Heating through fractures to expand a shale oil pyrolyzing cavern

Claim 1

IN A SHALE OIL PRODUCING PROCESS IN WHICH A RELATIVELY SOLIDS-FREE, RUBBLE-CONTAINING CAVITY IS FORMED WITHIN AN OTHERWISE SUBSTANTIALLY NON-POROUS AND IMPREMEABLE SUBSTERRANEAN OIL SHALE, AND FLUID IS INJECTED INTO AND WITHDRAWN FROM THE CAVITY, THE IMPROVEMENT WHICH COMPRISES: FORMING AT LEAST TWO VERTICALLY-SEPARATED, SUBSTANTIALLY HORIZONTAL FRACTURES THAT EXTEND BETWEEN THE CAVITY AND AT LEAST ONE ADJACENT WELL; INFLOWING A HOT NON-SOLVENT-GAS INTO THE CAVERN THROUGH AT LEAST ONE OF SAID FRACTURES; OUTFLOWING A HOT FLUID CONTAINING OIL SHALE PYROLYSIS PRODUCTS FROM THE CAVERN THROUGH AT LEAST ONE OTHER OF SAID FRACTURES; AND ADJUSTING THE RATE AND TEMPERATURE OF THE FLUID INFLOWING AND OUTFLOWING THROUGH THE FRACTURES SO THAT THE FRACTURE WALLS ARE HEATED AND BECOME VERTICALLY SEPARATED, GENERALLY PLANAR HEAT SOURCES FROM WHICH HEAT IS TRANSFERRED TO PORTIONS OF THE OIL SHALE FORMATION SURROUNDING THE WALLS OF THE CAVITY.