RFT and MDT application in Field Development

1. RFT & MDT APLICATION FOR
FIELD DEVELOPMENT

2. PRESENTATION OUTLINE
2
▰ INTRODUCTION
▰ BASIC DATA ACQUISITION & APPLICATION
▰ CASE STUDY
▰ SUMMARY

3. INTRODUCTION
3
1
Brief Summary of RFT & MDT

4. WHAT ARE THEY?
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Courtesy of Schlumberger
Definition
RFT : Repeat Formation Tester
MDT : Modular Formation Dynamic Tester
RFT and MDT basically are wireline “Formation Tester” which
mainly run in open hole section during well drilling.
What For?
➢ The main objectives are to measured reservoir pressure,
Mobility, and to get fluid content at exact reservoir interval
When We Need It?
➢ RFT/MDT are beneficial at both exploration and
development phases

5. 5
WHEN WE NEED IT?
Well test are conducted at all stages in the life of reservoir :
Exploration Development Production Injection
➢ It is performed mostly in open hole using a cable-operated formation
tester and sampling tool after the proper depth is determined from log.
Commonly it is tested after the result of petrophysic analysis,
➢ They are used as a quick and inexpensive alternative to DST tests

6. WHAT FOR?
These pressure measurements are useful in determining:
➢ Variation in pressure among various formation
➢ Gradient of fluid pressure within a formation that can indicate fluid contact
➢ Gas-oil or oil-water contact
➢ Formation permeability
➢ Conduct controlled local production and vertical interference
Oil, Gas and Water has different gradients.
➢ Gas = 0.55 g/cc
➢ Oil = 0.88 g/cc
➢ Water = 1.0 g/cc
These are density gradients of different fluids. Where your
gradient changes you can mark the Gas-Oil contact, Gas-
Water contact, Oil-Water contact.
The deeper pressure points should have higher value of
pressure. If this is not following, then it means the data is
not correctly recorded.

7. GENERAL TOOL EVOLUTION
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FT
Formation
Tester
RFT
Repeat
Formation Tester
MDT Modular
Formation Dynamics
Tester
1955 - 1975 1990-Present
(New Generation)
1975 - 1990
Courtesy of Schlumberger
FT
• Earliest tool, Specifically to collect reservoir fluid
samples, but could only collect one sample per trip
RFT
• Multiple Pressure measurement, profiles and mobility
• Sampling w/ max two Chambers
• Strain Gauges used, limited pressure and poor
quality fluid samples
MDT
• Multiple Pressure measurement, profiles and mobility
• Live Fluid Analyser (LFA)
• Sampling w/ max 6 Chambers. 100’s of pre-test
possible with dozen or more fluid samples per run.
• Use highly accurate quartz gauges (resolution 0.1psi)
• Many different tool configuration possible for
different application (eg. SRFT, CHDT, XPT, QS, Saturn,
Dual Packer, etc.)

8. BASIC TOOL CONFIGURATION
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Main Components of MDT Tool
1. Formation Pressure Gauges (Strain & Quartz)
2. Formation Resistivity Gauges
3. Pump Out; Live Fluid Analyser
4. Sample Chamber

9. COMPARISON

10. BASIC DATA ACQUISITION
10
2
How Do They Work

11. OPERATIONAL MDT
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a. Retracted Tool
b. Tool Set

12. Formation
Time
Pressure
Packer Pretest Piston
Gauge
After Tool is Set Flowline is at Mud Hydrostatic Pressure
PRESSURE TEST : How Do Wireline Tools Measure Pressure
1
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13. Formation
Time
Pressure
Packer Pretest Piston
Gauge
PRESSURE TEST : How Do Wireline Tools Measure Pressure
2
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14. Formation
Time
Pressure
Packer Pretest Piston
Gauge
PRESSURE TEST : How Do Wireline Tools Measure Pressure
3
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15. Formation
Time
Pressure
Packer Pretest Piston
Gauge
PRESSURE TEST : How Do Wireline Tools Measure Pressure
4
15

16. Formation
Time
Pressure
Packer Pretest Piston
Gauge
PRESSURE TEST : How Do Wireline Tools Measure Pressure
5
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17. Formation
Time
Pressure
Packer Pretest Piston
Gauge
Formation delivers fluid at the same rate the pretest
piston expands the flowline volume
PRESSURE TEST : How Do Wireline Tools Measure Pressure
6
17

18. Formation
Time
Pressure
Packer Pretest Piston
Gauge
PRESSURE TEST : How Do Wireline Tools Measure Pressure
7
18

19. Formation
Time
Pressure
Packer Pretest Piston
Gauge
PRESSURE TEST : How Do Wireline Tools Measure Pressure
8
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20. Formation
Time
Pressure
Packer Pretest Piston
Gauge
Piston Stops
PRESSURE TEST : How Do Wireline Tools Measure Pressure
9
20

21. Formation
Time
Pressure
Packer Pretest Piston
Gauge
Pressure Equalizes With Formation
PRESSURE TEST : How Do Wireline Tools Measure Pressure
10
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22. Formation
Time
Pressure
Packer Pretest Piston
Gauge
Constant Flowing Pressure or
“Steady State” Pretest
> 1 mD/cp
PRESSURE TEST : How Do Wireline Tools Measure Pressure
11
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23. PRESSURE TEST
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Typical Pressure Measurement (Normal Pretest)
Tight/Dry Test Supercharging
A Tight Test. If the sample is very impermeable the sampling
pressure drops to near zero.
Stuck Tool. Usually when the tool has been set at a given depth for
some time.
Plugging. Sand grains from the formation may enter the tool and
block the flow lines, especially in unconsolidated samples.
Seal Failure. If the packer fails, the drilling mud will be sampled and
the mud pressure will be recorded.
Supercharge. Very Low Permeability and near wellbore is
overpressured due to mud filtrate invasion that has not dissipated
during pretest.
Potential Problems During Testing

24. LIVE FLUID ANALYSIS
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Optical Spectroscopy
OFA-OBM Spectral Presentation

25. FLUID SAMPLING
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26. APPLICATION
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TYPICAL APPLICATION
▪ Formation Pressure and Mobility
▪ Downhole fluid typing
▪ High Quality fluid sampling
▪ Reservoir properties (permeability,
skin, anisotropy) – Mini DST
DETAILED EVALUATION NEEDS
▪ Define reservoir hydrodynamic description
(correlation)
▪ Investigate stage of reservoir depletion
▪ Combine with material balance analysis or simulation study
▪ Fluid contact investigation
▪ Gas Oil Contact
▪ Water Oil Contact
▪ Acreage investigation
▪ Combine with material balance study
▪ Formation permeability and its deliverability
▪ PVT Analysis
▪ Completion Design & Method

27. PRESSURE ANALYSIS CONCEPT ON CONTACT
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Alternative interpretation:
A. Connected water/aquifer of main reservoir, will has similar water gradient & pressure
B. Pressure could be shifted from the main trend, probably the results of “un-connected” reservoir.
Pressure tend to be lower, could be connected to surface and released some pressure. But it
mainly higher if perfectly isolated from other reservoirs/surface.

28. STUDY CASE
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3
Case in Oil and Gas Development

29. SUMMARY
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4

30. SUMMARY
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RFT/MDT application :
▪ Formation Pressure and Mobility
▪ Downhole fluid typing & Sampling
▪ Reservoir properties (permeability, skin, anisotropy)
RFT/MDT Limitation :
▪ Good result only in good porosity and permeability reservoir
▪ Limitation use in Shaly sand & Carbonate reservoir
▪ Geological consideration is a must to determine RFT/MDT sampling
point

31. THANK YOU!
Let’s Discuss
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