ABSTRACT

The Midland Basin of west Texas contains numerous large conventional oil and gas fields, including the giant Kelly -Snyder field (Penn. reef, Horseshoe Atoll) and Spraberry Trend (early Permian deep-water clastics). Recently, the Wolfcamp shale and Spraberry Formation have emerged as two of the nation’s leading unconventional plays. Bounded by the Lower Strawn Limestone below and by middle Permian units above, this thick (~4,000 ft.) package of strata record the history of basin-fill during Late Pennsylvanian - early Permian time. To facilitate the development of these massive unconventional resources, the Wolfcamp – Spraberry interval is now informally subdivided into a number of lithostratigraphic-based operational units and sub-units. Major units include, from oldest to youngest, the Wolfcamp D, Wolfcamp C, Wolfcamp B, Wolfcamp A, Dean, Lower Leonard Shale, Jo Mill, and the Lower, Middle, and Upper Spraberry.

The Wolfcamp D consists of a series of semi-starved, basinal cyclothems deposited during…