Oil and gas operators are increasingly engaging remotely operated aerial vehicle (ROAV) technology to reduce personnel risk and improve efficiency by cutting back on nonproductive time required for asset inspection activity.

Advances in ROAV design mean the small-scale vehicles, which use helicopter rotor technology and feature high-definition cameras, can be deployed to complete visual checks while operations are still under way.

Previously, such activity was carried out using rope access specialists, which required a full shutdown of the asset and posed a high-risk activity in often challenging weather conditions. These projects can traditionally last for several days.

ROAVs can enable operators to survey assets without the need for shutdown or exposing teams to additional risk.

ROAV use pioneered in East Irish Sea

Centrica Energy Upstream has pioneered the use of ROAVs in offshore inspection in the East Irish Sea, with flights carried out by remote technology specialist Cyberhawk achieving major cost and time savings. Similar to underwater ROVs in subsea operations, which can be deployed in place of divers, the aerial technology has been created by adapting principles used in military hardware. The craft are similar to unmanned aerial vehicles (UAVs) or “drones” that are normally used in war-zones and have been specifically developed for use in civilian applications.

An ROAV is elevated on eight rotors, is less than 1 m (3 ft) in length, and weighs less than 4 lb. The technology carries still, video, and thermal cameras. Battery-operated, it avoids the need for liquid fuel to be used on site, meaning one less hazard.

While the craft are capable of flying several kilometers beyond control equipment, they are operated within the line of sight to meet strict safety and regulatory provisions.

They are operated by a specialist offshore ROAV pilot, who controls the craft’s position in the air, and an offshore inspection engineer, who monitors the live video feed streamed from the air, analyzing data and capturing still images.

All ROAV activity is regulated by the Civil Aviation Authority. All craft must be operated within line of sight in the UK to ensure they do not pose a hazard to other airspace users.

Temperature extremes

Built predominantly from carbon fiber, the technology can operate in extremes of temperature – with work carried out in the last British winter where air temperature with wind chill was as low as -15°C (5°F) with 25-knot winds while surveying asset components with temperatures running to 300°C (572°F).

High-definition camera arrays provide detailed imagery in a live feed to inspectors and engineers on the asset floor – offering a step change from the use of full-scale helicopter inspection and people deployed on rope systems used to date, both above and below deck.

Centrica deployed an ROAV, operated by Cyberhawk, to inspect the flare tip on the Morecambe Central Platform in the East Irish Sea off the west coast of the UK, representing the first time this new inspection technique had been used in the area.

Flare tips operate at very high temperatures in excess of 300°C and face extreme weather far out at sea, where they are open to corrosion. There is the potential for them to crack and, in a worst-case scenario, they can detach from the asset.

“The ROAV acts as a diagnostic tool, providing information on the condition of our assets without the need to expose inspection teams to the risks attached to any rope access operation,” Gary Livingston, senior mechanical integrity engineer at Centrica, said. “An ROAV was deployed to take detailed close visual inspection images of the flare tip on Central while it was still burning ahead of planned works to replace it during a forthcoming shutdown.

“Completing the flare tip inspection in service in this manner was previously not possible using traditional rope access techniques since they must be carried out during the planned shutdown itself to be safely completed,” he continued.

Live streaming images

Images sent back to inspectors on the deck, streamed live in the same manner as a subsea ROV, showed no degradation of the flare tip beyond that recorded at a previous inspection, allowing postponement of the work until a longer shutdown scheduled for the following year.

ROAVs have been tested flying under decks and drilling derricks in the North Sea, and the technique was recognized during industry association Oil and Gas UK’s 2012 Business Efficiency awards.

The remote monitoring program will now be extended by Centrica to include the inspection of the underside of a number of its other East Irish Sea platforms.

The use of ROAVs to inspect assets and components before shutdown was initially established as best practice at onshore refineries after being employed to enable better planning of turnarounds and shutdowns.

“We carried out focused R&D to allow our remote inspection solutions, initially used for the inspection of flare and chimney stacks at onshore refineries, to be used specifically in the more challenging offshore environment,” Craig Roberts, CEO of Cyberhawk, said.

“Using an ROAV to inspect live assets enables operators to assess conditions and make informed decisions about shutdowns, reducing the risk of budget and timescale overruns and often enabling shutdowns to be postponed if asset condition is better than first thought,” he added. “Cyberhawk’s ROAV also reduces or eliminates the need for Centrica staff or contractors to work at height, dramatically reducing the overall project safety risk. These cost and safety benefits represent a step change for the industry.

“Other operators are now following that lead, and the potential for ROAVs to be used for more than inspection work definitely exists as the flight range of the airframes is extended and the quality of imaging technology continues to improve,” he said.