ABSTRACT

The Sunniland Formation is a wedge of carbonates and anhydrites of Late Trinity, Early Cretaceous age. To date, it is the only productive formation in South Florida.

The first test that penetrated the Sunniland Formation (1943) became the discovery well for Sunniland Field. Wildcat activity during the next 20 years averaged three wells per year and resulted in only one non-commercial discovery. In 1964, after the discovery of the Sunoco-Felda field, wildcat activity tripled averaging nine tests per year. Six additional discoversies occured between 1966 and 1975. Daily production climbed from 1,300 barrels of oil per day to the present 13,000 barrels of oil per day. Cumulative production through 1964 was 8,000,000 barrels of oil, and by the end of the 1975 totaled 42,000,000 barrels of oil.

The main reservoirs are found in the upper part of the Sunniland Formation (average depth 11,500) in porous and permeable skeletal-pelletal carbonates. These shelf carbonates were deposited in beach and shoal-type environments along a northwest-southeast trending band. Updip from this favorable trend, the carbonates become micritic-skeletal with resulting low permeabilities. An anhydrite facies is present downdip. Regional dip is a gentle 1/2° and known structures are low relief. Hydrocarbon accumulations are both structurally and stratigraphically controlled with structure being the most important factor.

The increase in exploration during the past 11 years in South Florida can be attributed to several factors. Additional well control has provided necessary data for a better understanding of stratigraphy. This new information has also permitted a realistic understanding of the Sunniland Formation's potential as a hydrocarbon reservoir. Initial production of 300-500 barrels of oil per day is typical. Production history indicates that many wells will ultimately produce in excess of 1,000,000 barrels of oil.