In situ recovery of shale oil

A method for converting kerogen in a zone of fragmented oil shale formation to liquid and gaseous products in an in situ retort in a subterranean oil shale formation and recovering the products which comprises the steps of:

• excavating subterranean oil shale formation to form open space in the volume of the subterranean oil shale formation to become an in situ retort, the open space having a volume in the range of from about 10 to 25 percent of the volume of the zone of fragmented oil shale formation to be formed in the in situ retort;
• fragmenting the oil shale in the volume of the subterranean oil shale formation to become the in situ retort and expanding it into the open space to produce a zone of fragmented oil shale formation in the in situ oil shale retort, the zone having an approximately rectangular horizontal cross section and having a height in the range of about two to five times the horizontal dimension of the longest side of the horizontal cross section and an average void fraction in the range of from about 10 to 25 percent of the volume of the zone;
• providing means for introducing gas at the top of the in situ retort;
• providing means for recovering gaseous and liquid products from retorting fragmented oil shale formation at the bottom of the in situ retort;
• igniting the top of the fragmented oil shale formation in the in situ retort for establishing a combustion zone;
• introducing an oxygen supplying gas into the top of the in situ retort for advancing the combustion zone toward the bottom of the in situ retort and producing flue gas;
• moving flue gas from the combustion zone through the fragmented oil shale on the advancing side of the combustion zone for establishing a retorting zone wherein kerogen in fragmented oil shale formation is converted to liquid and gaseous products;
• and
• recovering said products from the bottom of the in situ retort.

A method for retorting oil shale in situ comprising the steps of:

• forming an in situ retort having sides in a subterranean oil shale formation, said in situ retort having a height in the range of from about two to five times the horizontal dimension of the longest side of the retort and containing a zone of fragmented oil shale formation having an average void fraction in the range of from about 10 to 20 percent of the volume of the zone;
• introducing a gas in one end of the in situ retort for advancing a retorting zone through the fragmented oil shale wherein kerogen in fragmented oil shale formation in the retorting zone is converted to liquid and gaseous products;
• and
• recovering the liquid and gaseous products at the other end of the in situ retort.

A subterranean in situ oil shale retort system comprising:

• first and second vertically elongated in situ retorts, each of said retorts having a substantially rectangular horizontal cross section, and containing a zone of fragmented oil shale formation having a height in the range of from about two to five times the horizontal dimension of the longest side of the in situ retort;
• said in situ retort system having a pillar of unfragmented oil shale separating the zones of fragmented oil shale formation in the first and second in situ retorts, the horizontal cross section of the pillar relative to its height being less than sufficient for supporting overburden over the first and second in situ retorts, each of said zones of fragmented oil shale formation having an average void volume in the range of from about 10 to 25 percent of the volume of the zone of fragmented oil shale formation for providing lateral support for the pillar for assisting in supporting the overburden;
• means for introducing gas at the top of each in situ retort;
• and
• means for recovering liquid and gas at the bottom of each in situ retort.