CLARK, CHRISTIAN J., Core Laboratories, Houston, TX; and ARNOLD H. BOUMA and BRUCE A. SAMUEL, Department of Geology Geophysics, Louisiana State University, Baton Rouge, Louisiana 70803
The Lower Atoka Formation along US Highway 5, northwest of Jacksonville, Arkansas, has been described as part of an ancient submarine fan complex. Three facies have been identified from this outcrop: lowstand and transgressive tract deposits in a channelized mid-fan to outer fan setting, channel levee or overbank deposits, and highstand or avulsionary shales. This paper explores the complexities within the numerous shale facie found at this locality, attempt to understand the subtle differences that exist between them, and how they change morphologically and structurally laterally. A variety of changes are, occurring in the shales, and it is geologically important to understand how these changes affect the clay mineralogy, seal stability, the overall reservoir architecture, and how these deposits should be interpreted and classified.
It is our contention to re-classify these shales into specific categories by using laser particle size analysis and a variety of other petrographic techniques as they may relate to fluid flow. Analytical techniques such as x-ray diffraction, x-ray radiography, laser particle size analysis, SEM work, total organic carbon, mercury pressure injection, thin section petrography and previous studies have been employed to ensure a comprehensive evaluation of the shale deposits found within this formation.
CLARK, CHRISTIAN J., ARNOLD H. BOUMA, and BRUCE A. SAMUEL
AAPG Search and Discovery Article #90908©2000 GCAGS, Houston, Texas