Description
For the model calculation we applied EM3D using completion diagram of CaMI site and a background resistivity consistent with the borehole logs. It was also important to use the accurate position of the return electrode. We note that for the data fit the code also incorporated well casings for well INJ and the other observation well, either OB1 or OB2, in the calculation.
In summary, we demonstrate here, for this particular case, that the DC results may be a reasonable approximation to the low frequency EM data collected at CaMI. If this approximation continues to hold, then the extreme computational efficiency offered by the hierarchical modeling used in the DC simulations will permit us to explore far more model complexity, especially the pervasive and troublesome data artifacts that arise when doing EM surveys in mature, culturally developed sites.
In Brief, both the low frequency and DC simulation codes provided very consistent results that match the field data really well, indicating their capability to help monitoring borehole integrity with the low frequency EM method.
Resources
| Name | Format | Description | Link |
|---|---|---|---|
| CaMI Summary Report.docx | Doc | Document summarizing the model calculation, the comparison of field data to forward-modeled data, and preliminary conclusions. Includes plots of total potential (V) versus position (m) and plots of electrostatic field (V/m) versus position (m). | Open resource |
| CaMI Top Casing 5hz Interpretation.PNG | PNG | Measured low frequency versus DC simulation total field (V/m) data for excitation of OBS1 and OBS2 with respect to the injection well. | Open resource |
| CaMI Top Casing Source Configuration.PNG | PNG | Oblique view diagram showing locations of OBS1, OBS2, INJ, the receiver profile, and the return electrode. | Open resource |
| Field Data OBS1 Excited 5hz.txt | Text | Field low frequency EM data for excitation of Observation Well 1 using a 5 Hz source frequency. Data is provided as distance form wellhead (m),Ex field amplitude (V/m), and Ex phase (degrees). | Open resource |
| Field Data OBS2 Excited 5hz.txt | Text | Field low frequency EM data for excitation of Observation Well 2 using a 5 Hz source frequency. Data is provided as distance form wellhead (m), Ex field amplitude (V/m), and Ex phase (degrees).. | Open resource |
| Numerical Data OBS1 Excited 5hz.txt | Text | DC simulation data for excitation of Observation Well 1 using a 5 Hz source frequency. Data is provided as distance form wellhead (m) and Ex field amplitude (V/m). | Open resource |
| Numerical Data OBS2 Excited 5hz.txt | Text | DC simulation data for excitation of Observation Well 2 using a 5 Hz source frequency. Data is provided as distance form wellhead (m) and Ex field amplitude (V/m). | Open resource |
Tags
- 5-hz
- borehole
- borehole-logs
- cami
- canada
- casing
- cmc
- containment-and-monitoring-institute
- corrosion
- data
- dc-model
- electric-field
- electric-fields
- electromagnetic
- electrostatic-rsponse
- em
- em3d
- energy
- excitation
- experiment
- fdem
- fem
- field
- field-data
- forward
- frequency-domain
- geophysics
- geothermal
- hierarchical-modeling
- integrity
- low-frequency
- low-frequency-em-method
- modeling
- modelling
- numerical
- potential-field
- sandia
- simulated
- simulation
- validation
- well
- wellbore
- wise-casing