Abstract: Deep-Water Reservoir Sandstones of the Texas Gulf Coast

By

Robert B. Halley

Reprinted from GCAGS Transactions V31 p31.

Core studies have revealed that many downdip sandstones in the Texas Gulf Coast are turbidites. These sandstones are found in several distinct depositional settings, and each is characterized by different reservoir morphologies. Submarine fans are present in the upper Wilcox at Katy field, and bed associations observed in cores show stacked-channel, middle-fan, and outer-fan facies. Fans also are represented in the upper Wilcox at Northeast Thompsonville field. Constructional channel-fill sandstones are found in the lower Vicksburg at McAllen Ranch field. Submarine canyons in the outer shelf are shale-filled and form truncation traps at Yoakum and Valentine fields. Channel sandstones within canyon fill are reservoirs in Oligocene Hackberry fields. Channel sandstones on unstable slopes are found in the Upper Cretaceous Woodbine in Seven Oaks field and in a slumped, lower Wilcox section at South Hallettsville field. In both areas, slope instability was controlled by Lower Cretaceous carbonate-shelf margins. Turbidite deposition was controlled by growth faults in Frio sandstones at Nine Mile Point field and by a shale diapir in lower Vicksburg sandstones at McAllen Ranch field.

Recognition of turbidite reservoirs, and their different modes of occurrence, is important in exploration. Abundant evidence for turbidity current transport indicates that even the deepest parts of the Gulf Coast basin may contain reservoir sandstones.

End_of_Record - Last_Page 2---------------

Copyright © 2005 by Houston Geological Society. All rights reserved.