3924680 is referenced by 255 patents and cites 7 patents.

A method of pyrolysis of coal in situ includes the steps of establishing a pair of passages between a sub-surface coal formation and the surface with the coal passages being adapted to separately remove liquids and gases from the coal formation, establishing a sump at the bottom of the passages which extends at least partially below the coal formation to receive liquid volatile material released from the formation, and heating the coal formation so that initially tars in the formation will migrate radially until they go beyond the heated area whereupon they will solidify and form a hermetic barrier around the zone to be pyrolyzed to confine gaseous liquid volatile materials released from the coal as a result of the pyrolysis. The released gaseous materials can then flow to the surface through one of the passages and the liquid volatile material can flow into the sump and be pumped to the surface through the other passage.

Method of pyrolysis of coal in situ
Application Number
Publication Number
Application Date
April 23, 1975
Publication Date
December 9, 1975
Terry Ruel C
Burton Crandell & Polumbus
In Situ Technology
E21B 43/26
E21B 43/24
E21B 33/138
E21B 43/247
E21B 43/16
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