Not a lot of detail, but interesting:

http://www.nytimes.com/2008/07/29/us...&ex=1217476800

Nobody knows for certain how big an area the Haynesville Shale covers — no government entity has mapped it. But energy companies and experts say it is large, possibly the largest in the lower 48 states, with an estimated 250 trillion cubic feet of recoverable gas. (Last year, the United States consumed 23 trillion feet.) It is up to 13,000 feet underground, extending into East Texas. A few initial wells are already producing startling amounts of gas, and the country’s appetite for the stuff is only growing larger as petroleum becomes more expensive.
...
“we’re talking about doubling the nation’s gas reserves from two fields,”