REFERENCE SECTIONS FOR JURASSIC COTTON VALLEY & LOUARK GROUPS, NORTH LOUISIANA SUBSURFACE

Consistent stratigraphic nomenclature is an integral component of successful exploration and management of natural resources. Publications of stratigraphic nomenclature are typically generated and maintained by geological surveys and bureaus. However, at present much of north Louisiana subsurface stratigraphy is inadequately documented in the form of a comprehensive, easily accessible reference base.

The present study identifies field-specific reference stratigraphic logs for north Louisiana oil & gas fields. Reference logs are constructed from geological and geophysical data obtained from intra-field oil & gas wells and by correlation to neighboring fields. Reference well selection is based upon data quality, well location and total depth (TD), and similarity of geophysical profiles to those of field mate wells. Following the guidelines of the North American and International Stratigraphic Codes, the stratigraphic logs are constructed from publicly available open-hole electrical logs and drill cuttings. These data are augmented by other geophysical profiles and drill cores. The result is a graphic representation of the lithostratigraphic section with contacts assigned according to nomenclature established in publications and by common usage. Intra-field correlations and extension to neighboring fields permits refinement of the full stratigraphic nomenclature with respect to historical naming conventions while minimizing name revisions or additions.

The study thus far has produced reference sections for the Jurassic Cotton Valley – Louark interval in Carterville, Cotton Valley, Ivan, and Shongaloo fields of Bossier and Webster Parishes, Louisiana. These sections constrained by lithology samples have proven useful in other studies of regional subsurface geology in north Louisiana and northeast Texas.