The Minerals Management Service says that, as of the close of 1997, about 3.21 billion barrels of oil and 30.8 trillion cubic feet of gas remained in 789 active oil and gas fields in the federal portion of the Gulf of Mexico. Unproved reserves stood at 1.03 billion barrels of oil and 3.9 trillion cubic feet of gas, located in 51 unproved active fields. The MMS notes that the Outer Continental Shelf hosted 856 active fields, including 16 unproved active fields that were not studied. As of December 1997, cumulative production from the federal lands in the Gulf of Mexico totaled 10.46 billion barrels of oil and 127.6 trillion cubic feet of gas. The mean daily production for 1997 was 1.1 million barrels of oil and condensate and 14.1 billion cubic feet of gas. The MMS notes that from 1990 to 1997, 2,837 exploration wells were drilled in federal waters, resulting in the discovery of 119 proved fields. From the mid-1940s through the 1960s, Miocene reservoirs accounted for the largest number of discoveries. In the 1970s, Pleistocene finds dominated activity in the Gulf. In the 1980s, the Jurassic Norphlet was developed, and Miocene exploration was revived thanks to advances in seismic and drilling technologies. For the 1990s, the focus has been on deepwater discoveries in Miocene, Pliocene and Pleistocene reservoirs. That history is reflected in the reserve totals for each area. Fields in water depths less than 200 feet contained 67% of the OCS original proved reserves; accumulations in water depths less than 650 feet accounted for 90% of the original proved reserves. The emerging deepwater area presently contains a sizeable amount of original unproved reserves in a small number of fields. -Peggy Williams