Shell, in conjunction with the United States of America Department of Energy, is conducting a gravity stable displacement field test of the miscible CO/sub 2/ process. The test is being conducted in the portion of a fault sealed reservoir lying below a subsea depth of -12,750 feet. Injection of the CO/sub 2/ slug at the producing gas-oil contact commenced in October 1978. Injection of the 860 MM cubic foot slug was completed in February of 1980. The slug of CO/sub 2/ was moved downward through the watered out sand by production of downdip water. The leading edge of the displacement has reached the producing perforations and production of the oil column commenced on January 26, 1981. Conventional cores and the log-inject-log technique were used to determine residual oil saturation in a well drilled as the pilot producer. Pulsed neutron logging devices have been used to detect the CO/sub 2/ slug and monitor its subsequent movements in the vicinity of the production well. The monitor logs indicate the thickness of the oil column had increased during the displacement to the production perforations located 130 feet below the level of CO/sub 2/ injection. The 23 foot oil column remaining at initiation of the project had apparently grown to 57 feet. PVT samples production data indicate CO/sub 2/ has penetrated the oil column and free gas is being produced with the oil. However, the qualitative measurements of the logs do not indicate a large gas or CO/sub 2/ content in the oil column.