The Yates Unit Oil Field is located on the southeastern tip of the Central Basin Platform in eastern Pecos County, Texas. It produces from Middle Permian strata, primarily the upper San Andres Formation. Locally, the productive upper San Andres Formation is comprised of successively vertically stacked progradational shelf carbonates. Stratigraphically overlying the Yates Field reservoir, the Toborg Field produces from the uppermost Triassic and Cretaceous units. Both fields are bounded on the north and east sides by the Pecos River, which has remained entrenched in its current location since the early Tertiary. As mapped, the top of the San Andres Formation is an unconformity representing erosional topography that does not truly reflect the subsurface structural configuration.
Stafford, Kevin W.; Behnken, Fred H.; and White, Jesse G., "Hypogene speleogenesis within the Central Basin Platform: Karst Porosity in the Yates Field, Pecos County, Texas, U.S.A." (2008). Faculty Publications. 9.