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Title: Two-Phase Flow Within Porous Media Analogies: Application Towards CO2 Sequestration

Abstract

Geologic carbon dioxide sequestration (GCO2S) involves the capture of large quantities of CO2 from point-source emitters and pumping this greenhouse gas to subsurface reservoirs (USDOE, 2006). The mechanisms of two-phase fluid displacement in GCO2S, where a less viscous fluid displaces a more viscous fluid in a heterogeneous porous domain is similar to enhanced oil recovery activities. Direct observation of gas-liquid interface movement in geologic reservoirs is difficult due to location and opacity. Over the past decades, complex, interconnected pore-throat models have been developed and used to study multiphase flow interactions in porous media, both experimentally (Buckley, 1994) and numerically (Blunt, 2001). This work expands upon previous experimental research with the use of a new type of heterogeneous flowcell, created with stereolithography (SL). Numerical solutions using the Volume-of-Fluid (VOF) model with the same flowcell geometry, are shown to be in good agreement with the drainage experiments, where the defending fluid wets the surface. This computational model is then used to model imbibition, the case of the invading fluid preferentially wetting the surface. Low capillary flows and imbibition conditions are shown to increase the storage volume of the invading fluid in the porous medium.

Authors:
;  [1];
  1. (Clarkson University, Potsdam, NY)
Publication Date:
Research Org.:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, and Morgantown, WV; Clarkson University, Potsdam, NY
Sponsoring Org.:
USDOE - Office of Fossil Energy (FE)
OSTI Identifier:
913368
Report Number(s):
DOE/NETL-IR-2007-123
TRN: US200802%%794
DOE Contract Number:
None cited
Resource Type:
Conference
Resource Relation:
Conference: 1000 Islands Fluid Mechanics Meeting, Gananoque, Ontario, Canada, April 20-22, 2007
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; CAPILLARY FLOW; CARBON DIOXIDE; DRAINAGE; FLUID MECHANICS; GEOMETRY; GREENHOUSE GASES; MULTIPHASE FLOW; NUMERICAL SOLUTION; OPACITY; PUMPING; STORAGE; TWO-PHASE FLOW

Citation Formats

Crandall, D.M. Clarkson University, Potsdam, NY), Ahmadi, G., and Smith, D.H. Two-Phase Flow Within Porous Media Analogies: Application Towards CO2 Sequestration. United States: N. p., 2007. Web.
Crandall, D.M. Clarkson University, Potsdam, NY), Ahmadi, G., & Smith, D.H. Two-Phase Flow Within Porous Media Analogies: Application Towards CO2 Sequestration. United States.
Crandall, D.M. Clarkson University, Potsdam, NY), Ahmadi, G., and Smith, D.H. Fri . "Two-Phase Flow Within Porous Media Analogies: Application Towards CO2 Sequestration". United States. doi:.
@article{osti_913368,
title = {Two-Phase Flow Within Porous Media Analogies: Application Towards CO2 Sequestration},
author = {Crandall, D.M. Clarkson University, Potsdam, NY) and Ahmadi, G. and Smith, D.H.},
abstractNote = {Geologic carbon dioxide sequestration (GCO2S) involves the capture of large quantities of CO2 from point-source emitters and pumping this greenhouse gas to subsurface reservoirs (USDOE, 2006). The mechanisms of two-phase fluid displacement in GCO2S, where a less viscous fluid displaces a more viscous fluid in a heterogeneous porous domain is similar to enhanced oil recovery activities. Direct observation of gas-liquid interface movement in geologic reservoirs is difficult due to location and opacity. Over the past decades, complex, interconnected pore-throat models have been developed and used to study multiphase flow interactions in porous media, both experimentally (Buckley, 1994) and numerically (Blunt, 2001). This work expands upon previous experimental research with the use of a new type of heterogeneous flowcell, created with stereolithography (SL). Numerical solutions using the Volume-of-Fluid (VOF) model with the same flowcell geometry, are shown to be in good agreement with the drainage experiments, where the defending fluid wets the surface. This computational model is then used to model imbibition, the case of the invading fluid preferentially wetting the surface. Low capillary flows and imbibition conditions are shown to increase the storage volume of the invading fluid in the porous medium.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Apr 20 00:00:00 EDT 2007},
month = {Fri Apr 20 00:00:00 EDT 2007}
}

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  • The amount of CO2 that can be sequestered in deep brine reservoirs is dependant on fluid-fluid-solid interactions within heterogeneous porous media. Displacement of an in-place fluid by a less viscous invading fluid does not displace 100% of the defending fluid, due to capillary and viscous fingering. This has been studied experimentally and numerically with the use of pore-throat flow cells and pore-level models, respectively, in the last two decades. This current work solves the full Navier-Stokes and continuity equations in a random pore-throat geometry using the Volume of Fluid (VOF) method. To verify that the VOF model can be accuratelymore » applied within narrow apertures, qualitative agreement with the well-documented phenomenon of viscous fingering in a Hele-Shaw cell is first presented. While this motion is similar to the fingering observed in geological media, the random structure of rock restricts flow patterns not captured by flow in Hele-Shaw cells. To mimic this heterogeneous natural geometry, a novel experimental flowcell was created. Experiments of constant-rate injection of air into the water saturated model are described. This situation, where a non-wetting, invading fluid displaces a surface-wetting, more-viscous fluid, is known as drainage. As the injection flow rate was increased, a change from stable displacement fronts to dendritic fingering structures was observed, with a corresponding decrease in the fractal dimension of the interface and a decrease in the final saturation of invading air. Predictions of the VOF computational modeling within the same flowcell geometry are then shown to be in good agreement with the experimental results. Percent saturation and the fractal dimension of the invading fluid were calculated from the numerical model and shown to be similar to the experimental findings for air invasion of a watersaturated domain. The fluid properties (viscosity and density) were than varied and the viscosity ratio and capillary number of the fluids were shown to affect the percent of displaced fluid, with lower capillary number and higher viscosity ratio displacing a greater amount of the wetting fluid. Displacement of a non-wetting, in-place fluid by a less viscous, wetting fluid (the case of imbibition; contact angle > 90°) is then studied with the numerical model. The invading fluid is shown to preferentially move into small throats and displace a larger percent of the in-place fluid than observed in the drainage case. The interface was also observed to have a higher fractal dimension, closer to 2. These results highlight the potential for greater fundamental understanding of liquid-gas-solid interactions in heterogeneous, porous media that can be obtained from computational fluid dynamics (CFD). Situations, which are difficult to experimentally study, can be examined with CFD in a manner that more accurately accounts for the geological conditions relevant to CO2 sequestration. This allows for greater accuracy in the prediction of storage capacity within known geological structures. This study shows that as the contact angle between the invading fluid and the defending fluid increase, a greater portion of the porous medium is invaded. Thus, a greater portion of CO2 can be sequestered in reservoirs that are not strongly water wet. Low flow rates are shown to increase the final percent saturation of the invading fluid as well, regardless of wetting conditions.« less
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  • Abstract not provided.
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