The Montana courier. [volume] (Shelby, Mont.) 1922-192?, 1922-09-13

well shows near the base of the Col
orado a bed of conglomerate six inche,
thick, consisting almost entirely Q.
ebert pebbles cemented with lime.
Kootenai Formation-The Kootena
formation, of Lower C~rctaceous age
is apparently about 240 feet thick. Il
comprises sandstones. and ~vari-coloret
shales. Where exposed around the
Sweetgrass hills most of the Kooten-
al is a dark rusty brown, contrasting
sharply with the acknowledgement OF
the underlying Ellis formation.
Ellis Formation-The Ellis forma-
ton, Of Upper Jurassic age, is from
$50 to 200 feet thick. 1t consists of
acknowledgement calcareous shale and
inter-bedded shaly limestone. In two
of the deep wells in the Kevin-Sun-
burst field there is reported to be from
4 to 10 feet of o~il-saturated sand just
above its contact with the Madison.
The Troy-Sweetgrass well, bored with
a diamond drill, found no sand at this
horizon but about four feet Of caver-
nous limestone.
Madison Limestone-The Madison
limestone, Of lower II.ssissippian age,
is about 600 feet thick. Between it
and the Ellis formation there is an
unconformity, which on the south near
the Wyoming line, is occupied by the
Chugwater, Embar, Tensleep and
Amsden formations. Both in the
Sweetgrass hills and in the only well
in the field that has been drilled deep
into the Madison limestone, that for
nation appears to be massive lime
stone throughout. In the well refer
red to a black shale is reported at the
base of the limestone, but this shale
probably belongs to the underlying
Devonian.
Devonian-In the Kevin-Sunburst
field the Devonian is probably repre-
scented, at least in part, by black shale.
Structure
A very broad dome with few irreg-
ularities occupies most of the field.
It's form is shown by means of so
foot contours on the structure map
accompanying this report. It's high
est point, neal the Troy-Sweetgrass
well, is only about 500 feet, structur-
ally, above the Campbell and Sun
burst wells, which are more than 10
miles away.
1t is not expected that this broad
dome will be productive throughout.
A number of distinct pools may be
found in it, their locations having been
fixed by particularly favorable condi-
of porosity and possibly by mi
nor crumpling in the oil-containing
formations. These formations include
The Colorado, KS tenai, Ellis, Madison
and perhaps the underlying Devon
an.
History Of Exploration
A well on the James Miller ranch,
%, T. "a N. R a W., described
~ Stebinger in bulletin GAL of the
States geological survey,
cached a depth of 1855 feet. Three
mall flows of gas from the upper
,art of the Colorado shale were re-
'orted but neither oil nor gas from
he Kootenai. Mr.. Miller also af-
rms the discovery of a showing of 4,
il less than 800 feet from the sur :
ace in a shallow well. When the :
ands were taken up by farmers small :
ows Of gas came from a number of :
hallow wells drilled for water. One
f these wells was in section II, T. SO
f., r. 2 W.; another was in section !
1, T. "a NJ, R 1 W., where the Troy J
w-eetgrass well has since been drilled. l
The first well to report commercial !
reduction was the Gordon Campbell !
ell in section Is, T. 35 N, R. 3 W.. \
his well had a flow of gas, probably .
ON 100000 to 100000 cubic feet '
day, from the sand at the base of Il
le Colorado and a showing of oil II
ear the top of the Ellis formation,
10 feet above the Madison limestone,
i'd it reached the productive oil pool y
a sand 10 feet thick just above the y
assive Madison limestone. The well ~
God idle from March until June, =
'22, when about 100 barrels was I
lmped from it in one day. It's yield
estimated at from five to ten bar le
Is a day. u
The Sunburst well, in section "a, T. W
NJ, R. 2 w, was completed early NJ
June, 1922. | t encountered gas in o'
E sand at the base of the Colorado ~
ale. The productive sand is in the
formation about 1926 feet be-
v it's top. The first day of pumping pl
slded about 200 barrels. After a 81
IL &C z+o,Lx, r,-or,- +lo ,yo11 ,voc vi