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OIL AND GAS RESOURCES Al'fD PETROLEL'M GEOLOGY OF WIPP SITE
Overview
The WIPP site is situated in the Delaware Basin (Fig. 7). Strata range in age from
Cambrian through Permian (Fig. 8). The Delaware Basin is the deep-marine pan of the
Permian Basin and is bordered on the north and west by the Northwest Shelf and on the
east by the Central basin platform. The Permian Basin became differentiated into these
paleobathymetric elements during the Pennsylvanian. By the Wolfcampian (Early
Permian), the shelf margin was constructional rather than tectonic and was marked
successively by the Wolfcamp, Abo, Getaway, Goat Seep, and Capitan bank and barrier
reef complexes (Figs. 9, 10). Regional structural dip is toward the center of the Delaware
Basin (Fig. 11). In the vicinity of the WIPP site, oil and natural gas have been extracted
commercially froth the Delaware, Bone Spring, Wolfcamp, Strawn, Atoka, and Morrow
(Fig. 8). Presently nonproductive units which may bear undiscovered oil and natural gas
in the area are (descending): Mississippian, Siluro-Devonian, and Ordovician sections;
significant volumes of oil and gas are produced from these stratigraphic units elsewhere
in the New Mexico part of the Pennian Basin.
History of oil and gas drilling in WIPP area
According to comprehensive well records on me at the New Mexico Bureau of
Mines & Mineral Resources, 532 wells had been drilled in search of oil and gas in
the nine-township study area centered on the WIPP site as of the end of 1993 (Fig.
2). Additional drilling was done in 1994, but 1994 wells were not included in these
statistics because complete data for the year were not available at the time this report
was written. Few wells were drilled in the area prior to 1960 (Fig. 12). From 1960
until 1989 drilling activity increased but was sporadic and never exceeded 20 wells
per year. In 1990, however, drilling increased markedly. Annual totals increased to a
maximum of 140 wells per year during 1993; most of these wells were drilled for oil
(Fig. 13) in the Brushy Canyon Formation of the Delaware Mountain Group. The
increase in well completions during the 19905 can be partially attributed to opening up
hitheno restricted areas of the Potash Area to drilling (see Ramey, this report, for a
summary of drilling restrictions in the Potash Area). However, the lower parts of the
Delaware Mountain Group (Cherry Canyon and Brushy Canyon Formations) were not
generally recognized as exploratory and development targets until the late 19805 and
early 19905. Prior to that time, they were usually bypassed during drilling with little
or no thougbl that they might contain economic oil reservoirs. Although these two
formations had been penetrated by thousands of wells throughout the Delaware Basin,
few attempts were made to adequately test them.
The main reason for bypassing these formations during drilling was a lack of
understanding of their reservoir production characteristics. Water saturations calculated
from analysis of electric logs were often high and did not differentiate oil-productive
sandstones from sandstones that would yield mostly water upon completion.
However, recent developments in log analysis (Asquith and Thomerson, 1994) have
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