High pressure shales and their depositional facies, southern Louisiana Cenozoic

The volume and proportion of overpressurized-low resistivity shale units in the middle and upper Cenozoic marine sediments of southern and offshore Louisiana increases basinward with increasing depositional water depths. Middle and outer neritic low resistivity shales form the bulk of the studied high pressure shales. A decrease in the "low": "normal" resistivity shale ratios in Pliocene and Pleistocene sections is probably due to extreme undercompaction, resulting from the lack of cohesion between shale particles.