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XI-22
of approximately 7500 ft. The . 01 was discovered in 1993. Development of the pool
has been slow. with only three wells drilled by the end of 1993 and two more drilled
in 1994. WeH"dere drilled on 40-acre spacing. At the end of 1993, there was only
one active producing well in the pool; the other two wells drilled during 1993 have
not yet been brought into production. Cumulative production from the pooi totaled 11
KBO and 8.5 MMCF associated gas as of December 31, 1993 (Table 8). Although
data are limited by a paucity of wells, the isopach map of the gross thickness of the B
zone (Fig, 34) indicates a thick area trends south-southeast in the southwest part of
the WIPP land withdrawal area. These thick areas in the B zone coinc:e with thin
areas in the underlying D zone (Fig. 28) and appear to be infillings of bathymetrically
low interlobe areas in the lower submarine-fan environment. Although wells have
penetrated the B zone outside the established pool boundaries, they have been
drilled for hydrocarbons in c:c.per strata and have not adequately tested B zone
sandstones. The sparse data indicate that economic prod', '~tion is limited to areas
where the B zone is at least 80 ft thick; apparently, there is a sufficient net thickness
of reservoir sandstones in these areas to yield economic volumes of oil.
The trap at Quahada Ridge Southeast is a combination structural/stratigraphic
trap. In addition to the stratlf:::::hic control that reservoir thickness exerts, production
may also be limited to the east :.y structure. Although .Gi are sketchy, it appears that
an oil-water coma::t may be approximately coincidem '''lth the -4100 ft contour of the
top of the lower Brushy Canyon (Fig. 25). If this is true, then the isc;:ach and
structure maps indicate that there are nine undrilled 4O-acre units withm the WIPP
land withdrawal area and 52 undrilled 4O-acre units that have probable oil and gas
within the additional study area (Fig. 26).
Three casing strings are used during drilling and completion operations in
wells drilled to develop the lower Brushy Canyon B zone in the Quahada Ridge
Southeast pool (Fig. 36). Typically, 13% inch surface casing is set and cemented at a
depth of approximately 600 ft. An intermediate string of 8% inch casing is then set
and cemented at a depth of approximately 3850 ft in the uppermos; part of the Bell
Canyon Formation. Production casing of 5 1 h inch diameter is then set and cemented
to total depth of approximately 7900 ft. Casing is then perforated in the B zone.
Before economic production can be obtained, the pay zone must be acidized and
artificially fractured. Volume of the acid Illad ranges from 1000 to 3000 gallons.
After acid treatmeIIt, the well is hydraulically fractured. Fracture treatments use
20,000 to 40,000 gallons of water and 70,000 to 120,000 Ibs ofsand.'...
Wells in the Quahada Ridge Southeast pOol have produced for an insufficient
length of time to determine ultimate primary recovery with the production-decline
technique used in this study. However, oil and gas are produced from the same
reservoir that produces from the lower Brushy Canyon in the Cabin :.alee pool. In the
absence of other data, the same ultimate recovery data are used as fOT me Cabin Lake
pool, 66 KBO and 46 MMCF gas for the average or typical well.