Field and Modeling Studies of Cyclic Carbonates: A Predictive Tool for Petroleum Exploration: ABSTRACT

In cyclic sequences containing large numbers of 1 to 10-m carbonate cycles, lack of well-defined markers generally prevents construction of detailed stratigraphic cross sections showing detailed facies changes. Fischer plots that graph cumulative cycle thickness corrected for linear subsidence using average cycle period can be used to correlate sections and show relation of individual cycle types to third-order sea level cycles. Interaction between simple or complex sea level curves defined by various frequencies and amplitudes; the sediment-surface, water-depth dependent sedimentation rate; lag time; and subsidence through time can be shown using one-dimensional models. Isostatically balanced two-dimensional models that incorporate the above variables, plus initial platform slope and thermotectonic subsidence (divided into rotational and regional components), can be used to construct detailed cyclic facies cross sections of carbonate platforms. These can be used to define regional relations between cycles; likely vertical and lateral facies changes; distribution of disconformities, conformities, and tidal-flat caps; relative water depths of facies likely to be developed on the platform; as well as likely location of early diagenesis. The integration of field and modeling studies provides a rigorous analysis of cycle deposition that could be of great predictive value in the exploration and development of petroleum reservoirs.