MiniROV manufacturers have worked hard to get past the many challenges it has faced after the deployment of smaller ROVs in offshore applications. During this time, they were able to better their operator’s capabilities using state-of-the-art technologies.
For instance Vortex generators permit MiniROVs will fasten firmly to and creep around structures, which keeps operators from needing to send out dive teams to do surveys. And, with the Enable-IT PoE and Ethernet Extender products, low-drag, long distance tethering has improved significantly.
This enabled MiniROVs to keep up with their extreme maneuverability while they offered the capability to hand-launch and carry out larger, work-class ROVs.
MiniROVs: What Are They Actually?
MiniROVs are actually bigger than micro ROVs, which don’t have the ability or payload to work in currents or handle more than one camera, lights and up to two sensors. With the MiniROV, however, the bigger size allows for a more powerful set of tools, sensors and other technologies.
MiniROVs are smaller than standard ROVs, which typically need the costly, complicated Launch and Recovery Systems (LARS). LARS isn’t needed with MiniROVs, and they can be used to with their own tether if strong enough. This is when more decisive technologies start.
What Are The Primary MiniROV Technologies
The initial design for MiniROVs was geared toward shallow water applications. However, before any operation beyond 1,000 meters, there were a few challenges that had to be addressed. What challenges?
• Miniaturization of control electronics
• Design of lightweight pressure housings
• Data and power transmission over extremely long umbilical lengths/tether/cable
In the last decade, this industry has been able to effectively get past these challenges and help the MiniROVs to copy the abilities seen with the larger systems. A number of MiniROV manufacturers have come up with technologies that weren’t thought up initially but have proven to be extremely useful in various offshore applications.
Why Tethers Are An Issue For MiniROVs
When it comes to tethers, they’re an issue in the deep water for ROVs due to their thickness and coarseness. It causes the tether to have a cumulative drag, and leads to more thrust and need for better maneuvering from the smaller ROVs.
The issue is non-existent when the tether is hydrodynamic streamlining because the cable sheathes are smooth. However, thinning the tether at the cross-section is rather difficult. After all, the MiniROVs need to send and receive an array of signals and a significant amount of power.
This generally needs a lot of fiber, shielding and wiring.
But, with the PoE and Ethernet extension technology, the cross-section of tethers thins out to 8.99mm, which is much less than you see with traditional ROV tethers (typically 20mm). Enable-IT, the Ethernet extension technology inventors, came up with the ability to shrink the size of deep sea-worthy Ethernet extenders.
Once this was accomplished, the manufacturers of MiniROV were able to increase their transmissions and send PoE to MiniROV with just one to two pair of standard copper wiring. The Ethernet extenders can send this information beyond the 328 feet Ethernet limit – no gaps in between. Basically, less wires leading to extremely thin, all-copper tether that produces less drag on the MiniROV. Thus, MiniROVs can be lowered – by hand – into the water. There’s no reason for a pricey launching system.
What About Non-Magnetic Vortex Generators?
Non-magnetic vortex generators have been extremely useful, being a crawler attachment that gives MiniROVs the ability to crawl pipelines, hulls and an array of other structures. Vortex generators don’t use thrusters or magnets – they used impeller – to produce a low-pressure pocket under the MiniROV.
There are a number of benefits operators have with this kind of system:
It has an excessive amount of force that ensures precise operations even when the vessel is moving or subjected to strong currents when in port. It permits operators to operate their vessels in a safe, economical way that doesn’t require the need of dive teams… even in hostile environments.
Cameras and imaging equipment generate superior-quality data and images because they’re maintained at a safe distance from the main structure.
MiniROVs offer stability, and ensures operators are not near as tired and will focus on the incoming information.
A Look At Automated Navigation
In the past, technologies that needed automated navigation – Doppler velocity logging – couldn’t be easily diminished for MiniROV use. Still, a number of operators were happy to find out that miniROV’s had an automated navigation built into them. The MiniROVs, using a technology similar to sonar tracking, does a number of tasks including but not limited to:
• Locks onto a target and traverses by waypoint
• Maintains a position
• Do a programmed search
A single MiniROV can circle around the locked-on target. The reality is that the benefits of this option are rather translucent.
For instance, it reduces the chance of an operator feeling fatigued, boosting the opportunity for success in completing other tasks like data monitoring. Plus, with this type of navigation, it can save operators a lot of money and time.
How MiniROVs Work To Address Company Situations
The MiniROVs’ size, abilities and agility does just as well as the larger version of the ROV. This was the case for FMC Technologies, a well-known oil and gas supply service company, which needed to cap off three subsea manifolds that were missing their small valve caps that had been installed.
Unless these caps were installed, there was no way for oil production to commence. And, trying to recover the 160 ton manifolds meant spending millions of dollars. FMC went to their ROVs to solve the issue but realized right away that neither the observation class ROVs or work-class ROVs would do the job in the tight operating space.
The company then decided on MiniROVs, picking an operation where the MiniROV was equipped with a special torque tool that would tighten every cap. FMC used the work-class ROV to put the MiniROV in place, which was situated in a basket, close to all manifolds and the tether released. This means the bigger ROV was supporting the MiniROV while it worked, which it did.
The operator of the MiniROV was able to get through the first manifold, even though it was a bit tight. It got to the right valve and tightened the cap with the torque tool. With the second and third manifolds, the relevant valves had temporary test caps, which means the miniROV needed to remove them and recover it before the actual cap could be put in place.
With the second manifold, the WROV accidentally caused the basket of the miniROV to open up but was quickly addressed. On the third manifold, the operator used a small mirror with the torque tool, allowing the operator to see the test cap. The final cap was put into its place.
When MiniROV’s Can Be Used To Supplement ROVs
MiniROVs are useful in many applications such as those that need crawling and/or an attachment. For instance, in 2009, the UK-based Inspectahire carried out a survey on a Persian Gulf oil rig, analyzing the oil rig’s legs on one of the world’s biggest oil and gas exploration and production companies. The rig was constantly under the tide’s pressure, and analyzing the legs previously using an observation class ROV proved to be fruitless.
The company knew it needed something more… something better!
Upon hearing about the crawling aspect with MiniROVs, the company opted for them with amazing results. Their tethering and portability features allowed Ispectahire to carry out their inspections successfully, launching their MiniROV and directing it on the platform above every leg.
According to the company’s managing director Cailean Forrester, the Little Benthic Crawler is a groundbreaking, state-of-the-art piece of equipment, enabling them to carry out the survey in an effective way and get past the issues they were previously dealing with.
Their alternative? Use divers who would need magnetic clamps to make sure the current didn’t sweep them out to sea.
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