The Sotacarbo Fault Lab is designed to study gas migration processes in faults and to test a wide range of monitoring technologies. The facility is based on a borehole to inject small amounts of CO2 near and through a selected fault located in Matzaccara (SW coast of Sardinia, Italy). The facility includes a system for CO2 compression and temporary storage and a wide network of piezometers for monitoring the groundwater. Several vertical observation wells will be also drilled in order to collect reliable data on CO2 diffusion process. The purpose of the research is to better understand gas migration along the faults (via observations and fluid flow modelling), to improve monitoring technologies and to develop a protocol to define the fault permeability to gas migration. This infrastructure will include a 200 m deep vertical injection borehole, 7 shallow piezometers / monitoring wells, a 200 m deep vertical monitoring well, and the CO2 injection system. Leakage through the faults will be characterized (discrete vents vs. diffuse leakage at the surface, continuous vs. intermittent). In order to develop a monitoring strategy, a good understanding of the impact of CO2 injection in the aquifer must be developed. A toolbox, based on water-gas-rock interaction on the potential reactivity of CO2 within a potable aquifer, will be tested on these sites. The effectiveness of this tool will be validated in the field. It will identify the geochemical changes to be expected and therefore steer the definition of the groundwater geochemical monitoring strategy by highlighting the most sensitive parameters to monitor. Geophysical measurements will be undertaken using downhole tools and surface techniques, to examine if the migration of CO2 along the fault and its proximity can be tracked. Seismic techniques will include borehole measurements using wireline and cross well applications. These will be integrated and compared with other geophysical and well results, such as electric and electromagnetic logs and surveys, to demonstrate the most effective integrated geophysical approaches for monitoring CO2 migration. The Sotacarbo Fault Lab is still under construction. It will be operative by the end of 2020, but the facility is partially available for several tests.
The uniqueness of the facility is given by the specific configuration of the selected fault located in Matzaccara (SW Sardinia). Moreover, the Lab will be a part of a wider infrastructure, which includes a test site for pilot-scale CO2 injection and an underground laboratory. All these facilities will operate in integration with the other Sotacarbo facilities for CO2 capture and utilization. Due to its specificity, the Sotacarbo Fault Lab offers a rare opportunity to advance understanding of technologies for monitoring CO2 leakage through faults beyond the state of the art
In the facility site there are no technical services or analysis instrumentation. The Fault Lab will be supported by the other facilities of the Sotacarbo Research Centre, located nearby. Sotacarbo laboratories are equipped for water and gas analysis, as well as rocks analysis (XRF, multi-stage triaxial test system, drill core scanning and structural analysis).