Depositional Architecture of Springer "Old Woman" Sandstone, Central Anadarko Basin, Oklahoma
Michael R. O'Donnell, John P. Haiduk
The fluvial meander belt containing the "Old Woman" sandstone served as a conduit for clastics transported into the Anadarko basin. Mappable for a distance of more than 30 mi (48 km), sand bodies characterizing this system average 0.5 mi (0.8 km) in width and attain maximum thicknesses of 50-70 ft (15-20 m). Channel and point-bar sandstone facies display a fining-upward sequence and sharp basal contact, as inferred from gamma-ray and resistivity logs.
Sandstones of the "Old Woman" fluvial complex overlie the laminated shales and silts of the penecontemporaneous flood-plain environment. These flood-plain deposits are underlain by crinoidal wackestones and packstones deposited in the subtidal regime. Encroachment of the fluvial complex into a marine setting is interpreted from this sequence. Thin flood-plain deposits and lack of shallow marine clastic sediments suggest rapid advancement.
Quartzitic and petrologically mature, the "Old Woman" sandstone is fine grained, with small-scale troughs and laminations, and a few mudstone rip-up clasts. Diagenesis has altered the mineralogic composition mainly by siliceous and carbonate cementation. Porosity is secondary, resulting from dissolution of various metastable constituents.
The "Old Woman" sandstone was established as a hydrocarbon reservoir in the early 1960s, and sporadic development continued for years. The present-day petroleum market has prompted a resurgence in drilling activity owing to the economic viability of this reservoir. Successful wells are concentrated in newly discovered meander-belt bends; however, the elusiveness of this fluvial system challenges today's exploration geologists as it has for the past quarter century.
AAPG Search and Discovery Article #91039©1987 AAPG Mid-Continent Section Meeting, Tulsa, Oklahoma, September 27-29, 1987.