1. Bruno PINGUET & Samia BIFOUT May 2013
4/19/2017
Why a Multiphase Flowmeter can significantly reduce the Rejection Rate of Well Test versus Separator
Bruno PINGUET & Samia BIFOUT
May 2013

2. 4/19/2017
© 2013 Schlumberger. All rights reserved. An asterisk is used throughout this presentation to denote a mark of Schlumberger. Be certain is a mark of Schlumberger. Other company, product, and service names are the properties of their respective owners.

3. 4/19/2017
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5. Contents Why Well Testing? History & Vx Technology Data Principle
4/19/2017
Contents
Why Well Testing?
History & Vx Technology Data Principle
How to set a multiphase flow meter (Vx technology)
New Model Development for faster and better measurement in Periodic Testing
Conclusion
Surface mapping of production data: the 4-D model for large field. 5

6. Why Well Testing or Production Testing?
4/19/2017
Why Well Testing or Production Testing?
The drivers for improved access to Production Testing data..
Primarily for the Asset Manager to meet the target production volume
Allocation for optimized Well & Reservoir management
Minimize Deferred Production & Production Optimization
Optimized selection of well candidates for Work-over and Intervention
Reservoir modeling and matching for improved Field Management
Timely startup of injection for pressure maintenance
Water management
De-bottlenecking & Flow Assurance
Facilities planning
Allocation for regulatory requirement & Partner-sharing (hydrocarbon accounting)

7. Why Well Testing & Who Needs Measurement Data?
4/19/2017
Why Well Testing & Who Needs Measurement Data?
Allocation
Hydrocarbon Accounting
Reservoir Management
Regulatory Reporting
Reservoir Management
Model verification
Drive Management
EOR
Facilities Management
De-bottlenecking
Water management
Flow assurance
Production Management
Lift & Injection Optimization
Decline curves
PI monitoring
Everyone
Lets start with understanding why we need Accurate Production Measurements and who needs this information. [Click]
The first group that comes to my mind is the Facilities Management Group [Click] They need it for De-bottlenecking, Water Management, Flow Assurance, etc.
Then there is also the Production Management Group [Click] and the Reservoir Management Group [Click]. And finally we need it for Allocation, to account for our hydrocarbons produced, and regulatory Reporting.
So in essence “EVERYONE” uses the Production Measurements.
Production Measurements
Rate Measurements
Trending
Sampling

8. Some Indication of Performance Indicators (KPI) & Schlumberger
4/19/2017
Some Indication of Performance Indicators (KPI) & Schlumberger
Allocation factors
oil volume to 0.90
water volume to 0.90
gas volume to 0.90
Rejection rate ~ %
Reproducibility - Repeatability
Data delivery time, including QA and “validation”
Well Testing Operations > 80 years
Culture of Excellence in Training
24/7 Support Helpdesk
Pride in Technology & Service Quality
Dedicated Engineering, Reservoir and Production Engineers
QHSE Culture and performance
Status quo

9. Conventional Test Separators
4/19/2017
Conventional Test Separators
Gas metering
Daniel differential orifice meter
Liquid metering
Low flow rate High flow rate
‘Floco’ positive displacement ‘Rotron’ Vortex

10. Vision of Schlumberger for Periodic Well testing
Back to the beginning of the 1990’s; Schlumberger had a vision of being much more time and cost effective by developing of a multiphase flowmeter for Periodic Well Testing
Accurate flow rate measurements

11. Vx Technology Description
Data Acquisition
Flow Computer
Gamma Ray
Detector
Barium-133
Differential pressure
Transmiter
Pressure
Transmitter
Bernoulli Equation or ISO 5167
Fraction Meter based on the attenuation of g-ray and composition dependent

12. Vx Technology Overview
PhaseTester*:
Periodic Testing (service/rental)
Vx Technology Overview
Introduced in 1998
Continuous rate measurements
No stabilization required
No phase separation, No moving parts
No Emulsion, No foaming dependency
No Sensor in direct contact with the fluid
No tuning factor, No flow calibration
High Pressure Solution > 5,000 psia
Compact Solution: 1.6x1.7x1.8 m3
Lightweight: 1,500 kg
Different sizes: 29, 52, 88 (100 – 150,000 bpd)
Lowest Total Pressure Lost
145
Cumulative Years of experience with Vx Technology:
TOP SIDE: > 5000 years
SUBSEA: > 1500 years
PERIODIC WELL TESTING: > 1000 years

13. Fraction Measurement & “Full” Gamma Ray Spectrum
Gas
Oil
Fresh Water
5% Salinity
10% Salinity
15% Salinity
When flowing through a fluid (ex: Gas, Oil & Water molecules) the -rays will collide with the e- (electrons) of these molecules and depending on the initial energy of these -rays different reactions take place.
If the -rays has low energy (ex: 32 KeV), it will collide with the electron, pass all the energy it has to the electron. By passing all its energy to electron, the -rays will not have any more energy and will vanish. This is called Photoelectric Absorption.
If the -rays has relatively high energy (ex: 81 KeV), it will collide with the electron, pass part of its energy to the electron and continue to exist as a lower energy -rays. The -rays will be deflected from its original path. This is called Compton Scattering.
We say that the ability of fresh water to absorb low energy -rays is higher than its ability to absorb high energy -rays. That is what we call the Mass Attenuation with  symbol and unit m2/kg.
Obviously, the higher the salts concentration in the water (NaCl, FeCl2, KCl, SrCl2, etc…) the higher the number of electrons will be and the higher the Mass Attenuation of the water will be for the same energy level of -rays.
Therefore, the Mass Attenuation will be different according to the type of elements that the phase (Oil, Gas or Water) is made of and the energy level of the -rays flowing through.
Compton interaction
f (density)
Energy Level
Photo-electric effect
f (composition, density)
Compton interaction
f (density, composition)

14. Gamma Ray Spectrum & Solution Triangle
Low Energy Linear attenuation
High Energy Linear attenuation
Counts Ratio at high energy
Counts Ratio at low energy
Gas ao aw
When flowing through a fluid (ex: Gas, Oil & Water molecules) the -rays will collide with the e- (electrons) of these molecules and depending on the initial energy of these -rays different reactions take place.
If the -rays has low energy (ex: 32 KeV), it will collide with the electron, pass all the energy it has to the electron. By passing all its energy to electron, the -rays will not have any more energy and will vanish. This is called Photoelectric Absorption.
If the -rays has relatively high energy (ex: 81 KeV), it will collide with the electron, pass part of its energy to the electron and continue to exist as a lower energy -rays. The -rays will be deflected from its original path. This is called Compton Scattering.
We say that the ability of fresh water to absorb low energy -rays is higher than its ability to absorb high energy -rays. That is what we call the Mass Attenuation with  symbol and unit m2/kg.
Obviously, the higher the salts concentration in the water (NaCl, FeCl2, KCl, SrCl2, etc…) the higher the number of electrons will be and the higher the Mass Attenuation of the water will be for the same energy level of -rays.
Therefore, the Mass Attenuation will be different according to the type of elements that the phase (Oil, Gas or Water) is made of and the energy level of the -rays flowing through. ag
Photo-electric effect
f (composition, density)
Compton interaction
f (density, composition)
Oil
Water

15. Accurate Measurement means proper setting of the meter
Linear Attenuation at high energy
Linear Attenuation at low energy
Gas
Oil
Water
WLR = 0.63 GVF = 0.24
It is a reference measurement made at the Venturi throat giving the fluid mass attenuations.
It reflects the ability of each phase to absorb gamma rays or scatters gamma rays
Every fluid has its own specific mass attenuation (a kind of finger print).
Counts Ratio at high energy
Counts Ratio at low energy

16. In-Situ Reference  Mass Attenuations
4/19/2017
In-Situ Reference  Mass Attenuations
30-45 minutes for each fluid
The heart of the Vx is the DEFM from where we get phases proportions.
The flow from the well is passing through this pipe with this particular shape.
A nuclear source emits gamma rays of different levels of energy (graph).
The gamma rays travel through the flow. Part of them are absorbed by OG&W the remaining arrives to the other side and are measured by a Detector.
By comparison between GR from the source and GR at the detector, we find the MA, which is the ability of to absorb GR.
The DEFM gives us the MA of the mixture. In order to get the phases proportions we need to tell the meter the MA of each phase.
In-situ Reference: Pouring oil sample into the Venturi
Gamma rays counts
Mass Attenuations
Accurate flow rates
Density of given fluid 16

17. Production Testing with PhaseTester
Truck mounted PhaseTester Unit
How to be more efficient?
How to improve Quality Measurement?
The Wish to Reduce Time
& Improve Quality
is always a challenge 17

18. How to measure the quality of the Periodic Well Testing Service
By regulation, in most of the countries, well testing is necessary each month for each well, it is not necessary achieved and then penalty is paid in one way or another.
The trend is to use local company because it is cheaper or “politically correct”.
However Periodic Well Testing can bring relevant information beyond the classical flow rates
Meanwhile, the quality of a Well Testing company can be quickly evaluated by looking the back allocation factor? Is it close to 1 or not!
Average worldwide is around 0.85 [ i.e. 15% off].
Dealing since 100 years with the separator does not indicate it is the best measurement!
Papers have been published too with MPFM and back allocation factor lower than 0.6 [Bad]
The best indicator is the Rejection rate; there is no cancellation effect between two wells, but this requires some historical data or some basic knowledge of the reservoir

19. Let’s see the Water Mass Attenuation Modeling: H2O +NaCl
1- Mix volumes dilution water + saturated formation water
2- Create a range of salinities
3- Made water insitu reference for all samples
4- Study resulting model
Water Mass Attenuation Correlation was a success
In fact I mixed formation water and dilution water to create many samples simulating all the possible produced water which can be found in the job.
Each represent a sample with different density (density is proportional to salinity but is easier to measure that’s why it has been used)
Each sample has a density and for each of them I measured the Att.
Then, plotting Att/Density for each level of energy I see that we get a line and a line can be described by an equation of first order.
Which is a helpful correlation which can be used in the field at any time to get correct attenuation to update the Vx.
Somebody can say: we had already correlations…but this one is different, it’s not generic, it’s customized, found working on Hassi Berkine samples.
1’15” - 12’45”
ai : mass fraction of components i
miE : mass attenuation for component i and energy E
Quality check and/or Replacement of Water InSitu Reference

20. How modeling the Oil Mass Attenuations?
Challenges of oil mass attenuation
Different compositions are expected
Different fraction of elemental components
Composition may change with age of the well
ai : mass fraction of components i
miE : mass attenuation for component i and energy E
Source : National Institute of Standards and Technology
Green is less than 1% change
Yellow is less than 2% change

21. One first field: Complete Analysis with > 1,600 well tests
4/19/2017
One first field: Complete Analysis with > 1,600 well tests
Validation
Validate data (Simulation + field testing)
Isolate high deviant points
Make a statistical study on deviation occurrence
Determine an oil mass attenuation model versus density
Study the possible outcomes of a scatter of the 3 energy levels
Incorporate the database in Oilfield Manager/map with Excel
Input the results in an Access database
Playback and filter all Vx-campaign jobs
Execution
Study

22. Main part of the Project Execution
Re-Process, filter, re-calculate all Vx campaign Data (again more than 1,600 jobs)
Input densities,
wells Access database

23. Isolation principle of high deviant points
Average
(A)
Model
(B)
23-Feb-09 (C )
A/B [%]
A/C [%]
LE(32keV)
0.77
5.24
HE(81keV)
1.10
4.95
XE(356keV)
0.11
4.63

24. Building Correlations for Oil Linear Attenuations
3 levels of energy
Linear model created
Model simulation
In fact I mixed formation water and dilution water to create many samples simulating all the possible produced water which can be found in the job.
Each represent a sample with different density (density is proportional to salinity but is easier to measure that’s why it has been used)
Each sample has a density and for each of them I measured the Att.
Then, plotting Att/Density for each level of energy I see that we get a line and a line can be described by an equation of first order.
Which is a helpful correlation which can be used in the field at any time to get correct attenuation to update the Vx.
Somebody can say: we had already correlations…but this one is different, it’s not generic, it’s customized, found working on Hassi Berkine samples.
1’15” - 12’45”

25. Field Test & Mass Attenuation Model Validation
Study possible effects on accuracy of Mass Attenuation of the model versus field measurement
Deviation [%] LE
(32 keV) HE
(81 keV) XE
(356 keV)
<0.5
49.7%
41.9%
44.7%
<1.0
76.1%
72.7%
78.6%
<1.5
86.7%
88.6%
94.4%
<2.0
94.3%
96.7%
98.4%
<2.5
98.8%
98.7%
99.3%
<3.0
99.9%
2/3 of the data set
used for modeling
Errors study for all energy levels (32keV, 81keV, and 356keV)
1/3 data to validate &
200 well tests later
LE Input (32 keV)
HE Input (88keV)
XE Input (356kev)
Oil Rate Output
Gas Rate Output
GVF Output
Real Case
0.49%
0.42%
0.39%
0.53%
0.12 %
0.08%
Worst Case 3%
1.57%
0.77%
0.34%

26. Conclusion (#1)
Vx Technology is based on fluid properties measurement directly no combined factor to build following the fluid, or fuzzy logic used in the interpretation.
The PhaseTester setting requires only the inputs of density measurement and mass attenuation for each phase (with several ways to get it)
No Combined Factor like on a separator
On large field, and high activity it is demonstrated that using an in-situ modeling leads to uncertainty
< 0.5% on oil flow rate
< 0.1% on the gas flow rate (Oil well).

27. Conclusion (#2)
Either, it is possible to skip the in-situ reference now for the entire field and then be able to set the meter and start to flow immediately, saving time at the well site by up to 2:00
Or doing a real-time quality control at the well site and then guarantee that the field data measurement are immediately correct.
Overall one solution or another will lead to reduce drastically the rejection rate of the Periodic Well Testing <1% for comparison in some fields with local well test operators > 40%
Rejection rate is dollars not used in optimum way for oil companies and leads to poor reservoir management in the best case! (Middle East and One Watery Well)

28. Any question? Bruno Pinguet Marketing & Technical Manager
OneSubsea & Schlumberger Testing

29. A way beyond – The 4 D Production Data Mapping29

30. Production Data Mapping: Gas Density
Low SG
High SG 30

31. Production Data Mapping: GOR
Low SG & High GOR
High SG & Low GOR 31

32. Any question? Bruno Pinguet Marketing & Technical Manager
OneSubsea & Schlumberger Testing