Reservoir and Fluid Characterization with Formation Testers: Reducing Asset Uncertainties

1. Primary funding is provided by
The SPE Foundation through member donations
and a contribution from Offshore Europe
The Society is grateful to those companies that allow their
professionals to serve as lecturers
Additional support provided by AIME
Society of Petroleum Engineers
Distinguished Lecturer Program
www.spe.org/dl

2. Society of Petroleum Engineers
Distinguished Lecturer Program
www.spe.org/dl
Dr. Cosan Ayan, Reservoir Eng. Advisor
Reservoir and Fluid Characterization
with Formation Testers: Reducing
Asset Uncertainties

3. Wireline Formation Testing (WFT)
Applications
Land and Offshore
Pressures
Sampling and Downhole
Fluid Analysis (DFA)
Transient Testing
In-Situ Stress Testing
Reservoir
Characterization
3

4. Formation testing-evolution
Early formation testers: circa 1956
4

5. Current Wireline and Logging
While Drilling Formation Testers
 Real time monitoring and control
 Various downhole pumps
 Various probes, including focused
types
 Downhole sensors:
 Optical: contamination, GOR,
composition, pH
 NMR based
 Density, viscosity, acoustic, refractive
index, resistivity, capacitance
 Various sample chambers, including
single phase chambers
5

6. 28 Deepwater GoM Fields
6 Deepstar Industry Study (OTC 25173)
75 % Underperform on rate and recovery!
Good reserves
Goodproduction

7. From Measurements to Reservoir
Modeling
Single
Station
Analysis
Single Well
Analysis
Multiple Well
Analysis
Understand
Your
Reservoir
Pressure
Fluids
Transients
Gradients & Contacts
Multi Well Gradients & Contacts
Multi Well DFA Prediction
Common applications in land vs offshore. Offshore
is more critical in exploration and appraisal stage7
MicroFrac

8. Pressures
Sampling and
Downhole Fluid
Analysis (DFA)
Transient Testing
In-Situ Stress Testing
Reservoir
Characterization
8

9. Reservoir Characterization with
Pressures/Gradients, offshore
Free water level extrapolated from
pressures recorded in the oil and water
legs from two different wells
)1(
)1(121 222



KK
K
h
Dp 
Statistical Error. In this
case = 0.012 g/cc
Factors FWL error
(ft)
FWL
Depth accuracy +78 up/down
Pressure gauge accuracy +135 up/down
Gauge temperature sensitivity −207 down
Pressure gradient error (oil) +54/−112 up/down
Capillary (water zone OBM) +7 up (Water
Wet Sand)9

10. Gradient Errors: Effect on reserves,
offshore field
10

11. Pressures
Sampling and
Downhole Fluid
Analysis (DFA)
Transient Testing
In-Situ Stress Testing
Reservoir
Characterization
11

12. Effect of OBM on a near critical fluid
0
0.2
0.4
0.6
0.8
1
VolFracUpperLiq
0
0.01
0.02
0.03
0.04
0.05
VolFracLowerLiq
5000 6000 7000 8000 9000 10000
Pressure psia
Expt. Uncontaminated Expt.5 wt % Novaplus
EOS Uncontaminated EOS 5 wt% Novaplus
GOM Near Critical Fluid 180 F CCE
Phase Diagram
12
Exp. Uncontaminated Exp.5 % wt OBM Contaminated
EOS Uncontaminated EOS 5 % wt OBM Contaminated

13. Contamination Cleanup Behavior
Drains
Saturn
 3D numerical models were simulated:
Miscible and immiscible (liquids)
 Accurate representation of drain size and shapes
 Proxy models generated from thousands of runs
Time 1 Time 2 Time 3 Time 4
13

14. 10
-2
10
-1
10
0
10
1
10
2
10
-2
10
-1
10
0
Time [hrs]
Contamination
5% contamination
Saturn 3D Radial Probe
XLD Probe
Dual Packers
3D Radial Probe
Tool Cleanup
time
(5%)
[hrs]
3D Radial Probe 0.71
Extra Large
Dimension Probe
9.10
Dual Packers 1.00
3 Dimensional
Radial Probe
Probe Dual Packers
Contamination Cleanup Behaviour
Slope = -
5/12
Slope
= -2/3
1414

15. H2S in oil and gas industry and its
consequences
 Sulphur compounds in crude oil and
natural gas exists in various forms
 70% of crude oil and 40% of natural
gas reserves are sour (IEA)
 Sulphur content has been increasing
in produced crude (OPEC)
Commercial Impact
Operational Challenges
HSE Concern
15

16.  New sensor based on electrochemistry
 Membrane for H2S diffusion between
the flowline and measurement cell
 Integrated measurements:
• pH to correct for CO2
• Baseline concentration
• Temperature
Downhole InSitu H2S sensor
Buffer +
Mediator
Electrode
Bulkhead
Membrane (diffusion)Fluid Flow with H2S
Flowline
Measurement cell
Flowline
Electrode
bulkhead
Membrane
Sensing
chamber
Connector
16

17. Flory-Huggins-Zuo (FHZ) EoS to predict asphaltene content variation
 Connectivity
 Compartments
 Tar Mats
 Heavy oil
 Compositional
gradients
 Disequilibrium
Reservoir and Fluid Characterization
with Downhole Fluid Analysis
17
Optical density (color)
TrueVrticaldepth,ft)
EoS
model for
two zones
Measured

18. XX15 Sand Multiwell Oil Column
Pressures and Fluids
A 2-D representation is getting complex,
not easy to understand !18

19. 3-D Representation of WFT analysis: India
• Start in 3D
• Line of section
• WS Window
• 3D Showing OD distribution
19

20. Pressures
Sampling and
Downhole Fluid
Analysis (DFA)
Transient
Testing
In-Situ Stress Testing
Reservoir
Characterization
20

21. DeltaP
Saturn
Probe
h= 12.2 m
Kh =640 mD
Kv= 125 mD
μ =370 cp
DeltaP
Observation
Probe
Rate
History
Pressure
Match
Conventional WFT Transient
Testing: Mexico
21

22.  Can use existing inlet
devices (Dual packers, 3D
Radial Probe)
 High power downhole pump
(up to 71 bbl/day)
 Slip joint for pipe expansions
 Drill-pipe conveyed, can
circulate mud while pumping
Hydrocarbon
Mixture
Drilling Mud
ReservoirQuad-Packer
High Capacity
Downhole Pump
Circulating
Equipment
Slip Joint
3DRadialProbe
QuadPacker
DualPacker
New – WFT Deep Transient Testing
22

23. Cores
Logs
FT pretests
WFT Transient Tests
Well
Testing
Radius of investigation
WFT Deep Transient Testing
Understanding the reservoir deeper
23

24. Flow Regime Identification and model
match: Norwegian sea
Three buildups; 11 Darcy permeability. Flow rate was 71 rb/d
 Total station time 26 hr, with 6 hr flow period.
 Radius of investigation was 576m.
24

25. Multiphase Transport Properties
from Petrophysics and WFT
• WFT sampling operation provides
bottom-hole pressure and water-
cut data
• Multi-depth resistivity logs provide
invasion profile (electromagnetic-
EM modeling)
• A numerical model determines
multiphase flow properties in an
inversion workflow
25

26. Field Example: WFT pressure and
water cut match
Match of measured pressures and
water-cut. Inverted capillary pressure
and relative permeabilities
26

27. Field Example: Near wellbore
saturation images
Oil saturation is from 0.15 (blue) to 0.70 (red)
End of
dynamic
filtration at
0.5 day
Laterolog
logging at
2.0 days
Beginning of
WFT cleanup
at 6.6 days
End of WFT
cleanup at 6.7
days
End of
pressure
buildup at
6.7 days
27

28. Pressures
Sampling and
Downhole Fluid
Analysis
Transient Testing
(IPTT)
In-Situ Stress
Testing
Reservoir
Characterization
28

29. Pore Pressure and Fracture Gradient
Established workflow in the industry to
define a safe drilling window for well
construction (circa 1970s)
Questions always arise …
 Impact of faults?
 Tectonic stresses?
 Rock properties?
 Calibration techniques?
1 Equivalent Mud Weight (g/cc or PPG) 3
TVD
Overburden
Stress
Fracture
Gradient
“Leak off” tests
Pore
pressure
calibration
Mud
Weight
Pore
Pressure
29

30. Industry Advancements: 3D
Geomechanical Models
 Detailed integrated
geology
and reservoir
modeling
 Highly precise
calculations
 Still requires well
control
and calibration
30

31. Fracture
initiation
Closure pressure
Breakdown pressure
The micro-hydraulic fracturing
with WFT packers + images
31

32. What we desire in Next Generation Wireline
Formation Testers?
 Easy/tailor-made survey design and conduct
 Ultra-pure samples in much shorter time in every
environment
 Deep transient testing
 Conveyance independent deployment
 Real time fluid modeling
 Early reservoir insights
Lessons learned from ~20 years of pumpout WFT’s
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33. Concluding Remarks
Reservoir and Fluid Characterization with Formation Testers:
Reducing Asset Uncertainties
Pressure, fluid analysis, transient test results and stress
tests are seamlessly getting integrated into RE software
and workflows
Advanced downhole sensors will be included
New Generation tools are emerging with more
capabilities
Transient testing capabilities are improved, reducing
risks in reservoir evaluation
33

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Distinguished Lecturer Program
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