SMACKOVER DEPOSITION AND DIAGENESIS AND STRUCTURAL HISTORY OF THE BRYAN’S MILL AREA, CASS AND BOWIE COUNTIES, TEXAS
GILL HARWOOD, CHRIS FONTANA, 1984. "SMACKOVER DEPOSITION AND DIAGENESIS AND STRUCTURAL HISTORY OF THE BRYAN’S MILL AREA, CASS AND BOWIE COUNTIES, TEXAS", The Jurassic of the Gulf Rim, William P. S. Ventress, Don G. Bebout, Bob F. Perkins, Clyde H. Moore
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Production from the Bryan’s Mill, Frost, and Carbondale Fields in the Bryan’s Mill area is from Jurassic Upper Smackover dolomitized ooid grainstones. Within the Upper Smackover, three coarsening-upwards sequences culminating in ooid grainstones extend across the area. Shortly after deposition, leaching by meteoric fluids resulted in development of oomoldic porosity in many of the ooid grainstones; other carbonate facies were little affected. During early diagenesis, dolomitization enhanced permeability by preserving existing porosities and by generating an effective intercrystalline porosity. After dolomitization, brittle compaction during burial further increased permeability by interconnecting oomolds.
The center of the Bryan’s Mill area was a positive feature during late Smackover deposition. Faulting during Buckner deposition resulted in a series of southeasterly tilted fault blocks, perhaps due to regeneration of basement structures. Later, post-Hosston faulting had an east-west trend and was possibly associated with doming of the sediments over two highs. There is little evidence of Jurassic or Early Cretaceous movement on the east-west trending faults.
Hydrocarbon production in the area depends on a combination of structural, stratigraphic, and diagenetic factors. Although the grainstones are continuous across the northernmost structural high, production is limited to the dolomitized areas. Thus, diagenesis, and in particular dolomitization, is the ultimate control on production in the area.