Abstract

The organic-rich upper Wolfcamp horizontal play has proven to be a viably economic play in both the Delaware and Midland basins, specifically within the paleodepositional basin floor environment. The question posed herein is whether similar variables that allow the play to work in the basin could be present within the paleodepositional slope environment? In 2012, Whiting Oil & Gas decided to test this hypothesis on acreage within the SE Delaware Basin Slope.

Specific to the paleodepositional slope, the upper Wolfcamp play concept includes:

• Relative to the Leonardian-Wolfcamp section, upper Wolfcamp strata are one of the richest source zones defined by measured TOC and kerogen.

• Dominate organic-rich lithology is comprised of quartz siltstone (ORS) with minor amounts of clay; results in sufficient permeability and frackable rock, without the need of a conduit bed. ORS is the source and reservoir.

• Upper Wolfcamp sequences consistently map across the slope; carbonate turbidite and debrite beds thicken and comprise more of the gross section moving up slope, thus these beds may provide more positive reservoir quality rock resulting in storage capacity for migrated oil (from adjacent ORS).

• Upper Wolfcamp strata are over pressured.

• Historical vertical production of upper Wolfcamp strata within the slope regime demonstrate a pattern of initial rapid decline (drainage of migrated oil from carbonate reservoirs and fractures), followed by a shallow decline (drainage of insitu oil from ORS).

• Horizontal play; thought not to be suited for economic vertical completions due to difficulty in effectively stimulating enough rock volume.

• Proper analogies include current horizontal play in Midland Basin, west-central Delaware Basin (Petrohawk/Eagle/Concho acreage), and Avalon Play in north-central Delaware Basin.

Basis for the play concept is found in the use of several observations, measurements, and resulting interpretations using petrophysical logs (standard and image), mudlogs, core (facies and analyses), geochemical analyses, and production profiles. Examples of these observations, measurements, and interpretations will be presented for discussion.