A controlled CO2 release experiment in a fault zone at the In-Situ Laboratory in Western Australia

Abstract

A controlled-release test at the In-Situ Laboratory Project in Western Australia injected 38 tonnes of gaseous CO2 between 336-342 m depth in a fault zone, and the gas was monitored by a wide range of downhole and surface monitoring technologies. Injection of CO2 at this depth fills the gap between shallow release (<25 m) and storage (>600 m) field trials. The main objectives of the controlled-release test were to assess the monitorability of shallow CO2 accumulations, and to investigate the impacts of a fault zone on CO2 migration. CO2 arrival was detected by distributed temperature sensing at the monitoring well (7 m away) after approximately 1.5 days and an injection volume of 5 tonnes. The CO2 plume was detected also by borehole seismic and electric resistivity imaging. The detection of significantly less than 38 tonnes of CO2 in the shallow subsurface demonstrates rapid and sensitive monitorability of potential leaks in the overburden of a commercial-scale storage project, prior to reaching shallow groundwater, soil zones or the atmosphere.Observations suggest that the fault zone did not alter the CO2 migration along bedding at the scale and depth of the test. Contrary to model predictions, no vertical CO2 migration was detected beyond the perforated injection interval. CO2 and formation water escaped to the surface through the monitoring well at the end of the experiment due to unexpected damage to the well's fibreglass casing. The well was successfully remediated without impact to the environment and the site is ready for future experiments.

A (not so) shallow controlled CO2 release experiment in a fault zone

“…This section presents a summary of the more interesting monitoring results from DTS and cross-well seismic. Please refer to Michael et al [15] for a more comprehensive description of the monitoring activities at the ISL and detailed results of specific monitoring technologies are provided in separate publications [21,22,23] Electronic copy available at: https://ssrn.com/abstract=3820206…”

“…The In-Situ Laboratory (ISL) in Western Australia (Fig. 1) was established to address the two above-mentioned challenges of CO2 leakage from a reservoir and more details are provided by Michael et al [15]:…”

Lessons Learned: The First In-Situ Laboratory Fault Injection Test

“…This was not planned during the drilling but was subsequently confirmed by seismic data. At the top of the Yalgorup Member throw is anticipated to be of the order of 750 m and reconstruction of the fault in the area tested suggests a 200-300 m fault zone [8]. Evidence is seen in the continuous core, though this is nuanced.…”

“…Initially to be located at either Harvey-3 or -4 [7] to test the top of the Wonnerup Member, the unconformity at the boundary with the overlying Yalgorup Member and the Yalgorup's sealing potential (Figure 1B), access became problematic (Issue #1) and the site moved to Harvey-2. The project was rapidly replanned (Issue #2), and new science questions developed to test the geological environment in the new location, which included the potential to test the F10 fault, intersected by Harvey-2 [3], at approximately 750 m at the top Yalgorup [8].…”

“…Further details of the geology, the recompletion of Harvey-2, drilling of the monitoring well ISL OB-1 and the first test are discussed in detail in [8] and at this conference. The site set-up is shown in Figure 3.…”