The Magazine for Underwater Professionals
The National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA), Australia’s offshore regulator, has issued a safety alert following a recent incident where a vessel lost position while diving activities were being carried out approximately 130 metres from a hydrocarbon facility offshore Western Australia.
The safety alert did not name the vessel operator or hydrocarbon platform, but stated that the incident could have resulted in a diver fatality.
NOPSEMA said: “The loss of position was caused by a deactivation of the forward/aft automatic positioning function by unintentionally deselecting the ‘Surge’ button on the DP console located on the bridge which then deactivated the ‘Auto Position’ mode. The deselection was thought to have occurred by the placement of a notepad on the side of the console. The vessel drifted off location by over 40 metres and this drift was initially noticed by a diver when his umbilical started to become taut.”
Once the DPO (dynamic position operator) became aware of the excursion, the ‘Auto Position’ mode was reactivated causing the vessel to stop moving and remain in position.
During this time, the diver had followed his umbilical, moved clear of any obstacles, and walked with the vessel.
A loss of position during diving could cause diver fatalities if their umbilicals or other equipment becomes entangled or snagged on subsea infrastructure during the excursion. A loss of position whilst working in close proximity to a hydrocarbon facility could also potentially cause a collision, leading to a loss of hydrocarbon containment and subsequent fire or explosion. In both cases the consequences could involve multiple fatalities.
Due to the potential severity of the consequences of the incident, NOPSEMA conducted an investigation on board the facility. The investigation identified that the auto DP mode buttons (‘Surge’, ‘Sway’ and ‘Yaw’) were located in the left hand corner of the console next to desk space commonly used for completing DP related checklists and logs. Consequently, these buttons were susceptible to accidental activation by personnel.
“The inspectors found that although the incident arose by an accidental and unknowing double press of a button by the DPO, the design of the DP system allowed a human error to escalate this act into a dangerous occurrence by neither requiring any positive confirmation of deactivation of ‘Auto Position’ mode nor providing any alarm that required acknowledgment that ‘Auto Position’ mode had been deactivated,” said NOPSEMA.
The Authority added that the situation was exacerbated and recovery impeded as deselecting the ‘Surge’ button automatically deactivates the excursion alarms in that axis and the DP display was no longer providing useful feedback in terms of the loss of position event as the excursion rings started to track with the vessels movement.
“If either of the controls identified above were in place, it is unlikely the incident would have escalated to a loss of position event. In order to rectify the issue the operator, with assistance from the manufacturer, are currently upgrading the control systems software to provide a separate dialogue box confirmation requirement when deactivating the ‘Auto Position’ mode,” it said.
Fugro, the Netherlands, has deployed multi-purpose offshore survey vessel Fugro Gauss to join the Fugro Brasilis offshore Mexico, to help complete the world’s largest seep-hunting survey for multiclient geoscience data company TGS, Norway.
Both vessels are using hull-mounted multibeam echosounders and sub-bottom profiler systems to map an area of approximately 625,000 square-kilometres in the deep waters of Mexico. The data acquired will assist in identifying sites where deep hydrocarbon-rich fluids are escaping to the seafloor and will be used to target hundreds of sites for coring and geochemical analysis.
“Fugro has a dedicated centre of excellence in Houston for seep-hunting,” explained Jim Gharib, Fugro’s global product line manager for seep studies. “The team includes several of the world’s leading geoscience experts responsible for bringing seep-hunting to the offshore industry. Our recent successes include nine seep data collection and geochemical analysis projects in the Gulf of Mexico, the Caribbean and South East Asia.”
The survey is being conducted for TGS as part of its industry-funded, multiclient ‘Gigante Survey’ which also includes a regional 2D seismic survey of approximately 186,000 kilometres, gravity and magnetic data and a regional seismic structural interpretation.
EdgeTech reports its sidescan sonar equipment has played a key role in the discovery of a large coral reef at the mouth of the Amazon river.
“The recently publicised finding is exciting for researchers as they learn more about the area and the unique marine life and characteristics of the distinctive environment,” said a spokesman for the USA-based company.
One of the leading researchers on the project is Dr Michel Michaelovitch de Mahiques of the Oceanographic Institute of the University of São Paulo, Brazil. The Institute used an EdgeTech 4200 sidescan sonar system operating at 100/400kHz to find and map the coral reef.
“The 4200 Series is a versatile sidescan sonar system that can be configured for almost any survey application from shallow- to deepwater operations,” said the spokesman. “The 4200 utilises EdgeTech’s Full Spectrum CHIRP technology to provide crisp, high-resolution imagery at long ranges allowing customers to cover larger areas and save money spent on costly surveys.”
The spokesman said one of the unique features of the 4200 is the optional multi-pulse (MP) technology, which places two sound pulses in the water rather than the one pulse used by conventional sidescan sonar systems. This allows the 4200 to be towed at speeds of up to 10 knots while still maintaining 100% bottom coverage, he said.
“In addition, the MP technology will provide twice the resolution when operating at normal tow speeds,” he added.
A research cruise this summer, led by the National Oceanography Centre (NOC), UK, will address the massive technical challenges in exploring for seafloor mineral deposits. The expedition is taking place on board the RRS James Cook, marking a decade of service that has seen the ship travel 218,972 miles (352,401 kilometres) in pursuit of science – the equivalent of circumnavigating the globe 10 times.
Seafloor hot-springs, or hydrothermal vents, form deposits of minerals rich in copper, zink, gold and rare-earth elements, and may prove to be future resources for these important metals. While active hydrothermal vents are home to rich and exotic ecosystems, this expedition will only study extinct vents from which the associated fauna have long since moved on.
The RRS James Cook left Southampton, UK, for the Mid-Atlantic ridge at the end of June to test innovative technology aiming to enable theses deposits to be detected and their constituent minerals to be assessed.
Dr Bramley Murton, who is leading the expedition from the NOC, said: “The challenges posed by deep-sea exploration are similar in scale to space exploration. The technology that allows us to reach these hidden worlds is vital to our understanding of them. The deep-seafloor we will be exploring during our expedition is an extreme environment of intense-pressure and eternal darkness hiding a rugged landscape akin to a combination of the Grand Canyon and Monument Valley 3.5 kilometres beneath the waves.”
Dr Murton added: “While at sea we will be using new technology to navigate underwater instruments between extinct volcanoes, 20-metre high cliffs and towering chimney structures built by long-dead hydrothermal vents.
“The British Geological Survey’s robotic drilling rig will bore holes deep into the deposits to extract samples of the minerals and take readings of the interior conditions.”
The robotic drill has been fitted with an adaptation to enable it to drill through these hard deposits. Samples taken from the drill will help scientists determine if the minerals deposited by hydrothermal vents are able to withstand the degrading effects of the seafloor environment long after they have become extinct.
During the research cruise the team will test new systems for detecting mineral deposits, two of which work in a similar way to a CT scanner, and another is more akin to a giant metal detector. The former two, developed by the University of Southampton and the team’s German partners from GEOMAR, involve looking for distortions in an electric field transmitted through the seafloor – indicating the presence of buried mineral deposits.
In addition, a robotic underwater vehicle, HyBis, has been fitted with a special colour spectrometer, developed by researchers at the University of Trondheim, Norway, so it can study the composition of the seabed.