Recovery of hydrocarbons by in-situ hydrogenation

Claim 1

A SECONDARY RECOVERY METHOD FOR RECOVERING RESIDUAL LIQUID HYDROCARBONS FROM A PERMEABLE UNDERGROUND FORMATION TRAVERSED BY INJECTION AND PRODUCTION WELLS WHICH COMPRISES: (A) CONTINUOUSLY SUBJECTING THE HYDROCARBONS IN THE FORMATION BETWEEN SAID WELLS TO CONTROLLED IN-SITU COMBUSTION IN WHICH A COMBUSTION FROM HAVING A TEMPERATURE OF BETWEEN ABOUT 400*F. AND ABOUT 850*F. IS PROPAGATED THROUGH SAID FORMATION TO CONVERT A PORTION OF THE HYDROCARBONS THEREIN TO HYDROGENATABLE, RESIDUAL CARBONACEOUS MATERIAL; (B) CONTACTING THE RESIDUAL CARBONACEOUS MATERIAL WITH A HYDROGENATING GAS AT A PRESSURE EXCEEDING ABOUT 500 P.S.I.G. AND A TEMPERATURE OF FROM ABOUT 400* F. TO ABOUT 950*F. FOR A PERIOD SUFFICIENT TO SUBSTANTIALLY LOWER THE VISCOSITY OF SAID RESIDUAL CARBONACEOUS MATERIAL BY INJECTING HYDROGENATING GAS THROUGH A FIRST ONE OF SAID WELLSE; (C) RECOVERING SAID HYDROGENATED RESIDUAL MATERIAL FROM THE FORMATION THROUGH A SECOND ONE OF SAID WELLS.