Stratigraphic Capture: A Depositional Process Facilitating Fluid and Gas Movement Between Porous and Permeable Beds

Abstract

ABSTRACT Stratigraphic capture is a depositional process that permits vertical and/or lateral movement or flow, of fluids and gases between porous and permeable facies. The process is driven by pressure-density differences between formation fluids and/or gases. It is exclusive of flow along fault planes, across unconformities, and involves no flow from a porous, permeable sandstone into an adjoining shale, or vice versa. Communication between beds can occur as the result of scouring and channel filling during development of a distributary channel, or infilling by bar sands of scoured tidal channels. In addition to fluid exchange across stratigraphic boundary interfaces, stratigraphic capture includes fluid flow resulting from contact of porous and permeable strata with fractured lignite (coal). Stratigraphic capture is observed in the Lake Curry Field, Concordia Parish, Louisiana, where the Artman and underlying Nichols sand reservoirs are the primary oil producers of the field. Artman production is confined to the southwest and northeast parts of the field where the reservoir is in stratigraphic contact with the Nichols sand. Other examples of oil reservoirs believed to originate from the stratigraphic capture process are the overlying C/5 Turner, Yakey, Miller and Tew Lake sands.