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

• Our research activities

• Our RPSEA project and collaborators

• Preliminary results (from CSM)

• Goals and objectives

RPSEA Piceance Basin Research Review April 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

• Our group’s research activities focus on pore-scale physics and flow using direct simulation and experiments

• In very tight reservoir rocks, both measurement techniques and our understanding of the physics are being challenged

• We propose to use a combination of pore-scale numerical model and laboratory experiments to improve our understanding of flow and transport on the nanoscale

RPSEA Piceance Basin Research Review April 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 – “Using Single-Molecule Imaging System Combined with Nano-Fluidic Chips to Understand Fluid Flow in Tight and Shale Gas Formation”

– 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 Review April 21, 2011, Denver, Colorado

P E T R O L E U M E N G I N E E R I N G

Conventional laboratory studies

• Porosity and permeability measurement

• Mercury porosimetry

• Linear core flooding

• PVT

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 Review April 21, 2011, Denver, Colorado

P E T R O L E U M E N G I N E E R I N G

“Unconventional” laboratory studies

• What makes flow in unconventional reservoir rocks unconventional? – Surface interactions

– Non-continuum slippage

– Heterogeneity in surface properties

– Geometry heterogeneity

– Microfractures …

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 Review April 21, 2011, Denver, Colorado

10 micron wide channels on polymer substrates

100 nm channels (right) on silicon substrates

P E T R O L E U M E N G I N E E R I N G

Preliminary results from microfluidic chip experiments

Data and photo provided by Keith Neeves and Melissa Wu,

Chemical Engineering, Colorado School of Mines

RPSEA Piceance Basin Research Review April 21, 2011, Denver, Colorado

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rme

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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

Two-phase experiments conducted on 10 micron wide 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 structure Relative permeability Effect of stress Adsorption / Desorption

RPSEA Piceance Basin Research Review April 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 important for rock typing and understanding geomechanical effects on fluid flow

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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 Review April 21, 2011, Denver, Colorado

k: permeability s: specific surface area Data shown were obtained from lattice Boltzmann simulations (no-slip)

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

• Data from homogeneous and heterogeneous geometries can be collapsed on a universal porosity-permeability correlation because small pores control the permeability

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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 Review April 21, 2011, Denver, Colorado

Conductive porosity = total porosity – vuggy porosity in heterogeneous geometries

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

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Porosity

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Parallelized, 3D pore-scale simulator

3D Representative Geometries

3D Porosity-Permeability Data

3D Simulator Parallel Speedup

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RPSEA Piceance Basin Research Review April 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 physics Increasing 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 Review April 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)

– Mellisa 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%