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Abstract: Scanning Electron Microscope Examination of Shale in Core from the Frio Formation, Brazoria County, Texas

P. D. Alley-McReynolds

Scanning electron microscope (SEM) examination of additional core from shallower geopressured and nongeopressured Frio Formation wells in Brazoria County shows similar fracture patterns and clay textures to those reported earlier in the Skrabanek 1 well. The additional wells examined by SEM are 1-B Minnie Mettler, 2847 to 3254 m; Pleasant Bayou 1, 3532 to 4750 m; and Phillips Petroleum JJ 1, 4919 to 5128 m. We noted that shales occurring from 2744 to 5488 m have similar grain orientation and fracture patterns. Pleasant Bayou 1 is strikingly similar to Skrabanek 1, having coarse flakes and grains of quartz and feldspar disbursed throughout. Phillips Petroleum JJ 1 is more uniform in appearance, lacking distinct clay flakes and scattered grains. 1-B Minnie Mettler is similar in appearan e to Phillips Petroleum JJ 1, having a uniform distribution of components; however, the clay flakes are less densely packed. Fractures are present in all three wells. The abundance of both horizontal and vertical fractures at varying depths could act as avenues of fluid flow within geopressured shales.

AAPG Search and Discovery Article #90983©1994 GCAGS and Gulf Coast SEPM 44th Annual Meeting, Austin, Texas, October 6-7, 1994