Secondary recovery of viscous crude oil

Claim 1

A METHOD FOR RECOVERING LOW-GRAVITY, VISCOUS CRUDE OIL FROM HEAVY OIL RESERVOIRS COMPRISING: (A) PROVIDING FIRST AND SECOND WELLS IN THE RESERVOIR, SAID WELLS SPACED APART A DISTANCE THROUGH WHICH GAS COMMUNICATION CAN BE ESTABLISHED, (B) TREATING THE RESERVOIR AFTER ESTABLISHING GAS COMMUNICATION BETWEEN THE FIRST AND SECOND WELLS TO CREATE A COMMUNICATION ZONE OF HIGHER PERMEABILITY TO FLUIDS THAN THE REMAINDER OF THE RESERVOIR BETWEEN THE MENTIONED WELLS, (C) IGNITING THE HYDROCARBONS IN THE COMMUNICATION ZONE ADJACENT TO ONE OF SAID WELLS, (D) MOVING AN IN SITU COMBUSTION BURNING ZONE BY SUPPLYING A COMBUSTION-SUPPORTING GAS TO THE IGNITED HYDROCARBONS BETWEEN THE FIRST AND SECOND WELLS TO PROVIDE A HEAT STORAGE REGION SURROUNDING THE WELLS IN WHICH HEAT STORAGE REGION THE TEMPERATURE OF THE RESERVOIR IS INCREASED SUFFICIENTLY TO PREVENT A LIQUID BLOCK FROM DEVELOPING DURING THE ADVANCE OF A SUBSEQUENT DIRECT IN SITU COMBUSTION BURNING ZONE THERETHROUGH, (E) PROVIDING A THIRD WELL IN THE RESERVOIR DISPOSED SUBSTANTIALLY EQUIDISTANT FROM THE FIRST AND SECOND WELLS, THE THIRD WELL BEING SPACED FROM THE NEAREST PORTION OF THE HEAT STORAGE REGION NOT IN AN EXCESS OF THE DISTANCE IN WHICH A LIQUID BLOCK OCCURS IN THE UNHEATED RESERVOIR BEFORE A DIRECT IN SITU COMBUSTION BURNING ZONE ADVANCING THERETHROUGH, (F) IGNITING THE HYDROCARBONS IN THE RESERVOIR ADJACENT THE THIRD WELL, (G) PASSING A COMBUSTION-SUPPORTING GAS FROM THE THIRD WELL TO THE FIRST AND SECOND WELLS IN CONTACT WITH THE IGNITED HYDROCARBONS FOR MOVING A DIRECT IN SITU COMBUSTION BURNING ZONE FROM THE THIRD WELL TO SAID FIRST AND SECOND WELLS, AND (H) PRODUCING THE CRUDE OIL DISPLACED BY THE LAST-MENTIONED BURNING ZONE FROM THE FIRST AND SECOND WELLS WITHOUT LIQUID BLOCKING.

Claim 2

A METHOD FOR RECOVERING LOW-GRAVITY, VISCOUS CRUDE OIL FROM HEAVY OIL RESERVOIRS COMPRISING: (A) PROVIDING FIRST AND SECOND WELLS IN THE RESERVOIR, SAID WELLS SPACED APART A DISTANCE THROUGH WHICH GAS COMMUNICATION CAN BE ESTABLISHED, (B) TREATING THE RESERVOIR AFTER ESTABLISHING GAS COMMUNICATION BETWEEN THE FIRST AND SECOND WELLS TO CREATE A COMMUNICATION ZONE OF HIGHER PERMEABILITY TO FLUIDS THAN THE REMAINDER OF THE RESERVOIR BETWEEN THE MENTIONED WELLS, (C) IGNITING THE HYDROCARBONS IN THE COMMUNICATION ZONE ADJACENT TO ONE OF SAID WELLS, (D) MOVING AN IN SITU COMBUSTION BURNING ZONE BY SUPPLYING A COMBUSTION-SUPPORTING GAS TO THE IGNITED HYDROCARBONS BETWEEN THE FIRST AND SECOND WELLS TO PROVIDE A HEAT STORAGE REGION SURROUNDING THE WELLS IN WHICH HEAT STORAGE REGION THE TEMPERATURE OF THE RESERVOIR IS INCREASED SUFFICIENTLY TO PREVENT A LIQUID BLOCK FROM DEVELOPING DURING THE ADVANCE OF A SUBSEQUENT DIRECT IN SITU COMBUSTION BURNING ZONE THERETHROUGH, (E) PROVIDING A THIRD WELL IN THE RESERVOIR DISPOSED SUBSTANTIALLY EQUIDISTANT FROM THE FIRST AND SECOND WELLS, THE THIRD WELL BEING SPACED FROM THE NEAREST PORTION OF THE HEAT STORAGE REGION NOT IN AN EXCESS OF THE DISTANCE IN WHICH A LIQUID BLOCK OCCURS IN THE UNHEATED RESERVOIR BEFORE A DIRECT IN SITU COMBUSTION BURNING ZONE ADVANCING THERETHROUGH, (F) IGNITING THE HYDROCARBONS IN THE RESERVOIR ADJACENT THE THIRD WELL, (G) PASSING A COMBUSTION-SUPPORTING GAS FROM THE THIRD WELL TO THE FIRST AND SECOND WELLS IN CONTACT WITH THE IGNITED HYDROCARBONS FOR MOVING A DIRECT IN SITU COMBUSTION BURNING ZONE FROM THE THIRD WELL TO SAID FIRST AND SECOND WELLS, AND (H) PRODUCING THE CRUDE OIL DISPLACED BY THE LAST-MENTIONED BURNING ZONE FROM THE FIRST AND SECOND WELLS WITHOUT LIQUID BLOCKING.