Depositional and diagenetic controls on reservoir quality and petrophysical responses of the DeBroeck Member of the Rodessa Formation in Northwest Louisiana.

The DeBroeck Member of the Lower Cretaceous Rodessa Formation is an overlooked hydrocarbon reservoir in Northwest Louisiana. The formation was deposited on a carbonate platform within the North Louisiana Salt Basin. Core analysis identified fourteen lithofacies within the DeBroeck Member with maximum porosity and permeability values of 21.3% and 49.6 mD. The lithofacies indicate a shallow, open marine depositional environment. Porosity is present as primary interparticle/intraparticle and secondary moldic. Petrographic and SEM imaging show that porosity and permeability are affected by carbonate mud recrystallization and calcite, anhydrite, and pyrite cementation. Diagenesis occurred in three stages: marine, meteoric, and burial, with all stages affecting porosity and permeability. Advanced porosity analysis determined that large amounts of microporosity/irreducible water are present within the formation, causing the resistivity log response to appear ‘water-wet’. Backscatter SEM image analysis shows that pyrite is locally abundant and interconnected within stylolites, which also affects the formation’s petrophysical response.