Petroleum and Natural Gas Fields in Wyoming Page: 62
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PETROLEUM AND NATURAL GAS FIELDS IN WYOMING
Circle Ridge field (fig. 37) is in the adjoin-
ing corners of Tps. 6 and 7 N., Rs. 2 and 3 W.
(Wind River Indian Meridian), Fremont
County. The structure is a northwest-south-
east-trending anticline with vertical dips on
the southwest flank. Faulting in the field con-
sists of an eastward-dipping thrust fault, a
few minor tear faults, which are associated
with the thrust, and a few minor transverse
faults. The structural conditions are com-
plicated by the eastward-dipping thrust fault
which has displaced the crest of the fold west-
ward into fault contact with the southwest
flank. Dips on the east and northeast flanks
average about 350. Beds on the southwest
flank near the center of the fold are vertical
to overturned. The oil-productive area has a
little over 1,000 feet of closure. The Phos-
phoria formation forms the surface at an ele-
vation of about 7,200 feet.
In 1923 a well in the NE1/4SE1/4 sec. 1 was
drilled to 655 feet. Initial daily production
was approximately 132 barrels of 24 API
gravity black oil from the Tensleep sandstone
at 592 to 655 feet. Only 154 feet of 121/-inch
casing was in the hole, leaving both the Phos-
phoria and Tensleep zones exposed. In 1941,
8/8-inch casing was cemented at 370 feet,
which shut off the Phosphoria zone. The well
was operated for a short time in 1923 and then
shut in until 1941, when drilling and produc-
tion were resumed in the field.
Oil was discovered in the Madison limestone
in December 1946, when a well in the SE1/
SW1/4NW1/4 sec. 6 had an initial daily produc-
tion of 137 barrels of 23.2 API gravity oil.
The producing interval was 1,630 to 1,655 feet.
In May 1955 a well in the SE1/4NW1/4SW1/4
sec. 6 was completed in the Darwin sandstone.
Initial daily production was 312 barrels of oil
from the interval of 1,252 to 1,277 feet. The
possibility of some oil production from the
Amsden formation was indicated in at least
Initial production of 53 wells completed in
the Phosphoria formation ranged from 5 to
1,020 barrels, averaging 410 barrels. Forty
wells in the Tensleep sandstone had an initial
production ranging from 48 to 1,072 barrels,
averaging 342 barrels; three wells in the Dar-
win-Amsden horizon averaged 210 barrels.
Initial production of six welfs in the Madison
limestone averaged 260 barrels. The amount
of water produced with the oil indicates an
active natural water drive in all producing
The log of well No. 4M in the SE1/SW'/4
NW1/4 sec. 6 shows the depth, in feet, to the
top of formations as follows: Dinwoody, 318;
Phosphoria, 410; Tensleep, 690; Amsden, 982;
Madison, 1,285; Darby, 1,970; Big Horn dolo-
mite, 2,035; fault, reenter Madison. 2,090; and
total depth, 2,864. Analyses of oil and water
from the Embar (Phosphoria), Tensleep, and
Madison formations are given on pages 351
and 352 and in table 9 (p. 293).
The daily production and number of wells
on December 15, 1957, were as follows: 671
barrels oil and 1,948 barrels water from 55
wells in the Embar (Phosphoria); 867 barrels
oil and 2,140 barrels water from 49 wells in
the Tensleep; 168 barrels oil and 400 barrels
water from three wells in the Darwin-Ams-
den; and 134 barrels oil and 405 barrels water
from six wells in the Madison. Oil produced
at Circle Ridge in 1956 was 977,788 barrels to
bring the cumulative total to the end of 1956
to 8,747,174 barrels.
Oil produced at the field is pumped through
a 4-inch pipeline to Maverick Springs field,
thence to a pipeline station about 10 miles
farther south, where it enters the main pipe-
line system transporting oil to Casper, Wyo.
Drilling in the western part of the Mush
Creek field and the West Mush Creek field
yielded mostly small-capacity wells. Thus,
when the discovery well in the Clareton field
was completed in 1950, it attracted very little
attention. Only moderate development fol-
lowed until the latter part of 1953, when a
number of "wildcat" wells to the south and
west were completed, and a "boom" was
started. Development proceeded at a rapid
rate, and much confusion prevailed as to the
names and number of fields in the area. The
names Clareton, South Clareton, Black Thun-
der Creek, and Cheyenne River were the most
prominent in usage, but considerable overlap-
ping of areas existed. The Wyoming Field
Names Advisory Committee prepared a list of
names for the fields and areas and submitted
it to the State mineral supervisor for ap-
proval; he accepted them, effective April 1,
1954. This report has been prepared in ac-
cordance with the approved names, as shown
by figure 38. Each of the areas is discussed
separately under the main heading of Clare-
ton. As these fields and areas were designated
geographically, it is to be expected that the
boundaries and reservoir limits do not neces-
From the east side of the Skull Creek field
in T. 44 N., R. 62 W., this series of fields, some-
times referred to as a "trend," extends in a
southwesterly direction for about 36 miles into
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Biggs, Paul & Espach, Ralph H. Petroleum and Natural Gas Fields in Wyoming, report, 1960; Washington D.C.. (digital.library.unt.edu/ark:/67531/metadc38797/m1/76/: accessed February 28, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.