Expro International Group had a successful application of its Cableless Telemetry System (CaTS) for the monitoring of the reservoir pressure and temperature response in an abandoned subsea well. The CaTS technology was successfully applied in the Clair Ridge appraisal well 206/8-T, operated by BP Exploration Ltd. in the UK North Sea.

CaTS is a revolutionary development in the field of reservoir monitoring and control that allows real-time information to be transmitted to and from downhole without the use of cabling or wireline in the well. Its two-way transmission capability enables the remote control of downhole instrumentation, opening the path to the radical redesign of downhole completions.

CaTS schematic for subsea abandoned wells application. (Image courtesy of Expro International Group)


The CaTS system was installed in the 206/8-T well in early June 2006 as part of the final abandonment process. CaTS transmits its data from the reservoir to the seabed using Expro’s market leading wireless telemetry technology. The data is collected, processed and stored at the seabed using a specially developed CaTS subsea receiver. The data is transmitted from the receiver, on demand, to a supply vessel located overhead the abandoned well. A first data interrogation visit took place in early July and post abandonment reservoir pressure and temperature data was successfully uploaded for analysis by the reservoir engineers. Further data interrogation visits are planned for later in the year.


By using CaTS in this application, it is possible to monitor the long-term reservoir pressure build-up subsequent to the production tests performed during the Drill Stem Test and also to monitor for any interference effects resulting from production or injection activity on the Clair platform located nearby. This information will assist BP in gaining a better understanding of the overall structure of the Clair reservoir.

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