MPFM Vx Training

Vx Theory of Operation

Oct 2019
Schlumberger-Private
Vx Technology Presentation
VX MAIN COMPONENTS

• Access Port

• Venturi Section :
• Detector Assembly
• Ba-133 Source Assembly

• Blind Tee
• Outlet Pipe

Schlumberger-Private
Flowrates Measurement
SIMPLIFIED FLOWCHART
Total Mass Flowrate
150

100
Flowrates at Line Condi- Flowrates At Standard Condi-
50 tions 150 tions

0 150

100
PVT 100
Series 1
50
Mode 50
l
Phase Fraction 0 0
Oil Water Gas Oil Water Gas

Oil Gas Water

Schlumberger-Private
Flowrates Measurement
VENTURY EQUATION

D V
P1
1

P1 + ½ r V12 = P2 + r g Hv+ ½ r V22

1

Energy conservation
(Bernoulli)
D2
V
P2 Mass conservation Qm = ¼ p D22 V2 r = ¼ p D12 V1 r
2

(Bernoulli)
b = D2 / D1
Hv
Beta Ratio
V
D P1
1
1

Schlumberger-Private
Flowrates Measurement
VENTURY EQUATION

d 1
   2 P  P   gHv ρ
2

Q C  
f
4 1 
total mass 1 2 mix mix
4

Applied to real multiphase flow, with some compressibility, energy losses due to turbulences
(depending on the geometry of the venturi) :

Discharge coefficient = f(viscosity, GVF)

Expansion Factor=f(rgas, rliq @ LC, GVF)

Schlumberger-Private
Flowrates Measurement
GAMMA SYSTEM
When passing through matter, gamma looses energy due to collisions with atomic.
Ba133 gamma ray spectrum shows 3 energy level peaks.
d

Counts
Detector

radioactive source:
emits -ray photons Venturi 32 81 356
throat Energy Level (Kev)

N  N ed  
Nx: number of counts measured
No: number of counts in vacuum
d: distance X O
ν : mass attenuation
ρ: density

Schlumberger-Private
 Flowrates Measurement
GAMMA SYSTEM EQUATION
N X  N ed
O
   Oil  OilOil  Water WaterWater   Gas  GasGas

 d    0le
N Xle  N eO

 d    0he
N Xhe  N eO

 d ( o . o .ole  w  w w
le    le )
g g g
N xle  Nole e
 d ( o . o .ohe  w  w w
he    he )
g g g
N xhe  Nohe e

o  w   g  1

Schlumberger-Private
 Flowrates Measurement
SOLUTION TRIANGLE -1/d Ln (Nle / Nvacuumle) 0
Low Energy Linear attenuation for a triphasic fluid
aoronole+agrgngle+awrwnwle

High Energy Linear attenuation for a triphasic fluid

-1/d * Ln (Nle / N0le) =
ao.nole.ro + ag.ngle.rg + aw.nwle.rw

aoronohe+agrgnghe+awrwnwhe
-1/d * Ln (Nhe / N0he) = Gas (ag=1,aw=ao=0)

ao.nohe.ro + ag.nghe.rg + aw.nwhe.rw

-1/d Ln (Nhe / Nvacuumhe)

Any mixture of these 3 single
phases will be described by a
point within this “Solution
B
Triangle”

WLR = OA/OW
GVF = OB/OG
Oil (ao=1,ag=aw=0)

Water A
(aw=1,ag=ao=0)

Schlumberger-Private
Flowrates Measurement
PVT MODEL
Line conditions Standard conditions

 Density: ρo, ρw, ρg

 Volume Factor: bo, bw, bg
 Stock tank Gas Oil Ratio: Rst (GOR2)
 Gas Phase Condensate Gas Ratio: rgmp (CGR)
 Stock Tank Gas Water Ratio: Rwst
 Liquid viscosity: µ

Schlumberger-Private
Conclusions
The high frequency Gamma Detector measures the phase fractions, based on nuclear
linear attenuations
The Vx venturi measures the total mass rate
Primary Output:
 Qmass and r mixture
 Phase hold-ups
 Gas Volume Fraction (GVF)
 WLR
Secondary Output:
 qgas at Line conditions
 qoil at Line conditions
 qwater at Line conditions
Final Output
 Computation of flow rates from line conditions to standard conditions using VX
Fluid Properties Models

Schlumberger-Private
Question ?

Schlumberger-Private
Recap with

Schlumberger-Private
Mixture density is at

1. Line condition
2. Standard condition
3. Separator condition

0% 0% 0%

1 2 3

0 of
10
Answer Now
15
Schlumberger-Private
BSW is calculated in standard conditions?

1. True
2. False
3. Possibly

0% 0% 0%

0 of 1 2 3
10

Answer Now
17
Schlumberger-Private
Which of the following is Vx primary output?

1. Flow rates at Line

condition
2. Flow rates at Standard
condition
3. WLR, GVF, hold-ups
0% 0% 0%

1 2 3

0 of
10

Answer Now
21
Schlumberger-Private