2,845 research outputs found
Nano- to Millimeter Scale Morphology of Connected and Isolated Porosity in the Permo-Triassic Khuff Formation of Oman
Carbonate reservoirs form important exploration targets for the oil and gas industry in
many parts of the world. This study aims to differentiate and quantify pore types and their relation to
petrophysical properties in the Permo-Triassic Khuff Formation, a major carbonate reservoir in Oman.
For that purpose, we have employed a number of laboratory techniques to test their applicability for
the characterization of respective rock types. Consequently, a workflow has been established utilizing
a combined analysis of petrographic and petrophysical methods which provide the best results for
pore-system characterization. Micro-computed tomography (μCT) analysis allows a representative
3D assessment of total porosity, pore connectivity, and effective porosity of the ooid-shoal facies but it
cannot resolve the full pore-size spectrum of the highly microporous mud-/wackestone facies. In order
to resolve the smallest pores, combined mercury injection capillary pressure (MICP), nuclear magnetic
resonance (NMR), and BIB (broad ion beam)-SEM analyses allow covering a large pore size range
from millimeter to nanometer scale. Combining these techniques, three different rock types with
clearly discernible pore networks can be defined. Moldic porosity in combination with intercrystalline
porosity results in the highest effective porosities and permeabilities in shoal facies. In back-shoal
facies, dolomitization leads to low total porosity but well-connected and heterogeneously distributed
vuggy and intercrystalline pores which improves permeability. Micro- and nanopores are present
in all analyzed samples but their contribution to effective porosity depends on the textural context.
Our results confirm that each individual rock type requires the application of appropriate laboratory
techniques. Additionally, we observe a strong correlation between the inverse formation resistivity
factor and permeability suggesting that pore connectivity is the dominating factor for permeability
but not pore size. In the future, this relationship should be further investigated as it could potentially
be used to predict permeability from wireline resistivity measured in the flushed zone close to the
borehole wall
A GPU-accelerated package for simulation of flow in nanoporous source rocks with many-body dissipative particle dynamics
Mesoscopic simulations of hydrocarbon flow in source shales are challenging,
in part due to the heterogeneous shale pores with sizes ranging from a few
nanometers to a few micrometers. Additionally, the sub-continuum fluid-fluid
and fluid-solid interactions in nano- to micro-scale shale pores, which are
physically and chemically sophisticated, must be captured. To address those
challenges, we present a GPU-accelerated package for simulation of flow in
nano- to micro-pore networks with a many-body dissipative particle dynamics
(mDPD) mesoscale model. Based on a fully distributed parallel paradigm, the
code offloads all intensive workloads on GPUs. Other advancements, such as
smart particle packing and no-slip boundary condition in complex pore
geometries, are also implemented for the construction and the simulation of the
realistic shale pores from 3D nanometer-resolution stack images. Our code is
validated for accuracy and compared against the CPU counterpart for speedup. In
our benchmark tests, the code delivers nearly perfect strong scaling and weak
scaling (with up to 512 million particles) on up to 512 K20X GPUs on Oak Ridge
National Laboratory's (ORNL) Titan supercomputer. Moreover, a single-GPU
benchmark on ORNL's SummitDev and IBM's AC922 suggests that the host-to-device
NVLink can boost performance over PCIe by a remarkable 40\%. Lastly, we
demonstrate, through a flow simulation in realistic shale pores, that the CPU
counterpart requires 840 Power9 cores to rival the performance delivered by our
package with four V100 GPUs on ORNL's Summit architecture. This simulation
package enables quick-turnaround and high-throughput mesoscopic numerical
simulations for investigating complex flow phenomena in nano- to micro-porous
rocks with realistic pore geometries
Microstructure Characterization Techniques for Shale Reservoirs : A Review
Funding This work was funded by the National Natural Science Foundation of China (Grant nos. U19B6003-03-01 and 42030804).Peer reviewedPublisher PD
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