re: Deepwater Horizon - question about the cement

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Suppose they had determined that the cement was faulty (either by running the extra test or from deciding they didn't like the previous results), what would they do about it?


If there are indications of bad cement they can perform a remedial cement job.

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Is there a method for fixing the cement?


Yes, many, depending on what the problem is. The simplest solution is just to pump more cement.

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Or do they have to drill it out and do it over?


Ideally, most of it would be in the annular region between casing and open hole with the losses being in the formation, so you can't take that out, but if it never makes it out of the shoe, then yeah you could drill that. It may not be clear without some troubleshooting.

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Or do they just plug the hole and dig an all new one?


In extreme cases, yes, but probably not a whole new one, just pull back a bit and sidetrack.

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How long would all that take? Is it common?


Sidetracks are fairly common mostly for other reasons.. abandoning the well entirely is not.
Because of the geology of the gulf and the depths involved, cement jobs can be very tough.

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Why not just leave the pipe they used to drill the hole in place? Is the pipe that expensive?


Mostly because it's too small. Wells are a series of smaller pipes inside bigger pipes. It's difficult or impossible to design a well with a single pipe. There is some work on drilling with casing and expandable liners, but it's not quite what you're thinking.

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