Deep Pays in Delaware-Val Verde Basins: ABSTRACT

Abstract

The Delaware-Val Verde Basins are a continuous elongate northwest-southeast-trending downwarp extending from Eddy County in southeast New Mexico to Edwards and Kinney Counties in Texas. Deep production consists mostly of petroleum condensate and gas containing substantial amounts of carbon dioxide, and is confined primarily to the Ellenburger Group of the Ordovician; the Devonian; the Morrowan, Atokan, and Strawn Series of the Pennsylvanian; and the Wolfcampian Series of the Permian. Original water salinity distribution in the Ellenburger and Devonian formations appears to have been highly modified by hydrodynamic movement of meteoric waters in the west, southwest, and south parts of the trough. This flushing, extremely active in early Pennsylvanian, late Permo-Pennsylvanian, and Triassic-Jurassic periods, continues in a minor degree to the present time. Charged meteoric water which introduced carbon dioxide to the subsurface had as its major origin the solution of carbonate and bicarbonate components in the exposed rocks of the Ouachita, Marathon, and Diablo Platform areas. The most likely periods of generation were early Pennsylvanian, late Permo-Pennsylvanian, and during the Tertiary igneous disturbance. Forceful emplacement of carbon dioxide and methane may ha e occurred in the Val Verde Basin throughout early Pennsylvanian and mid-Wolfcampian folding and thrusting in the Ouachita-Marathon region. Absence of oil production from the deep zones in the Delaware-Val Verde Basins appears to be the result of two major factors. The first is the hydrodynamic flushing of crude accumulations from all but the deeper and larger closures. This scattering of oil occurred coincident with the major periods of hydrodynamic activity. The second factor is that restored maximum overburden, as well as present overburden in many cases, exceeds the gas-condensate conversion point for Delaware-Val Verde Basin oils. These oils, derived from the Simpson, Woodford, and Permo-Pennsylvanian shales, diassociate into gas-condensate and gas below 14,000, 13,000, and 8,000-9,000-foot depths, respectively. End_of_Article - Last_Page 2074------------