Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1941-01-04

Rear river where such conditions
are fulfilled, but nothing IS known
regarding the details OF local
Nos. / and 2. Bear Island and
.Cp, wells OF the Northwest Oil
company. and the well OF the Fort
Norman OH company were drllleo
on westward dipping beds on the
vest 1lank OF the anticlinal Iold
winch forms the Norman range.
me Bear island and &C" wells
are down the dip from Nos. 1 and z
weus and seem 10 indicate tnat
no oil may De expected IN that
uIectlOn aIong the dip slope. ~
IS very di1flcu4t 10 UNDERSTAND no"
..,,. ON las Deen accumulated at nos.
.au Tels OIL the Northwest Oll
,n4pany IN d snaIe formation (f OFT
,.iecaJ Nulcn wItn the associated
.,,.Ao,4uns UPS uniformly west
.a.A anu comes TO the surface only
., uilles east Oh the Wells. In
.Ae ron. Geek I0rmatlOn on Jan
yun ana ermIAlOn creeks d sand
eoAe uJrlIOn % 20 ~ ieet thlck
r.s louuu isOOuL SUI teet above the
.,ase Ul the formation. IN a former
.y,or, 1t was sugges eed tnat the
accumulation OF vi IN the YIclnlty
~. .Le weus nlgnt De due 10 the
ureseiice OI the sandstone horizon
~, occurs On Canyon creek, out
ms sandstone is not present Ia
40. 2 Wei. No local folding with
ulcn the concentration OF OH
might be associated has been de-
lsc.ed in the vicinity OF the oil
weils.
AS already stated two large
cross-folds are known at the north
END Of the basin structure, but
since each erosion has revealed
the core OF Middle Deyonian rocks
heir value as oil structures is
very doubtful and depends only on
the possibility that oil might be
present in the brecciated limestones
underlying the DeyOnian rock, AS
already stated, these in places are
sufficiently porous TO act as OIL
reservoirs and are known 10 De
somewhat bituminous.
1t has been stated that some see
pages on the east side of Mackenzie
river come from the Bosworth for
nation which outcrops over large
areas. AS there is no cover to pre-
vent the free escape Of the oil at
the outcrop no production could be
hoped for from this formation over
the area where it is exposed at the
surface. If, however, local struc-
lures could be located in the areas
10 the west where the BOsworth IS
overlain by Cretaceous shales, the
prospects for oil accumulation IN
the Bosworth would seem to De
good. Since the Bosworth formation
is thinner at &C" well than on Car
.caiou river to the west, the stra-
ia of the uppermost part OF e
we'll we're at first considered to be-
long to the Bosworth formation, but
are now confidently believed to be
Cretaceous shales. Thus at &C
we'll there is a cover OF Creta-
ceous shales which would prevent
the escape Of the oil upwards, but
since &C" we'll is down the dip
from the Nos. ! and wells of the
Northwest Oil company and no To-
cal structure is known, there is no
apparent reason why any oil orig
inally present in the Bosworth for
nation should not have migrated
I'D the dip and escaped at the out
crops on the eastern side of the
Mackenzie river. That such pro-
cess is taking place seems to be
indicated by seepages at the out
crop. The structural conclusions to
he drawn from these two wells
seems to be that no accumulation OF
oil is likely to occur on the west
side of Mackenzie river except
where there is local structure
superimposed on the basin struc-
ture such as would prevent the
migration of the oil to the out
crop.
The migration of the oil up the
din in eastward direction assumes,
on the basis of the hydraulic theory
of oil migration, an underground
flow of water in the basin struc-
ture from west to east, and this
seems to be borne out by the
springs and seepages on the east side
Of Mackenzie river. The relatlVe
elevations OF the structure OF the
Deyouian on the east and west
sides of this basin are imperfectly
known, but the country in the VI
entity of Carcapou mountains where
the Bosworth beds outcrop is some
what higher than the territory oc-
cupied by the Bosworth formation
on the east side of Mackenzie riv-
or This difference in elevation may
provide the hydrostatic head neces-
/ sary to cause the eastward mlgra-
ton of the underground waters, as
a result of which the oil would be
I flushed toward the eastern side OF
the basin and would appear at
the outcrop in seepages such as
do occur. BY such theory the
most favorable prospect for OH
would lie toward the eastern out
crop. where local folds on the main
fold are of such nature that the
eastward flow is prevented and the
oil caused to Accumulate. If such
local folds are not present the OIL
would be flushed to the outcrop
would be lost, and no Commercial