In the light of the current oil leak in the Gulf of Mexico off the coast of the United States it would seem that not enough engineers thought about how the well might be plugged in the event of such a leak. I was disappointed to learn on TV news that initial attempts to stem the leak have been unsuccessful. The difficulty of working at a depth of a mile below the surface of the ocean is not to be underestimated. I am not familiar with all the technologies that are used, but I could not avoid thinking about the problem over the past few days.
The principle I would use to plug a leaking well would be that of a taper. I would introduce the thin end of a long taper into the broken pipe at the seabed. It would be necessary to apply sufficient force, eventually, to the taper to exceed the full static pressure of the oil over the cross section of the well riser at the level of the sea floor.
In order to insert the taper I would place a heavy cigar-shaped weight over the broken well riser. This would serve a number of purposes.
- It would provide a steady support from which to manipulate the fine tip of the taper into the broken pipe. A remotely operated robot would be required.
- The cigar would divert the oil flow in a symmetrical way around the taper without containing the oil in any way.
- The cigar would be heavy enough to eventually apply the necessary force to the taper.
- The cigar would contain a vertical bore through which the taper would be fed.
The cigar weight would be supported by a tripod. A gimbal-based mount could be used to ensure that the cigar could be installed vertically. This mount could be designed to allow angular positioning movement while the cigar was supported from above, but would lock in position when the full weight of the cigar was applied.
For ease of fabrication I would make the taper of cylindrical lengths (perhaps of cable, then rod, then water-filled tube) with tapered transitions. The taper would be lowered from the surface and might require the lateral support of heavy guide rings at a number of levels to keep it straight. The weight of the taper itself would be sufficient to allow it to be introduced into the pipe riser.
Before inserting the taper fully (to fill the full bore of the well riser) I might need to carry out some clean-up of the broken end of the well riser. Once I had fully inserted the taper I could lock it to the cigar and then remove the long length from the surface.
This sounds easy. I know it is not.