^ A sound wave is transmitted down through sediment/rock from a variety of sources. These sound waves reflect back off underground layering and are detected by geophones. You then convert the two way travel time of the sound wave (between transmission and receiving) into distance using whichever velocity of sound is relevant for the sediment/rock encountered.
For my work I'm only looking a max of around 30m below seabed, but usually no more than 5m - for pipeline routes, piling structures or platform leg settlement. Exploration geophysicists may interpret several km below ground, loking for oil/gas deposits.
I've never worked onshore but I guess the seismic lines will be cables with geophones laid out on a grid. For offshore explorarion seismic vessels may tow streamers several 100s of metres long containing the geophones. For my work we'll stick a single geophone on an ROV.
I worked on the Far Samson this year.
Which claims to be the most powerful offshore vessel ever built.
https://www.ship-technology.com/projects/far-samson/
With all the shit threads on here now this one is a great one. Thanks for something worth looking at.
^
The information for non industry savvy posters is especially helpful and appreciated.
Recently completed offshore (subsea) project in S. Thailand. My team just spent one month onboard an FPSO (floating production storage & offloading) vessel. Our task was to coordinate with divers to injection-seal around 12 subsea Ball valves on a subsea PLEM (pipeline end manifold). Valves were passing N. gas and could not be isolated for continuation of the pipeline.
FPSO about to leave Songkhla port:
Ball valves on seabed are 25 years old. Thankfully, the valves and injection nozzles are still in decent nick. Our team provided injection equipments and sealants, plus training onboard and topside comms to divers 80 meters below.
Video from PLEM: <a href="https://www.metacafe.com/watch/11989048/subsea-80m/" target="_blank">http://<iframe width="560" height="3...lt;/iframe>
Last edited by kmart; 14-11-2019 at 11:30 AM. Reason: add video
^ Interesting stuff Kmart. I've spent more hours than I like to think of watching ROVs perform similar tasks. Most of my work is deep water so everything has to be designed to be ROV friendly.
A couple of other FPSOs...
Asgard A (Norwegian Sea)
And offloading to a tanker
Norne (also Norwegian Sea)
There was talk above about helicopter accidents. In 1997 12 people were lost when a Super Puma went down enroute to Norne. I was working elsewhere in the Norwegian Sector at the time and all non-essential helicopter flights were temporarily banned after the Norne accident which meant our vessel had to start going alongside for crew changes. This didn't last long - money will always win over safety.
Another dirty looking lay barge in West Africa, the Polaris. Old and tired, but great at her job and a real work horse - a money spinner for the operators, although I think the 2015 downturn took her out of service.
The Polaris was DP controlled (using thrusters), so no anchors and anchor lines to worry about when providing survey/ROV support.
With stinger up, preparing to start a lay.
And from the same project - one of the Hereema heavy lift barges. Not a great photo as we are kept out of the way when the really expensive stuff is going on, but I think a topside was being put on it's legs the other side of the barge.
Job done, the cranes are stowed and the barge transits to the next lift. These barges travel the world, from one lift to the next.
And the Hereema Thialf in the North Sea. Weather windows are calculated before towing out a topside for a lift. The sea state limits are stringent and the last thing an operator wants is a topside stored on a barge getting caught in unexpected bad weather. If the weather delays a lift, Hereema will just keep their barge on location waiting, and smiling while raking in the money. The Thialf can do a lift up to around 14,000 tons.
Last edited by Mendip; 14-11-2019 at 08:17 PM.
^The North Sea... Wouldn't want to be on a rig there this time of year. *brrrrrrrrrrrrrr*
a great thread. and thanks to all contributors. hats off to u all.
^Yes, correct. Got it arse about face.
It was a fairly pleasant evening last night, surprisingly. There's frost in Aberdeen.
Last month on the Alba North was cold enough to freeze the balls off a brass monkey. Bitterly cold.
I'm on the chopper at 1pm today. I was gonna wrap it up for winter and fly back home to Thailand on Monday but my agency are pushing me towards a North Sea coil tubing job next week. If it's 7-10 days max I'll take it.
I went to work in April this year and our 2nd son was born end of May. I've only been home for 6 days since then.
Kmart, are you spending much time in Songkhla? I own a couple of bars and my old man has one too.
Lang may yer lum reek...
^ I missed the birth of my second daughter... I was in Aberdeen about to join a boat when she was born in Korat, six weeks early. She was due right in the middle of my next 4 week leave. The best laid plans and all that...
Congrats, by the way!
I managed to plan time off just perfect for our first boy. Second one I was at the heliport in Aberdeen going to the Elgin/Franklyn Platform. We choppered out there and couldn't land because of fog. I was delighted, couldn't wait to go for a pint and video call my Mrs. The fuckers held onto us all day and managed to get us out there at 9pm.
Alas, my days of offshore working here are mostly over. I now have an experienced Thai workforce that do all the offshore work. (We are mostly onshore-based, but get occasional specialist requests, like this one). I sometimes go to Songhkla for meetings and surveys. I'll PM you next time.
Sounds good mate!
This rig has a dedicated PlayStation 4 room.
Oh yes, here she blows.
Lucky you!
Did my eighth survival with HUET this February in Samut Prakan. Reckon I've got another three to go to see me through.
My first survival in 1991 was done in Warsash, near Southampton, UK. They didn't have a pool back then and the HUET was done in Yeovelton, Somerset. The same pool the SBS did their training in. For those that don't know, HUET stands for Helicopter Underwater Escape Training (being dunked underwater in a fake helicopter, upsidedown). Thirty years ago it was pretty frightening, my last submersion at Yeovelton was in near pitch black with artificial waves. Today, with the aging workforce and HSE ,the divers practicaly push you out of the damn thing. But everyone hates it, none the less.
The FAULK centre at Samut Prakan this year. The HUET training module.
A few crew changes...
Basket transfer, West Africa.
Even at these heights it's not much fun. Many years ago I did a basket transfer from the back deck of a small survey vessel to the Oseberg A helideck. A long way up and I damn near shit meself. That kind of stuff is banned nowadays, apart from in emergencies.
A surfer transfer. A small boat takes you out to the work vessel. Common in West Africa and relatively relaxing. Just have to time the step on to the ladder right.
And of course the helicopter. (a crew change of kine in a pic above) Dirk will be way more familiar with this than me. In the North Sea it's all survival suits and compressed air breathing sets. I absolutely loathe it. My last helicopter crew change was a few years ago in Brazil, where T-shirt and flip-flops were quite acceptable in a 5 man helicopter. I think the Super Pumas and Sikorskies of the North Sea take 18 at a time? All crammed in. Dirk?
Brazil...
But for me, the only way to join or leave a vessel, with my advancing years... Alongside using a gangway.
Last edited by Mendip; 17-11-2019 at 12:18 AM.
I have been to offshore drilling rigs a few times. Just enough times to find it exciting. I have also been lifted on- and off the vessel with a basket. If you were new you usually got the dip. That means that when you were lifted from the vessel the basket was lowered into the water just enough to get wet feet. No chance to comment on- or look for repercussions for the crane driver.
Interesting thread. My dad worked on the rigs all his life, Aberdeen mostly, a year in the US and then Singapore to see him into retirement.
He never encouraged me to follow him into the trade...
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