A 3D model reflecting the dynamic generating process of pore networks for geological porous media

Pore-network is a useful tool in the study of porous media. It makes it possible to exam the structure of a porous media and to carry out simulations in a macroscopic way. For instance, with a pore-network, the calculation of permeability can be done by implementing Darcy’s law, a formula in a proportional form. In this paper, the inscribed sphere algorithm is introduced to extract the pore-network from micro-CT images. Also methods for determining shape factor and conductance are introduced. Several samples with different porosity are used for test. Absolute permeability is calculated based on two different ways of evaluating conductance, and the results are compared and analyzed.

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Modeling Flow in Porous Media With Double Porosity/Permeability: Mathematical Model, Properties, and Analytical Solutions

Journal of Applied Mechanics ◽

10.1115/1.4040116 ◽

2018 ◽

Vol 85 (8) ◽

Cited By ~ 7

Author(s):

Kalyana B. Nakshatrala ◽

Seyedeh Hanie S. Joodat ◽

Roberto Ballarini

Keyword(s):

Mathematical Model ◽

Porous Media ◽

Analytical Solutions ◽

Spatial Scales ◽

Double Porosity ◽

Flow In Porous Media ◽

Parabolic Pdes ◽

Pore Networks ◽

Pressure Profiles ◽

Vuggy Carbonates

Geomaterials such as vuggy carbonates are known to exhibit multiple spatial scales. A common manifestation of spatial scales is the presence of (at least) two different scales of pores with different hydromechanical properties. Moreover, these pore-networks are connected through fissures and conduits. Although some models are available in the literature to describe flows in such media, they lack a strong theoretical basis. This paper aims to fill this gap in knowledge by providing the theoretical foundation for the flow of incompressible single-phase fluids in rigid porous media that exhibit double porosity/permeability. We first obtain a mathematical model by combining the theory of interacting continua and the maximization of rate of dissipation (MRD) hypothesis, and thereby provide a firm thermodynamic underpinning. The governing equations of the model are a system of elliptic partial differential equations (PDEs) under a steady-state response and a system of parabolic PDEs under a transient response. We then present, along with mathematical proofs, several important mathematical properties that the solutions to the model satisfy. We also present several canonical problems with analytical solutions which are used to gain insights into the velocity and pressure profiles, and the mass transfer across the two pore-networks. In particular, we highlight how the solutions under the double porosity/permeability differ from the corresponding ones under Darcy equations.

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Lattice Boltzmann Simulations of Fluid Flow in Continental Carbonate Reservoir Rocks and in Upscaled Rock Models Generated with Multiple-Point Geostatistics

Geofluids ◽

10.1155/2017/7240524 ◽

2017 ◽

Vol 2017 ◽

pp. 1-24 ◽

Cited By ~ 8

Author(s):

J. Soete ◽

S. Claes ◽

H. Claes ◽

N. Janssens ◽

V. Cnudde ◽

...

Keyword(s):

Porous Media ◽

Fluid Flow ◽

Lattice Boltzmann ◽

Flow Characteristics ◽

Software Tool ◽

Ct Scanning ◽

Carbonate Reservoir ◽

Multiple Point ◽

Pore Networks ◽

Continental Carbonates

Microcomputed tomography (μCT) and Lattice Boltzmann Method (LBM) simulations were applied to continental carbonates to quantify fluid flow. Fluid flow characteristics in these complex carbonates with multiscale pore networks are unique and the applied method allows studying their heterogeneity and anisotropy. 3D pore network models were introduced to single-phase flow simulations in Palabos, a software tool for particle-based modelling of classic computational fluid dynamics. In addition, permeability simulations were also performed on rock models generated with multiple-point geostatistics (MPS). This allowed assessing the applicability of MPS in upscaling high-resolution porosity patterns into large rock models that exceed the volume limitations of the μCT. Porosity and tortuosity control fluid flow in these porous media. Micro- and mesopores influence flow properties at larger scales in continental carbonates. Upscaling with MPS is therefore necessary to overcome volume-resolution problems of CT scanning equipment. The presented LBM-MPS workflow is applicable to other lithologies, comprising different pore types, shapes, and pore networks altogether. The lack of straightforward porosity-permeability relationships in complex carbonates highlights the necessity for a 3D approach. 3D fluid flow studies provide the best understanding of flow through porous media, which is of crucial importance in reservoir modelling.

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Oil Fragmentation, Interfacial Surface Transport and Flow Structure Maps for Two-Phase Flow in Model Pore Networks. Predictions Based on Extensive, DeProF Model Simulations

Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles ◽

10.2516/ogst/2017033 ◽

2018 ◽

Vol 73 ◽

pp. 6 ◽

Cited By ~ 4

Author(s):

Marios S. Valavanides

Keyword(s):

Porous Media ◽

Flow Structure ◽

Phase Flow ◽

Interstitial Flow ◽

Flow Conditions ◽

Two Phase ◽

Pore Networks ◽

Volume Fractions ◽

Model Pore ◽

Ganglion Dynamics

In general, macroscopic two-phase flows in porous media form mixtures of connected- and disconnected-oil flows. The latter are classified as oil ganglion dynamics and drop traffic flow, depending on the characteristic size of the constituent fluidic elements of the non-wetting phase, namely, ganglia and droplets. These flow modes have been systematically observed during flow within model pore networks as well as real porous media. Depending on the flow conditions and on the physicochemical, size and network configuration of the system (fluids and porous medium), these flow modes occupy different volume fractions of the pore network. Extensive simulations implementing the DeProF mechanistic model for steady-state, one-dimensional, immiscible two-phase flow in typical 3D model pore networks have been carried out to derive maps describing the dependence of the flow structure on capillary number, Ca, and flow rate ratio, r. The model is based on the concept of decomposition into prototype flows. Implementation of the DeProF algorithm, predicts key bulk and interfacial physical quantities, fully describing the interstitial flow structure: ganglion size and ganglion velocity distributions, fractions of mobilized/stranded oil, specific surface area of oil/water interfaces, velocity and volume fractions of mobilized and stranded interfaces, oil fragmentation, etc. The simulations span 5 orders of magnitude in Ca and r. Systems with various viscosity ratios and intermediate wettability have been examined. Flow of the non-wetting phase in disconnected form is significant and in certain cases of flow conditions the dominant flow mode. Systematic flow structure mutations with changing flow conditions have been identified. Some of them surface-up on the macroscopic scale and can be measured e.g. the reduced pressure gradient. Other remain in latency within the interstitial flow structure e.g. the volume fractions of − or fractional flows of oil through − connected-disconnected flows. Deeper within the disconnected-oil flow, the mutations between ganglion dynamics and drop traffic flow prevail. Mutations shift and/or become pronounced with viscosity disparity. They are more evident over variables describing the interstitial transport properties of process than variables describing volume fractions. Τhis characteristic behavior is attributed to the interstitial balance between capillarity and bulk viscosity.

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Aggregate formation dynamics driven by 3D fluid flow in natural porous media

10.5194/egusphere-egu2020-13488 ◽

2020 ◽

Author(s):

Thomas Ritschel ◽

Kai Totsche

Keyword(s):

Porous Media ◽

Fluid Flow ◽

Reactive Transport ◽

Colloidal Particles ◽

Pore Space ◽

Three Dimensional ◽

Space Distribution ◽

Aggregate Formation ◽

Undisturbed Soil ◽

Pore Networks

<p>Fluid flow and reactive transport in natural porous media take place in a three-dimensional, hierarchically organized network of voids and pores in the size range of sub-micrometers inside small aggregates to several millimeters in, e.g., earthworm burrows or cracks. Thus, fluid flow regimes are manifold with consequences not only for the transport of solutes, but also for the displacement of colloidal particles and organic matter and thus, for their inclusion into soil aggregates. Therefore, we incorporated the simulation of three-dimensional fluid flow in pore networks typical for natural porous media into our recent approach to model soil aggregate formation using DLVO theory and diffusion-limited aggregation to overcome its previous limitation to suspensions at rest. To visualize the model capabilities, we simulated aggregation in pore networks that were either synthetically designed to represent certain structural features such as pore junctions and dead-end pores, or taken directly from X-ray &#181;-CT measurements of undisturbed soil cores. We explored the development of structural aggregated features that evolve in response to flow, transport and the topology of the soil pore space. The resulting three-dimensional arrangement of compounds and the entire aggregates were classified according to their morphological metrics, e.g. the pore space distribution, and functional properties, e.g. the water retention capacity, that are provided by these structures. By this fusion of complementary modeling approaches, we significantly contribute to the fundamental mechanistic understanding of the complex interplay and feedback of structure, interactions and functions on the scale of (micro-)aggregates.</p>

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