Hydrocarbon reservoir formation: paleoenvironment and structural interrelationship in the Jurassic Smackover FM. , Jay Field, Florida

The Jay Field Smackover Formation (Oxfordian Age) is a complex, three-dimensional, somewhat unpredictable, network of producing horizons. Structural data, thickness data, petrography, and paleoenvironmental analyses indicate that the location of producing horizons is strongly related to the original depositional environment and the later diagenetic history. Studies of both modern and ancient carbonates have proven the sensitivity of carbonate lithology to bathymetry and water chemistry. The use of a paleoenvironmental analyses, combined with structural information, as a predictive tool for locating producing horizons is examined. The paleoenvironmental parameters determine the porosity and permeability of the initially deposited sediment. Grainstones found on structural highs provide initial porosity necessary for oil migration. Diagenetic episodes, responsible for secondary (reservoir) porosity formation, were also strongly influenced by original paleoenvironmental parameters. Both paleoenvironment and diagenesis were in turn influenced by structures active both during and after Smackover deposition. Thus the location of producing horizons, dependent on original lithology and diagenetic alteration, may be estimated from a combination of paleoenvironmental and structural data.