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NIO, S. D. YANG, Intergeos B.V., Leiderdorp, Netherlands

ABSTRACT: High-Frequent Cycles and Sequence Stratigraphy: New Aspects for Hydrocarbon Field Development and Re-Evaluation

A new development in the application of sequence stratigraphic concepts in subsurface hydrocarbon exploration, development and production is the recognition of high-frequent cyclic patterns in rock successions. Numerous studies of subsurface rock successions from different geological periods show an intimate relationship between the high-frequent cycles and sequence organization. Comparisons between a simulation modeling and the Exxon's third order curve show that a major part of the curve is a composite of these higher-order cycles. Some of the results from our studies can be summarized as follows:

1. An intimate relationship exists between climate changes and sea level fluctuations. Changes in climate within the time dimensions of the third-order Exxon chart are for a large part responsible for the sequence stratigraphic organization.

2. Fourth and higher-order cycles (mainly Milankovith cycles) are the major controlling parameters for changes in sedimentary facies and/or subfacies. For continental basins, a climate-forcing model is used in sequence analysis, while in transitional and marine basins an integrated climate-forcing and sea level model is used.

This interrelationship allows an accurate quantitative evaluation of each sequence and/or systems tract. The InterGeos' cyclicity analysis tool (MILABAR) was designed for well analysis using wireline logs. A zonation into sequences where the sequence boundaries can be calibrated as well as the net duration and net accumulation rate of each measured sequence can be estimated. The results are summarized in a Well Composite Chart, which include e.g. Interval Time Estimates (ITE), Net Accumulation Rates (NAR), etc. In correlations an accuracy of 500-100 Ka can be obtained. Vertical as well as lateral continuity of lithofacies (e.g., reservoirs, permeability barriers, etc.) can be computed and predicted.

AAPG Search and Discovery Article #90988©1993 AAPG/SVG International Congress and Exhibition, Caracas, Venezuela, March 14-17, 1993.