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High-Resolution Biostratigraphy: Providing a Framework for Correlating Reservoir Sands

RAGAN, GERALD M., Mobil E & P United States, New Orleans, LA, Richard C. Becker, Mobil E & P Services, Dallas, TX, and William H. Abbott, ARCO Oil & Gas Company, Plano, TX

Correlating individual sands is critical to field development and reservoir management. High-resolution biostratigraphy can provide this correlation by supplementing standard paleotops with local bioevents, recognized in thin hemipelagic units. These events provide an additional framework for calibrating and refining well logs and seismic record sections. This high-resolution data set can be used to reduce the risk in development drilling.

Standard regional extinction datums (paleotops) are typically separated by hundreds or even thousands of feet. Although they permit calibration of regional mapping horizons, most reservoir objectives occur between these datums. Therefore, a high-resolution technique is necessary to correlate the sands between these extinction datums.

Detailed studies in the United States Gulf of Mexico and Indonesian Neogene reveal local and semiregional signals between those regional extinctions. These signals, or events, are caused by physical and chemical fluctuations in the oceanic water masses through time. Planktonic foraminiferal and calcareous nannofossil assemblages imprint these events onto the accumulating sediments and yield a reproducible signal that can be interpreted and correlated. Identifying and documenting these events is the principle behind high resolution biostratigraphy. When integrated with electric logs and transferred to seismic sections, such signals produce a more refined correlation and subdivision of sediment packages.

This poster session examines the procedure for applying this technique. We will discuss data generation, integration, interpretation, and display using specific computer software. We present three field studies where local high-resolution biostratigraphic zonations have permitted a finer subdivision of sediment packages and correlation of sands.

 

AAPG Search and Discovery Article #91007© 1991 AAPG International Conference, London, England, September 29-October 2, 1991 (2009)