OR/18/049 Conclusions

From Earthwise
Jump to: navigation, search
Tamayo-Mas, E, Harrington, J F, Brรผning, T, Kolditz, O, Shao, H, Dagher, E E, Lee, J, Kim, K, Rutqvist, J, Lai, S H, Chittenden, N, Wang, Y, Damians, I P, Olivella, S. 2018. DECOVALEX-2019 project: Task A - modElliNg Gas INjection ExpERiments (ENGINEER). Nottingham, UK, British geological Survey. (OR/18/049).

The different modelling teams have shown that a wide range of models may be applied to numerically describe gas migration in plastic clays, see Table 10. At this stage of the modelling exercise, models have been validated against a single experiment and thus, future work is still needed to further develop them. So far, existing fits show that after a calibration process (often a very large set of input parameters need to be adjusted), plausible descriptions of the laboratory experiment can be achieved. In a number of cases, these realizations required adjustment of porosity and intrinsic permeability values beyond specified parameters for the material, suggesting the physical description of the system remains incomplete.

Two-phase flow models (with different deformation behaviours and/or preferential pathways) have been implemented to model gas flow. These approaches are able to match some key aspects such as stress evolution or pore pressure but they are not capable of describing the full complexity of gas migration processes in such low-permeability materials. Thus, although they are highly extended and employed, the modelling to date suggests that two-phase flow models are not capable of reproducing the full range of behaviour exhibited experimentally, so their practicality will depend upon the intended usage. Discrete approaches to describe dilatancy-controlled gas flow have shown physically plausible representations can be obtained noting that extra effort is required to calibrate such a large set (even larger) of input parameters. New conceptual models may be hence developed to explain the complexity of the physical processes. Their development is still in a very preliminary phase and at the current stage of the work, they are not able to reproduce physically-observed features. Thus, from a pragmatic perspective, enhanced two-phase flow models (either by different deformation behaviours, explicitly incorporating different pathways and/or evolving fractures) remain the only viable tool to represent these systems at this time. However, the complexity of the physical processes combined with detailed calibration processes, currently limit their use in the quantitative prediction of gas flow.

Table 10    Summary of the proposed strategies.

Model

Approach

Software

Basic parameters

Results

Flow

Stress

Pore pressure


E


๐‚๐‚


๐“๐“


k


P


S

P

S

T

P

S

T

1

2

3

I

B

1

2

3

I

B

1

2

3

I

B

1

2

3

1

2

3

1

2

3

BGR/UFZ

2D 2-phase flow

OpenGeoSys

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

-

~

โˆš

โˆš

โˆš

-

โˆš

โˆš

โˆš

-

โˆš

โˆš

~

~

โˆš

โˆš

โˆš

โˆš

CNSC-E

3D 2-phase flow

COMSOLยฎ

โˆš

โˆš

โˆš

โˆš

โˆš

~

~

โˆš

โˆš

โˆš

โˆš

โˆš

CNSC-D

3D 2-phase flow

COMSOLยฎ

โˆš

โˆš

โˆš

โˆš

โˆš

~

โˆš

โˆš

โˆš

~

~

~

~

โˆš

โˆš

โˆš

~

~

~

KAERI

3D 2-phase flow

TOUGH-MP
FLAC3D

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

~

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

LBNL-C

3D 2-phase flow

TOUGH-FLAC

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

~

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

LBNL-D

2D discrete

TOUGH-RBSN

โˆš

โˆš

โˆš

โˆš

โˆš

~

~

โˆš

โˆš

~

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

NCU/TPC

2D 2-phase flow

THMC 7.1

โˆš

โˆš

-

-

Quintessa/
RWM

1D 2-phase flow + pathways

QPAC

โˆš

โˆš

-

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

~

~

Sandia

discrete

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

UPC/
Andra-H

3D 2-phase flow

CODE_BRIGHT

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

โˆš

โˆš

โˆš

UPC/
Andra-HM1

3D 2-phase flow + pathways

CODE_BRIGHT

~

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

~

โˆš

~

~

~

~

โˆš

โˆš

โˆš

~

~

~

UPC/
Andra-HM2

3D 2-phase flow + pathways

CODE_BRIGHT

โˆš

โˆš

~

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš

โˆš