Steam drive oil production method

Claim 1

A METHOD OF RECOVERING OIL FROM AN UNDERGROUND OIL-BEARING FORMATION WHICH IS PENETRATED BY A PLURALITY OF ALTERNATELY-DISPOSED WELLS WHICH MAY BE DIVIDED INTO STEAM-INPUT WELLS, CONDENSATE-REMOVAL WELLS AND OIL-OUTPUT WELLS, SAID METHOD COMPRISING ESTABLISHING COMMUNICATION BETWEEN BOTH THE INPUT WELLS AND THE CONDENSATE REMOVAL WELLS WITH THE OIL-BEARING FORMATION AT ONE LEVEL THEREOF, ESTABLISHING COMMUNICATION BETWEEN THE OIL OUTPUT WELLS AND THE OIL-BEARING FORMATION AT A LEVEL SUBSTANTIALLY BELOW THAT OF THE OTHER WELLS, HORIZONTALLY FRACTURING THE OIL-BEARING FORMATION FROM SAID INPUT AND CONDENSATE REMOVAL WELLS AT ONE LEVEL OF THE OIL-PRODUCING FORMATION AND IN A MANNER SUCH THAT THEE FRACTURE ARE IN OPEN COMMUNICATION WITH EACH OTHER, HORIZONTALLY FRACTURING THE OIL-BEARING FORMATION FROM OIL OUTLET WELLS AT A LOWER LEVEL THAN SAID FIRST FRACTURE AND IN A MANNER SUCH THAT THE LOWER HORIZONTAL FRACTURES ARE IN OPEN COMMUNICATION WITH EACH OTHER, CONTINUOUSLY INJECTING STEAM THROUGH SAID INPUT WELLS WHILE CONTINUOUSLY REMOVING CONDENSATE FROM THE CONDENSATE REMOVAL WELLS AND INJECTING STEAM THROUGH SOME OF THE OIL OUTLET WELLS WHILE REMOVING CONDENSATE FROM OTHER OF THE OIL OUTLET WELLS FOR A TIME SUFFICIENT TO PREHEAT THE ZONE OF SAID OIL-BEARING FORMATION BETWEEN THE UPPER AND LOWER FRACTURES, SUBSEQUENTLY DISCONTINUING THE INJECTION OF STEAM INTO THE OIL OUTPUT WELLS, INJECTING STEAM INTO THE UPPER PORTION OF SAID OILBEARINGS FORMATION THROUGH SAID INPUT WELLS TO PRODUCE OIL BY A DOWNWARD STEAM DRIVE TO SAID OIL OUTPUT WELL, AND RECOVERING SAID PRODUCED OIL FROM SAID OIL OUTPUT WELLS.

Claim 2

A METHOD OF RECOVERING OIL FROM AN UNDERGROUND OIL-BEARING FORMATION WHICH IS PENETRATED BY A PLURALITY OF ALTERNATELY-DISPOSED WELLS WHICH MAY BE DIVIDED INTO STEAM-INPUT WELLS, CONDENSATE-REMOVAL WELLS AND OIL-OUTPUT WELLS, SAID METHOD COMPRISING ESTABLISHING COMMUNICATION BETWEEN BOTH THE INPUT WELLS AND THE CONDENSATE REMOVAL WELLS WITH THE OIL-BEARING FORMATION AT ONE LEVEL THEREOF, ESTABLISHING COMMUNICATION BETWEEN THE OIL OUTPUT WELLS AND THE OIL-BEARING FORMATION AT A LEVEL SUBSTANTIALLY BELOW THAT OF THE OTHER WELLS, HORIZONTALLY FRACTURING THE OIL-BEARING FORMATION FROM SAID INPUT AND CONDENSATE REMOVAL WELLS AT ONE LEVEL OF THE OIL-PRODUCING FORMATION AND IN A MANNER SUCH THAT THEE FRACTURE ARE IN OPEN COMMUNICATION WITH EACH OTHER, HORIZONTALLY FRACTURING THE OIL-BEARING FORMATION FROM OIL OUTLET WELLS AT A LOWER LEVEL THAN SAID FIRST FRACTURE AND IN A MANNER SUCH THAT THE LOWER HORIZONTAL FRACTURES ARE IN OPEN COMMUNICATION WITH EACH OTHER, CONTINUOUSLY INJECTING STEAM THROUGH SAID INPUT WELLS WHILE CONTINUOUSLY REMOVING CONDENSATE FROM THE CONDENSATE REMOVAL WELLS AND INJECTING STEAM THROUGH SOME OF THE OIL OUTLET WELLS WHILE REMOVING CONDENSATE FROM OTHER OF THE OIL OUTLET WELLS FOR A TIME SUFFICIENT TO PREHEAT THE ZONE OF SAID OIL-BEARING FORMATION BETWEEN THE UPPER AND LOWER FRACTURES, SUBSEQUENTLY DISCONTINUING THE INJECTION OF STEAM INTO THE OIL OUTPUT WELLS, INJECTING STEAM INTO THE UPPER PORTION OF SAID OILBEARINGS FORMATION THROUGH SAID INPUT WELLS TO PRODUCE OIL BY A DOWNWARD STEAM DRIVE TO SAID OIL OUTPUT WELL, AND RECOVERING SAID PRODUCED OIL FROM SAID OIL OUTPUT WELLS.