Flex-lay myths: redundant reel drives

Offshore "flex lay" operations play a pivotal role throughout different stages of a field's lifecycle.

The term refers to the installation of flexible pipelines or flowlines on the seabed to connect a subsea structure with another facility, which may be floating offshore or located on land. Typically, this is to either transport fluids or to enable remote control of the subsea structure over a period of time.

The eponymous flexible nature of these products means they can be stored in coils; and depending on their overall length, those coils can be packed into large carousels or more portable reels.

For the latter, the common deployment tool is - unsurprisingly - a “reel drive system "; but - beware - this is not a catch-all term.

If you have been involved in planning a flex-lay project, you will have heard of Under Rollers or Spoolers; and while they can certainly rotate a reel, they do not match the capability of a Reel Drive System (RDS).

If you ever had to choose a solution for handling reels, you may have wondered how the more advanced RDS can truly benefit an operation that - on paper - a less complex system can do more cheaply?

In our Flex-lay Myths series we aim to debunk the common misconceptions surrounding the flexible handling market. In this issue, we shed light on the differentiators among reel drive systems and explore their versatile applications beyond SURF, or flex?lay?- and help you see how choosing the cheapest option by day rate, is hardly ever the best value to ensure your overall project success…

Debunking the myths?

Myth 1: Reel drive systems are complex and difficult to operate.

Fact: Disregard any preconceived notions you may have from flex-lay veterans using outdated equipment. MDL's Reel Drive Systems (RDS) are thoughtfully designed with user-friendliness in mind, as they boast advanced automation features, intuitive controls, and user-friendly interfaces, making operation straightforward.

These RDS systems operate on PLC systems and seamlessly integrate with other back-deck equipment, ensuring a smooth and safe operation by allowing different elements of the lay spread to communicate with each other. Moreover, you have the option to choose between electro-hydraulic RDS and fully electric ones, which significantly impact the controls' responsiveness.

Thanks to the intuitive design, experienced personnel can quickly adapt to these systems, and the incorporation of built-in failsafe technology and all-stop ESD integration effectively minimises the risks stemming from human error.

Furthermore, maintenance is a breeze with modern RDS as they are engineered for reliability, resulting in minimal downtime and enhanced operational efficiency.

Myth 2: Reel drive systems are expensive and not cost-effective for smaller projects.?

Fact: While Modern RDSs do require a higher initial investment compared to less specialised reel handling systems, their long-term benefits and cost savings far surpass the upfront expenses.

The efficient installation process enabled by RDS significantly reduces project timelines and minimises the need for offshore personnel, thanks to their intuitive controls and automation.

Moreover, these advanced features optimise the handling of the product and improve installation accuracy, resulting in reduced risks of repeat pay-outs/pay-ins and the associated costs. Whether it's a large-scale offshore SURF project, a smaller subsea installation, or beach-pulls, RDSs prove to be remarkably cost-effective, enhancing the overall project budget substantially.

Myth 3: Reel drive systems have limited adaptability to different project requirements.

Fact: If you envision RDS as bulky towers and occupying extensive space with a large track system, it's time to reconsider. Our rental fleet boasts three generations of reel drive systems, each equipped with a diverse set of advantageous features and optimized for specific reel types and sizes. These variations stand as a testament to the adaptability of RDS, allowing for customization to meet specific project requirements.

Furthermore, our RDS effortlessly integrate with other subsea installation equipment, including tensioners and carousels, to create a streamlined and efficient installation spread, tailored precisely to the project's scope. The versatility of RDS opens the door to countless applications and combinations, making them a highly versatile solution for various projects.

Myth 4: Reel drive systems are only suitable for offshore SURF installations.

Fact: While earlier we discussed "flex lay" in the context of O&G operations, the application spectrum of RDS extends far beyond that narrow scope.

RDS are incredibly versatile, finding utility in a wide range of subsea operations, including SURF (subsea umbilicals, risers, and flow lines), cables, polyester mooring ropes, and flexible product installation, transpooling, recovery, or decommissioning scopes. This adaptability makes RDS a valuable asset not only in the oil and gas industry but also in the renewable energy sector, interconnector installations, and other construction scopes requiring precise handling of flexible products within set parameters to ensure optimal deployment and safe execution.

Consider the application of RDS in mooring rope deployment. The precision control over torque and speed offered by reel drive systems results in consistent and controlled deployment, preventing overstretching or damage to the ropes. This ability to maintain optimal tension significantly enhances the integrity and reliability of the mooring system.

With such versatility and precision, RDS prove to be indispensable tools in a wide array of subsea operations, supporting efficient, safe, and reliable execution across diverse industries and projects.

Putting the benefits in motion: Unveiling the true potential of RDS

We've highlighted the distinction of RDS from other reel rotating methodologies. However, it's essential to understand that not all RDS are created equal.

Our portfolio comprises three generations of reel drive systems, each equipped with unique features that set them apart from the rest. Let's explore how the MDL range stands out by examining the journey of flexible products to deployment:

Step 1: Loading onto the Installation Reel

Transpooling the product onto the installation reel can be challenging, especially when done by third parties not involved with the offshore deployment scope. Poorly packed product often leads to time-consuming challenges offshore, requiring repeated pay-ins and pay-outs to achieve the required tension on the line. Inaccurate spooling direction and end termination positioning can also create alignment issues with offshore installation methods.

To address these concerns, correct packing on the reel while still onshore is crucial. Using an RDS ensures precise control over torque and speed, along with easy spooling direction changes to correct the layering and packing. All three generations of MDL reel drives boast a varied transpooling track record, each suitable for different reel diameter ranges.

In cases where onshore transpooling isn't feasible due to tight schedules or large product volumes, offshore transpooling becomes the best option. We offer a specialized package for such situations, featuring:

• Gen 1 RDS with a power pack that moves alongside the towers on the track system to handle a large number of reels efficiently. The small and compact nature of the system maximises the available back-deck space, whilst still being able to handle both small reels with custom drive interfaces, and larger Coflexip-type reels.
• Gen 2 RDS, capable of torquing in both directions, serving as a transpooling and installation tool in one.
• High-capacity installation reels, modified to handle polyester rope with an attached chain.

Here's that spread in action - and you can also read more on it here.

Step 2: Mobilisation onto the Installation Vessel

MDL Generation 3 RDS stands unparalleled when it comes to the mobilisation of the reel onto the installation vessel. By following our mantra of minimising idle time on a project, we developed the most compact and integrated RDS on the market, resulting in significantly faster mobilisation.

The features that expedite mobilisation include:

• HPU (Hydraulic Power Unit) built into one of the towers, reducing cable runs, lifts required, and overall system footprint.
• Independent towers that do not require tying or lashing together.
• Integrated Track and Cradle system, eliminating the need for welding down cradles, particularly advantageous for multi-reel projects.
• ?Lashing points on the RDS track system to secure the reels during transit, further reducing welding on the vessel's deck.
• Towers serving as sea fastening for the first reel, designed to withstand storm conditions, reducing the need for additional reel sea fastening.

These features translate into considerable time and cost savings during mobilisation, with an average of 12 hours saved per typical 3-reel project without interim reel swaps. Additionally, an extra 6 hours are saved when clearing the deck at the end of the job. Moreover, the narrow profile of Generation 3 RDS offers more free space on the vessel or the option to charter a smaller back deck, adding further time and cost benefits.

Step 3: Overboarding - Subsea Product Deployment

During the deployment of the product subsea, the reel drive comes into action, spinning the reel in the desired direction. MDL's automated skidding and clamping system, pioneered by our flagship Generation 2 RDS, facilitates the swift movement of towers between reels, approximately 4-6 times faster than systems from other providers. Additionally, Generation 2 RDS features the integrated grillage of Generation 3.

The MDL cradle system provides ample clearance from the bottom of the reel in the cradle to the deck during deployment, offering increased flexibility for reel installation sequences and handling large end fittings, even with larger reels.

Automation is key during deployment, delivering efficiency and safety benefits. Our wireless control system allows the operator to stand in the optimum position on deck, eliminating the need for personnel working at height, as seen with other systems. It also features remote dialup for service and maintenance, providing additional peace of mind.

Beyond "lay": the applicability of RDS in other operations

The advantages of RDS extend beyond "lay" operations. When it comes to product retrieval, such as mooring line replacements or infrastructure scrapping at the end of a field's life, Steps 2 and 3 deliver similar benefits in reverse order.

Even in disposal scenarios, where you need to release yourself from the burden of product disposal, MDL RDS can provide a solution, giving flexible products a new lease of life.

We hope we managed to bust some of the misconceptions around reel drive systems and help you see a new opportunity in using or owning a modern RDS. If you’re ready to improve your projects’ efficiency, get in touch so that we can identify what system suits your needs best.