West Hackberry Field in Cameran Parish, Louisiana, is a typical "watered out" Gulf Coast oil reservoir. The formation lies 8,800 to 9,000 feet deep and is steeply tilted, dipping as much as 35 degrees from horizontal. After decodes of production, reservoir pressure has declined by 25%, and water has intruded into the formation, preventing economical production; as much as one-half of the field's original oil remains unproduced. Now, as part of a Department of Energy Oil Recovery Field Demonstration project, Amoco will attempt to repressurize the reservoir by injecting air. The plan is to create a gas cap and force the water level to recede to its original position. The target zone is the Camerina sands on the west flank of the field. Amoco researchers believe that once the necessary gas caps are created, the natural tilt of the reservoir will allow oil to drain to the lower section of the reservoir, a process called "gravity drainage." Properly placed wells drilled into this section should be able to recover most of the remaining oil. A secondary effect-spontaneous combustion of oil with oxygen could create a front of combustion gases in the reservoir. These gases could push oil more rapidly through the rock, accelerating the drainage process and boosting production. Speed, however, is relative. In this project, the reservoir's response is measured in years. Gas caps con be created within about four years, but the process of gravity drainage is expected to take much longer. If successful, additional oil from the West Hackberry Field could be recovered for as long as 15 more years. Air injection began in November 1994. Well tests indicate that reservoir pressure is increasing and combustion is occurring. Production has increased in wells high on the geologic structure. Reservoir pressure and production are being monitored.