Method and apparatus for producing oil wells

Claim 1

A METHOD OF PRODUCING OIL WELLS INDIVIDUALLY IN AN OIL-PRODUCING AREA BY FLUID PRESSURE SUPPLIED FROM THE SURFACE, COMPRISING THE STEPS OF CEMENTING A PRIMARY CASING WHICH EXTENDS THROUGH THE OIL SAND TO FORM A SEAL BETWEEN THE CASING AND THE OIL SAND, TO THE ENTIRE DEPTH OF THE OIL SAND, PERFORATING THE PRIMARY CASING AND SEAL WITHIN THE OIL-PRODUCING SAND ADJACENT THE TOP, AND BOTTOM THEREOF WHILE LEAVING THE CASING SEALED TO THE OIL SAND BETWEEN THE SAID PERFORATIONS, POSITIONING A SECONDARY CASING OF SMALLER DIAMETER WITHIN THE PRIMARY CASING AND BONDING THE FORMER TO THE LATTER AT PRESSURE-TIGHT JOINTS, ONE ABOVE THE OIL SAND AND THE OTHER CENTRALLY THEREOF, SAID LAST MENTIONED BOND BEING LOCATED INTERMEDIATE THE UPPER AND LOWER PORTIONS OF THE OIL BEARING SAND, AND INTERMEDIATE THE PERFORATIONS IN SAID CASING AND SEAL, INTRODUCING A PRESSURE MEDIUM THROUGH THE UPPER PERFORATION OF THE PRIMARY CASING AND SEAL INTO THE TOP OF THE OIL-BEARING SAND IN EXCESS OF THE ROCK PRESSURES EXISTING THEREIN, RECOVERING FLUID OIL FROM THE BOTTOM OF THE OIL SAND, THROUGH SAID LOWER PERFORATION OF THE PRIMARY CASING AND SEAL AND THROUGH SAID INNER CASING.