Many of the in-well iDAS™ and DTS applications targeted at the upstream oil and gas industry are also a natural fit for CO2 well monitoring. Silixa have played an active part in the installation of fibre optic enabled monitoring systems for carbon capture and storage projects and continue to acquire data on several of these projects for a variety of reasons.
With a permanent fibre optic cable installed in a CO2 disposal or observation well the user has access to on-demand, and time lapse, borehole seismic data which can help to describe the growth of the CO2 plume within the reservoir.
Concerns over the integrity of the cap rock, or indeed the wellbore, can be addressed by passively monitoring for potential micro-seismic events, an area that is developing quickly as the iDAS sensitivity improves through system development and signal processing.
Temperature offers a traditional method of continuously monitoring the injection of CO2 so that early detection of leaks or gas migration can be facilitated. As a result many CO2 projects elect to routinely instrument wells with a permanent DTS system coupled to a realtime monitoring system.
The iDAS can complement this measurement by adding acoustic detection for gas migration and leaks; retrofitting an iDAS to an existing monitoring system is generally simple for Silixa but the unique ability of the iDAS to operate on either single-mode or multi-mode fibre without the introduction of any additional apparatus and without any appreciable difference in data quality means that iDAS can also be fitted to installations originally intended only for DTS where only multimode fibres are available.
The image above shows the installation at a well site in Spain, Europe.