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dpack
Joined: 02 Jul 2005 Posts: 46247 Location: yes
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dpack
Joined: 02 Jul 2005 Posts: 46247 Location: yes
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Mistress Rose
Joined: 21 Jul 2011 Posts: 15996
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Shane
Joined: 31 Oct 2005 Posts: 3467 Location: Doha. Is hot.
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Posted: Tue May 30, 17 9:58 am Post subject: |
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I'm a big fan of leaving some infrastructure in place after decommissioning an oil field in selected circumstances, precisely because of the artificial reef effect.
Before I start, it's important to understand that there are, simplistically speaking, two kinds of oil rig: those that float, and those that are support by the seabed. Those that float should, in all circumstances, be towed to a yard and dismantled responsibly at the end of their working lives. This includes mobile drill rigs of the kind discussed in the "where oil rigs go to die" (strictly speaking, these kinds of rigs aren't "oil" rigs anyway" - they are rigs that drill for oil but do not generally produce it).
For those that don�t float, all equipment and structures above the water line (which generally represents tens of thousands of tonnes of steel) should also be removed and sent back to shore, along with anything near enough the surface to be a danger to shipping (unless the conservation aspects dictate otherwise, in which case access to the area should be restricted to prevent marine incidents).
A project I worked on in the North Sea some years back, and that shall remain nameless, was the first one that I am aware of that intentionally set out to study the artificial reef effect. Two years before anything man-made was put in place teams of divers were studying the full depth of the sea to perform what's nowadays referred to as a baseline environmental review, which is basically to understand the nature of the environment in which you'll be plonking your rig while that environment is still pristine. These divers reported several observations on the behaviour of marine wildlife that were new to science (but commonly observed by the amused deep-sea divers, who were all industry professionals � a special breed of person, if you�ve never met one). The resultant rigs have been in place for a good few years now, and still have a long life ahead of them, but in-depth environmental reviews are periodically carried out and will continue to be carried out over the lifetime of the facilities so that the best decision can be made as to whether to completely remove all infrastructure on cessation of production or whether to leave some in place. The cost of removing and disposing of the jackets (the steel legs that the topsides stand on), although significant, is only a small proportion of the total cost of abandoning, decommissioning, removing and dismantling an installation, so I would expect the decision to be made primarily on an environmental rather than a cost basis.
Whilst I�ve not had any feedback on the artificial reef study of the facility I mention above, I have been following similar research that we do on our facilities out here, and have seen with my own eyes the artificial reef effect. There are very few items of note in the marine landscape out here, and although we do have fields of sea grass in the coastal shallows supporting a reasonable population of dugongs and a few small reefs dotted around here and there, the deeper waters further offshore are pretty barren (with the frankly awesome exception of one of the world�s largest agglomerations of whale sharks, but they come for the seasonal tuna eggs rather than anything more permanent). One of the biggest issues we have in our oil field is keeping the fishing boats (each one a potential ignition source should there ever be a gas release) out of our 500m zones. They come day in, day out for the lucrative pickings around our rigs in a Gulf that is being rapidly emptied of biomass by overfishing, covering up their registration marks so that the authorities can�t track them down. They know they�ll more-than-likely lose their livelihoods, or at least face a steep fine if they�re caught, but they come regardless as the fishing is the best in the region. I�ve seen with my own eyes the huge numbers of fish that call the jackets of our rigs home, and love visiting the cellar deck of one of our platforms in particular as it always has countless reef sharks lazily hanging in the water underneath it. When one of them bolts for a passing fish, the whole sea comes alive as enormous shoals of decent-sized fish make a swim for it. The only reason all these fish are here at all is because of the huge metal frames that have been pinned to the seabed over the past 25 years.
When our platforms have finally had their day, I will be a strong advocate for removing everything above the water line, but I�ll feel equally as strongly about leaving as much of the steelwork as possible below the water line, because to completely remove it would completely wipe out the ecosystem that has grown up and flourished here over the past quarter of a century.
It may sound like I�m looking at things through the rose-tinted glasses of somebody who earns his crust in the oil industry, but I look forward to the day that jobs like mine don�t exist, and I hope it happens while there�s still a good proportion of today�s hydrocarbons still in the ground. In the meantime, in a world that�s going to use oil and gas regardless of who produces it or how, I�ll keep doing my little bit to make sure it�s produced as sensitively as possible. |
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dpack
Joined: 02 Jul 2005 Posts: 46247 Location: yes
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Shane
Joined: 31 Oct 2005 Posts: 3467 Location: Doha. Is hot.
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dpack
Joined: 02 Jul 2005 Posts: 46247 Location: yes
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NorthernMonkeyGirl
Joined: 10 Apr 2011 Posts: 4630 Location: Peeping over your shoulder
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Mistress Rose
Joined: 21 Jul 2011 Posts: 15996
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Shane
Joined: 31 Oct 2005 Posts: 3467 Location: Doha. Is hot.
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Mistress Rose
Joined: 21 Jul 2011 Posts: 15996
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Shane
Joined: 31 Oct 2005 Posts: 3467 Location: Doha. Is hot.
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Posted: Thu Jun 01, 17 11:41 am Post subject: |
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Mostly, I think. Until recently, jack-ups were limited to around 150 metres or so water depth, but the newer generation can now hit around the 300 mark.
Floating drilling rigs have been around for ages, so I'd imagine its the new, deeper-water jack-ups that you've heard of. I could, of course, be completely wrong You'll normally find that anything up to 150m is exclusively the realm of jack-ups, between 150 - 300m is a mix, and anything over 300m is exclusively floaters. Of course, with rig rates in freefall and units being cold-stacked all over the place, oil companies are spoilt for choice right now, so that might throw the dynamic a little - in shallower water, at least. |
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Nick
Joined: 02 Nov 2004 Posts: 34535 Location: Hereford
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Mistress Rose
Joined: 21 Jul 2011 Posts: 15996
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Shane
Joined: 31 Oct 2005 Posts: 3467 Location: Doha. Is hot.
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