Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1937-02-06
BY L G. E. BIGNELL

1 ~ - ~sa ~ RANELNAAA
Petroleum engineer and staff writer
OF the on q Gas journal, Tulsa, Okla
II Cut Bank had as many PRODUCING
wells as east Texas, it would have :
daily production comparable with the
! present daily runs Of east Texas Cut
Bank has 200 wells producing IO.25C
barrels per day, under partial prora-
! ton, an average Of 80 barrels per well
East Texas has 81 900 wells producing
100000 barrels per day under uniform
proration, an average Of 81 barrels
per well.
Mr.. Bignell1s article on the Cut
Bank field as published in the Tulsa
/ OIL 81 Gas Journal, follows:
THE most active field at this time
! is the Cut Bank area having nearly
10000 acres Of proven oil production
and from 10000 to 10000 additional
acres of gas fields. The oil field Is
about % miles long and from to z
miles wide. Wells are spaced in the
center of 40 acres and about 255 have
been drilled. The oil is found at from
$500 to $500 feet and the wells cost
from $4,000 to 500, 500 each to COM
plete. This cost does not include equip
ping the wells for production and many
are on the pump.
TANK batteries cost considerable for
tanks with insulated shells and heat
ing coils. Last winter the temperature
dropped to so degrees below zero and
for many days registered 80 degrees
below. Where the wells make water
along with the oil it is necessary to
provide rather elaborate treating sys-
TENS and many unique layoutS have
been developed by the companies to
handle this emulSified oil.
1T viii be noted that the Cut Bank
field has a proven oil and gas area
larger than east Texas Like east Texas
this field is found on the west flank
of a great regional anticlinal fold
about so miles across from east to west
and extending northward from Great
Falls, Mont, into Canada, about 200
miles The axis or crest of this fold
dips or plungeS northward so that the
rock formations exposed at the sur
face near Great Falls are 1900 feet
below the surface at Shelby and $500
or more feet deep at Lethbridge in
Canada. The average dips of the strata
are about so feet to the mile. The Sweet
Grass arch lies east of the Rocky
mountains
Surface evidence indicates the arch
is of late Cretaceous age and the |
Virgelle Eagle) sandstone forms |
conspicuous eScarpment 10 miles west |
of its crest. The Eagle sandstone is in |
about the middle of the upper Creta- /
ceous section and below this there are
many exposures of Colorado shale at |
the base Of the upper Cretaceous for
nations.
1.-THE producing formations range /
in age from lower Cretaceous with the /
Sunburst sand of the Kootenai for I
nation productive in Kevin-Sunburst |
and Cut Bank oil fields to the Ellis /
oil sand, the upper member of the |
Madison limestone of Mississippian |
age. The Triassic, Permian and Pen
lsylvania formations are missing over
this arch which was apparently an an
Gent land surface during those geo.
logical periods.
@The geology of the Cut Bank field
mas not been worked out yet to the |
of all biologists. That is
70 say they are not In accord on many
important features and until more evil
fence has been developed by drilling
{ will be hard to make final decisions.
t does seem apparent that in this
lrea the productive formations once
ormed the shore line of ancient seas
md many of the sands are of the lent
cular type with photographic changes
)art in the trapping of the oil and gas.
One Causes Discussion
"One well on the west edge of the
Tut Bank field has caused much dis
ussion. It was drilled to a total depth
4 2,978 feet into the Ellis oil sand and
eSted only 2 barrels of oil and IL bar
els of water. The casing had been set
bove this producing horizon and there
7as about AZ feet of shale between the
Ills shale and the Sunburst sand
1hich had been cased off. 1t was re-