bob-sez.com

I’ve been a small part of a discussion on Grist.com regarding solutions for stopping the Deepwater Horizon oil leak.

I’m going to re-post the solution contained in my latest comment regarding a solution to reduce the flow enough to allow a top kill process to work:

First, a few questions… the answers either make the ideas that follow ridiculous or elegantly simple and very effective:

Is is safe to assume the drill head is stuck in rock below the bottom of the casing?  Wouldn’t that make an ideal “anchor” for a gradually-introduced mechanical block (explained shortly)?

Does the relief well solution or directional bore that would be used to kill the well require the drill stem be removed?

How is the drill stem assembled?  Threaded sections?  Pins? What is a typical drill stem diameter compared to the casing over the depth of the well? Would a properly sized pipe be able to fit over the drill stem and make it all the way to the bottom?

The following I like better for the mechanical blockage aspect and it involves a series of simple self-capturing/anchoring devices on pipes put on the drill stem then pushed to the bottom of the casing to GRADUALLY reduce the effective diameter of the well bore, or increase the effective diameter of the drill stem, whichever your perspective.

The self-anchoring device would use properly sized cams not unlike the small ones used in a plumber’s wrench.  A steel frame would hold three of these so they could be pushed down the length of the drill stem.  Any reverse motion would force them to grip the drill stem via their cam shape. The force of the crude pushing against them would reinforce their self-anchoring action. (steel “chinese handcuffs”)

Keeping the profile small enough to incur forces each assembly can handle is important.  They’d have to start small, and be left at the “right” depth, the “pusher pipe” removed for the next one, which would be slightly larger.  Reducing the flow rate would allow for gradual buildup via increasingly larger drill stem “sleeves” equipped with similar self-anchoring devices.  The larger surface area of the sleeve pipes would add to the forces experienced by the anchoring mechanisms, so flow would have to be reduced first, I think.  Then, with flow greatly reduced, a top kill effort through the BOP would be efffective.

Anchoring to the drill stem would help avoid some dangerous forces on a suspect casing.

The shafts through the cams have to be a large enough diameter to resist shearing during self-anchoring action. The drill stem “ring” with these cams could have several more to distribute the load, but this would work against the assembly should it get hit by a rock on the way out of the well.  It’s been 25+ years since I did a differential (or closer to 29 years since Nature of Engineering Materials labs), so I’d only have wild-assed guesses at the appropriate sizes.

With the forces being equal to the pressure times the effective surface area, the required load carrying capability of each cam axis be calculated.

The other idea I had may have already been thought of and dismissed: Feed two or three pipes down the casing alongside the drill stem (think of a golf bag with indidual club sleeves to picture this) to the bottom, pump mud straight to the bottom of the well. To not increase pressure at a dangerous rate, this may require oil being able to rise in these pipes as they are built and inserted… messy, but at the surface. Viscosity and diameter are issues as well as being able to pump appreciable volumes over the smaller diameter through the 3-5 mile pipe(s).

I just can’t see how even intercepting the the well a mile below the surface would allow for a “top kill” with mud with the well so open on top.

Since I wrote yesterday, it’s become obvious they have the necessary sawblade at the bottom of the Gulf. Now it is stuck… This may be a good thing for now.

The leak can be greatly reduced by the simplest action…
1. cut slot in riser pipe.
2. insert steel plate, greatly reducing diameter of pipe open to the ocean.
3. The velocity of escaping crude will be greatly diminished.
4. NOW do the Top Kill. With the flow reduced, the injected mud and junk has a chance to form a solid blockage.

I’ll update with a diagram on how to reinforce a steel plate flow restrictor.

This is a crude block diagram of a clamp on apparatus that could be used to block most of the flow from the Deepwater Horizon riser pipe leaking in the Gulf.

The clamp-on apparatus is extremely simplified for this rushed drawing. It would be relatively “easy” to make a mid-sized machine shop and laser cutting shop.

This would require one of the “circular saws” the robotic subs are currently using to cut up pipes to cut the slot in the outer diameter of the pipe.

Actuating the various screws to complete the plug operation could be done by robotic sub or dedicated undersea electric motor or pneumatic tool driven by compressors on the surface…. I’d defer to deep-sea equipment specialists for the selection.

The shaped plug plates can be laser cut and laminated to any thickness.

A 2″ drilled hole on the “bottom” of the pipe diameter as depicted would allow for greater support for a 2″ steel bar spanning the entire diameter and mechanically support the plates and protect them from bending. This bar can be cam-shaped (crude cam) so that the “P” shaped plates can be pushed forward toward the well (vs the surface) for a better seal.

This can be made in a few days in a mid-sized shop.

DON’T CUT THE RISER PIPE WITHOUT A MECHANICAL PLUG BACKUP TO THE DOME!!!
THE KINKS ARE RESTRICTING FLOW! THE FLOW WILL BE GREATER!!!

t

External apparatus clamped to outside diameter of riser pipe

I’ll post a little detail on the clamp on rig later. I’m just trying to get the idea out that there’s a not-so-complex apparatus that can be made and put on the riser. Anything… Anything to decrease the effective diameter and the flow rate of crude into the gulf.

A slot is cut in outside diameter wide enough for steel plates insertion

screw mechanism drives overlapping plug plates into pipe bore

The steel plates inserted overlapping each other are shaped like the letter “P” so that they can be moved to block more of the diameter.
There is a risk of bending, even if they are thick. There are ways to deal with this rather simply though.

My point is that it’s not brain surgery. And yes, there are all kinds of challenges operating at this depth, but the robotic subs are already cutting pipes with a circular saw down there. This is big, fairly crude steel gizmo construction. Crystallized methane hydrates won’t be a factor if the pipe is plugged.

Screw mechanism spreads plug plates to block nearly entire diameter of riser pipe