speatwdubai-eorlabqaqc

1. SPE Workshop:
Petrophysical Challenges in Reservoir Life Management
27 – 29 April 2015
Dubai, United Arab Emirates

2. LABORATORY QA/QC – ITS IMPORT ON EOR FEASIBILITY
Jules Reed
LR Senergy

3. Objectives
15ADU5 - SPE WORKSHOP: Petrophysical Challenges in Reservoir Life Management
Proper QA/QC of laboratory EOR feasibility studies is more important than QA/QC of
more routine and/or special core analysis results because economic margins are tighter
• Data for decision making
• Cost of EOR
• EOR feasibility study objectives
• QA versus QC – what’s the difference?
• QA/QC in EOR studies – sources of error

4. Data Quotes
15ADU5 - SPE WORKSHOP: Petrophysical Challenges in Reservoir Life Management
A theory is something nobody believes,
except the person who made it.
An experiment is something everybody
believes, except the person who made it.
- Albert Einstein
You can use all the quantitative data you
can get, but you still have to distrust it and
use your own intelligence and judgment.
- Alvin Toffler
You can have data without information, but
you cannot have information without data.
- Daniel Keys Moran
Data is not information,
Information is not knowledge,
Knowledge is not understanding,
Understanding is not wisdom.
- Clifford Stoll

5. EOR Costs
IEA 2008
EOR economic return is more marginal due to higher investment and production costs
over primary and secondary production techniques

6. EOR Feasibility Study Objectives
• Assess potential incremental recovery
• Improve microscopic sweep efficiency
• Can remaining oil saturation be moved towards residual?
• Requires accurate understanding of true Sor
Np = OOIP · ER
Np = Cumulative oil produced (STB)
OOIP = Original oil in place (STB)
ER = Recovery Efficiency (fraction)
ER = EA·EI·ED = EV·ED
EV = Volumetric sweep efficiency (fraction)
EA = Areal sweep efficiency (fraction)
EI = Vertical sweep efficiency (fraction)
ED = Displacement sweep efficiency (fraction)

7. QA vs QC
15ADU5 - SPE WORKSHOP: Petrophysical Challenges in Reservoir Life Management
• Quality Assurance (QA) – ensuring the process is fit for purpose
• Quality Control (QC) is preventing/identifying defects and removing
• QA includes test design to fit objectives, to represent the reservoir
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
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0 0.2 0.4 0.6 0.8 1
Residual
Oil
Saturation
(v/v)
Initial Oil Saturation (v/v)
Clean
State
Fresh
State
Restored
State
C = 0.6
C = 1.5
C = 2.5
C = 10

8. QA vs QC
15ADU5 - SPE WORKSHOP: Petrophysical Challenges in Reservoir Life Management
• Numerous labs do not have a traceable/accredited QC system
• Labs with QC accreditation, most often merely focus on calibration, i.e. the equipment
reads correctly
– Few labs focus on finding/eliminating defects in results, thus results may contain errors
– Few labs report the supporting data to allow full quality review
• Data results come from experiments - defects always occur
Some data errors can be
interpreted and corrected
Others may not. Data must be ignored.

9. EOR QA/QC – sources of error
15ADU5 - SPE WORKSHOP: Petrophysical Challenges in Reservoir Life Management
• Poor sample selection
• Incorrect basic rock properties
• Incorrect conditions (wetting, fluids)
• Improper QC during testing, only performed
retrospectively (if at all)
• Inappropriate experimental procedures/
methods
• Not accounting for method sensitivities
Sample ID 1A
Expected K 700 mD
Measured K 15 mD
Pore Volume 11.43 ml
Fluid volumes measured 12.52 ml
Volume error 10%

10. EOR QA/QC – sources of error
15ADU5 - SPE WORKSHOP: Petrophysical Challenges in Reservoir Life Management
0.00001
0.0001
0.001
0.01
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1
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Relative
Permeability
Water Saturation [fraction]
Relative Permeability Curves per Methodology
Steady State Unsteady State Centrifuge
• Results can be method sensitive
• Flooding methods do not provide accurate residual answers
• Most EOR studies require flooding
• Few labs understand the
impact of this and fail to
make the necessary
corrections
• This is one of the most
common sources of error in
EOR flood tests

11. EOR QA/QC – sources of error
15ADU5 - SPE WORKSHOP: Petrophysical Challenges in Reservoir Life Management
• Capillary end effects may not be negligible (as is assumed)
• Capillary end effects are not present deep reservoir
• Certain EOR tests may mostly measure removal of end effects
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0 1 2 3 4 5 6 7 8
Water
saturation
[fraction]
Sample Length [cm]
Swi Sor -water Sor-polymer Sor W-real Sor-P real
Recovery Factor (%OOIP)
measured directly (solid
lines)
72%  83%
EOR = 11 %OOIP
More realistic deep reservoir
84%  87%
EOR = 3.2 % OOIP

12. Invest in data quality
15ADU5 - SPE WORKSHOP: Petrophysical Challenges in Reservoir Life Management
Please keep all your pictures, graphics, charts and/or inserted
shapes within the white area to obtain best clearance for the
information provided.

13. Summary
15ADU5 - SPE WORKSHOP: Petrophysical Challenges in Reservoir Life Management
i. Data > Information > Knowledge > Understanding > Wiser investment choices
ii. Laboratory feasibility studies provides information towards this goal
iii. Study processes/procedures must be quality assured
iv.Results must be simultaneously quality controlled as testing is ongoing
v. Data corrections will be necessary for all flooding analyses