Green Imaging Technologies, Inc'

1
Comparison Study of Capillary Pressure Curves
Obtained using Traditional Centrifuge and
Magnetic Resonance Imaging Techniques
Derrick P. Green1, Josh R. Dick1, John Gardner2,
Bruce J. Balcom3, Charles Couturier3, and Bing
Zhou3 1Green Imaging Technologies, 46 Dineen
Drive, Fredericton, NB, Canada 2CoreLab, 6316
Windfern Road, Houston, TX, USA 3University of
New Brunswick, Fredericton, NB, Canada
2
Outline

• Background
• New MRI based capillary pressure technology
• Comparison Study Results

3
Capillary Pressure Measurement

• Capillary pressure, Pc, is the
• difference in pressure across two immiscible
  fluids
• Pc is important for understanding the saturation
  distribution in the reservoir and the affects of
  fluid flow through the rock
• Performed on rock cores plugs in the lab
• There are three separate curves, primary
  drainage, imbibition, and secondary drainage.
• Currently Pc can be measured three main ways
  Porous plate, Centrifugation, and Mercury
  Injection

4
Traditional Centrifuge Pc

• Measure the expelled water at different
  rotational speeds ? and compute the average water
  saturation

• Assumption Pc(r2) 0 (i.e. 100 saturation at
  the outlet face)

5
Traditional Centrifuge Pc

• The measured average water saturation must be
  converted to the saturation at the inlet face

• This equation CANNOT be directly solved. A
  number of approximate solutions for the above
  equations exist (Hassler-Brunner, Forbes, etc)

6
MRI Pc (GIT-CAP)

• S(r) directly determined by MRI
• Different Pc values obtained by using radius r as
  our variable not w saving time
• As few a one centrifuge speed
• Capillary pressure curve determined directly by
  the relations of S(r) and Pc(r), no approximations

7
NMR/MRI

• Magnetic resonance imaging (MRI) alters the
  magnetic field to localize the signal (1D, 2D, or
  3D images)
• MRI can directly determine the amount of hydrogen
  (water and/or oil) at a given location

8
One Dimensional MRI

• Quantitative fluid content mapping method
• 
  tpltltT2
• Ideal for porous media application
• T2 is single exponential and does not depend on
  water saturation
• Distinguish water and oil with D2

9
Saturation Distribution
30 saturation data points along sample at each
rotational speed
Outlet Face
10
MR Pc Curve
Porosity 14.5 Permeability 0.908mD
11
Pc Instrument Configuration

• 6.2MHz Field Strength, standard 2 sample access
• Standard Rock core centrifuge
• Turn-key instrument

12
Market Validation Trial (MVT)

• Phase 1
• Conducted at UNB with the support of GIT and
  NSERC
• Retest older core plugs provided by Oil companies
  and compare results to existing capillary
  pressure results
• Wide variety of core types from industry
  participants Chevron, ConocoPhillips, Exxon,
  Shell

13
Market Validation Trial (MVT)

• Phase 2
• 8 Month On-site at CoreLab in Houston with Bruker
  equipment
• Conduct side-by-side comparisons of capillary
  pressure curves acquired using GIT-CAP and the
  traditional acquired methods
• Goals
• Generate results required to prove the technology
  to industry
• Deliver a solution the industry wants

14
Comparison of Centrifuged Pc and GIT-CAP
Porosity 14.5 Permeability 2.28mD
15
Comparison of Centrifuged Pc and GIT-CAP
Porosity 13.3 Permeability 13.30mD
16
Comparison of Porous Plate Pc and GIT-CAP
Porosity 19.5 Permeability 9.21mD
17
Comparison of Porous Plate Pc and GIT-CAP
Porosity 13.4 Permeability 4.24mD
18
Comparison of Porous Plate Pc and GIT-CAP
Porosity 19.8 Permeability 1030.00mD
19
Comparison of Porous Plate Pc and GIT-CAP
Porosity 22.0 Permeability 3.10mD
20
Comparison of Porous Plate Pc and GIT-CAP
Porosity 15.3 Permeability 108.00mD
21
QUICK-CAP

• Use the data from a single centrifuge speed and
  use a Pc model to extend the curve

• Use the Leveret J function to select the speed

22
QUICK-CAP
Porosity 19.8 Permeability 1030.00mD
23
QUICK-CAP
Porosity 22.0 Permeability 3.10mD
24
Fluid Redistribution

• How fast does the fluid redistribute in the rock?
  
• Two processes
• free fluid will spontaneous imbibed into the
  rock very quickly (minutes)
• Fluid in the pore does NOT redistribute quickly
  (hours or days)

25
Fluid Redistribution
Porosity 19.5 Permeability 9.21mD
26
Fluid Redistribution
Porosity 16.7 Permeability 691.00mD
27
Traditional Centrifuge Pc

• STEPS
• Clean, Dry and fully saturate the plug
• Place in centrifuge at first speed for 24-48
  hours
• Measure the amount expelled water
• Calculate the average saturation using the
  measured expelled water
• Use one of the many methods to translate the
  average water saturation to the saturation at the
  inlet face
• Use Hassler-Brunner Pc equation to compute Pc at
  the inlet for each speed
• Plot 5 versus 6
• Repeat 2 through 7 from between 8 to 10 times

28
MRI Pc

• STEPS
• Clean, Dry and fully saturate the plug
• Place in centrifuge at first speed for 24-48
  hours
• Remove the rock and place in MRI equipment
• Measure the water saturation as a function of
  position
• Use Hassler-Brunner Pc equation to compute Pc at
  each MRI measured saturation position
• Plot 5 versus 6
• Repeat 2 through 7 from between 1 to 3 times

29
GIT-CAP Advantages

• Speed/Throughput Fewer equilibrium speeds, 30
  samples in a centrifuge, Pc curves may be
  acquired dramatically faster
• Accuracy Analytical result, no approximations
• Adaptable Friable and unconsolidated samples may
  be applicable to this new method

30
Future Work

• Oil/Water capillary pressure
• Relative permeability measurements
• Overburden
• Core Flooding experiments

31
Acknowledgements
John Gardner, Robert Lee, Paul Martin, and staff
at CoreLab Houston The oil companies who supplied
cores and other support Chevron, Shell,
ExxonMobil, ConocoPhillips Josh Dick, and staff
at Green Imaging Technologies Bruce Balcom and
staff at University of New Brunswick National
Science and Engineering Research Council of
Canada (NSERC) Petroleum Research Atlantic Canada
(PRAC)
32
Contact Information
Thank You
Questions?

• Derrick Green
• President and CTO
• Green Imaging Technologies Inc.
• Derrick.Green_at_greenimaging.com
• [phone]

33
Comparison of Porous Plate Pc and GIT-CAP
Porosity 20.4 Permeability 5.74mD
34
Comparison of Porous Plate Pc and GIT-CAP
Porosity 13.7 Permeability 9.70mD