P E T R O L E U M E N G I N E E R I N G
Numerical and Laboratory Study of Gas Flow through Unconventional Reservoir Rocks
RPSEA Piceance Basin Tight Gas Research Review
Xiaolong Yin, Assistant Professor
Petroleum Engineering, Colorado School of Mines
April 21 2011
P E T R O L E U M E N G I N E E R I N G
Presentation Outline
• Challenges and our research activities
• Our RPSEA project and collaborators
• Preliminary results
• Goals and objectives
RPSEA Piceance Basin Research ReviewApril 21, 2011, Denver, Colorado
P E T R O L E U M E N G I N E E R I N G
Background
• In very tight reservoir rocks, both measurement techniquesand our understanding of the physics are being challenged
• Our group’s research activities focus on pore-scale physics and flow using direct simulation and experiments
• Specifically, we investigate what makes unconventional rocks unconventional– Surface interaction
– Non-continuum slippage
– Heterogeneity in pore structure and rock-fluid interactions
RPSEA Piceance Basin Research ReviewApril 21, 2011, Denver, Colorado
P E T R O L E U M E N G I N E E R I N G
Our RPSEA Project
• RPSEA 09122-29 – 02/2011 – 02/2014– Use nanofluidic chips and single-molecule detection techniques to
visualize fluid flow in nano-sized pores
– Combine core flooding test and SEM imaging to correlate fluid flow in tight rocks to pore structures
– Develop pore-scale numerical models to provide information that cannot be easily obtained from experiments, such as three-dimensional motion of fluids
• Our Team– Missouri University of Science & Technology – B. Bai (core flooding),
Y. Ma (single-molecule detection)
– Colorado School of Mines – X. Yin (pore-scale models), K. Neeves(nanofluidic chips)
RPSEA Piceance Basin Research ReviewApril 21, 2011, Denver, Colorado
P E T R O L E U M E N G I N E E R I N G
Traditional laboratory studies
• Pulse-decay permeability measurement
• Mercury porosimetry
• Linear core flooding
• Ultra-centrifuge
• PVT (CSM)
These equipments allow us to study
•Porosity and permeability•Storage capacity and transport•Multiphase flows and formation damage
A CMS-300 Pulse-Decay Permeameter
RPSEA Piceance Basin Research ReviewApril 21, 2011, Denver, Colorado
P E T R O L E U M E N G I N E E R I N G
Non-traditional laboratory studies
• What makes flow in unconventional reservoir rocks unconventional?– Surface interactions
– Non-continuum slippage
– Heterogeneity in surfaceproperties
– Fractures and cracks
– In-situ stress
– …
Some of these effects can be studied using micro (right) and nano-scale (below) porous media analogs constructed on silicon / polymer chips
Photo courtesy of Keith Neeves
Chemical Engineering
Colorado School of Mines
This list is probably far from complete.
RPSEA Piceance Basin Research ReviewApril 21, 2011, Denver, Colorado
P E T R O L E U M E N G I N E E R I N G
Preliminary results from micro-chip experiments
Data and photo provided by Keith Neeves and Melissa Wu ,
Chemical Engineering, Colorado School of Mines
RPSEA Piceance Basin Research ReviewApril 21, 2011, Denver, Colorado
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
1 2 3 4 5
Pe
rme
abili
ty (
Dar
cy)
Experiment LB Simulation
Permeability comparison
Air-water two phase flow test: Left: The geometry is initially saturated with water
Below: Air is injected in the lower left corner forcing water out of the channels
P E T R O L E U M E N G I N E E R I N G
Simulation of micro- and nano-scale flows
• Numerical tools have been and are being developed to study fluid flow with non-continuum effects in nano-sized pores
Representative porous media geometry models
Experimentally measured φ and k and pore structure
Direct numerical simulation models:•Lattice-Boltzmann (for Navier-Stokes)•DSMC (for non-continuum flows – being developed)
Pore structureRelative permeabilityEffect of stressAdsorption / Desorption
RPSEA Piceance Basin Research ReviewApril 21, 2011, Denver, Colorado
P E T R O L E U M E N G I N E E R I N G
Preliminary results from pore-scale modeling
• Porosity-permeability relation is the key to rock typing and understanding geomechanical effects on fluid flow
0.0000
0.0005
0.0010
0.0015
0.0020
0.0025
0.0030
0.00 0.10 0.20 0.30 0.40
ks2
Porosity
Homogeneous Geometry
Heterogeneous Geometry
Ideal, channelized geometry – porosity-permeability shows a strong correlation
More realistic, heterogeneous geometry –porosity-permeability shows large scattering
RPSEA Piceance Basin Research ReviewApril 21, 2011, Denver, Colorado
P E T R O L E U M E N G I N E E R I N G
Preliminary results from pore-scale modeling
• A universal porosity-permeability correlation can be developed by recognizing that the large pores do not contribute to permeability
0.0000
0.0005
0.0010
0.0015
0.0020
0.0025
0.0030
0.00 0.10 0.20 0.30 0.40
ks2
Conductive Porosity
Homogeneous Geometry
Heterogeneous Geometry
• These data are from our scoping studies using 2D geometries
• 3D simulations and experiments are underway
• Such a correlation can be used to determine the geometry of pores from bulk measurement without resorting to image analysis
RPSEA Piceance Basin Research ReviewApril 21, 2011, Denver, Colorado
P E T R O L E U M E N G I N E E R I N G
0 0.05 0.1 0.15 0.2 0.25 0.3 0.350
0.005
0.01
0.015
0.02
0.025
Porosity
ka
v2
Parallelized, 3D pore-scale simulator
3D Representative Geometries
3D Porosity-Permeability Data
3D Simulator Parallel Speedup
100
101
102
103
10-3
10-2
10-1
100
101
Number of CoresS
imula
tion t
ime
-1 (
s-1
)
Slope = 1
RPSEA Piceance Basin Research ReviewApril 21, 2011, Denver, Colorado
P E T R O L E U M E N G I N E E R I N G
Goals and objectives
Simulations with controlled
geometries and assumed physics Micro- and nano-
fluidic experiments with controlled
geometries and real physics
Core-scale experiments with
real geometries and real physicsIncreasing level of
reality
The combined approach will significantly improve our understanding of fluid flow on nano-scale and unconventional reservoir dynamics
RPSEA Piceance Basin Research ReviewApril 21, 2011, Denver, Colorado
P E T R O L E U M E N G I N E E R I N G
Acknowledgements
• Collaborators– Baojun Bai, Yinfa Ma (MUST)
– Keith Neeves (CSM, ChemE)
– Qinjun Kang (Los Alamos National Lab)
• Students– Feng Xiao (PE)
– Lei Wang (PE)
– Melissa Wu (ChemE)
• Funding– RPSEA
P E T R O L E U M E N G I N E E R I N G
Simulated vs. measured permeability
• Simulation of flow through digital cores from CT-scan
– CT and experimental data from Imperial College
– Numerical simulations are done in CSM
A1 BSS C1 F42A S1 S2
Porosity 42.9 19.6 23.3 33 14.1 24.6
Resolution 3.85 5.345 2.85 9.996 8.683 4.956
K (exp) 7,220 1,286 1,102 59,000 1,678 3,898
K (sim) 8,675 1,507 1,192 59,331 2,006 4,076
% error 20.2% 17.2% 8.1% 0.6% 19.6% 4.6%
