Print this pageSequence-Keyed, High-Resolutlon Reservoir Zonation of Middle Jurassic Haynesville Ramp Carbonates in the Gladewater Field, East Texas Salt Basin
GOLDHAMMER, R. K.
The East Texas Salt Basin contains numerous gas fields within Middle Jurassic Haynesville ramp-complex reservoirs. A sequence-keyed, highresolution reservoir zonation scheme was developed for the Haynesville Formation in the Gladewater field (areal extent of 94 mi{2}, estimated ultimate recovery of 700 Bcf, by integrating core, well-log, seismic, porosity, and permeability data. The Haynesville at Gladewater represents a high-energy ramp system, localized on paleotopographic highs induced by diapirism of Callovian age salt (Louann). Laterally discontinuous ramp crest grainstones serve as reservoirs. We have mapped the distribution of reservoir facies within a hierarchy of upward-shallowing parasequences grouped into low-frequency sequences. The vertical stacking patterns of parasequences and sequences reflect the interplay of eustasy, sediment accumulation pattems, and local subsidence (including salt movement and compaction). In this study, we draw on regional relationships from analogous, Middle Jurassic systems in Mexico to constrain the stratigraphic architecture, age model, and facies model. Additionally, salt-cored Holocene, grain-rich shoals from the Persian Gulf provide excellent facies analogs. The result is a new high-resolution analysis of reservoir architecture that has been constructed at a parasequence scale, linking reservoir facies to depositional facies. Our new zonation scheme demonstrates that different geographic portions of the field have markedly distinct reservoir intervals, both in terms of total pay and the sequence-stratigraphic interval within which it occurs. Results from this study are used to evaluate infill drill well potential, to plan wells, to update reservoir models, and to refine field reserve estimates.