High-frequency cyclicity in shelf-edge deltas, common from late highstand to early transgression, can produce hydraulically isolated sandstone bodies. Such compartmentalization may be recognized with careful high-resolution log correlation and detailed 3-D seismic analysis, resulting in opportunities to capitalize on reservoir heterogeneity to develop increased reserves.

Reservoirs in middle Miocene third-order falling-stage deltas of the Vienna pull-apart basin were investigated as part of an integrated characterization study, the goal of which was the identification of remaining resources in the mature supergiant Matzen field. Detailed well log correlation, supported by 3-D seismic interpretation, identified clinoform geometries in the 9th and 12th Badenian reservoirs that were the consequence of rapid progradation of a moderate-relief (100-m) deltaic wedge. Because these fluvial-dominated deltaic sandstone intervals, as much as 30 m in thickness, occupy the upper part of each clinoform, they had previously been correlated as a single body. Integration of geological/ geophysical information with reservoir fluid flow behavior documented previously unrecognized compartmentalization caused by high-frequency flooding surfaces that separate individual clinoform bodies.

Documentation of clinoform-induced lateral compartmentalization has created infill drilling opportunities at updip clinoform terminations. Localized traps are formed where undrilled isolated clinoform units pinch out updip or are draped over structural closures, some faulted, and presence of sandstones can be confirmed from offset wells.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas