Brian Champion, Global Sales Director, Wireless Well Solutions:
Reservoir risk and uncertainty is a key contributor to the failure of development projects. With the relentless downward pressure on costs, both in the North Sea and global markets, there is a natural tendency to minimise appraisal activity. This means that that too much uncertainty may be carried into the project design and execution phase. For instance, undetected flow barriers and general uncertainties in reservoir connectivity may lead to disappointing production and the need to drill additional wells, thus incurring significant additional cost.
More cost effective and innovative technologies and techniques are required that allow well testing and appraisal activities to maximise data collection whilst minimising costs. One example of such innovation, which is experiencing rapid market uptake in the North Sea and global markets, relates to advancements in wireless reservoir monitoring technologies for the post-abandonment monitoring of appraisal wells.
Expro’s CaTSTM Wireless transmitting pressure and temperature gauges, based on electromagnetic (EM) telemetry technology, are able to transmit high accuracy and high resolution P/T data from the sand face to seabed using the well’s casing as a signal conduit. There is no requirement for a tubing string in the well, and the EM signal propagation is not affected by cemented casing or liner, or by cement plugs or bridge plugs, making it ideally suited to wireless reservoir monitoring in the abandoned well environment.
By instrumenting an abandoned appraisal well and observing for interference with adjacent producing or injecting assets, it is possible to gather high value data about reservoir connectivity and compartmentalisation. Alternatively, the abandoned well monitoring gauges are being used to record long term pressure build-ups beyond the end of a drill stem test. The data is then used to determine the connected volumes or the presence of any flow barriers in the reservoir, which may have a significant impact on the field development planning. Importantly, the implementation of these high value wireless monitoring solutions are achievable at low incremental well cost.
CaTS wireless EM technology has already been used in the North Sea for barrier verification during plug and abandonment and in the suspension of subsea wells. As this mature region moves increasingly towards the decommissioning and abandonment phase, the requirements for wireless technology will only increase to monitor the long term post-abandonment integrity of these wells.