Robert F. Lindsay¹

(1) Chevron USA Production Company, Midland, TX

ABSTRACT: Meteoric Recharge, Displacement of Oil Columns and Development of Residual Oil Intervals in the Permian Basin

Numerous Permian Basin gas/oil fields contain residual oil intervals beneath producible hydrocarbon columns.

Residual oil intervals were formed by massive recharge of meteoric water into the Permian Basin in the Middle Tertiary. Source of this water was the east dipping limb of the Rio Grande Rift. This rift developed in three phases. First, was initial uplift of a large, tilted, slowly extending landmass (Late Oligocene-Early Miocene). Second, was rapid extension and normal faulting (Middle-Late Miocene). Third, was slow extension (Pliocene-Recent).

East limb of the rift covered an area from its center (present-day Rio Grande River) to the western edge of the Central Basin Platform. First phase of initial uplift, tilting and slow extension of the rift recharged massive volumes of meteoric water into the subsurface. Recharging water had enough hydrostatic head (energy) to partially to completely sweep oil columns to residual oil saturation (Sorw). Second phase of rapid extension broke the eastern limb of the rift into numerous horsts and grabens. Once classic Basin and Range province horsts and grabens developed only small landmasses were available to recharge much smaller volumes of meteoric water into the Permian Basin. Many oil columns resaturated, some with gas instead, while others stayed at residual oil saturation (Sorw). Third phase of slow extension recharged only small volumes of meteoric water into the Permian Basin.

Though residual oil intervals may not have any primary/secondary recovery potential, they may be additional targets of opportunity for tertiary CO2 floods.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado