Sounding the alarm

Michael Cole, Fugro’s manager of survey prospects, explains how dynamic alarms coupled with office assisted remote services, can help provide better early warnings and navigation for end users.

Vessel alert zones (depicted in yellow) from the Stone Energy project. Images from Fugro.

Offshore driller Ensco had recently modified the ENSCO 8503 semisubmersible rig by adding four additional mooring lines to enable moored operations in the Gulf of Mexico’s shallow waters, where DP (dynamic positioning) operations no longer provide sufficient watch circles.

With the ENSCO 8503 under contract to Lafayette, Louisiana-based Stone Energy at a shallow water location in Mississippi Canyon Block 26, a high-temperature, high-pressure (HPHT) subsea completion was to be installed as part of the firm’s Amethyst project.

An eight-point taut mooring system with OMNI-Max anchors was designed by Delmar Systems to provide the most robust station keeping capability due to subsea infrastructure, to minimize offsets relative to the subsea tree during completion activities, and with ability for the rig to evade potential hurricanes. However, the taut mooring system resulted in shallow mooring lines near the rig, which support vessels could cross over and come into contact with, creating a potential hazard.

Dynamic avoidance zones are modeled in real time from the rig fairleads.

One solution investigated involved divers setting buoys on the mooring lines to give vessels a visual approach; however, this was not considered a viable option due to the desired quick response times for evading storms, and vessels would not be warned when approaching potential danger zones. As a result, Stone Energy contacted Fugro to explore a variant of the Starfix.Moor mooring position software, which had been developed by Fugro, along with mooring specialist Delmar Systems, some years before.

Starfix.Moor can compute a straight line 3D profile of each mooring leg and also provides 2D profiles of each mooring leg along with the ability to create audible and visual alarms when predetermined minimum clearances are reached. When integrated with Fugro positioning software, it provides a computation engine and visualization environment, utilizing the industry proven Delmar Systems DelCat catenary algorithms, and providing real-time in situ positioning and monitoring of the rig, anchor handling vessels (AHVs), and 3D visualizations of the mooring lines in relation to the seafloor and those assets that reside on it.

OARS operations are monitored 24/7 by the command center.

The solution

Stone Energy required a method to monitor and alarm when vessels entered into potential danger zones, and to ensure operations were not interrupted.

They also recognized this was the first eight-point mooring system designed and installed in hurricane season post-Ivan, Katrina and Rita (IKR). Further, federal regulators (The US Bureau of Environmental and Safety Enforcement, and the US Coast Guard) would be very interested in the performance and management of the system.

Full OARS display with alert zones and rig’s position.

After meeting with Stone Energy, Fugro’s OARS (Office Assisted Remote Services) support team, the research and development group, and senior management, came together to see if a diverless solution could be implemented within the tight 30-day deadline set by Stone Energy for development and testing.

Fugro’s OARS system, on which a patent is pending, had originally been developed to reduce costs, but it also means the surveyor is located in a command center, rather than aboard a vessel offshore.

The OARS Command Center (there are currently two, one in Lafayette, Louisiana, and the other in Aberdeen, UK, with more planned) is like an air traffic control center, with multiple vessels being displayed and tracked simultaneously, each with an individual project scope, and without an actual personnel presence on the vessel. The onboard system consists of computer servers, Fugro’s Starfix GNSS positioning receivers and GNSS-based heading solutions in a single unit; it also includes a phone and headsets for direct communication with the OARS Command Center.

Staff in the Command Center can assist in maneuvering, mooring and positioning, as well as monitoring and planning survey work, as if they were on board.

For Stone Energy, flexibility was key in the search for a solution. Within a few days, a plan was in place to modify the new Fugro global survey platform (Starfix.NG) and the OARS solution. The proposed updates included dynamic avoidance zones, advanced automated information system (AIS) integration and alarm notifications.

Local systems testing and integration efforts by the OARS team were run in parallel with the development of the system, enabling real-time feedback as issues arose.

Stone Energy approved the system and Fugro’s global research and development group set to meet, and met, the 30-day deadline. The system was mobilized in Q3 2015. Since installation there has been no survey downtime on the project and the feedback from Stone Energy has been very positive.

“Recognizing the hazard is good,” says Craig Castille, director of deepwater drilling & completions, Stone Energy. “However, putting a system in place that provides early warnings to vessels better protects Stone, Ensco and vessel owners, and raises awareness amongst vessel captains and provides a record of vessel movements for reference in case of an event occurring.

“Controlling work with integrated systems better enables real-time visual operations,” he says. “During winter, with a rig that has always worked in DP mode, and thus having only two approach zones, this enabled vessels to better navigate to and from the rig in a safe manner.”

The ENSCO 8503 was the first drilling rig to use the new dynamic alarms feature that is utilized with Fugro’s OARS system. Now current systems in the field on dive vessels (where the market quickly saw the benefits, including reduced costs, more bunk space, improved food and transportation logistics, as well as fewer delays for job start-up), derrick barges and dynamically positioned vessels, are being updated with the new features, and there has been a high volume of interest from across the industry.

Michael Cole joined Fugro in 2004, starting as an offshore field surveyor. In 2009, he became a project manager. During the Deepwater Horizon incident, Cole was deployed to the BP command centers in Mobile, Alabama, and New Orleans. He also served as Fugro’s dedicated project manager for Shell’s Arctic drilling operations. In late 2014, he became Manager of Survey Projects. He has a bachelor’s degree from the University of Louisiana at Lafayette.