Controls on Hydrocarbon Production in Bryan's Mill Area, Cass and Bowie Counties, Texas: ABSTRACT

Abstract

ABSTRACT 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 have been recognized which extend across the area. Shortly after deposition, leaching by meteoric fluids resulted in oomoldic porosity in many of the ooid grainstones; other carbonate facies were little affected. During early diagenesis, dolomitization both preserved existing porosities and generated an effective intercrystalline porosity, so enhancing permeability. After dolomitization, brittle compaction during burial further increased permeability by the interconnection of 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 is 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. Production in the area is dependent on a combination of structural, stratigraphic, and diagenetic factors. Although the grainstones are continuous across the northernmost structural high, production is only from dolomitized areas. Thus diagenesis, and in particular dolomitization, is the ultimate control on production in the area.