Branko
Bijeljić, Imperial College
London
“In situ micro-CT
scanning of multiple phases at high temperature
and pressure”
Some research questions and challenges in porous
media flow are outlined. Specifically, the
nature of transport in dispersion in highly
heterogeneous media and the pore-scale controls on
capillary prapping. The implications for the
design of carbon dioxide storage are
discussed. Then some results of research are
presented, using a combination of core floods,
micro-flow experiments on small core samples imaged
at the micron scale using micro-CT scanning and
numerical modelling. I will present a carbon
fibre flow cell that allows the pore-scale imaging
of fluids at elevated temperatures and pressures and
show some preliminary pictures of super-critical
carbon dioxide in the pore space. Future and
ongoing research is discussed.
David DiCarlo, The University of Texas at Austin, USA
"Benchmarking dynamic pore-scale models against REV-level experiments"
Imaging technology has provided the basis for modeling single- and multi-phase flow in porous media from first principles. The REV-scale predictions from the models are often tested against two-phase pressure-saturation and relative permeability curves. In these predictions, it is generally assumed that capillary forces dominate at the pore-scale, although it is recognized that at high capillary number viscous forces should be included. These models are known as dynamic models and testing and developing the correct physics to be included in the dynamic models is still in its infancy. In this presentation, we will discuss REV-scale data sets that cannot be explained by capillary force domination, and thus require dynamic models. We will show how dynamic models can in principle replicate the experimental behavior, and outline how the data sets can be used (along with imaging) in testing and verifying the next generation of dynamic models.
Joanne Fredrich, BP Upstream Technology,
Houston, TX
"Applications of
Image-based Modeling & Simulation in E&P"
This presentation will discuss applications of
'digital rocks' technology, meaning image-based
modeling & simulation, within exploration &
production in the energy industry.
Marios
Ioannidis,
University
of
Waterloo, Canada
"Heterogeneity and
structure across multiple scales in image analysis
for porous media"
Three-dimensional images of the void structure are
of fundamental value to understanding fluid
transport in natural porous media. An ideal 3D image
would be of sufficiently large size to capture
heterogeneity over multiple length scales and of
sufficiently high-resolution to resolve the finest
pore length scale of interest to transport.
Unfortunately, despite significant advances, such
images cannot be obtained using any single imaging
modality presently available. This presentation
introduces the idea of statistical fusion as a means
to integrate data of different dimensionality and/or
resolution obtained from different experimental
probes of the pore structure. Two applications
of statistical fusion are discussed. One leads
to estimates of a continuous pore size distribution
reflecting fractal and Euclidean aspects of the pore
space across length scales ranging from nm to
mm. The other offers a possible solution to
the problem of unresolved length scales in
experimental (x-ray tomographic or magnetic
resonance) images of porous media, attempting to
infer high-resolution details of a particular sample
from the pattern of low-resolution
measurements. Computational challenges with
the practical implementation of statistical fusion
to image data are also discussed and hierarchical
simulated annealing (HSA) is proposed as a viable
alternative to currently available algorithms for
image reconstruction.
Zuleima
Karpyn,
Pennsylvania
State
University, USA
"Pore-scale flow
dynamics in fractured permeable media"
We investigate fracture flow characteristics at the
pore-scale, and evaluate the influence of the
adjacent permeable matrix on the fracture’s apparent
permeability. We use x-ray computed
microtomography to produce three-dimensional images
of a fracture in a permeable medium. These
images are processed and directly translated into
lattices to be used by single-phase lattice
Boltzmann simulations. Three simulations are
presented for the imaged volume, a simulation of the
pore space, the fracture alone and the matrix
alone. We show that the highly permeable
matrix significantly enhances flow in the
fractures. Our results are then used to
evaluate previously proposed methods of estimating
fracture permeability from the fracture pore space
characteristics. The previously proposed
formulations for estimating fracture permeability
for fractures with impermeable walls are found to
produce reasonable estimates of fracture
permeability. However, estimations for the
case of fractures with permeable walls remain
elusive.
Richard
Ketcham,
The
University
of Texas at Austin, USA
“The finite
resolution of CT data and its effects on
quantification and modeling”
Abstract TBA
W.
Brent
Lindquist, Stony Brook University, Stony Brook,
USA
"Dependence of
Up-Scaled Reaction Rate on Flow Rate in Porous
Media"
With D. Kim
Due to inherent heterogeneities in structure,
mineral placement and fluid velocity in rock, bulk
reaction rates realized during reactive flow through
porous media may differ significantly from that
predicted by laboratory measured rate laws. In
particular, rate laws determined in batch reactor
experiments do not capture any of the flow
dependence that will be experienced in the porous
medium. Based on network flow model simulations of
anorthite and kaolinite reactions in two sandstone
pore networks under acidic conditions commensurate
with CO2 sequestration, we compute up-scaled
reaction rates at the core scale and investigate the
dependence of the observed reaction rates on flow
rate. For the anorthite
reaction which, under these acidic conditions is far
from equilibrium and dominated by pH, we find a
power law dependence of reaction rate on flow rate.
For the kaolinite reaction, which is near
equilibrium, a more complex dependence emerges, with
the up-scaled rate tending to rapidly increasing net
precipitation at low flow rates, then reversing and
tending toward net dissolution at high flow rates.
Pål-Eric
Øren,
Numerical
Rocks,
Norway
"Image-based
upscaling of multiphase flow for carbonate rocks"
Abstract TBA
Maša Prodanović,
University of Texas at Austin, USA
"Representative 3D
Modeling of Tight Gas Sandstones: Interplay of
Fractures, Porous Matrix, and Microporosity"
With Peter Eichhubl, Steven Bryant, J. S.
Davis, E. C. Wanat
Diagenetic changes (e.g. cementation, compaction) in
tight gas sandstones (TGSS) often disconnect the
original, inter-granular pore space and further
create microporosity within the original grains
(e.g. by dissolution) or by filling the
inter-granular porosity with clay. A petrophysically
rigorous fundamental model of TGSS that accounts for
microporosity would make the evaluation, development
and stimulation of tight gas sandstone development
more robust. The reduced connectivity of matrix
pores has a profound effect on transport properties
such as absolute and relative permeability,
resistivity and capillary pressure - saturation
relationships. To address this, we construct an
image-based network model that incorporates both
inter-granular (primary) porosity and
microporosity. In addition, we present
preliminary image analysis of a quartz filled
fracture from the same outcrop and discuss it’s
potential influence of flow properties.
Elisabeth
Rosenberg,
Institut
Français
du Pétrole, France
“Numerical and
experimental study of multiphase flow in porous
media at the pore scale”
With S. Youssef, D. Bauer, S. Bekri, O. Vizika
We present a methodology combining high resolution
μ-CT characterisation with Pore Network Modelling in
order to simulate fluid flow and electrical
properties of rocks. The Pore Network Models (PNM)
take into account explicitly pore space
geometry/topology as well as the flow and
displacement mechanisms at the pore scale to
calculate multiphase flow and electrical properties
in porous media. The predictability of such models
depends on the accuracy with which the network
captures the complex geometric and topological
properties of the pore network and on the knowledge
of the physical mechanisms at the pore scale.
In a first part we show how the contribution of high
resolution Computed Micro Tomography (μ-CT) is
essential in defining the pore network geometry and
topology. The pore space is extracted, Flow and
electrical properties of rocks are simulated using
either a single porosity approach (monomodal pore
size distribution) or a dual network approach
(bimodal pore size distribution). combining the
classical approach with the macroscopic properties
of the microporosity, assuming that the two systems
act in parallel. The resolved macropore network is
extracted and analysed directly while the
characteristics of the microporous phase are
partially deduced by means of µ-CT images
(intrinsic porosity, fraction in contact with
macroporosity..). Combining µ-CT images and
PNM provides information on the influence of the
spatial distribution of the microporous and the
solid phase on the properties. Considering
heterogeneous carbonates and taking in account the
spatial distribution of the microporous phase leads
to electrical properties that are in better
accordance with experimental data than those
obtained by an effective medium approximation. We
show that in double porosity systems the electrical
behavior strongly depends on the spatial
distribution and connection of the microporous
areas.
In a second part, we show how high resolution
Computed Micro Tomography (μ-CT) can help in
understanding mechanisms at the pore scale in real
pore spaces. An overburden micro cell has been
specifically developed to follow in-situ multiphase
flows at the pore scale and describe the fluid
distribution, the fluid/fluid and fluid/solid
interfaces as well as their evolution at different
steps of the capillary pressure curve (drainage and
imbibition). As the sample is not removed from the
cell during the experiment, there is no risk of
fluid re-organisation. Multiphasic fluid flows can
be then numerically and experimentally performed on
the same 3D pore structure with different fluid
systems thus enabling the comparison of oil trapping
configurations.
Adrian
P.
Sheppard,
Applied
Mathematics, Research School of Physics and
Engineering, Australian National University
Dynamic tomography
for capturing the dynamics of transport in porous
media.
with Glenn Myers, Andrew Kingston, Trond Varslot
Traditional tomography suffers the constraint that
the sample must remain unchanging while a complete
set of projections are acquired. Any movement
or change in the sample during the data
acquisition results in inconsistent projection data
and degraded images. We have developed a set
of new “dynamic tomography” algorithms for the
high-resolution, time-resolved imaging of
continuous, complex processes, such as two-phase
fluid flow. By exploiting geometric constraints
arising from the underlying physics, we are able to
improve on current frame rates by at least an order
of magnitude. Furthermore, we are able to
image continually evolving systems without
introducing artifacts. To demonstrate this
approach, we have conducted two-phase fluid
displacement experiments in simple porous media such
as sphere packings and clean sandstones.
Preliminary results from these experiments will be
presented and discussed.
Karsten
E.
Thompson,
Louisiana
State University, USA
"Pore-scale
modeling using FEM: challenges and opportunities”
Pore-scale, image-based modeling of flow has been
dominated by two methods: network modeling and the
lattice Boltzmann method. While these two techniques
will remain important tools, we can also expect to
see increased use of traditional CFD methods for
pore-scale modeling. The finite element method (used
with unstructured meshes) is particularly well
suited for geologic porous media because it
naturally accommodates the heterogeneous and/or
multiscale structures characteristic of these
materials. In the past, the main hurdle to using FEM
was the difficulty in meshing the pore space
directly from digital images. However, numerous
commercial and research codes are now available that
perform mesh generation directly from voxel data.
Hence, the key challenge has now become how to
choose a meshing strategy, boundary conditions, and
numerical scheme that together produce reliable
results. This talk will highlight a collection of
results from both synthetic and real data that point
to a surprising sensitivity to image quality, mesh
structure, and element type, along with surprising
flexibility with regard to mesh resolution and
boundary conditions. These results lay the
groundwork for designing a modeling strategy that
can take full advantage of mesh refinement to
improve accuracy and computational
efficiency.
Dorthe Wildenschild,
Oregon State University, USA
“Interfacial
Configurations and Capillary Pressure Measurements
from Microtomographic Images”
with Ryan Armstrong
Recent synchrotron-based tomographic data sets of
air-water and oil-water drainage and imbibitions
scenarios have been analyzed to quantify phase
saturations and interfacial areas, and separate
connected from disconnected fluid phases. This
allows us to follow the drainage and imbibition
processes in great detail, assess equilibrium
states, and understand the effects of fluid phase
disconnection and re-connection on the resulting
capillary pressures, interfacial areas, and
curvatures.
This analysis also allows for estimating capillary
pressure based on the calculated curvatures and
compare to capillary pressures measured externally
with transducers. Preliminary analysis indicates
effects on hysteresis, and strong dependence on
whether a phase is connected or disconnected
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