Let’s get predictable

If topsides asset integrity management is a bane, imagine looking after subsea assets. Elaine Maslin reports on the challenges associated with keeping up with both older equipment and newer, more complex equipment.

A subsea field layout. Image from Aker Solutions.

Subsea asset integrity was a popular topic at February’s Subsea Expo, from operator-contractor collaboration on predictive maintenance to university research into sensors and modeling.

Subsea asset integrity is a key topic for the North Sea, as it moves into what industry body Oil & Gas UK recently called a “super mature” era. Asset integrity has been under the spotlight of the UK’s Health & Safety Executive (HSE) and Subsea UK has a Subsea Asset Stewardship workgroup, run in collaboration with the Oil and Gas Authority, the UK industry’s new regulator, and led by Aker Solutions’ Matt Corbin, head of subsea product management.

“We are one of the most mature basins in the world,” said Gordon Drummond, project director at the National Subsea Research Initiative (NSRI), who led Subsea Expo sessions with an asset integrity focus. “Because, we have such extensive architecture in place, there are challenges facing us. There is a need for new inspection technologies, especially for flexibles and composites.”

Internal corrosion also remains a number one threat, he said. “Many companies make money looking from the outside in, but this is flawed,” Drummond said. “Pigging might be difficult [in some circumstances]. [For] life extension projects, how do you justify reliability and performance of subsea architecture once it is in place?

“There is also a need for data analytics and condition monitoring. Even more so with the advent of reciprocating and rotating equipment in the [subsea] field. We maybe have struggled with static plant [subsea]. When it comes to the active plant, it’s a real challenge.”

Yet, Drummond said, data monitoring, trending and analysis haven’t seemed to really take off in field. Indeed, the HSE’s KP4 report on aging and life extension (OE: September 2014) said data trending was not being used enough by the industry. It might finally be time to redress that situation, both to correctly assess the state of existing infrastructure, but also as the industry continues its move towards the total subsea factory, as Statoil calls it.

GE Oil & Gas’ unified operations dashboard. Photo from GE Oil & Gas.

In control

Some are trying to do just that. Aker Solutions and Shell presented work, at Subsea Expo, that they are doing around subsea controls integrity management, or predictive services. The two firms started working together about 18 months ago after Aker asked operators what they wanted in terms of subsea controls system integrity management, shortly after the HSE’s KP4 report highlighted subsea controls as an area requiring focus, due to how it is linked to safety and environmental systems on the seabed.

“We know about the system and have information – that people don’t use – about how it works, said Roy Stenhouse, subsea integrity business manager, Aker Solutions, a subsea control system supplier. “The control system carries a lot of capability that can help to manage the integrity of the systems it is connected to. Through the data in the control system we can infer information about the subsea tree, such as degradation in a spring in an actuator.”

Having the data, or information, about the status of the system, enables operators to develop better ways to maintain systems. However, it’s not quite as simple as data mining. An understanding of the operating envelope of the system is needed, and in some cases it is not fully understood, said co-presenter Tom Moore, principal subsea engineer, Shell, at Subsea Expo.

Giving Aker Solutions access to data from the subsea control systems in a particular field meant Aker was able to identify faults and then predict when these might happen in the future. In one instance, the firm was able to show that one of Shell’s subsea control systems was not working to its optimum, because it was trying to communicate with a production well that hadn’t actually been drilled, wasting its energy, Stenhouse said. By telling it to no longer seek information from the non-existent well – which involves looking for information from 50-60 non-existent data points – the system was able to operate more efficiently. Shell also learned it had inbuilt capacity to connect up another well with little work, if it needed to.

In addition to enabling a more preventive operating regime, this system allows for life extension work, due to having the understanding of the status of the facility and also the ability to predict the condition of the system. “How can we extend the life [of equipment of facilities] if we don’t know how they have been performing and the failure mechanisms? It is understanding real root causes, and how we turn the data we have into information we can use is really important,” Stenhouse said.

Knowing more about the status of equipment and sharing that information with the equipment vendor also means that vendor can improve the product, Stenhouse highlighted. What’s more, he said, by knowing the condition of the system you’re more likely to be able to sell it on as spares when it’s no longer required.

The offshore industry needs to catch up, Stenhouse said, not least when it comes to achieving the subsea factory, which, in order to be successful, needs this level of ongoing predictive maintenance. “A lot of other industries have moved into much more predictive models, aerospace and automotive, for example, and they are in a much better position. We should move away from being reactive and be more prepared.”

As a result of the KP4 report and its work with Shell in this area, Aker Solution’s has now also put forward a new guidance document to the UK’s Energy Institute, and which, once approved, will be available to the entire industry.

Fundamental research

Meanwhile, universities are looking at some more fundamental research. Srinivas Sriramula is working at the Centre for Safety and Reliability Engineering at the University of Aberdeen covering two research areas: developing reliable modeling techniques for condition monitoring and applying the information or data produced to understand the reliability of actual systems.

“On the reliability side, we are looking at tools to improve reliability of riser systems,” Sriramula said at Subsea Expo. This includes sensor systems, new models, and establishing protocols for exchange of information. “The next area is a model for corrosion using probabilistic modeling. If we have data looking at wall loss, we can look at inspection frequencies and how to manage inspection schemes,” for example, he said. The university is also looking at aging infrastructure, such as fixed jackets that are over 25 years old, which means having to know uncertainties, loads, degradation and damage mechanisms – i.e., they need the data.

This is the way to go, agreed Matthew Franchek, a professor and director of the subsea engineering program at the University of Houston, who presented on the Institute of Subsea Operational Integrity Management. But, all of this work, real-time monitoring, making sense of data, will require a new type of worker, he said. “Real-time monitoring is going to be very important in coming years,” Franchek told Subea Expo. “It means better monitoring of equipment, not tests every two weeks – you can change the frequency of testing.” But, he said, the work force you need in the industry to do this work is going to be different.

Cradle to grave

Federico Noera, senior vice president subsea engineering at GE Oil & Gas, told OE: “The real opportunity is making sure the right people with the right data are available at the right time.”

But, for Noera, it’s not just about asset integrity. Building a model of the asset, from design through to decommissioning, including performance, structural, environmental data, etc., would improve understanding of the asset, result in optimized field configurations and equipment, aid standardization and reduce costs/add value. He calls it a “digital thread.” “That’s where GE is playing a role with Predix,” a cloud based application built for big data and analytics for industry, including oil and gas, he says.

It is already happening in other industries, from aerospace to offshore wind, Noera says, echoing Stenhouse. There, problems are identified before they happen so they can be fixed proactively. “The good news is we can learn from other industries, power and automation, for example, and wind. Its evolutionary steps.”

V-integration

Viper Subsea’s V-IR concept. Image from Viper Subsea.

Technology firms, such as Viper Subsea, are providing some of the tools needed to help monitor subsea infrastructure. The firm, part owned by Oceaneering, which already launched V-LIM, a topside monitor of insulation resistance and electrical integrity of subsea electrical umbilicals, has now also created V-SLIM, a subsea electronics node that measures a range of electrical integrity data and transmits it back to the surface. 

Together, V-LIM and V-SLIM will form V-IR to offer an integrated system that provides a complete subsea distribution system electrical integrity map. V-SLIM is rated to 3000m water depth and the complete system started a three-month shallow-water trial including use of a 2km-long subsea cable early this year.