Petroleum and Natural Gas Fields in Wyoming Page: 251

                                
REVIEW OF OIL AND GAS FIELDS

permeability of this 26-foot zone was 8 milli-
darcyes. The log of the well showed the
following depth, in feet, to the top of forma-
tions: Cody, 4,555; Frontier, 7,295; First
Frontier sand, 7,595; Second Frontier sand,
7,714; Third Frontier sand, 7,860; Fourth
Frontier sand, 8,000; Mowry, 8,048; Thermo-
polis, 8,370; Muddy sand, 8,545; Cloverly,
8,755; Dakota, 8,815; Morrison, 8,872; Sun-
dance, 9,155; Gypsum  Spring, 9,420; Chug-
water, 9,555; Dinwoody, 10,400; and Phos-
phoria, 10,460. Analyses of oil and gas from
the Phosphoria limestone are included on page
498 and in table 8, (p. 290), respectively.
Of the 10 wells drilled in the field, 8 were
completed as oil wells. Because of the high
hydrogen sulfide content of the gas, the wells
were shut in, except for testing, until the sul-
fur-recovery plant at Manderson field was
completed early in 1955. Since that time the
gas has been piped to Manderson for process-
ing. About seven long tons of sulfur is
recovered, from each million cubic feet of gas.
During November 1957 eight wells were
operated in the field. Daily production during
the month was 761 barrels of oil and about
1.03 million cubic feet of gas. Oil and gas
produced at Slick Creek field during 1956
totaled 368,026 barrels and 422 million cubic
feet.  Cumulative production to 1957 was
940,799 barrels and 776.5 million cubic feet. Oil
from the field is piped to South Fork field,
thence southwestward to Chatham, Wyo. The
gas is piped to Manderson, where it is proc-
essed and sold to a utilities company.
SOUTH FORK
The South Fork structure (fig. 151) is in
the southwest corner of T. 46 N., R. 91 W.,
and the southeast part of T. 46 N., R. 92 WV.,
Washakie County. It is situated on a north-
west-southeast-trending  anticline  that  has
about 400 feet of closure. The anticline is
nearly symmetrical ; the northeast flank is the
steeper side. South Fork was discovered after
seismic study of the area. The Wasatch is
exposed on the surface at an elevation of 4,400
feet.
The field was discovered in April 1947, when
a well in the SE1aSE'1/ sec. 24, T. 46 N., R.
92 W., was completed with an initial daily
production of 384 barrels of 280 API gravity
oil from  the lhosphoria limestone between
10,046 and 10,110 feet. The small amount of
gas produced at South Fork is sweet, while
gas from the same formation in nearby fields
contains considerable quanties of lhydrogen
sulfide. A second well was drilled in 1949.
The discovery well tested the Tensleep, Ams-

den, and Madison formations without success.
The depth, in feet, to the top of formations
in this well was as follows: Cody, 4,300; First
Frontier, 7,203; Second Frontier, 7,335; Third
Frontier, 7,495; Muddy sand, 8,140; Dakota,
8,430; Chugwater, 9,030; Dinwoody, 10,000;
Phosphoria, 10,052; Tensleep, 10,246; Amsden,
10,482; and Madison, 10,715.
In December 1957 the two wells were pump-
ing a total of 70 barrels of oil a day. Analysis
of the Plhosphoria oil is given on page 498.
South Fork produced 29,458 barrels of oil
during 1956, and a total of 474,733 barrels had
been produced through 1956. The two wells are
over a mile apart and may delineate a large
producing area. A gathering line carries the
oil to a main pipeline at Chatham, Wyo., which
extends to Casper, Wyo.
SOUTH FRISBY
The South Frisby structure is a dome, the
crest of which appears to be in sec. 24, T. 47
N., R. 92 W., Washakie County (see fig. 150,
p. 250). The Wasatch formation, which covers
the surface at an elevation of about 4,330 feet,
shows no evidence of the subsurface structure.
South  Frisby  was discovered   by  seismic
methods.
The field was discovered in September 1949,
when a well in the SE1/SW1/4 sec. 24 was
completed with an initial daily production
by pumping of 42 barrels of 30 API gravity
oil from the Phosphoria limestone between
10,580 and 10,665 feet. The producing forma-
tion was very hard and tight, and large acid
treatments failed to increase production more
than a few barrels a day. No other wells have
been drilled. The log of the well shows the
following depth, in feet, to the top of forma-
tions:  Cody, 4,610; Frontier, 7,345; First.
Frontier, 7,675; Second Frontier, 7,790 (dry);
Third Frontier, 7,950 (dry); Muddy sand,
8,650; Cloverly, 8,854; Dakota, 8,925; Morri-
son, 8,980; Sundance, 9,260; Gypsum Spring,
9,618; Cllugwater, 9,665; Nugget, 9,760; Din-
woody, 10,525; and Phosphoria, 10,575.
In )ecember 1954 the well was pumping
about 7 barrels of oil a day. The small amount
of produced gas, which contained hydrogen
sulfide, was burned in a flare. Analysis of the
oil is given on paoe 499. South Frisby field
had produced 26.567 barrels of oil by January
1, 1956. The well was plugged and abandoned
in September 1955.
SPENCE DOME
The Spence Dome oilfield (fig. 152) is in
the northern part of T. 54 N., R. 94 W., Big
Horn County. It is on a dome that has about

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