| abstract |
A method for producing shale oil from a subterranean oil shale formation wherein a chimney of fragmented oil shale is formed in the formation by exploding a relatively high energy explosive device therein, the chimney having a substantially void space formed at the top thereof. A liquid is flowed through the voids formed between the oil shale fragments, the liquid being adapted to selectively bypass small voids and plug larger voids formed between the fragments at least in the substantially vertical central portion of the chimney. Hydrocarbons at substantially the top of the chimney are ignited and a combustion supporting fluid is flowed into the chimney at substantially the top thereof, thereby advancing a combustion front down the chimney to substantially the bottom thereof. The fluid flow path of the fluid supporting the combustion tends to be substantially confined to the vertical outlying portions of the chimney and the untreated small voids within the chimney until the heat from the combustion front thermally mobilizes the liquid plugging the larger voids thus decomposing the plugging liquid thereby pyrolyzing substantially all of the fragmented oil shale along a substantially horizontal level within the chimney without the combustion front bypassing the portions of the fragmented oil shale adjacent to the small voids as the combustion front proceeds down the chimney. |