Environmental Engineering Reference
In-Depth Information
Surface
Shale Bed
fig. 9.2
Horizontal drilling to enhance gas recovery from
shale beds. New drilling technology makes gas production
economical from previously unusable sources.
deep underground and not very permeable to gas move-
ment. If old-style vertical wells were needed to extract the
gas it would be far too costly because many wells would be
needed over the entire area of the shale bed. The amazing
technology developed in the oil industry of turning a drill
from a single well from vertical to horizontal has made it
practical to run an extraction pipe for long distances
through a relatively thin layer and extract gas over a long
range with one well as is sketched in
Figure
.
In the United States, shale gas has changed the story. In
the
.
first edition, I noted that gas reserves were growing
because of the start of shale gas production. So much
shale gas is now being produced, and natural gas prices
have fallen so far, that it has become the fuel of choice for
electric power generation. Only
five years ago coal was
used for
% of electric power generation and gas for
% in the United States. Today coal is used for
%of
