Which is the better system for an operator of semi-subs? To have them as DP rigs do they save money on rig moves and hiring anchor handlers to move a rig, or are they more expensive as they burn more fuel?
Are there still semi-subs with anchor systems being built, or will they die out within a generation? Most of new ones are all DP rigs that I have seen.
What are the other pros and cons comparing Anchor Systems to DP systems?
[QUOTE=follow40;131363]Which is the better system for an operator of semi-subs? To have them as DP rigs do they save money on rig moves and hiring anchor handlers to move a rig, or are they more expensive as they burn more fuel?
Are there still semi-subs with anchor systems being built, or will they die out within a generation? Most of new ones are all DP rigs that I have seen.
What are the other pros and cons comparing Anchor Systems to DP systems?[/QUOTE]
An anchor system is definitely the cheaper route from a build and operational standpoint. Sure, you have to spend money to move it, set anchors, etc… but a DP rig has to be towed too as far as I know.
[QUOTE=Saltine;131390]An anchor system is definitely the cheaper route from a build and operational standpoint. Sure, you have to spend money to move it, set anchors, etc… but a DP rig has to be towed too as far as I know.[/QUOTE]
A Maersk drill rig we were working with moved 1,500 NM under its own power. Less than 4 kts.
[QUOTE=Saltine;131390]An anchor system is definitely the cheaper route from a build and operational standpoint. Sure, you have to spend money to move it, set anchors, etc… but a DP rig has to be towed too as far as I know.[/QUOTE]
That is not entirely true about being cheaper. I can think of other pros and cons, but at the end of the day they are probably about the same to operate. The DP rigs may be a little cheaper even. You start dealing with rental equipment, anchors, synthetic rope, chain, suction piles, the huge boats required to operate in deep water, ROV crews, anchor handling companies and engineering required to set out a rig in 10,000 foot of water then DP is probably cheaper. You operate in 1500-4000 feet of water then maybe moored rigs. I have worked only on DP semis, but I have set out many anchored semis from an anchor handling vessel. To me DP is the winner hands down.
I navigated this rig from Singapore to Mexico without a tug.
[QUOTE=Saltine;131390]An anchor system is definitely the cheaper route from a build and operational standpoint. Sure, you have to spend money to move it, set anchors, etc… but a DP rig has to be towed too as far as I know.[/QUOTE]
I dont remember the last DP unit to ever be towed! I really can’t see the benefit anymore in building anchored semis, and I think most drilling contractors see it the same. You also have to put it into context for day rates as well, if a moored semi gets $300-$400k a day, and thats generous, and DP Rigs can command upwards into $650K a day, that difference alone justifies the higher daily operating costs, because they are still making more money with those units.
DP units sound like they are the future, but what about for harsh weather condition in areas such as grand banks of canada or the north sea, are DP rigs able to hold their position as well as anchored in these areas?
Are anchored semis even getting built anymore? I’m not aware of any, only seen new DP units.
[QUOTE=follow40;131584]DP units sound like they are the future, but what about for harsh weather condition in areas such as grand banks of canada or the north sea, are DP rigs able to hold their position as well as anchored in these areas?
Are anchored semis even getting built anymore? I’m not aware of any, only seen new DP units.[/QUOTE]
Atwood built an anchor semi not that long ago but I do not know why exactly. I was always perplexed by the decision made at R&B Falcon to build DEEPWATER HORIZON as DP and DEEPWATER NAUTILUS as anchored. Anyone know why that was? Did Shell want anchored only?
[QUOTE=c.captain;131592]Atwood built an anchor semi not that long ago but I do not know why exactly. I was always perplexed by the decision made at R&B Falcon to build DEEPWATER HORIZON as DP and DEEPWATER NAUTILUS as anchored. Anyone know why that was? Did Shell want anchored only?[/QUOTE]
Shell did want the moored rigs. Not sure why but that is what they wanted at that time. It was pretty amazing what how we moored the Nautilus in Great White (Perdido) on Suction piles, vertical lift anchors, synthetic rope and submersible buoys. The Nautilus was DP assist at one time. It had a few thrusters, before they were ripped off during hurricane Rita. After that it was a little tougher to set her out. I have moved that Nautilus several times. Shell and Delmar had a very good relationship.
vertical lift anchors …wanted to know what they were, so I google image searched…not what I was expecting!
[QUOTE=z-drive;131602]vertical lift anchors …wanted to know what they were, so I google image searched…not what I was expecting![/QUOTE]
Good one! And an interesting search!