In situ method and system for extraction of oil from shale

A process for retorting and extracting hydrocarbons from a subterranean body of oil shale in an oil shale deposit located beneath an overburden, said process comprising the following steps:

• (1) Drilling at least one energy delivery well generally downward from an entry end thereof at the earth's surface, said well passing through the overburden, said well extending to the bottom of the body of oil shale to be retorted, at a proximal end of said body;
• (2) Continuing said energy delivery well therefrom in a generally horizontal direction through the oil shale deposit across and beneath the body of oil shale to be retorted, to a distal end thereof, and then generally upward therefrom to return through the oil shale deposit and the overburden to an exit end of said energy delivery well, said exit end located at the surface;
• (3) Placing at least one fluid transmission pipe within said energy delivery well, said fluid transmission pipe extending uninterruptedly all the way through said energy delivery well, said fluid transmission pipe having an injection end that extends out from said entry end of said energy delivery well, said fluid transmission pipe having a return end that extends out of said exit end of said energy delivery well, said fluid transmission pipe running generally horizontally beneath and across the body of oil shale to be retorted, from said proximal end to said distal end;
• (4) Drilling at least one hydrocarbon production well having an upper end located at the surface and having a lower end located at or near the bottom of the overburden;
• (5) Drilling at least one spider well, said spider well communicating at an upper end thereof with said hydrocarbon production well, said upper end of said spider well located at or near the bottom of the overburden, said spider well extending generally downward from said upper end thereof to the bottom of the body of oil shale to be retorted, said spider well adapted to transmit retort vapors upward therethrough and to transmit retort liquids downward therethrough, said spider well further adapted to permit retort vapors or liquids to pass between said spider well and the body of oil shale to be retorted;
• (6) Drilling a central well downward past said upper end of said spider well to extend said hydrocarbon production well to approximately the bottom of the body of oil shale to be retorted;
• (7) Locating a sump below said hydrocarbon production well, said sump adapted for collecting condensed liquid hydrocarbons retorted from the oil shale deposit;
• (8) Placing a product gathering pipe within said hydrocarbon production well, said product gathering pipe having a collection end at said upper end of said hydrocarbon production well, said product gathering pipe extending through said hydrocarbon production well down to said sump;
• (9) Delivering to said injection end of said fluid transmission pipe a heating fluid heated to at least a retorting temperature, passing said heating fluid through said fluid transmission pipe to said return end thereof, reheating said heating fluid back to at least a retorting temperature, and repeating this step, thereby heating to at least a retorting temperature the body of oil shale above and proximate to said fluid transmission pipe running generally horizontally, thereby causing portions of the body of oil shale to retort, and thereby causing hydrocarbon vapors to ascend through the spider well;
• and
• (10) Extracting retort vapors from said upper end of said spider well and pumping retort liquids out of said product gathering pipe, thereby collecting hydrocarbons retorted from the oil shale.