Leading international oilfield services company, Expro, has successfully accomplished the world’s first proven wireless transmission of reservoir pressure data to surface, from a recently abandoned subsea appraisal well which incorporated a rock-to-rock cement plug.
The system was installed in the North Sea and will be used to improve understanding of the reservoir and to optimise future development planning of the field, while ensuring full compliance with local well abandonment regulations.
This achievement provides operators with a more cost effective option for well abandonment design and consideration of wider well barrier techniques, while maintaining the ability to monitor the reservoir or plug integrity.
Expro’s cableless telemetry system (CaTSTM) wireless gauges, using electromagnetic (EM) technology, were installed in the reservoir of the main bore and casings were cut below the side-track kickoff point to install the cap rock cement plug.
CaTS repeaters placed in the side-track enabled data transmission across the open-hole section and to the seabed transceiver for storage and transmission to an overhead vessel.
The system provided continuous reservoir data, which began immediately after the drill stem test (DST), allowing extended pressure build-up analysis without rig support.
Expro’s Executive Vice President, Alistair Geddes, commented: “This latest achievement demonstrates our leading position in understanding the physics behind downhole EM telemetry. It allows us to instrument more wells with casing breaks or longer open-hole sections, partnering with customers to develop the most effective plug and abandonment strategies.
“For nearly two decades, Expro has pioneered the use of EM for long-term reservoir monitoring, delivering advancements in 3D analysis models for open-hole communication - without the need for a continuous metallic path for data transmission.
“We recognise the value that technology brings to our industry, which is why we continue to expand our capability and deliver maximum value through innovative new applications.”
CaTS gauges can deliver substantial cost savings in side-tracked wells with appropriate well barriers, as this permits long term interference testing to be completed from the main bore to side-track, without the need to drill a separate appraisal well.
Expro has the most extensive track record of instrumenting subsea abandoned wells and has successfully deployed CaTS gauges for its Advance Reservoir TestingTM (ART) application.