STRICKLIN JR., F. L.
Trend Exploration Analyses, Woodlands, TX

Abstract: The Woodbine Turbidite Fan at Double A Wells Field, Polk County, Texas: A Rich Gas Find in Upper Cretaceous Sandstones of a Submarine Canyon

Almost 180 BCFG and 10.5 MMBC have been produced from exceptionally porous, pressured sandstones in this newly discovered downdip field.

The trap is a pinchout of fine-grained sandstones across a structural nose and beneath a marine disconformity that separates gulfward-dipping, clinoform beds from onlapping marine transgressive deposits. The sands, transported by a stream that originated on the Sabine Uplift and continued across a narrow submarine shelf then down the continental slope, comprise the 1) delta front Damascus Field 2) an upper slope turbidite fan at Hortense Field and 3) another turbidite fan downslope in a large submarine canyon at Double A Wells Field.

Sandstones, unusually porous for their 14,000' depth, lie in close stratigraphic proximity to Austin Chalk source rock. A present reservoir temperature of 325-350° suggests that the mature source rock is currently downcharging wet gas through 20-40' of intervening Rapides Shale and also across a fault juxtaposition window. Emplacement of an initial oil charge beginning at around 8,000' and followed by gas as burial and temperature increased, may account for porosities of up to 22% and permeabilities of up to 1.3 darcies, and suggests that pore cementation may have been "shut down" by implaced hydrocarbons.

Other lucrative fields will likely be discovered in the downdip Woodbine Trend. Exploration approaches should include seismic analysis of depositional slope morphology and clues provided by sand distribution patterns.

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