Against the current market backdrop, offshore operators and drilling contractors are looking for technological and engineering innovations that provide that extra competitive edge, helping reduce operational time and risk, protecting asset integrity and ensuring maximum efficiencies.
Questions that need answering: How does my vessel react to different sea states? How can I ensure safe connections between accommodation platforms and the main rig? And what are my optimal mooring line arrangements, and how can I ensure maximum precision in these?
The following will examine how some of these questions are being answered, delivering significant efficiencies and cost savings while still adhering to the highest safety standards.
Availability and forecast response analysis
One example of offshore innovation is the availability and forecast response analysis that facilitates the linkup of floating offshore accommodation platforms (also known as flotels) to their host unit.
One of the most important tasks for offshore accommodation vessels is providing a safe passage for personnel to the host installation. In such cases the accommodation vessels are positioned alongside the rig and connected by means of a telescopic gangway.
But despite the latest dynamic positioning (DP) systems on the accommodation vessels, unpredictable weather and the understandable need to err on the side of caution means that in questionable conditions in which there is extreme weather, such gangways are sometimes nonoperational. This can lead to drilling and production downtime and an increase in costs.
What if operators could estimate the movement of the vessel based on the latest weather forecasts and be assured of accurate predictions on how such floating units will respond?
Such a scenario is being achieved through an innovative partnership between Deep Sea Mooring (DSM), a provider of offshore mooring services and part of Vryhof, and StormGeo, a provider of decision-support services for weather-sensitive operations.
By combining hydrodynamic software and weather forecasts to accurately predict the relative movement of the accommodation rig and the gangway stroke to the attached platform, operators can forecast gangway motion, maximize availability, reduce risk and optimize operations.
In one North Sea application, the predictive software and DSM’s engineering expertise helped determine the best heading and optimal loading required to maintain gangway connections. The combination of DSM’s offshore expertise and StormGeo’s weather forecasting analysis provides an important decision-support tool that will allow the captain to foresee expected disconnections in advance and increase the availability of the operation by selecting the optimal heading.
Using this specific application over the course of a few months, gangway connectivity increased 2%. Taking into account that such accommodation vessels can house hundreds of personnel—all on high day rates—as well as the rig and support vessel hire costs, the increased connectivity can lead to substantial cost savings.
There is also a need for optimal offshore mooring arrangements and increased precision and flexibility in such operations.
Many installations (especially in areas such as the North Sea) are based around existing infrastructure. In the case of LNG, floating storage units and floating storage regasification units often are based very close to land-based operations and alongside infrastructure such as jetties. Different seabed and soil conditions also are present.
In meeting these challenges DSM’s Advanced Distance and Positioning System is attached to anchors prior to deployment, ensuring the anchor lands in the required position within engineering tolerances and provides the pitch and roll of the anchor along with the depth of penetration. When there is a minimal distance between the anchor and any subsea infrastructure, this type of information is crucial and also eliminates the need for ROV work during pre-lay operations and rig moves.
This need for precision also is included in anchor designs.
Vryhof anchors are ready for deployment on an Australian semisubmersible unit. (Source: Vryhof)
Vryhof Anchor’s patented Stevtensioner technology enables operators and contractors to install anchors with smaller leads in more constrained areas. The Stevtensioner is a chain-shortening clutch with the active mooring chain connected on one side and a reaction chain running through it. A repeated heaving up and slacking of the Stevtensioner in a yo-yo action builds up the load in the mooring chain until the required tension is achieved.
Vryhof’s patented Stevtensioner technology makes it possible to install anchors with smaller leads. (Source: Vryhof)
This ability to use anchors with shorter leads enables operators to use smaller and cheaper vessels in mooring installations, allows two opposing anchors to be cross-tensioned simultaneously and can bring down installation time by up to 40%—all potential sources for cost savings and an example of engineering innovation adding value.
The evolution of drag embedment anchors (i.e., anchors that are pulled/dragged into the seabed) also are improving offshore operations. Vryhof’s Stevpris Mk6 anchors, for example, can provide security in all seabeds and soil conditions with holding power more than 30% higher than any other drag anchor. Whether it is FPSO units, drilling rigs, single-point mooring buoys, barges or pipelaying vessels, the result is securer, safer and more effective offshore operations.
Finally, there is a need for the real-time monitoring of offshore equipment. A good example of simple yet innovative tools is a series of unique ID bands that are fitted on all Vryhof equipment. The bands are highly durable, easy to read and fitted with radio frequency identification chips, providing reliability in documentation and logistics while saving time during mooring and anchor-handling operations.
Another tool includes a hydro-acoustic subsea deployment hook to facilitate the release of pennant wires without the need for ROV or weak link operations. Benefits include the effective subsea release of laydown wires and reduced operational time and costs.
The RFID ensures traceability and identification of all mooring equipment. (Source: Vryhof)
Having the right processing capabilities in place
When multiple simulations and in-depth engineering analysis are required, there is also a need for high-level computing power to provide the answers.
Hydrodynamic and vessel motion analysis, mooring and DP analysis, riser analysis, and probabilistic and deterministic stability analysis for ship types and fl oating structures often require powerful computing capabilities.
With this in mind, the new engineering unit within DSM plays host to one of the industry’s largest servers with parallel processing capabilities. These capabilities will enable DSM to carry out 120 simultaneous engineering simulations, shortening computational times, reducing assumptions and simplifications, and delivering highly accurate and less conservative engineering analysis for customers.
Engineering innovation for challenging times
Engineering innovation is important to operators as a means of increasing efficiencies and managing costs during these challenges times.
It’s encouraging to see that offshore operators and contractors have a variety of new technologies they can turn to, leading to viable engineering solutions and highly accurate information and analysis for real-life challenges.
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