  Throughout the zone of interest, condition on preflush(es) satisfied for 10 mins.  When using Chemical Wash, viscosity is taken as 5 cP.

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Turbulent Screen

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Turbulent Graphics

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Effect of Pipe Eccentricity on Bingham Plastic Fluid Q D1 V1

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

D2

p  Q D2 > D1 V2 > V1

V2

w2

ELF Flow  Four criteria are associated with the laminar flow

regime to improve the mud removal. – Density hierarchy. – Flow all around the pipe 

Minimum Pressure Gradient.

– Friction-pressure hierarchy. – Differential velocity criterion

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The Density-Differential Criterion  The density of the displacing fluid must be higher

than the density of the displaced fluid



mud <

23



spacer <



slurry

The Minimum Pressure Gradient (MPG) Criterion  Comparison of the wall shear stress on the narrow

side and the fluid yield stress to check the possibility of flow. – – – – p l

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is a function of standoff. does not apply to pipes perfectly centered. only applies to fluids with Yield Points gives a lower limit for flow rate.

displacing>

4 y STO (D0 - D1)

+ (  displaced -  displacing) g cos



Friction Pressure Hierarchy Criterion  The friction pressure generated by the displacing

fluid must be higher than the pressure generated by the displaced fluid. p p displacing > 1.2 displaced l l  A relatively flat and stable interface with no possibility for the development of displacement instabilities.

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The Differential Velocity Criterion  Verification that the interface between the

displacing and displaced fluid does not rise faster on the wide side than on the narrow side of the casing – is a function of standoff. – does not apply to pipes perfectly centered. – gives an upper limit for flow rate

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Laminar Screen

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Laminar Graphics

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Summary  Type of Flow  Slot Flow  Turbulent Flow  Effective Laminar Flow

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