There are many elements and mechanics to an offshore oil or gas platform, but the simple premise is that the platform has an array of long pipes with drill bits at the end, which dig into the seabed, releasing oil or gas.
These pipelines are an integral part of the operation but can also become subject to a range of issues, including corrosion and erosion, as well as non-related age issues, such as accidental overpressure and dropped object damage. Maintenance, inspection and control of these pipelines is, therefore, a must for any operator in order to avoid catastrophic problems, such as environmental damage, compromised employee safety, company reputational damage, and limited energy supply.
In recent years, technological solutions for inspecting pipelines both above and below the sea surface have advanced. Some solutions require human assistance and others are completely autonomous, but ultimately, they aim to help maintenance personnel and operators save on inspection time and, more importantly, quash any safety issues.
DEEPWATER DIVING
Under the surface, many service providers are using unmanned underwater vehicles, including autonomous underwater vehicles (AUVs) and non-autonomous remotely operated underwater vehicles (ROVs), to carry out inspections and maintenance of pipelines.
Simply defined, AUVs are robots that travel underwater and do not require input from an operator. ROVs, on the other hand, are controlled and powered from the surface by an operator using either a remote control or umbilical.
In February, Kawasaki Heavy Industries announced the launch of Kawasaki Subsea (UK) in Aberdeen, Scotland – its new subsidiary that aims to specialise in the production, sale, and post-sale servicing of AUVs. The firm says that it has been developing an AUV equipped with a robot arm for performing subsea pipeline inspections, with a view to launch the machine in fiscal 2020. Kawasaki also intends to launch operations and maintenance services businesses using AUVs in the future.
Forum Energy Technologies is a global oilfield products company that serves the subsea, drilling, completion, production and infrastructure sectors of the oil and natural gas industry. Among its devices is the XLe Spirit (pictured), an electric ROV that has a depth rating of 1,000m and power rating of 8 kW.
Designed and manufactured in-house at Forum’s Kirkbymoorside Yorkshire facility, the XLe Spirit is the company’s first of a new generation of observation class ROV. The vehicle is the smallest in the new range but is powerful enough to perform subsea maintenance and repair work with the use of its optional electric or hydraulic five function manipulator arm. The vehicle’s self-regulating power feature is also said to compensate for tether losses, ensuring a constant and stable power delivery regardless of tether length.
System standard equipment includes a depth sensor (accuracy 0.3m), while system options include video cameras, stills cameras, dimmable LED lights, echosounder, and a cleaning brush, to name a few (www.is.gd/capusa). Kevin Taylor, Forum’s VP for subsea vehicles, says: “We recognised the time was right to introduce a new range of electric ROV’s as confidence begins to return to a depressed market. The XLe Spirit is the first vehicle in the range with innovative features which will meet the expectations and requirements of operators.”
Another system supplied by Forum is the ‘Ultra Compact Perry XLX-C work-class ROV’. The device has 150hp and has a depth rating of 3,000 msw (metre sea water). Standard equipment for the device includes: up to eight cameras (including low light, colour, zoom and HD); up to six individually dimmable lights; pan and tilt; and obstacle avoidance sonar or multibeam acoustic camera (www.is.gd/orezij). International subsea operating company DOF Subsea has recently taken order of three Ultra Compact Perry XLX-C work-class ROVs. It plans to deploy the vehicles onto three of its ROV support vessels for projects in Brazil.
GETTING AIRBORNE
AUVs and ROVs are not the only unmanned vehicle making waves in the inspection of offshore pipelines. Last year, OE highlighted the many uses of drones, also known as unmanned aerial vehicles or unmanned aircraft systems, with oil and gas being a popular sector because of difficult to reach infrastructure (www.is.gd/igijaw). Philip Buchan, commercial director of CyberHawk Innovations, an engineering company in the UK and US, spoke about how drones reduce the need for people to carry out hazardous inspections and make these essential processes quicker and cheaper.
Drones come in a range of sizes and weights. For external use, CyberHawk uses drones that are typically about 2kg in weight and around one metre in size, with eight independent rotors. Different cameras specs are also used based on scope of work, weather conditions, available light, and the type of drone being used, although the firm has the capability to capture up to 42.4 megapixels (or an image having 6,500 pixels per side).
In terms of controlling the drone, it uses a two-man team on site – a pilot controls the drone and makes sure it is in the air properly, while an engineer controls the camera.
SLIDING ALONG
Away from the vehicle front are offshore inspection units. Earlier this year, for example, remote intervention tooling and subsea engineering specialist ToolTec and its offshore inspection device won the manus award 2019 – a prize awarded by igus for the creative use of plastic bearings. The firm wanted to develop a ‘robust, reliable and low-maintenance’ mechanism for cleaning and testing underwater riser cables and tubing.
The inspection unit works by allowing operators to clean and inspect pipelines remotely, rather than having to use divers. The device wraps itself around the pipe, like a sleeve, and moves forward on rollers, cleaning the pipeline and inspecting it for weak points. ToolTec believed that a device with x-, y- and z-axis, in which a 360° rotatable carriage collects data, offered an alternative to remote-controlled vehicles.
During the design phase, polymer bearings were considered by the engineers because metallic bearings would have been susceptible to corrosion. In total, 445 inventors from 32 countries applied for the award, with a judging panel, made up of representatives from the trade media, industry and research, placing the Scottish company in first place (www.is.gd/ulirad).
Presenting the award to the company, Frank Blasé, CEO of igus, told of how the device weighs 1.4 tonnes and gives data of the foundations of the pipes and offshore equipment. “Testing is very important,” he said. “We have been looking for courageous plastic bearing applications.”
These are just some solutions available to personnel in charge of the inspection and maintenance of offshore oil and gas pipelines. Inspections and checks must be undertaken to ensure that staff, the public and the environment are safe, and technology is likely to continue to play an important assistance role in such tasks.