Grid Project:   Experiment for CO2 Leak Detection
Grid Team Member: Terry Miller
Grid Versions: V01 and V02
Data Source: GMSH / Thomas
Delivered To: Thomas Kremer
Date Completed: Nov 6 2013

Purpose of Project

Create cylinder mesh for FEHM modeling experiments of detecting CO2 leakage in shallow subsurface. Studies made by Visitor Thomas Kremer. See Abstract.

Title: Spectral Induced Polarization method applied to the detection and monitoring of CO2 transfers in the shallow sub-surface

Abstract: During the last decade, the interest of induced polarization methods for environmental studies has undoubtedly grown. Here, we present a set of laboratory experiments aimed at assessing the ability of spectral induced polarisation (SIP) method to detect and monitor CO2 transfers in the subsurface. The objectives were the quantification of the influence of various parameters on the SIP response, such as the water conductivity, the chemical reactivity of the solid and of the gas phases, and the injection rate. SIP measurements in the frequency range 50 mHz – 20 kHz were thus performed during gas (N2 or CO2) injections in a metric-scaled, cylindrical tank filled with unconsolidated granular material (quartz or carbonate sands) and fully saturated with water.

The system was most reactive to gas injection in the high frequency range (>1 kHz). In quartz sand, the presence of gas in the medium tends to decrease the measured values of the phase angle. This effect becomes more important when increasing the injection rate, and thus the amount of gas trapped in the medium. The magnitude of this effect decreases when the water conductivity increases. Dissolution processes (CO2 in water and also solid matrix in the case of carbonate sand) were evidenced from chemical measurements (pH, conductivity and anionic concentrations). The increased ionic strength resulted in a decrease of the bulk resistivity and in an increase of the phase values at high frequency. An interesting parameter is the ratio of the increase in phase to the decrease in resistivity. When dissolution processes are involved, this ratio increases strongly with the initial conductivity of the saturating fluid. Hence, in some cases the measured phase values still bring measurable information on the system evolution even if resistivity variations are very small.

LaGriT Files for creating the mesh V01.

LaGriT Files to add vertical resolution V02.

Gallery of Project Images

Cylinder Mesh and embedded center
image description

The original cylinder mesh is created with the software GMSH. The gmsh format is converted to AVS/UCD format and imported into LaGriT to write FEHM setup files.
A few versions were created with GMSH, but resulting meshes were non-Delaunay with a very large number of negative coupling coefficients. So a new strategy was used:

Project Archive Location

FEHMN files and Directories:


GMSH Mesh (high resolution)
-rw-r--r-- 1 tamiller sft 9277207 Oct 10 08:55 vers04/mesh_cl1.fehmn
-rw-r--r-- 1 tamiller sft 9703279 Oct 10 08:55 vers04/tet_connect.fehmn
-rw-r--r-- 1 tamiller sft 13297060 Oct 10 08:55 vers04/tet_connect.stor

LaGriT Stacked Mesh V01
-rw-r--r-- 1 tamiller sft 2355704 Oct 16 09:09 lagrit_example_v01/cyl_tet.fehmn
-rw-r--r-- 1 tamiller sft  1948397 Oct 16 09:09 lagrit_example_v01/cyl_tet.stor

LaGriT Stacked Mesh V02 with higher vertical resolution
-rw-r--r-- 1 tamiller sft 5256424 Nov  6 14:53 lagrit_example_v02/cyl_tet.fehmn
-rw-r--r-- 1 tamiller sft  4326735 Nov  6 14:53 lagrit_example_v02/cyl_tet.stor

FEHM zone files:
Each file contains the list of node numbers for each zone:

These are the nodes that are at 0,0 of the mesh (well center)
Material  1 has        17 nodes. #nodes/nnodes is 0.202429154888E-02 

These are the nodes along the sides of the cylinder mesh
Material  2 has       119 nodes. #nodes/nnodes is 0.141700403765E-01 

These are the rest of the nodes in the mesh, and not part of the well
Material  5 has      8262 nodes. #nodes/nnodes is   0.983805656433 

Copy of Final Mesh for PC access:

drwxr-xr-x.  4 tamiller sft 8192 Oct 16 09:34 lagrit_example_v01/
drwxr-xr-x.  2 tamiller sft 8192 Nov 20 15:12 lagrit_example_v02/


LaGriT Files for creating the mesh V01.

LaGriT Files to add vertical resolution V02.

Gallery of Project Images


Grid Team Contacts

Carl Gable gable -at- lanl -dot- gov 505-665-3533
Terry Miller tamiller -at- lanl -dot- gov 505-667-8009