Fracture Model

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1

Hi All,

I am working on CO2 injection problems under the National Risk Assessment Partnership (NRAP) project. There is a fracture in one of my geometry. To understand the fracture model in the OGS, I used following references. According to Reference [3], (Equations 3 to 5, Page 1013-1014) the local displacement of the fracture is related to the global relative displacement. On the other hand, fracture width is a function of the global relative displacement, and also related to the fracture mechanical stresses via tangential and normal stiffness. Then in equation 5, the change of fracture aperture with respect to time (db/dt) is demonstrated, along with the coupled permeability function is discussed.

Question: Does the fracture width change during the simulation due to the mechanical stress? I am concerned with the assumption on page 1015, and it says “assume no fracture growth”.

References:

1.Watanabe, N. (2011). Finite element method for coupled thermos-hydro-mechanical processes in discretely fractured and non-fractured porous media PhD. Thesis, Technische Universitat Dresden.

2.Watanabe, N., G. Blocher, M. Cacace, S. Held and T. Kohl, Eds. (2017). Geoenergy Modeling III Enhanced Geothermal Systems. Springer Briefs in Energy Computational Modeling of Energy Systems, Springer.

3.Watanabe, N., W. Wang, J. Taron, U. J. Görke and O. Kolditz (2012). “Lower-dimensional interface elements with local enrichment: application to coupled hydro-mechanical problems in discretely fractured porous media.” International Journal for Numerical Methods in Engineering 90(8): 1010-1034.

Thanks in advance.

Regards,

Mohammad

2

Hi,

Question: Does the fracture width change during the simulation due to the mechanical stress? I am concerned with the assumption on page 1015, and it says “assume no fracture growth”

Yes it computes fracture opening/closing due to the mechanical stress. Fracture propagation is not considered there. Please note that preliminary implementation of this feature is available only in OGS6.

Regards,

Nori

···

Hi All,

I am working on CO2 injection problems under the National Risk Assessment Partnership (NRAP) project. There is a fracture in one of my geometry. To understand the fracture model in the OGS, I used following references. According to Reference [3], (Equations 3 to 5, Page 1013-1014) the local displacement of the fracture is related to the global relative displacement. On the other hand, fracture width is a function of the global relative displacement, and also related to the fracture mechanical stresses via tangential and normal stiffness. Then in equation 5, the change of fracture aperture with respect to time (db/dt) is demonstrated, along with the coupled permeability function is discussed.

Question: Does the fracture width change during the simulation due to the mechanical stress? I am concerned with the assumption on page 1015, and it says “assume no fracture growth”.

References:

1.Watanabe, N. (2011). Finite element method for coupled thermos-hydro-mechanical processes in discretely fractured and non-fractured porous media PhD. Thesis, Technische Universitat Dresden.

2.Watanabe, N., G. Blocher, M. Cacace, S. Held and T. Kohl, Eds. (2017). Geoenergy Modeling III Enhanced Geothermal Systems. Springer Briefs in Energy Computational Modeling of Energy Systems, Springer.

3.Watanabe, N., W. Wang, J. Taron, U. J. Görke and O. Kolditz (2012). “Lower-dimensional interface elements with local enrichment: application to coupled hydro-mechanical problems in discretely fractured porous media.” International Journal for Numerical Methods in Engineering 90(8): 1010-1034.

Thanks in advance.

Regards,

Mohammad

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3

Dear Nori,
Thank you for your kind reply. I will prepare *.prj file for OGS6.

Regards,

Mohammad

···

On Tuesday, 3 April 2018 16:47:10 UTC-4, 渡邉教弘 wrote:

Hi,

Question: Does the fracture width change during the simulation due to the mechanical stress? I am concerned with the assumption on page 1015, and it says “assume no fracture growth”

Yes it computes fracture opening/closing due to the mechanical stress. Fracture propagation is not considered there. Please note that preliminary implementation of this feature is available only in OGS6.

Regards,

Nori

–

Norihiro Watanabe, Dr.-Ing.

Researcher

Geothermal Energy Team,

Renewable Energy Research Center

Fukushima Renewable Energy Institute (FREA),

National Institute of Advanced Industrial Science and Technology (AIST)

2-2-9 Machiikedai, Koriyama, Fukushima 963-0298, Japan

TEL: +81 29 861 4463

FAX: +81 24 963 0828

EMAIL: norihiro…@aist.go.jp

URL: http://www.aist.go.jp/fukushima/

From: [email protected] [email protected] On Behalf Of Mohammad Islam

Sent: Wednesday, April 4, 2018 4:28 AM

To: ogs-users [email protected]

Subject: [ogs-users] Fracture Model

Hi All,

I am working on CO2 injection problems under the National Risk Assessment Partnership (NRAP) project. There is a fracture in one of my geometry. To understand the fracture model in the OGS, I used following references. According to Reference [3], (Equations 3 to 5, Page 1013-1014) the local displacement of the fracture is related to the global relative displacement. On the other hand, fracture width is a function of the global relative displacement, and also related to the fracture mechanical stresses via tangential and normal stiffness. Then in equation 5, the change of fracture aperture with respect to time (db/dt) is demonstrated, along with the coupled permeability function is discussed.

Question: Does the fracture width change during the simulation due to the mechanical stress? I am concerned with the assumption on page 1015, and it says “assume no fracture growth”.

References:

1.Watanabe, N. (2011). Finite element method for coupled thermos-hydro-mechanical processes in discretely fractured and non-fractured porous media PhD. Thesis, Technische Universitat Dresden.

2.Watanabe, N., G. Blocher, M. Cacace, S. Held and T. Kohl, Eds. (2017). Geoenergy Modeling III Enhanced Geothermal Systems. Springer Briefs in Energy Computational Modeling of Energy Systems, Springer.

3.Watanabe, N., W. Wang, J. Taron, U. J. Görke and O. Kolditz (2012). “Lower-dimensional interface elements with local enrichment: application to coupled hydro-mechanical problems in discretely fractured porous media.” International Journal for Numerical Methods in Engineering 90(8): 1010-1034.

Thanks in advance.

Regards,

Mohammad

–

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4

Dear Nori,
I read following references:

https://benchmarks.opengeosys.org/docs/benchmarks/hydro-mechanics/LIE_HM.pdf

···

According to git, LIE_HM.pdf and Reference 1, the fracture opening is working for the porous medium with solid and liquid. Now if the medium has two fluids like supercritical CO2 (injected fluid) and brine (porous medium fluid) or another way how to deal fracture opening model for two-phase flow? In OGS5, to couple two processes like H2M is straightforward. In the *.pcs file, two separate processes need to be added along with relevant changes in other files. But, for OGS6 (OGS: ProcessLib Directory Reference), it looks like for each coupling case (H2 or HM or HT) there is an individual process name (Please correct me if I am wrong).

Thanks in advance.

Regards,

Mohammad

[1] Watanabe, N., W. Wang, J. Taron, U. J. Görke and O. Kolditz (2012). “Lower-dimensional interface elements with local enrichment: application to coupled hydro-mechanical problems in discretely fractured porous media.” International Journal for Numerical Methods in Engineering 90(8): 1010-1034.

5

Dear Mohammad,

At the moment, the fracture stuff in ogs6 works only with a solid-liquid system. and I don’t know if someone has a plan to extend it to two phase flow. maybe you can try it by yourself if you are interested. Theoretically it should be straightforward.

for each coupling case (H2 or HM or HT) there is an individual process name

yes, you are right. I’m not sure whether they are going to be integrated or not.

Regards,

Nori

···

Dear Nori,

I read following references:

https://benchmarks.opengeosys.org/docs/benchmarks/hydro-mechanics/LIE_HM.pdf

https://github.com/ufz/ogs-data/tree/master/LIE/HydroMechanics

https://github.com/ufz/ogs-data/tree/master/Parabolic/TwoPhaseFlowPP

According to git, LIE_HM.pdf and Reference 1, the fracture opening is working for the porous medium with solid and liquid. Now if the medium has two fluids like supercritical CO2 (injected fluid) and brine (porous medium fluid) or another way how to deal fracture opening model for two-phase flow? In OGS5, to couple two processes like H2M is straightforward. In the *.pcs file, two separate processes need to be added along with relevant changes in other files. But, for OGS6 (https://doxygen.opengeosys.org/dir_7ff8304b9c696288aea9f2d937f3e992.html ), it looks like for each coupling case (H2 or HM or HT) there is an individual process name (Please correct me if I am wrong).

Thanks in advance.

Regards,

Mohammad

[1] Watanabe, N., W. Wang, J. Taron, U. J. Görke and O. Kolditz (2012). “Lower-dimensional interface elements with local enrichment: application to coupled hydro-mechanical problems in discretely fractured porous media.” International Journal for Numerical Methods in Engineering 90(8): 1010-1034.

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6

Dear Nori,
I will check the two-phase flow, and let you know the update.

I was trying to understand one of your project file named TaskB.prj and the relevant book chapter (Differences: in *.prj fault is elastic and in the book chapter it is elasto-plastic, Mohr-Coulomb type). Would you be kind to explain a couple of issues as follows:

  1. TaskB.prj: Line numbers: 190 & 194 ; 220-223. After reading the following link, it seems in OGS6 parameters can be defined by five possible ways. But, I am not understanding the explanation of “CurveScaled”. After reading the book chapter, I understood that the last values (22.9999) of is the time in sec (Book Chapter: Figure 8.3 & Figure 8.6). What do others mean (0 22.9999 0.7446)? like, 0 and 0.7446

https://doxygen.opengeosys.org/d6/d06/Parameter_8cpp.html

  1. in OGS5, there is an option for GRADIENT, by which we can assign “geostatic” or “hydro-static” condition. Is there any similar option for OGS6?

Thanks in advance.

Regards,

Mohammad

190 p_in_transient 191 CurveScaled 192 timeRamp_p_in 193 p_in 194 220 timeRamp_p_in 221 0 22.9999 23 99.9999 100 156.9999 157 212.9999 213 266.99999 267 316.9999 317 419.9999 420 452.9999 453 807 222 0.7446 0.7446 1.919 1.919 3.627 3.627 4.094 4.094 4.511 4.511 4.99 4.99 5.484 5.484 6.302 6.302 3.382 3.382 223

TaskB.prj.pdf (91.5 KB)

TaskB-Chapter 8.pdf (812 KB)

7

Hi,

1) TaskB.prj: Line numbers: 190 & 194 ; 220-223. After reading the following link, it seems in OGS6 parameters can be defined by five possible ways. But, I am not understanding the explanation of "CurveScaled". After reading the book chapter, I understood that the last values (22.9999) of <coords> is the time in sec (Book Chapter: Figure 8.3 & Figure 8.6). What do others mean (<coords>0 22.9999</coords> <values>0.7446<values>)? like, 0 and 0.7446

https://doxygen.opengeosys.org/d6/d06/Parameter_8cpp.html

<coords> corresponds to the time in sec. <values> defines a value at the specified time in <coords>. e.g. "timeRamp_p_in" curve will return 0.7446 at t=0, t=22.999, and 1.919 at t=23. Note that a linear interpolation is applied between the defined values.

2) in OGS5, there is an option for GRADIENT, by which we can assign "geostatic" or "hydro-static" condition. Is there any similar option for OGS6?

sorry I don't know if the feature is also supported in OGS6.
(I'm not familiar with the latest development of ogs6)

Regards,
Nori

···

--
渡邉教弘 / Norihiro Watanabe
[email protected]

________________________________________
差出人: [email protected] <[email protected]> が Mohammad Islam <[email protected]> の代理で送信
送信日時: 2018年4月7日 3:56
宛先: ogs-users
件名: Re: [ogs-users] Fracture Model

Dear Nori,
I will check the two-phase flow, and let you know the update.

I was trying to understand one of your project file named TaskB.prj and the relevant book chapter (Differences: in *.prj fault is elastic and in the book chapter it is elasto-plastic, Mohr-Coulomb type). Would you be kind to explain a couple of issues as follows:

1) TaskB.prj: Line numbers: 190 & 194 ; 220-223. After reading the following link, it seems in OGS6 parameters can be defined by five possible ways. But, I am not understanding the explanation of "CurveScaled". After reading the book chapter, I understood that the last values (22.9999) of <coords> is the time in sec (Book Chapter: Figure 8.3 & Figure 8.6). What do others mean (<coords>0 22.9999</coords> <values>0.7446<values>)? like, 0 and 0.7446
https://doxygen.opengeosys.org/d6/d06/Parameter_8cpp.html

2) in OGS5, there is an option for GRADIENT, by which we can assign "geostatic" or "hydro-static" condition. Is there any similar option for OGS6?

Thanks in advance.

Regards,
Mohammad

<parameter>
190 <name>p_in_transient</name>
191 <type>CurveScaled</type>
192 <curve>timeRamp_p_in</curve>
193 <parameter>p_in</parameter>
194 </parameter>

<curve>
220 <name>timeRamp_p_in</name>
221 <coords>0 22.9999 23 99.9999 100 156.9999 157 212.9999 213 266.99999 267 316.9999 317 419.9999 420 452.9999 453 807</coords>
222 <values>0.7446 0.7446 1.919 1.919 3.627 3.627 4.094 4.094 4.511 4.511 4.99 4.99 5.484 5.484 6.302 6.302 3.382 3.382</values>
223 </curve>

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8

Dear Nori,
Thank you for your kind help.

Regards,

Mohammad

···