ABSTRACT: Superimposed Multiple Orders of Sequences Predict Reservoir Distribution in Stratigraphically Trapped Haynesville Carbonate Reservoirs

NEUHART, DONNA M., Exxon Co. USA, Houston, TX, and ROBERT K. GOLDHAMMER, Exxon Production Research Co., Houston, TX

The Upper Jurassic Haynesville Formation is part of the Louark Group located on the east flank of the East Texas salt basin. Haynesville gas production is from ooid grainstones that formed on a gently dipping carbonate ramp. Hydrocarbon was sourced from underlying Smackover Formation basinal deposits and is stratigraphically trapped in multiple, stacked, ooid shoal pinch-outs. Prospecting for these subtle traps places a special emphasis on understanding the stratigraphy. Toward this end, the Haynesville was placed into a sequence stratigraphic framework.

Haynesville stratal stacking patterns and lithology distribution result from the superimposition of three orders of cyclicity. Evidence of second-order (>10 m.y. plate motion), third-order (1-10 m.y. eustatic sea level changes), and fourth-order (0.1-1 m.y.) sequences are found within the Haynesville data.

The third-order Haynesville sequence was upward-shoaling, consisting of transgressive and highstand system tracts. In-phase superimposition of second- and third-order transgressions resulted in extreme retrograde deposition. The results were large landward shifts in deposition centers accompanied by formation of unusually thick reservoir units.

Superimposing the observed multiple orders of cyclicity into a comprehensive geological model reveals the top Haynesville is both a third-order sequence boundary and maximum flooding surface in the second order. This observation resolves previous conflicts in interpretation. However, fourth-order cyclicity exerted the greatest control on ooid facies distribution. Mapping facies trends within fourth-order parasequences indicates the directions of ooid shoal movement and prospective areas.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)