As CNR started recovery operations on a Ninian South well, a problem arose downhole indicating damaged casing. Given the successful outcome of a downhole inspection to evaluate debris in an annulus on the Transocean John Shaw rig on CNR's Banff Field, CNR once again called in EV Offshore to carry out visual inspections downhole to assess the problem.
The next day, EV Offshore mobilized a full inspection package, which consisted of the EVOLeye camera inspection system, drill-pipe running tool, centralizers, and a full complement of back-up equipment. The EVOLeye was chosen for the job because it offers full, continuous hemispherical viewing - in color or monochrome - while running downhole. It is also capable of flushing turbid water and dislodging obstructions at target depth to offer a clear view.
Assessing Conditions Downhole Using Real-time Images
Within 48 hours, EV Offshore had an inspection engineer on the Ninian South Platform ready to commence the inspection operation. Following multiple runs in-hole with the EVOLeye, EV Offshore obtained accurate visual information of the situation downhole so that the problem could be assessed. Video images revealed significant corrosion damage to the casing strings in a very limited area at sea level.
Initial attempts by CNR's drilling crew to retrieve the 9 5/8" casing using a spear proved fruitless. The casing spear simply dropped between the 20-inch and 30-inch casings without latching the damaged casing. Undaunted, EV Offshore and CNR worked together to formulate several different approaches. Finally, one approach proved to be successful. By running the casing spear on drillpipe, while simultaneously operating the EVOLeye on tugger line to supply real-time images, CNR was able to manipulate the casing spear into the damaged casing and recover it.
Conducting Keyhole "Surgery" Downhole
In just 15 days from the arrival of the EV Offshore inspection engineer on the platform, CNR had resolved the problem, and Ninian South was back on track. "By using the EVOLeye to assess the problem, we were able to recover the well, retrieve the damaged casing and re-complete the well," said Chris Wark, Senior Drilling Engineer for CNR. "There is no question that EV Offshore is directly responsible for making that possible".
By delivering an effective way to inspect the target area downhole, EV Offshore provided CNR with an effective and efficient solution to the problem, eliminating costly contingencies. "This operation for CNR was truly challenging. However, by working together with CNR to extract the damaged casing with our technology and experience, the well was successfully completed," said David Clover, Operations Director for EV Offshore. "By reducing downtime we helped to reduce costs. By averting the well abandonment scenario and associated debris that may have been lost at sea, we also had a direct hand in reducing the impact on the environment," he added.
EV Offshore specializes in the design, manufacture and operation of downhole, well intervention, subsea and topside camera inspection systems and is a service provider for the international upstream and downstream oil and gas industries. Founded in 2000, EV Offshore is known throughout the world for its family of camera inspection systems that improve safety, reduce production downtime and operating costs and contribute invaluable information to the decision making process. EV Offshore's camera inspection systems have been deployed in excess of 200 mobilizations to carry out inspection services on behalf of global operators in every oil and gas-producing region. The company also provides a range of design consultancy services for a wide variety of subsea activities.
EV Offshore is dynamic, innovative company that has won a number of awards for technical innovation and business growth. With established facilities in Aberdeen, Scotland and Norwich, England, EV Offshore is an exciting growth company within the energy sector.
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