Rigs, Platforms and Oil Fields

[ombugge]

To kick off this new thread I will post a few pics from the Kikeh Field, offshore Sabah, East Malaysia, taken a couple of weeks ago.

This contains nearly everything that is covered by the thread.

Rig: Ocean Rover drilling Production Wells in the Kikeh Field:

Abt. 3,950 ft. / 1,200 m. water depth at the Kikeh Field, which is relatively shallow in today's context. (The record is over 10,000 ft. WD in GOM and Brazil)

Kikeh Spar: Production unit in the Kikeh Field:

The Spar is afloat and permanently anchored.

FPSO Kikeh w/ export tanker astern:

(Sorry, not a very good image due long range)

Crew/Utility Vessel "Pelican Glory" alongside "Ocean Rover" for crew transfer:


AHTS " Normand Ivan" approaching for anchor handling:


Dual purpose Anchor Winch on Ocean Rover: (Chain & Wire)

750 Kips (340 m.t) max. pull.

Traction Winch for the wire:


Wire Storage Drum for 8,000 ft./2,440 m. x 3 1/2" diam. wire:

Abt. 5,500 ft./ 1,675 m. of wire + 3,500 ft/ 1,070 m. chain is deployed at this time. (8-point mooring system)

The BOP Stack is on deck during Rig Move:


Marine Riser stowed as well:


The rig was moved between two locations in the field, which took 3 day 11 hrs. 50 min., using three AHTS; Normand Ivan, 240 t. BP, Normand Atlantic, 220 t BP (Anchor Handling) and Sanko Brilliance, 153 t. BP. (Towing)

At a daily cost of approx. USD 1 Mill. it is no wonder the Operator is in a hurry to get things done. My job was to do an audit on the performance and advise on ways to improve performance.

[ombugge]

I just browsed through the "old" Supply Boat thread and realised that there are at least 15-20 posts that rightfully should belong under this thread, mostly posted by me.

But I also realized that it isn't as simple as all that. If I where to move my posts, the comments and answer to these same posts would be "hanging in the air".
If all those posts were just copied here, all it would do is fill the forum with unnecessary duplicates, which serve no purpose either.

I therefore suggest that past sins are left well enough alone, and any future postings on the subject of "Rigs, Platforms and Oil Fields" etc. are posted here.

Since I have been the main sinner, I would probably also be the first one who has to follow my own advise as well.

[pakarang]

I therefore suggest that past sins are left well enough alone, and any future postings on the subject of "Rigs, Platforms and Oil Fields" etc. are posted here.

Since I have been the main sinner, I would probably also be the first one who has to follow my own advise as well.

I agree, we'll leave them where they are.... but also, these are not the worst sins in the world. I guess we can all live with them

Great new thread though!

[ombugge]

Most have probably seen the reports on the Blow-out that occurred in the Montara Field, offshore Kimberly Coast in Western Australia on 21. Aug.
The Operator for the field is Thailand's PTTEP, Australasia arm.

The J/U Drilling Rig "West Atlas", belonging to Seadrill ASA, Norway was drilling the first production well through a newly completed well head platform, installed and completed by the DLB "Java Constructor", owned and operated by Clough Engineering, Perth WA. only a few days earlier.

For those interested in seeing pix from time of the Blow-out and evacuation, here is a link to Perth Now: http://www.news.com.au/perthnow/stor...rom=public_rss

The relief rig "West Triton" was transported down from Singapore to drill a relief well in order to kill the blowing well with heavy mud.

Here is the rig on arrival at the site, 11. Sept.:

(c/o PTTEP)
Seen in process of pre-loading prior to elevating to drilling air gap.

The distance between the two is approx. 2 km. They will drill a diverted hole and try to intersect with the blowing well.
Not an easy task when you know that their target is a 9 5/8" diam. Casing.

A few days ago, while attempting to kill the well, it caught fire. Here is a string of pics received from a private source from an attempt to put out the fire:

Note that the Derrick is still standing.

Slightly different angle, ready to move closer from up-wind side:


The pics are now a bit blurry as the photographer had to move into the wheel house and water curtain is activated:


Fire monitors at full blast while moving ever closer:


It appears to work:


Moving a bit further away:


No, the fire is still there, but reduced in intensity:


First attempt aborted:

Note that the derrick is no longer erect. (Cold water on hot metal makes it brittle)

Here is a pics from the side: (Pix taken from Flicker)

The derrick has fallen inboard and taken one of the crane booms with it.
The Dog house is totally gone and the Cantilever appears to have been bent.

The well has now been killed and they are planning to plug and abandon it a.s.a.p. HOW is not yet clear.

It is going to be quite a job to get this rig back down in the water and away from the platform. The cantilever have to be retracted or removed and the jacking system on the aft legs is bound to be badly damaged or destroyed.

[pakarang]

This fire is really intense. Also, these images really gives an idea of the heat and extent of the damages. A chill goes down my spine...

[pilotdane]

Amazing pictures.

So is West Triton going to have to drill and actually hit the blown out well hole or do they just have to get close and start pumping mud?

How deep is the water where the rigs are working? Since West Trition is 2km away from the leaking West Atlas well I assume that it will take several km depth to get the new well over to the leaking one. I also assume that the well must start vertical for a distance before they can turn for the leaking well. That much drilling will take a while.

[ombugge]

Amazing pictures.

So is West Triton going to have to drill and actually hit the blown out well hole or do they just have to get close and start pumping mud?

How deep is the water where the rigs are working? Since West Trition is 2km away from the leaking West Atlas well I assume that it will take several km depth to get the new well over to the leaking one. I also assume that the well must start vertical for a distance before they can turn for the leaking well. That much drilling will take a while.

The water depth is around 90 m. (300 ft.) only, judging from the length of legs remaining above the jack houses.

As you will see from the above post the West Triton arrived already 11. Sept. to drill the relief well, which must have been completed some time ago since they were attempting to kill the well when the fire broke out.

From reports and pics taken during drilling of the relief well, it looks like it was mainly gas escaping. (Only abt. 400 Bbls./day of oil reported to have leaked out)

I don't know the details of this incident and how deep they had got when it happened, but on the pictures taken as it started (http://www.news.com.au/perthnow/stor...rom=public_rss) it appears that the well fluid is coming out outside the conductor. This could indicate "shallow gas", or that they have drilled "open hole", using the 9 5/8" casing as their drill string. This is quite common in Gulf of Thailand and may have been adopted here, but that is just speculations.

If they had set and cemented the 9 5/8" casing they should have been able to shut in the well with the BOP when they took a "kick". If so, they would be able to kill the well with heavy mud. Such gas "kicks" are not unusual and the whole thing would have been a non-event, except for the people on board and the Operator.

As for the depth to which they had to go to "kick off " to drill +/- 2 km. horizontally towards the blowing well? It depends on the formation, but normally not all that deep.
Maybe 300-400 m. (1000-1300 ft.)

If the target was at shallow depth below seabed they may even go down as far as required to build up the angle, drill a horizontal section and then drill upwards at the end. The drill bit is steerable and in exploration drilling it is not unusual to "bend" a well both vertically and horizontally to hit several targets with one bore hole.

This became a lot of guesswork. Better wait to see the official report.

[ombugge]

Here is the latest on the West Alpha situation, taken from Rigzone:

The fire on Seadrill's West Atlas jackup and PTTEPA's Montara wellhead platform in the Timor Sea was extinguished on November 3, 2009, following a successful operation by Seadrill's West Triton jackup to intercept and kill a leaking well.

Seadrill is now working to assess and establish the damage to the West Atlas. Visual inspection confirms that the rig's steel cantilever structure, which is extended over the Montara well-head platform, has been buckled and deformed by the fire.

The next step is to send a specialist team onboard the West Atlas to establish whether it is safe for additional personnel to board in order to continue well capping operations and to do a full assessment of the structural damage to the West Atlas.

Preliminary indications, based only on the visual inspection of the damage, indicate that it could take a number of months to remove the West Atlas rig from the vicinity of the Montara wellhead platform.

The West Triton currently remains on location, approximately two kilometres from the West Atlas, as it is still required by PTTEPA to monitor and complete well plugging operations.

[pilotdane]

WOW! I have been on some tough machinery installations. I cannot imagine what it is like to work on a fire damaged platform at sea. I hope they are paid well.

[ombugge]

I almost forgot about this thread and posted picture of the Deepwater Horizon fire and sinking under the Offshore Vessels thread.

Every time something is reported in the media about the Offshore Oil and Gas Industry there is a great deal of confusion about the terms used. The terms RIG and PLATFORM is use indiscriminately to describe just about anything Offshore related.

Maybe time to enlighten at least the CVF members. (The press is probably beyond salvation anyway)
The term RIG is actually the generic name for something that is used to drill wells, both onshore and offshore. (Although American Truck Drivers use the term to describe their truck)

It can be anything from a small wheeled and self-propelled Land Rig:

Used to drill small "pot holes" for shallow gas and oil, or for "work-over".

For deep wells onshore bigger rigs are used. These are assembled on site and moved on trailers between locations. (Some even by Helicopters)
Here is a diagram of the various components of a full size Land Drilling Rig:

The same basic components goes into any other Drilling Rig, whether onshore or offshore.

This is a typical full size Land Rig, able to drill to 30,000 ft. or more:


If we leave dry land, the next step is Inland Drill Barges/Swamp barges, which is a drilling rig placed on a raised deck above and ordinary barge. (Also known as a "Stilted Barge"):

They sit on bottom and can work in 5 to 20 ft. water depth in very sheltered waters. These are, as the name implies, used mainly in inland rivers and estuaries. (I have been involved in placing some of them in the "near offshore" on prepared "gravel pads" just outside Mahakam Delta, Indonesia)

The next step out into deep water were the Submersible Drill Barges:

Also bottom supported by filling ballast into the columns until they are held firmly in place by gravity. (Bottom reaction)
The picture shows one of the newest of this type, Atwood's "Richmond", able to work in up to 75 ft. water depth in reasonably benign areas like the GOM and offshore Nigeria etc.

Now we get to the true offshore Drilling Rigs, officially called "Mobile Offshore Drilling Units" (MODU), of which there are many types.
The first one is the "Modularized Platform Drilling Rig", which is placed on a fixed platform by means of Floating Crane. Each module can be as heavy as 2-300 m.t.:

Once the Production Wells are drilled, the Drilling Rig is removed and Production equipment takes it's place. (Not much used outside the GOM)

The next type is; "Self-erecting Tender assisted Drilling Rigs". This type consist of the Drill packet, which is lifted up and assembled on a Fixed Platform by a crane on the Tender Barge. The rest of the Drilling equipment is built int the Tender and does not need to be dismantled/assemble for every move. Most are barges with a 100 m.t. SWL crane and living quarters etc.

Here is a modern semi-submersible Tender Rig in operation:

Tenders can work in any water depth in which fixed platform can be installed.

There are still a few "Offshore Drill Barges" in operation. These are simple barges, anchored and with the Drill Packet permanently installed. No propulsion.
The most numerous is probably the Maracaibo Drill Barges. Here is a diagram of a typical such barge:

Used in the shallow Lake Maracaibo, Venezuela, where there are little or no tidal difference.

[ombugge]

The most numerous type of MODUs is the Jack-ups. (Officially "Self-elevating Drilling Platform") of which there are nearly 400 units in operation world wide.
The early jack-ups were multi-legged. One of the first, Mr. Louie, had 16 legs and is still in existence somewhere off West Africa as a production platform.

Here is a picture of the first Drilling Rig to find hydrocarbons in the North Sea, the Jack-up Sea Gem:

Only 10 legs on this one.
My early days in the Offshore business was with some of these old rigs, working in Indonesia, Malaysia and Brunei.
J/U "John C. Marthens" was an 8-legged rig with DeLong air operated jacking system. Originally intended to be a pier in Vietnam. A Land rig was placed on it and, viola, we have and Offshore Rig.

J/U "SantaFe Explorer" (Rig 85) was the first J/U Rig built in Europe (1956) and the first offshore rig to operated in S.E.Asia (As Orient Explorer. working off Brunei, owned by Shell)
4-legged with DeLong Hydraulic jacking system.

The J/U "Chris Seager" (ex.Mr. Cap) which was LeTourneau's Building No. 3, (also in 1956 as far as I can remember) and looked like this one:

The Helideck was originally on top of the Bow leg, which must have been quite interesting when working in shallow water.
(Luckily the deck had been brought down by the time I got involved with her)

These three were my "pet" rigs, as there were never a dull moment when moving those rigs.

No need to show pictures of the modern Jack-ups, as that is well documented in this and other threads here on CVF.

The second most numerous type of Drilling Rigs is the Semi-submersible, which was developed from the Submersible (shown above). Here is one of the early type, SEDO 135 series:

This is actually Scarabeo 3, belonging to Saipem and one of the last of the type to be built.

The modern Semi-subs has also been well documented earlier.

EDIT: I forgot Drillships. Here is an old anchored Drillship, the Energy Searcher:

I was Captain on this one for a short time back in 1997.

And a modern Dynamic Positioned Drillship:


I'll define the various Fixed and Floating Platform types in a later post.

[pilotdane]

Funny you should post this. I spent last night on Wikipedia learning about the different types of rigs.

[ombugge]

How often have you seen pictures of a Drilling Rig in the press or on TV and it is described as a Platform, or a picture of an Offshore Platform being described as a Rig?

I hope the following will interest some here on CVF and maybe even enlighten.
Here we go with a bit of clarification on the various contraptions that is commonly called "Platforms" in daily oil field lingo.

This covers very varied designs and purposes, from small Tripods, used as Well Head Platforms in very shallow water:

The function is simple to protect the Risers and support Well the Well Heads. Usually contains no processing equipment etc.
Drilling is done by a Jack-up Rig straddling the Platform.
Some has a small Helideck, which has to be removed whenever a Jack-up move in to work over the wells.

In a bit deeper water normal Steel Jackets are used. (Up to abt. 250-300 m. Water Depth)
This can be fairly simple structures, like the minimized Well Head Platforms used by Chevron in the Gulf of Thailand:


Or very large "Integrated Platforms" used in the North Sea and other places:

Where drilling, wellheads, production and injection equipment and living quarters are all on the same platform, supported by a single large steel jacket.

A more common way of developing large Oil and Gas Fields is with multiple Platforms for the various functions:

The Well Head Platforms (WHP) can be quite a distance from the Production Platform (PP) and the Living Quarters (LQ). The last two are usually connected with bridges.

A normal such Platform consists of a Steel Jacket and Topsides, which may contain "anything".
Here is a schematics of a typical small 4-pile Platform for shallow water: (<100 m.)


This is a typical such shallow water Platform:

Drilling of the wells will be performed by Drill Tender, or by a Jack-up Rig, which move in close and Cantilever the Drill Floor out over top of the Platform. (See earlier posts in this thread)

Topsides can be first stage separation, or full production, but usually remotly controlled from a larger facility, or from an FPSO anchored near by:
Here is a production Platform:


The Steel jackets are usually transported to the site on a barge, launched and up-ended and piled in place using a Crane Barge.
Topsides are then placed using the Crane barge, either in one piece or in the form of Modules.

There is another way, which is "Float Over". here is a typical Platform assambled by that method:

[ombugge]

Now, let's move into deeper water. This is a presentation of the various types of fixed and floating Production Platforms commonly used for Oil and Gas exploitation in deep water Gulf of Mexico:


Concrete Platforms are so far not part of the mix in the GOM.
Here is the Troll A Concrete Platform in the North Sea:

Of Discovery Channel fame. The tallest such structure, but not the heaviest. That title belong to Gullfax C, at 1.5 Mill. M.t.

FPSOs are not yet part of the GOM scene, but the first FPSO will be moving in this year. (Well documented elsewhere)

The Compliant Tower with tethered and the so called Sea Star where one-off attempts, while Floating Production Units (FPU) are more widely used elsewhere, notably deep waters off Brazil.

Tension Leg Platforms has been used successfully both in the GOM and the North Sea, but is not being constructed any more with the influx of FPSOs, which is less expensive and more flexible.
Here is a typical Tension Leg Platform:

On the surface it looks just like any FPU. The difference is in the Tethers and the under water hull configuration.

The latest GOM deep water developments has used the Spar technology. Here is a overview of the Spars of Technip design: (Not all for the GOM)


Most of these are built in Finland, transported to GOM by HLC:

Launched into the water, up-ended and anchored on location, before the Topsides are added by SSCV. All of which is done by foreign flag vessel, since there is no available Jones Act vessels able to perform such work, much to the irritation of American seafarers and Offshore Construction crews.

Here is a typical Spar in place in the GOM:

[wherrygirl]

Ombugge, a thank you for this from an ignoramus. I shall have to come back to it a few times to get my head round it but I found it really interesting and it has clarified things a bit for me so that I can now have some idea about what goes on off the north Norfolk coast. What was the final result of the West Atlas well? This is what they are attempting to do in the present GOM crisis, isn't it?
Stupid ignoramus questions: in the picture of the Spar being towed out how is it first "launched" into the sea, do they use a slipway as in launching ships or is it done by cranes? And why doesn't it sink while being towed? Flotation chambers of some sort? Told you they were stupid questions.

[ombugge]

Ombugge, a thank you for this from an ignoramus. I shall have to come back to it a few times to get my head round it but I found it really interesting and it has clarified things a bit for me so that I can now have some idea about what goes on off the north Norfolk coast. What was the final result of the West Atlas well? This is what they are attempting to do in the present GOM crisis, isn't it?

There is a VERY big difference here. The well in GOM is in 5000 ft. of water and there is no connection to surface any more, since the Drilling Rig has sunk and taken the riser with it to the bottom.

The relief well that was drilled to kill the W.A. Blowout was drilled from abt 2 km. away and hit the target, which was a 9 5/8" casing. That is no small feat, even with today's accurate drilling and control technology.
This is what they are hoping to do in GOM as well, but first they will be trying to cap the flowing well by placing that would look like a "funnel" over the Wellhead and connect a hose, or pipe, from the top of the "funnel" to surface, where the oil and gas can be controlled, until the relief well has been successfully drilled.
The second problem is that there is BOP Stack on the wellhead that cannot be functioned, or removed. In addition there is the broken riser to contend with, but all of that is problems that can be overcome with time and the right equipment. Hopefully the allow the best equipment in, regardless of national origin.

Stupid ignoramus questions: in the picture of the Spar being towed out how is it first "launched" into the sea, do they use a slipway as in launching ships or is it done by cranes? And why doesn't it sink while being towed? Flotation chambers of some sort? Told you they were stupid questions.

What you see on that pics is the Transport Ship (HLC) being submerged to float the Spar off his deck. The Spar is buoyant and will be towed to location by tugs. It remains buoyant at all times and use anchors or piles and chains/wires to maintain position over subsea well drilled by rigs like the Deepwater Horizon.

The process of loading and discharging floating objects from HLCs are well documented in another thread on CVF, called "Heavy Lift Carriers" (I just pushed it back on first page for you)

[Nichu]

Nice to see pictures of offshore "objects" from outside the North Sea.

Have you come across a semisub named "Nan Hai VI" ?

I did some trips on that one when it was named "Treasure Scout", and before it was sold to the PRC in 1989.
Wondering if it still is in use.

[pilotdane]

Thank you ombugge for the very interesting posts.

Do you have anything to show/tell us how they drilled accurately enough to intercept the W. A. well?

[ombugge]

Nice to see pictures of offshore "objects" from outside the North Sea.

Have you come across a semisub named "Nan Hai VI" ?

I did some trips on that one when it was named "Treasure Scout", and before it was sold to the PRC in 1989.
Wondering if it still is in use.

Yes I certainly have. She is now managed by Maersk Drilling and working in Australia.

I was first on this Rig in China back in March, 2006 to approve her for towage to Darwin, Australia.
A couple of pics taken before she departed from the anchorage somewhere off Shekou in the Pearl River Delta:




Then again in Darwin during Cyclone Monica. If you go to "World's Offshore Vessels", Page 4, Post 62, you will find a "report" about the Nan Hai VI in Darwin during the Cyclone.

Here is a picture of her at Anchor in Darwin Harbour:

which you will also find in that post.

My final involvement was for the towage to and positioning on the first drilling location in the Timor Gap area in May, 2006.

She is still operating in the same area, I believe.

[ombugge]

Thank you ombugge for the very interesting posts.

Do you have anything to show/tell us how they drilled accurately enough to intercept the W. A. well?

I don't have detailed knowledge of the technology used in directional drilling but it is quite complex, especially to hit such a small target as a 9 5/8" diam. Casing. It took several attempts at the Montara, I believe.
They use something called a steerable Drill Bit and a Mud Motor, together with very accurate positioning instruments to achieve this task.

I found this article, which draws comparison between the present GOM blowout and the one at Montara.
http://www.feedcry.com/archive/aid/6...+%3E+U.S.)Some relevant info there but, as usual also some disinformation, like the status of the Montara well at the time;
"The Montara oil well was in a much earlier stage of development than the BP well, and it had no blowout preventer on the sea floor".
This is wrong. It was a "producer" being prepared for production, not an exploration well being drilled at the time.
They are also talking about the Blowout Preventer "not being on the sea floor". The Montara well was one of several wells on a Well Head Platform, not a subsea completion. The BOP is therefore dry and on the Platform, with controls on the rig. There woulds also have been a dry Well Head on top of the well casing.

What they are trying to do now in the GOM is to manipulate the BOP that is on the seabed and attached to the Well Head, with a broken riser still attached and leaking oil. I don't know exactly what has transpired, but I believe the BOP Stack is intact, but not functioning since all connections to the surface is obviously broken.
Whether they have used up any stored Accumulator pressure, or if that is still available would be my first question. If pressure is available it is a question of being able to operate the functions, using ROVs. If not it becomes much more complicated.
Rigs drilling in Norwegian waters are required to have Acoustic Control, which can be operated from some distance, say from a Life Boat, if the on board controls (at least from three positions on the rig) are all damaged, or inaccessible. Whether this is also a requirement in GOM I'm not sure.

If anybody wonder what a BOP Stack for a rig like the Deepwater Horizon looks like, here is one on another GOM Rig:

A complex stack of Rams, one which can shear off drill pipe and at least two more which closed the well. Able to control well pressure of up to 20,000 PSI (In this case, approx 230 m.t in weight and abt. 12 m. high)
The bottom clamps on to the Well Head on the sea bed and Marine Riser connects at the top, leading up to more safety features on the rig itself.
Normal control is via umbilical to the Rig.
There is also Choke and Kill Lines to surface to enable killing the well with heavy mud, pumped in below the Rams.
All BOP Stacks are function tested and pressure tested regularly.

Here is a Dry BOP Stack on a Jack-up Rig for clarity:

This one has 4 Rams and is rated for 15,000 PSI

And this is the BOP Control Panel and Accumulators to go with it:


This is the Choke and Kill Manifold on the Rig Floor, also on a Jack-up:


This is the Remote BOP Control Panels at the Rig Floor/Driller's Shack on a jack-up:

There would also be one in the Rig Office, which is in the Accommodation block and possibly a third somewhere on open deck.

NOTE: All pictures are for illustration only and nothing directly to do with the West Atlas or Deepwater Horizon. I have no direct involvement with, or information about, any of those two incidents.