Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1939-08-05

foil we'll of the Kevin-Sunburst field
drilled by Gordon Campbell IN
1922, in sec. 16, T. S5, N. r. 3W
In this field oil is found in the
eroded and weathered top Of the
Madison limestone, in the basal
sandstone of the Ellis formation,
and in the Sunburst sand in the
upper part of the Kootenai for
nation. The Cut Bank sand, which
elsewhere is the basal part of the
Kootenai, is here replaced by a
Ifiner-grained facies called the
"Ribboned sandstone" which is
tight and non-productive. The
Madison limestone yields oil OF in
termediate base and of gravity be-
tween 31o and $40 A.P.I. in 81
wells that range in natural produc-
| tivity from a few barrels to lou
barrels a day. The productivity IS
generally increased by acidiZation,
so that wells yield as much as ESQ
barrels a day. The Ellis sand yields
oil Of gravity between 27o and BIO
APT. in IA wells of small individ-
ual capacity. The Sunburst sand
Yields oil OF intermediate base and
of gravity between $40 and 1925
APT. in % wells, which range
in productivity from 10 to 80 bar
rels a day. This sand yields gas
in wells.
The Border field. on the Inter
national boundary, in the north
eastern part of T. BIN, r. Avn,
Montana, and the southern part Of
T. 1, r. 16W, Alberta, was dis
covered through a well in Alberta
in 1929 and received its most active
development in 1880. 1t is descrtb-
ed in detail in a report prepared
jointly by c. e. Erdman, geologist,
and ]. r. Schwabrow, petroleum
engineer, which was released by
the Geological Survey in January
1884 for public inspection and con-
sultation in its field offices at Shell
by and Billings. Montana, Casper,
wyoming, and Denver, Colorado.
Structurally, the Border field
occupies an area of local flattening
on a nose that plunges northward
from the Kevin-Sunburst dome. In
this field oil is produced from the
Vanalta upper COsmos) and lower
AO6HlO6 Sduubf Which, arc C4uAF
to the Cut Bank sand at the base of
+, the Kootenai formation in the Cut
Bank field to the southwest In all,
As wells have been drilled in the
field, 10 in Alberta and 35 in Mon
tana. OF the Montana wells IS
were producing oil in October l.,
1898. and II had been abandoned
as either dry holes or exhausted
producers. Production from this
part of the field decreased from
42,216 barrels in 1897 to 1880
barrels in 1888 and averaged only
SIS barrels a day in January, 1889.
To the end of 1888 it aggre-
gated 74O,O79 barrels The oil is
of intermediate base and ranges in
gravity from $40 to 32.1o A. P. l..
The Cut Bank field includes a
gas-producing area about 85 square
miles in present extent, in TIPS. "a,
| 35, and 36N., r. W, Montana
which is thanked on the west by an
oil area roughly 4 miles wide and
rs miles long that extends north
ward from the northeastern part
OF T. 81, NJ, r. 6W., to the north
ern part of T. 35N., r CIV.
Oil in this field is obtained chief
ly from the Cutbank sand, the ba-
sal sandstone zone of the Kootenai
formation, but is also found locally
in beds of sandstone higher in that
! formation, particularly in the upper
Sunburst sand near its top. Its ac-
emulation is a consequence of up
dip migration into photographic
traps, of which there are several
/ types. In the northern part of the
oil area and in the gas area struc-
tural reformation has tended in
1 general to increase the effect OF
the photographic traps.
To December 81, 1888, a total of
562 wells had been drilled in the
1 Cut Bank field, of which 403 were
productive oil wells. GO gas wells,
and 96 dry holes. These figures in
clude so oil wells and II dry holes
| within the Blackfeet Indian Reser-
walton. The average drilling depth
in the oil area is 2,975 feet. and
the average cost of well $4,000.
The daily production of a relatively
good well usually decreases within
! 10 days after completion from 1870
! barrels to go barrels, and that of
poor we'll from 80 barrels to 10
| barrels The present average daily
production per well for the area is
26 barrels. and as the margin of
profit is small and the drilling
depth increases toward the west, it
is possible that the western limit
of the field will be determined by
economic consideration rather than
by the absence of oil. Oil from the
Cutbank sand is of intermediate
base and ranges in gravity from
$50 to $50 A. P. I.
In the gas area the initial pro-
duction of the wells ranges from