New North Sea Unmanned Platforms Save Cost and Could be Used More in the Future
The BP-operated Tambar Field, 16 km southeast of Ula, Norway, is one of the handful of unmanned wellhead platforms operating offshore Norway. It is remotely controlled from Ula
When it comes to utilising unmanned wellhead platforms (UWHP), Norway trails most others; however, a study released this month gives authorities and oil companies reason to consider putting the concept to use.
Commissioned by the Norwegian Petroleum Directorate (NPD), Rambøll Oil & Gas studied various unmanned wellhead platform concepts and determined that such platforms can be both cost- and production-effective development concepts particularly when used in shallow parts of the Norwegian Continental Shelf.
The Denmark-based engineering, design and consulting firm determined that a Type 3 minimalistic platform—which typically has between two and 12 wells and is designed to operate unmanned for as little as six months to as long as two years—is preferred for the Norwegian waters.
“As the concept is based on access by W2W [walk-to-work] bridges on a standby vessel or an offshore support rig, there should preferably be several UWHPs of this type in an area in order to distribute the operating costs of having [offshore service rigs] or W2W vessels in the area on more facilities, as the alternative would be to accept that the mobilisation time could be fairly long,” the report said.
However, more complex reservoirs—such as those with frequent well intervention operations and major rotating equipment like downhole pumps—call for Type 0 or Type 1 platform, according to the report. Both are equipped with helidecks and cranes, and are designed to be operated unmanned for a few weeks. Unlike type 1 and 3 platforms, Type 0 platforms have fire, water and processing equipment and are most similar to manned platforms, according to the report.
The NPD called for the study of UWHPs as an alternative to subsea developments. The study, which provides Norway with insight on the advantages and disadvantages of the platforms, also comes as the oil and gas industry looks for ways to operate more efficiently and cost-effectively in a low commodity price environment.
“The overall experience shows that the amount of equipment and systems should be minimized and only highly reliable equipment and noble materials should be used, which will reduce capital expenditure (capex) as well as operational expenditures (opex),” according to the report.
In an October 2015 new release on the study, NPD principal engineer Niels Erik Hald said “it is just as functional and robust as a subsea development, and it is also more accessible for inspection and maintenance.”
With Type 3 platforms a closed circuit TV is usually used to monitor the platform and remote shutdowns can be carried out, as stated in the report. Wellhead control, emergency shutdown systems, fire and gas systems and SCADA systems are integrated. Should the platform’s fixed fire detection system signal a fire, fire water can be provided from the drilling rig, the report said. Primary evacuation is via the W2W bridge; otherwise, a fast rescue boat or a life raft are used.
Interest in unmanned installations has been growing. But their use on the NCS has been low—making up only 5% of the region’s 99 platforms—mainly because of water depth, field size, distance to infrastructure and regulatory requirements, the report said.
