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Title: Colloid Mobilization and Porous Media Permeability Changes by Dynamic Stress Stimulations

Abstract

Laboratory experiments on porous rock cores have shown that seismic-band (100 Hz or less) mechanical stress/strain cycling of the rock matrix can mobilize sub-pore-size particles (colloids) trapped in the pore space and allow them to be expelled during steady-state water flow. This coupling of dynamic stress to colloid mobility is a potential key mechanism whereby seismic waves may alter formation permeability and porous mass transport in Earth's crust. Experiments where colloid suspensions were injected into Fontainebleau sandstone cores demonstrated that colloid size and the ionic strength of the suspending fluid are major parameters that will control the ability of the colloids to attach to pore walls or to form particle bridges at pore throats. Both effects can lead to significant changes in permeability. A unique core-holder apparatus that applies low-frequency mechanical stress/strain to 2.54-cm-diameter porous rock samples during constant-rate fluid flow was used for those experiments. Microsphere injection caused the core's permeability to decline due to colloid bridging at pore throats. It was found that dynamic stress at 25 to 50 Hz mobilized these trapped colloids mainly when the ionic strength is low, and thereby partially restored the permeability of the sample. These earlier experiments on natural rocks were difficultmore » to interpret in terms of how the colloids distributed themselves throughout the heterogeneous pore space and what interactions were occurring between the colloids and the solid matrix. Observed permeability changes appeared to be confined to the first 5-10 cm of the rock where the colloids were injected, yet significant transport of colloids was observed along the entire length of the sample. The 'natural rock' system is too complex geometrically at the pore scale to allow quantification of mass transport properties along its entire length. To remedy this problem, new colloid transport experiments were performed with a synthetic glass-bead pack. Unconsolidated 1-mm-diameter borosilicate beads were packed into a confining sleeve to a length of 30 cm. Sufficient radial and axial confinement pressures were applied to the sleeve to create a fluid seal and to introduce rigidity to the sample. Suspensions of 2-um polystyrene micro spheres in deionized water were injected into the bead pack while maintaining constant flow through the sample. Sample permeability and effluent microsphere production were measured before, during, and after low-frequency stress cycling, as in the previous experiments on rocks. Results of these dynamic stress mobilization experiments will be presented.« less

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. Los Alamos National Laboratory
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1044141
Report Number(s):
LA-UR-10-08225; LA-UR-10-8225
TRN: US201214%%335
DOE Contract Number:  
AC52-06NA25396
Resource Type:
Conference
Resource Relation:
Conference: U.S. Department of Energy Dynamically Determined and Controlled Permeability Conference ; December 11, 2010 ; San Francisco, CA
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; BOROSILICATE GLASS; COLLOIDS; CONFINEMENT; FLUID FLOW; MICROSPHERES; PERMEABILITY; POLYSTYRENE; PRODUCTION; SANDSTONES; SEISMIC WAVES; SLEEVES; TRANSPORT; WATER

Citation Formats

Abdel-Fattah, Amr I., Roberts, Peter M, Tarimala, Sowmitri, Ibrahim, Reem, and Beckham, Richard. Colloid Mobilization and Porous Media Permeability Changes by Dynamic Stress Stimulations. United States: N. p., 2010. Web.
Abdel-Fattah, Amr I., Roberts, Peter M, Tarimala, Sowmitri, Ibrahim, Reem, & Beckham, Richard. Colloid Mobilization and Porous Media Permeability Changes by Dynamic Stress Stimulations. United States.
Abdel-Fattah, Amr I., Roberts, Peter M, Tarimala, Sowmitri, Ibrahim, Reem, and Beckham, Richard. Fri . "Colloid Mobilization and Porous Media Permeability Changes by Dynamic Stress Stimulations". United States. https://www.osti.gov/servlets/purl/1044141.
@article{osti_1044141,
title = {Colloid Mobilization and Porous Media Permeability Changes by Dynamic Stress Stimulations},
author = {Abdel-Fattah, Amr I. and Roberts, Peter M and Tarimala, Sowmitri and Ibrahim, Reem and Beckham, Richard},
abstractNote = {Laboratory experiments on porous rock cores have shown that seismic-band (100 Hz or less) mechanical stress/strain cycling of the rock matrix can mobilize sub-pore-size particles (colloids) trapped in the pore space and allow them to be expelled during steady-state water flow. This coupling of dynamic stress to colloid mobility is a potential key mechanism whereby seismic waves may alter formation permeability and porous mass transport in Earth's crust. Experiments where colloid suspensions were injected into Fontainebleau sandstone cores demonstrated that colloid size and the ionic strength of the suspending fluid are major parameters that will control the ability of the colloids to attach to pore walls or to form particle bridges at pore throats. Both effects can lead to significant changes in permeability. A unique core-holder apparatus that applies low-frequency mechanical stress/strain to 2.54-cm-diameter porous rock samples during constant-rate fluid flow was used for those experiments. Microsphere injection caused the core's permeability to decline due to colloid bridging at pore throats. It was found that dynamic stress at 25 to 50 Hz mobilized these trapped colloids mainly when the ionic strength is low, and thereby partially restored the permeability of the sample. These earlier experiments on natural rocks were difficult to interpret in terms of how the colloids distributed themselves throughout the heterogeneous pore space and what interactions were occurring between the colloids and the solid matrix. Observed permeability changes appeared to be confined to the first 5-10 cm of the rock where the colloids were injected, yet significant transport of colloids was observed along the entire length of the sample. The 'natural rock' system is too complex geometrically at the pore scale to allow quantification of mass transport properties along its entire length. To remedy this problem, new colloid transport experiments were performed with a synthetic glass-bead pack. Unconsolidated 1-mm-diameter borosilicate beads were packed into a confining sleeve to a length of 30 cm. Sufficient radial and axial confinement pressures were applied to the sleeve to create a fluid seal and to introduce rigidity to the sample. Suspensions of 2-um polystyrene micro spheres in deionized water were injected into the bead pack while maintaining constant flow through the sample. Sample permeability and effluent microsphere production were measured before, during, and after low-frequency stress cycling, as in the previous experiments on rocks. Results of these dynamic stress mobilization experiments will be presented.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2010},
month = {12}
}

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