The Oil Drum

12 comments on In coal mines, the Penitent really was

Comments can no longer be added to this story.

wkwillis on October 17, 2005 - 2:40pm

That's correct. The pump is required to overcome friction losses of moving the water through the coal cleats. The friction loss in the well and the degasifier are much lower and hardly count. It's moving the brine through the coal that takes the power.
Of course, evey well is different.

Comments can no longer be added to this story.

Engineer-Poet on October 17, 2005 - 3:26pm

The PDF I linked mentioned that the pressure in the seam has to be dropped to the point where the methane comes out. This appears to require at least some water to be removed from the seam and placed elsewhere, for the duration of the production operation.

Pumping oxygen and steam down an injection well and drawing F-T synthesis gas (plus a lot of raw hydrocarbons) from another would appear to be a possibility once the seams have been dewatered. I'm rather surprised that the British haven't been doing this with some of their deep coal and undersea coal; they're facing a serious crisis with the decline of North Sea oil and gas. On the other hand, if they burn out the seams near shore, the land above subsides... right into the sea.

Comments can no longer be added to this story.

Heading Out on October 17, 2005 - 9:41pm

Some British mines ran more than five miles out to sea and mined out the coal in what is known as a longwall system. This allows the roof to collapse after the coal is removed. But the roof will only break to about one-and-a-half times the seam height above the coal. (The broken rock bulks up as it breaks and fills up the hole). Above that the rock has the flexibility to bend a bit, and does not break. This the breaks don't go to the sea bed, and the sea doesn't rush in, providing they are deep enough below it.