Fluvial Sedimentation in the Cotton Valley Formation in the Stringer Field, Jasper County, Mississippi

E. Heydari¹ and R. N. Townsend^2
1Mississippi Office of Geology, Jackson, MS
²Brandon, MS

Byron, Crawford Creek, East Sharon, Quitman, and Stringer fields are a few examples of major oil and gas production from the Cotton Valley Formation in Mississippi. A comprehensive study encompassing stratigraphy, depositional environments, and reservoir quality of this unit is lacking. Detailed study of two conventional cores from the Stringer Field, Jasper County, Mississippi, provides a glance into the complexity of lithofacies successions, depositional environments, porosity heterogeneity, and petroleum geology of the Cotton Valley Formation in this field. The study can provide insights for future exploration.

In the Spooner Petroleum #1 Viersen 30-11 core, the formation consists of a channel lag carbonate conglomerate overlain by point bar cross-laminated sandstones. This is followed by another carbonate conglomerate overlain by dark gray irregularly laminated sandstone, followed by red shales and siltstones with abundant root structures. The conglomerate-to-red shale succession represents facies characteristic of an abandoned channel. Another channel lag carbonate conglomerate and the associated point-bar sandstone complex overlie the abandoned channel by a sharp contact. The internal structures and carbonate mineralogy of gravel and pebble fragments in the channel lag conglomerates indicate that these particles were originally formed as nodules in soil zones of the adjacent overbank deposits and were delivered to channels during channel migration. The Spooner #1 Viersen 30-9 well shows a lithofacies assemblage similar to the 30-11 well. Overall, this section of the Cotton Valley Formation represents a meandering river system. The most porous intervals are the point-bar sandstones. Lithofacies correlation and petroleum geology history of the field suggest that the producing channel sands spread over a wide region and are in communication.

AAPG Search and Discovery Article #90901©2001 GCAGS, Annual Meeting, Shreveport, Louisiana