Factors Controlling Occurrence of Morrow and Cherokee Sands and Their Relation to Production in the Anadarko Basin

Abstract

ABSTRACT Stratigraphic and lithologic data from 1200 wells in the panhandle areas of Texas and Oklahoma and 600 wells in northwestern Oklahoma were recorded in a form suitable for computer processing. Maps were prepared for each of three subdivisions of the Morrow in the Panhandle area and for each of seven operational units selected to subdivided the lower Morrow in northwestern Oklahoma. These isopach and quantitative facies maps showing areal variation in thickness and rock types were used in combination with detailed stratigraphic relationships based on electric log correlations to interpret the depositional history and predict areas most favorable for development of porous sandstones. In the panhandles of Texas and Oklahoma and in northwestern Oklahoma, the Morrow Formation is the basal transgressive predominantly clastic unit of the Pennsylvanian system, unconformably overlying the Mississippian. The upper boundary is delineated by the base of the "Thirteen-finger" limestone, an electric log marker, and the lower boundary by the Pennsylvanian-Mississippian contact. Lower Morrow and basal Cherokee sandstone accumulations correlate closely with the residual structure on the top of the Mississippian unconformity of topography or early Pennsylvanian structural movement on the deposition of these sandstones. Apparently significant structure existed before or developed during deposition of these units. Isopachous and structural data indicate continued activity of these structures throughout Morrow deposition. Distribution of coarse terrigenous clastics within the predominantly fine terrigenous clastic Morrow Formation suggests one source of sand west of the Panhandle area and a second source on the northeast. The Wichita-Amarillo uplift south of the depositional basin began to supply coarse clastic material during deposition of the upper Morrow unit. In the Panhandle area, widespread sheet sandstone and sandstone beds at parallel trends of early Morrow shorelines are interpreted to be near shore marine sediments deposited as the early Morrow sea overlaps onto the shelf areas. The thin lenticular upper Morrow sandstone bodies are interpreted as having been deposited by a complex stream system flowing southeast toward the basin axis.