Methods of recovery of oil

Claim 1

A METHOD OF RECOVERING CRUDE OIL FROM A SUBTERRANEAN OIL RESERVOIR THROUGH A PRODUCING WELL WHICH COMPRISES THE STEPS OF: INJECTING A NORMALLY GASEOUS SOLVENT INTO SAID RESERVOIR THROUGH AN INJECTION WELL, SAID SOLVENT BEING CHARACTERIZED BY A SUBSTANTIAL DEGREE OF MISCIBILITY WITH OIL, SAID SOLVENT BEING LIQUEFIABLE AT THE TEMPERATURE OF SAID RESERVOIR AND BEING INJECTED IN SUFFICIENT AMOUNT TO ESTABLISH A BANK CONSISTING ESSENTIALLY OF SAID SOLVENT WITHIN SAID RESERVOIR IN THE NEIGHBORHOOD OF SAID INJECTION WELL; MAINTAINING A PRESSURE WITHIN SAID RESERVOIR HIGHER THAN THE VAPOR PRESSURE OF SAID SOLVENT AT THE TEMPERATURE OF SAID RESERVOIR DURING INDJECTION OF SAID SOLVENT TO ESTABLISH A LIQUID BANK OF SAID SOLVENT; THEREAFTER INJECTING INTO SAID RESERVOIR THROUGH THE INJECTION WELL, AT A PRESSURE SUFFICIENT TO MAINTAIN AND DRIVE SAID LIQUID BANK TOWARD SAID PRODUCING WELL, A NORMALLY GASEOUS DRIVE AGENT WHICH RETAINS ITS GASEOUS STATE AT THE TEMPERATURE AND PRESSURE CONDITIONS OF THE RESERVOIR, SAID LIQUID SOLVENT BEING CAPABLE OF VAPORIZING INTO SAID GASEOUS DRIVE AGENT AT THE PRESSURE AND TEMPERATURE CONDITIONS IN SAID RESERVOIR; AND WITHDRAWING FLUIDS INCLUDING SAID CRUDE OIL, SAID SOLVENT AND SAID GASEOUS DRIVE AGENT FROM SAID PRODUCING WELL.

Claim 2

A METHOD OF RECOVERING CRUDE OIL FROM A SUBTERRANEAN OIL RESERVOIR THROUGH A PRODUCING WELL WHICH COMPRISES THE STEPS OF: INJECTING A NORMALLY GASEOUS SOLVENT INTO SAID RESERVOIR THROUGH AN INJECTION WELL, SAID SOLVENT BEING CHARACTERIZED BY A SUBSTANTIAL DEGREE OF MISCIBILITY WITH OIL, SAID SOLVENT BEING LIQUEFIABLE AT THE TEMPERATURE OF SAID RESERVOIR AND BEING INJECTED IN SUFFICIENT AMOUNT TO ESTABLISH A BANK CONSISTING ESSENTIALLY OF SAID SOLVENT WITHIN SAID RESERVOIR IN THE NEIGHBORHOOD OF SAID INJECTION WELL; MAINTAINING A PRESSURE WITHIN SAID RESERVOIR HIGHER THAN THE VAPOR PRESSURE OF SAID SOLVENT AT THE TEMPERATURE OF SAID RESERVOIR DURING INDJECTION OF SAID SOLVENT TO ESTABLISH A LIQUID BANK OF SAID SOLVENT; THEREAFTER INJECTING INTO SAID RESERVOIR THROUGH THE INJECTION WELL, AT A PRESSURE SUFFICIENT TO MAINTAIN AND DRIVE SAID LIQUID BANK TOWARD SAID PRODUCING WELL, A NORMALLY GASEOUS DRIVE AGENT WHICH RETAINS ITS GASEOUS STATE AT THE TEMPERATURE AND PRESSURE CONDITIONS OF THE RESERVOIR, SAID LIQUID SOLVENT BEING CAPABLE OF VAPORIZING INTO SAID GASEOUS DRIVE AGENT AT THE PRESSURE AND TEMPERATURE CONDITIONS IN SAID RESERVOIR; AND WITHDRAWING FLUIDS INCLUDING SAID CRUDE OIL, SAID SOLVENT AND SAID GASEOUS DRIVE AGENT FROM SAID PRODUCING WELL.