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XI-27
recovery projects.
BONE SPRING FORMATION
The Bone Spring Fonnation (Pennian: Leonardian) is a major oil-producing
unit in the Delaware Basin (Broadhead and Speer, 1993). Bone Spring reservoirs are
carbonate debris flows and siliciclastic turbidites deposited downslope of the Abo
shelf edge (Fig. 9; Wiggins and Harris, 1985; Gawloski, 1987; Mazzullo and Reid,
1987; Saller et aI., 1989). These reservoirs are interbedded with and sealed by
impenneable dark basinal shales and micritic carbonates.The Bone Spring is informally
divided into six stratigraphic units in the Delaware Basin (Fig. 40). Carbonate
debris flows in the second and third carbonates are the primary Bone Spring reservoirs
in the Delaware Basin; they consiSt of dolomitized conglomerate breccias and
dolomitized bioclast-peloid packstones with secondary porosity. Significant production
is also obtained from carbonate debris flows in the fIrSt carbonate and siliciclastic
turbidites in the fIrst, second, and third Bone Spring sands. These turbidites are fInegrained
sandstones cemented by dolomite and authigenic clays (Gawloski, 1987;
Saller et al., 1989).
Throughout the Delaware Basin, hydrocarbon traps in the Bone Spring are
stratigraphic or combination stratigraphic/structural. Porous debris-flow and turbidite
reservoirs were deposited in channels perpendicular to the shelf margin (Gawloski,
1987; Mazzullo and Reid, 1987; Saller et al., 1989). Porous reservoirs pinch out
depositionally updip or combination traps are formed by depositional pinchout of the
reservoir across a structural nose.
Within the nine-township study area, the fIrSt, second, and third carbonates
and the fIrSt, second, and third sands have been productive (Fig. 41). There bas been
little or no systematic attempt to evaluate, test, and explore for Bone Spring traps in
this area. Generally, Bone Spring reservoirs have only been tested in wells drilled for
deeper Atoka or Morrow targets. Usually, the Bone Spring will be tested in these
wells only if a good show is noted on the mudlog or if open-hole density and neutron-porosity
logs crossover each other and exhibit "gas effect." Numerous Bone
Spring pools in the Delaware Basin have been discovered by re-entering old gas wells
in which production from the Atoka or Morrow bas declined to subeconomic levels;
in these wells, the Bone Spring may be perforated through casing if well logs or other
data suggest the presence of hydrocarbons in commercial quantities.
Because many of the exploratory wells that have discovered oil in the Bone
Spring originally targeted structural traps in deeper fonnations, discovered Bone
Spring pools are generally located on StruCtural noses (Fig. 42). With the exception of
the Red Tank pool, development of known pools within the study area bas been
limited and incomplete because operators have concentrated on drilling for deeper gas
in the Morrow and Atoka or shallower oil in the Delaware Mountain Group. There-
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