In-situ recovery of hydrocarbons from underground formations of oil shale

Claim 1

THE PROCESS OF RECOVERING HYDROCARBONS FROM UNDERGROUND FORMATIONS OF OIL SHALE COMPRISING THE STEPS OF: (A) SURROUNDING A PORTION OF AN OIL SHALE FORMATION WITH A HORIZONTALLY DISPOSED TUNNEL, (B) PROVIDING A PLURALITY OF SUBSTANTIALLY VERTICAL BOREHOLES TO SAID SHALE FORMATION WHEREIN SAID BOREHOLES EXTEND FROM THE EARTH''S SURFACE INTO SAID SURROUNDED SHALE FORMATION, (C) FRACTURING THE SURROUNDING SHALE FORMATION DISPOSED ABOUT ONE OF SAID VERTICAL BOREHOLES, AND INJECTING A HEAT CREATING GAS THROUGH SAID SUBSTANTIALLY VERTICAL BOREHOLE INTO SAID FRACTURED SHALE FORMATION TO HEAT SAID SHALE FORMATION FROM ADJACENT SAID BOREHOLE PROGRESSIVELY OUTWARDLY TO A TEMPERATURE SUFFICIENT TO DRIVE THE HYDROCARBONS CONTAINED IN SAID SURROUNDED SHALE FORMATION AWAY FROM SAID BOREHOLE AND INTO SAID TUNNEL, (D) THEREAFTER FRACTURING THE SURROUNDED SHALE FORMATION DISPOSED AROUND A SECOND OF SAID SUBSTANTIALLY VERTICAL BOREHOLES AND INJECTING A HEAT CREATING GAS THROUGH SAID SUBSTANTIALLY VERTICAL BOREHOLE INTO SAID FRACTURED SHALE FORMATION TO HEAT SAID SHALE FORMATION FROM ADJACENT SAID SECOND BOREHOLE PROGRESSIVELY OUTWARDLY TO A TEMPERATURE SUFFICIENT TO DRIVE THE HYDROCARBONS CONTAINED IN SAID SURROUNDED SHALE FORMATION AWAY FROM SAID SECOND BOREHOLE AND INTO SAID TUNNEL, AND (E) REMOVING THE RECOVERED HYDROCARBONS FROM SAID TUNNEL.