Automating data collection reduces operator exposure to offshore hazards, as well as making it easier, says Emerson Process Management’s Craig Abbott.
Statoil’s Gullfaks’ B platform. Photo from Statoil.
Flammable materials, transport, chronic exposure to chemicals and even the natural environment are common hazards for offshore workers. Operators are constantly looking for opportunities to improve safety, however, all project costs are now under intense scrutiny. Initiatives that have improved offshore safety and increased production are shining lights in the currently gloomy market.
At the core of successful projects lie solutions to common challenges; installed cost, infrastructure requirements, weight and installation time. The key strategy that overcomes all of these challenges is wireless instrumentation.
In terms of production, improved measurement leads to improved management. A broad range of sensors that are quick and easy to install would enable better wellhead management, leading to improved production. Indeed, WirelessHART, which includes devices that are compliant to the IEC62591 standard, has the broad, industry leading, range required. Instruments to measure pressure, temperature, level, flow, valve state, hydrocarbon leak detection, corrosion and vibration are just some of those available.
When discussing safety it is important to understand the hierarchy of risk control measures that are rigorously applied to reduce risk to as low as reasonably practicable. The hierarchy, in order of effectiveness is:
- Elimination of the hazard
- Substitution to a lesser danger source or reduced exposure
- Isolation of people from the source of harm, by time or distance
- Engineering to prevent access to harm
- Procedural controls
- Personal protective equipment
- Warnings and signage to assist vigilance
Wireless instrumentation strategies underpin the most effective risk control measures. Eliminate the task, reduce exposure or isolate staff from the hazard.
In the North Sea, any time workers step outside of the cabin, they are at risk; however, inspecting pressure gauges for casing leaks and checking flow rates for blockages are an important part of minimizing environmental risk and maintaining production.
Statoil installed WirelessHART transmitters on a number of platforms to monitor wellhead conditions from the control room. This has significantly increased the information available to allow operators to recognize adverse conditions sooner and respond faster. Workers are also safer, checking values from the control room, rather than moving around an exposed deck.
Obtaining the wellhead data could have been achieved using wired instruments, but WirelessHART made it easier. What’s more, these typically take around two hours to install compared with up to two days for a conventional wired unit, says Geir Leon Vadheim, Instrument Lead, Grane platform, Statoil.
The success of these projects was reinforced in 2015, by the addition of 150 of the light-weight, wireless, pressure transmitters to each of the three Gullfaks platforms.
An operator in the Gulf of Mexico, recognized that their aging pneumatic platforms posed several risks. There was the risk of environmental issues occurring before they could be detected and prevented. Process optimization, to improve production, required regular helicopter flights, a recognized safety risk. Workers risked arriving at a platform and being exposed to a hazardous atmosphere without any warning.
After reviewing several options, a WirelessHART solution was selected, resulting in reduced travel requirements and a greater awareness of facility conditions. With regular updates of the platform conditions available remotely, the operator has realized US$2 million/yr in increased production, reduced helicopter travel costs by $1.3 million/yr and significantly reduced operator exposure to hazards.
Wireless was selected as it was 700kg lighter and approximately $3 million cheaper to install than comparable solutions.
A standard pressure transmitter, manufactured from stainless steel, weighs approximately 5kg and requires the addition of cables, cable trays and junction boxes. The latest Rosemount wireless pressure gauge, manufactured from a corrosion resistant polymer and suitable for replacing gauges currently installed on offshore wellheads, weighs only 820g and requires none of the cabling infrastructure. It also replaces mechanical bourdon tubes with a digital sensor, reducing the risk of mechanical failure, another safety improvement.
Another global operator performed a similar upgrade of their pneumatic platform, off the Indonesian coast. Designed to be unmanned, the platform required daily trips by four personnel to collect process data. Pressures were read manually, and when issues were identified, an operations team also traveled to site, resulting in up to 24 hours of reduced production. Automation was clearly required to improve production and reduce the risk associated with staffing a platform that was never designed to be manned.
A combination of 10 wired and 77 WirelessHART transmitters were installed on the platform, across two decks and operating at greater than 99.9% reliability. This allowed operators to collect the process data remotely and investigate issues without travelling to site. A post project review concluded that compared to an equivalent, fully wired solution, the system saved 22% of the budgeted costs and 82% of the budgeted time.
The low oil price has created the need to shut-in wells and demobilize low producing platforms. Even when not producing, control systems must remain operational to monitor well integrity and mitigate environmental and safety risks. These systems are often powered by diesel or fuel gas generators. Diesel eventually runs out and fuel gas systems require regular maintenance, both requiring travel and ship or helicopter to platform transfers, which are identified safety risks.
To overcome this issue, Emerson Process Management is working with an operator in Australia to deliver a self-contained monitoring solution that includes WirelessHART pressure transmitters for monitoring casing pressure, gas and flame detectors, a radio, RTU, IP camera and navigational equipment. The solution includes an autonomous power system, utilizing solar panels, and can be craned onto a very small footprint. This independently operating solution will permit real-time monitoring, whilst mothballing all other infrastructure and practically eliminating travel to site.
Automating the collection of data reduces the exposure of operators to offshore hazards that could include explosive atmospheres, the environment and transport risks. A WirelessHART network that is lightweight, compact and requires minimal infrastructure makes it the ideal solution for quickly and easily adding instrumentation offshore and improving overall field safety.
Craig Abbott is wireless specialist, Emerson Process Management. He graduated from the University of Western Australia with a BSc (hons) in Computer Science and Information Technology and stepped straight into a career in Process Control and SCADA as a systems programmer.