Time lapse in-hole electrical resistivity surveying during a shallow release of CO2 gas: Harvey, Western Australia

Summary

An in-hole electrode array was installed and cemented behind a fibreglass casing in a vertical monitoring well as part of an in-situ laboratory test for CO₂ migration in a shallow fault zone in Harvey, Western Australia. The array consisted of 32 electrodes spaced at 3 m intervals, located between 277 m and 370 m below ground level. The intention of the experiments was to assess the value of permanent in-hole electrical resistivity systems, during a shallow-release of CO₂. The distance between the monitoring and injection wells was close to 7 m. Food grade CO₂ gas was injected through a perforated interval located between 336 m and 342 m below ground level. In the order of 100,000 time-lapse dipole-dipole electrode quadrupole measurements were acquired during the experiment. There was a clear change in measurements at the depth of the injection interval during the release of CO₂ gas. Results are being compared with seismic, pressure and temperature data from the monitoring and injections wells from periods before, during and after injection.

• ERI
• CCS
• CO₂
• shallow release