The analysis of reservoir sequence and cycle stratigraphy, of depositional and diagenetic facies, and of the interrelationships between these attributes and reservoir properties is key to the construction of an accurate reservoir framework needed for reservoir modeling and improved imaging of remaining hydrocarbons. Fundamental steps in such a rock-based process of model construction applied at Fullerton Clear Fork field, a shallow-water carbonate platform reservoir of middle Permian age, included (1) creating and applying an analogous outcrop depositional model; (2) describing and interpreting subsurface core and log data in terms of this initial model; (3) defining the sequence-stratigraphic architecture of the reservoir section; (4) developing a cycle-based reservoir framework; and (5) defining controls, interrelationships, and distribution of porosity and permeability. Data used in this analysis included cores, thin sections, three- and two-dimensional seismic data, borehole image logs, and outcrop models.

Key geological elements addressed and incorporated into the models include stratal architecture, differential dolomitization, karst fill, mineralogical variations, and rock-fabric distribution. These components were used to constrain interpretation and definition of flow units, permeability distribution, and saturation.

In addition to resulting in improved and more geologically realistic reservoir models, the rock-based methods used in this study provide key insights into the formation, characterization, and interpretation of carbonate platform reservoirs; these insights have widespread application worldwide.