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  1. #426
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    My apologies I miss read your post, thinking the initial survey utilised sensors on the ships hull.

    Does your software alert the person watching the video feed in realtime or is it up to the operator to identify any anomaly/unexpected event ?

    Quote Originally Posted by Edmond View Post
    Without wanting to go too OhOh
    Not having any experience of managing subsea surveys, unlike yourself, I may ask simple questions. To educate myself, along with I hope many reading this thread, here on TD.

    Every "industry" has their own meta language which may be unfamiliar to us Joe Bloggs.
    A tray full of GOLD is not worth a moment in time.

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    Quote Originally Posted by Mendip View Post
    Lom... your powers of detection are obviously not limited to Coco's thread!
    I happened to notice it when you mentioned Wisting and I checked the marinetraffic site to see where you were, nearby to you was a pearl band of brown dots which identified as Ram Tethys Cable and that made me curious.
    (Curiosity is a ferkin disease of mine which has been itching me since I was a toddler, can't get rid of it)
    May the bridges I burn light my way

    There is no plan for no deal because we're going to get a great deal - Boris Johnson in HoC 11 July 2017

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    Quote Originally Posted by Mendip View Post
    The gravel is poured down a chute that extends down to the seabed.
    That makes sense.

    Cool info in that post, cheers.

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    Mendip,
    what do you explain to us innocent is quite a unknown knowledge about all the associated activities to the cable (or a pipeline) laying. It's not just to lay a cable and bye-bye, never see again.

    So, there are companies that can do the job with more or with less quality of these additional activities. Is there any QC institution that supervise whether everything has been done as per specs? And I assume that for each project a detailed specs is created that different companies are bidding for.

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    Quote Originally Posted by OhOh View Post
    My apologies I miss read your post, thinking the initial survey utilised sensors on the ships hull.

    Does your software alert the person watching the video feed in realtime or is it up to the operator to identify any anomaly/unexpected event ?
    No problem... surveys are often conducted using vessel hull mounted multibeam systems, usually in conjunction with a towed 'fish', a torpedo-like gadget fitted with side scan sonar and sub-bottom profiler. The problem with using vessel mounted equipment is that the ships movement (pitch and roll) effects the data, with errors exaggerated the deeper the water. The ROV is independent of the ships movement and gives a stable survey platform, making us less weather dependent for some surveys.

    The online surveyor can watch all data coming in, in real time, and will hopefully alert us to anything significant... but in reality... (there is wifi throughout this boat)

    It used to be possible to monitor real time video coming in during visual surveys. but now for some surveys the survey speed can be so fast (4 to 5 knots) traditional video can't be used due to resolution limitations. A new system being piloted takes rapid HD digital stills which later have to be stitched together. They are impossible to view in real time.

    Quote Originally Posted by Klondyke View Post
    Mendip,
    what do you explain to us innocent is quite a unknown knowledge about all the associated activities to the cable (or a pipeline) laying. It's not just to lay a cable and bye-bye, never see again.

    So, there are companies that can do the job with more or with less quality of these additional activities. Is there any QC institution that supervise whether everything has been done as per specs? And I assume that for each project a detailed specs is created that different companies are bidding for.
    The fabrication of any cable, or pipeline lengths in the yard, is subject to stringent QC. For a pipeline, the corrosion coating and reinforced concrete weight coat will be subject to regular NDT and all well documented. On a lay barge every weld (field joint) joining the 12m pipe lengths is xrayed and documented.

    When a pipeline is laid, first an as-laid survey is carried out to document position and condition. Following flooding, pigging, any intervention works and hooking up to well-heads etc an as-built survey is carried out. This documents the condition of the pipeline on commissioning and handing over to the operator. All surveys are overseen by a client representative from the future pipeline operator. The operator will have to get government permission and a license to operate the pipeline and I imagine the various survey reports will be included in the mountain of paperwork assessed. In Norway it's the Norwegian Petroleum Directorate (NPD) who issue licenses to operate pipelines (I think). In the UK it would be the DoE.

    All subsea assets have to surveyed/inspected according to guidelines to allow the operator to keep producing hydrocarbons. This may include a visual introspection every four years and acoustic inspections in between, etc etc, depending on location and vulnerability.

    Everything is heavily controlled by bureaucracy, which is great for a greedy day-rater as it produces more work! As I mentioned before, the wonderful thing about inspection is that the work carries on regardless of the state of the industry.


    But today we are surveying the seabed for another new development (Halten Øst) that will tie in to existing infrastructure at Åsgard in the Norwegian Sea. New developments are also good for a greedy day-rater since it means there will be construction work followed by an increased inspection load in the future! Norway is looking very buoyant just now... despite the best efforts by Covid.

    The ROV being launched today to survey a future route... the Transocean Norge drilling a production well for the same project.


  6. #431
    Thailand Expat TheRealKW's Avatar
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    Quote Originally Posted by Mendip View Post
    also good for a greedy day-rater
    A day rater being someone paid per days they work. Contract work, such as yourself?

    What other options exist? Someone employed full time by BP or an employer like that?

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    Mendip
    As I sit and enjoy my morning coffee I just want to say thanks for the technical information it is very interesting.
    I am also impressed by the way you have virtually future proofed your employment prospects but increasing your qualifications.
    I hate to admit it but maybe there such a thing as a "smart" geologist after all!

    Have you had much to do with the placement of the "gravel"? I used inverted comma's as to me they are rocks not gravel, gravel is what they use to built roads and is a much smaller particle size that what they are placing. The reason i ask is because I am interested in the placement rate they achieve and the wear sustained on/in the drop pipe.

    I wonder what they did in the days before there were computers?

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    Thailand Expat lom's Avatar
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    Quote Originally Posted by ootai View Post
    I wonder what they did in the days before there were computers?
    My post-lockdown commute back to work-gperez_oilwelllubbock-jpg

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    @mendip - thanks for the pics & stories. Yes, keep this thread going. The info is interesting to land-based mammals like me (and others here). Like ootai, I sometimes browse TD during my morning coffee or during work-breaks (am not interested in the pissfights or mongering threads, which seem to be surfacing the past few days, heh). Cheers & keep on keeping on!

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    Quote Originally Posted by Mendip View Post
    I'm missing my morning cup of tea
    I thought you'd have someone local back in Blighty keeping you supplied with the West Country brew. I brought some of this back last trip and it is way better than PG Tips. At the risk of starting something, I'd say I prefer it to the (also good) Yorkshire tea.

    Attachment 56944

    And while I'm here, maybe someone can explain to me why the first time I upload the image it refuses my every effort to enlarge but the second time in the same message the same image will enlarge.
    My post-lockdown commute back to work-miles2-jpg

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    Quote Originally Posted by ootai View Post
    I wonder what they did in the days before there were computers?
    I believe there were not so many oil and gas pipelines around in the 60's and 70's. The processing platform was positioned over largest field the gas and oil clensed and then pumped ashore. The smaller ones were not viable.

    Nowadays there are lots of the smaller fields linked to a master processing platform or as we have seen here in this thread, a floating storage and processing platform.

    They sent these guys down with a crayon and a board. Annual surveys to find any problems, plan of action devised and the necessary equipments and divers taken to the offshore platforms and down they went.:



    Here's a link to a BBC radio programme describing their risks and rewards. In the 1970's allegedly £18 per day.

    Witness History - Pioneer North Sea Divers - BBC Sounds

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    ^I had a friend years ago who was an oilfield diver, got his training in the NZ Navy then made a good (but fairly brief) career out of diving under offshore installations. Made a ton of money but his stories of the depths they use to go to and what it was like being that far down scared the shit out of me. No thank you!

  13. #438
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    Quote Originally Posted by TheRealKW View Post
    A day rater being someone paid per days they work. Contract work, such as yourself?

    What other options exist? Someone employed full time by BP or an employer like that?
    Yeah... day-rater, freelancer, freeloader... there's many terms. Because the industry can be so erratic the contractors have to rely on a certain number of freelance personnel, or else risk the expense of a load of staff during a downturn. Many spreads run on around 60% staff / 40% freelance. I work for the contractors but there will be a client rep on board from the oil company we're working for, eg BP as you mentioned. This current work is for Equinor (Statoil). The client reps from the oil companies tend to be staff company guys, although when things get busy of course more freelancers turn up.

    Personally I can't see the point of being staff in such an unstable industry... these days picking up just one decent contract can save a contractor, or at least see them through another year. Staff guys claim they have more security, and maybe they do get some kind of a reliable work rota... but they'll be dropped like a stone during a downturn.

    For me, once I finish this work I'm free to head straight to another contractor who have more work during the winter. I never say no and work long trips... the contractors don't get that from their staff.


    Quote Originally Posted by ootai View Post

    "smart" geologist...
    I've been called a lot of things... but never been accused of that before.

    Praise indeed from a mining engineer... that must have hurt!

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    Quote Originally Posted by ootai View Post
    Mendip

    Have you had much to do with the placement of the "gravel"? I used inverted comma's as to me they are rocks not gravel, gravel is what they use to built roads and is a much smaller particle size that what they are placing. The reason i ask is because I am interested in the placement rate they achieve and the wear sustained on/in the drop pipe.

    I wonder what they did in the days before there were computers?
    Yes Ootai... as a geologist I should be more aware of my Wentworth's scale, but we have to dumb things down for the engineers!

    The 'gravel' dumped is much larger than gravel and the term 'gravel dump' is a generic one used in the industry, although they are often called 'rock dumps' as well, which should please you. I would say the particle size would be more akin to cobbles (64mm to 256mm).

    We carry out an inspection, and if for example a pipeline has a lot of long freespans (unsupported sections) it may be 'rock' dumped for stabilisation and support, and to prevent further scouring. These days the tendency is to hold off rock dumping as the initial scoured freespans form as part of the self burying process, depending on the sediment. A self burying pipeline in sand saves a lot of money... although once you have boulder clay a pipeline will never bury itself.

    Other small diameter flowlines may be rock dumped to prevent upheaval buckling... where a hot pipe will deflect upwards due to heat expansion. These flowlines are usually at a wellhead, and will first be trenched, and if that hasn't worked, will have rock dumped as well.

    Cables and pipelines will also be rock dumped in trawling areas for protection.

    I have never been involved with rock dumping, although we will maybe carry out a pre rock dump survey (with multibeam echosounder) and a post rock dump survey. Models of the seabed, pre and post dumping will be compared to calculate the volume of rock that has been dumped.

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    Quote Originally Posted by Mendip View Post


    I've been called a lot of things... but never been accused of that before.

    Praise indeed from a mining engineer... that must have hurt!
    You have no idea how much it hurt but I believe in giving credit when it is due.

    As for the "Wentworth scale" I had to look it up on Google so in future please dumb it down a little more for me, thanks.

    Many years ago I had an experience that really bought home the importance of defining exactly what you mean.
    I was spending some time with a couple of Metallurgists and they were complaining about us Underground guys sending them too many "big rocks".
    I asked them to describe what they meant by "big rocks" and they said anything that blocks the feeder under the ore stockpile, so probably anything larger than 6 inch (150mm) diameter.
    I asked them if they had ever been underground and they hadn't so i arranged a trip for them to come with me for a look.
    I took them to a stope that was in production and showed them what we (UG guys) called a "big rock" it was the size of a house and couldn't be moved using the remote loaders which were capable of lifting 15 tonne plus. To move it we would have to break it up somehow, how we did this is in itself is a long story.

    Another aspect of "placing fill" which is how I would describe what you are doing when dumping gravel is what is the maximum particle size that can be placed. The largest particle should be no more than 25% of the diameter of the hole/pipe it is going to be placed in. The theory behind that is that any larger and they can form a bridge across the hole and cause a blockage.

    Just in case you didn't know the weather here has been quiet hot lately so even if you did or were able to come back for a trip you would melt.

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    ^^^^ OhOh, a good friend of mine started in this industry in the early 80s, about ten years before me. In those pioneer days he carried out annual pipeline inspections from a manned sub. A pilot and observer were crammed into the two man sub, which was then flown along one side of the pipeline, and then turned around and flown along the other side, with the observer drawing diagrams and making notes in his notebook all the time... until the batteries started running out. Rather him than me.

    Incidentally, I also used to know a manned sub pilot well. An Aussie guy, who before going offshore was a pilot in the Royal Air Force when he flew Vickers Valiants. He had some good stories to tell. There used to be a lot of ex forces guys working offshore but there seems to be many fewer now. I don't know why... maybe it has become too specialised.

    ROVs transformed the industry in the 80s. The next big development will be AUVs (Autonomous Underwater Vehicles) where a mother ship will launch a fleet of AUVs which would be programmed to all independently carry out surveys of various pipelines, before being recovered and the data downloaded. The technology is just about there but a huge investment would have to be made to make it efficient and viable. Safety would be an obvious issue with unmanned vehicles flying around close to platforms.

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    Quote Originally Posted by Mendip View Post
    The next big development will be AUVs (Autonomous Underwater Vehicles) where a mother ship will launch a fleet of AUVs which would be programmed to all independently carry out surveys of various pipelines, before being recovered and the data downloaded. The technology is just about there but a huge investment would have to be made to make it efficient and viable. Safety would be an obvious issue with unmanned vehicles flying around close to platforms.
    Enter Elon Musk.

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    Quote Originally Posted by ootai View Post
    I wonder what they did in the days before there were computers?
    As with all industries, computers have transformed offshore work.

    Just one small example... back in the early 90s when mobilising for a project we would pack boxes full of literally hundreds of floppy discs containing navigation files for the pipelines to be surveyed. Once out in the field, if we'd forgotten one floppy it would mean a return to shore, or more likely a helicopter to bring out the disc, which would then have to be transferred from a platform to our boat. Now of course all that will be done with an email attachment.

    The biggest transformation I have seen was the introduction of GPS. Before satellite positioning we relied on survey land base stations and it was hit and miss if we were anywhere near where we though we were. GPS changed all that... at first it was accurate to around 17m but the first Gulf War changed that, and once the Americans took out the error code it became metre accurate, at least for surface positioning. That was when we discovered that buried pipelines we thought we'd been surveyed every year were in fact 200m from our survey lines.



    Quote Originally Posted by Shutree View Post
    I thought you'd have someone local back in Blighty keeping you supplied with the West Country brew. I brought some of this back last trip and it is way better than PG Tips. At the risk of starting something, I'd say I prefer it to the (also good) Yorkshire tea.
    Controversial to say the least... you've really put this Miles Tea up there on a pedestal. But as it's from the West Country I'll have to give it a try!

    It's gone on my list... I just have to get it over to Norway somehow.


    Quote Originally Posted by Edmond View Post
    Enter Elon Musk.
    Other people will have a much better knowledge than me... but my understanding is that once Elon Musk has his low orbit satellite network up and running it'll transform data streaming capabilities... and then data acquired offshore will be streamed to offices for interpretation and processing. That will change things big time... I hope it doesn't happen too soon as I need another 10 years out of this.

  19. #444
    Hangin' Around cyrille's Avatar
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    Quote Originally Posted by Mendip View Post
    you've really put this Miles Tea up there on a pedestal. But as it's from the West Country...
    It's not from the West Country though is it, any more than Yorkshire tea is from Yorkshire.

    All a bit silly, really.

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    ^ Hence my tongue in cheek comment.


    Another type of data we collect during seabed surveys is side scan sonar. Old technology that's been around for ages but it still has a place. Whereas the multibeam echosounder measures distance from sensor to seabed, so you can build a 3D model of the seabed, side scan sonar displays the intensity of returns.

    Sound pulses are transmitted and received after bouncing back off the seabed. The more reflective the seabed the stronger the return. Sand will give a stronger return than fine clay, etc, and with experience you can picture the seabed sediments from the side scan sonar record. Seabed objects, known as targets, will give a very strong return since they offer a greater angle of incidence and less of the transmitted signal is reflected away. Any object offering relief will produce a shadow (from the transmitted signal) therefore for a debris search you tune in to look for shadows (and straight lines for man made objects). Imagine a torch being shone across the floor.

    Side scan sonar gives a 2D record of the seabed. Here's fine marine clay (low reflectivity) with hard boulder clay coming close to the surface (higher reflectivity with targets/boulders). The linear features are trawl scars. The record was collected at 75m range (75m either side of the ROV. The path of the ROV is marked by the central strip).



    Compare this to a 3D model made from multibeam echosounder data which gives a 3D model but no indication of texture (purely distance from sensor). If you combine the two you get the seabed profile with sediment texture.

    Boulders along the shoulders of an iceberg ploughmark in a 3D digital terrain model from multibeam data. Engineers like this kind of presentation because it's so easy to visualise the seabed.



    Mosaics can be made by combining many strips of side scan data. This can be for a site survey before a template or platform is installed, or to cover a search area ensuring all seabed within the search area is imaged. Here is a 700m x 700m site survey area. The linear high reflectivity is hard clay along the shoulders of iceberg ploughmarks, the low reflectivity is soft marine clay deposited in the troughs.



    Side scan sonar is the tool of choice for a debris search. Anything offering relief should be resolved and produce a shadow (so long as you have a flattish seabed), and you're looking at raw data, so straight lines remain straight with no smoothing applied. Straight lines don't exist in nature so you tune in to that.

    As with other sensors, high frequency sound pulses give better resolution but less range, low frequency vice versa. We use 600 kHz for 75m range and 200kHz for around 250m range. The search for MH370 used a fleet of AUVs collecting side scan sonar at lower frequencies still, but at ranges of 500m plus (I think). Each survey line by each AUV would therefore cover a 1km corridor of seabed.

    A small wreck around 30m long from a route survey a while ago...



    And a much better image of a wreck from a project many years ago. This one lay close to a proposed pipeline route.



    I've posted the story of this wreck before.

    Random offshore pics
    Last edited by Mendip; 04-09-2020 at 01:08 PM.

  21. #446
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    Quote Originally Posted by Mendip View Post
    That was when we discovered that buried pipelines we thought we'd been surveyed every year were in fact 200m from our survey lines.

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    Quote Originally Posted by Mendip View Post
    That was when we discovered that buried pipelines we thought we'd been surveyed every year were in fact 200m from our survey lines.
    "Someone™ has moved the pipeline"

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    Quote Originally Posted by Mendip View Post
    The next big development will be AUVs (Autonomous Underwater Vehicles) where a mother ship will launch a fleet of AUVs which would be programmed to all independently carry out surveys of various pipelines, before being recovered and the data downloaded. The technology is just about there but a huge investment would have to be made to make it efficient and viable.
    I read about one in the news recently - last week I think. Did a job somewhere.

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    ^ It could have been the Seabed Constructor?

    An old friend of mine on this boat worked on the Constructor during the search for MH370, although I have no idea what she's doing now.

    This boat has a fleet of 8 AUVs, and uses unmanned surface vessels to receive satellite navigation and then relay acoustic positioning to the AUVs.





    Sounds pretty advanced... and meanwhile I've spent 2 hours tonight battling with a printer trying to get a pdf to fill the page.

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    We finished the project up north at the Åsgard field and spent nearly two days transiting southwards through bad weather. Now we're alongside at the CCB offshore base, just north of Bergen.

    There's more bad weather forecast, which is bad for me because I've had enough of this work and have another job to go to, starting 21st September.

    Meanwhile we're mobilising for the next couple of weeks work.

    Those huge metal cylinders on the quayside are suction anchors, used for the anchoring systems of FPSOs and the like.



    And that yellow thing on the flatbed is a boulder grabber. An upcoming project for us requires the identification and removal of seabed boulders prior to template installations.



    Never a nice sight... these drill rigs should be out working. Hopefully they're just in for some refurb. There's the leg of a jack-up just visible at the left of the picture as well, left of the crane.



    The COSLinnovator (yellow) and the Transocean Arctic behind are designed for deep water harsh environments.



    And another drill rig and jack-up across the bay... it's unusual to see so many rigs not working at this time of the season in what was set to be a very busy year. Not a good sign, and hopefully not a long term consequence of Covid.

    Last edited by Mendip; 05-09-2020 at 06:09 AM.

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