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

Abstract

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: 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. 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 more » 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 Rate (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. « less