Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1942-11-07

the Madison limestone near its top perhaps
in cavernous places. Two wells in Sec. 49,
34N-1W, have a small production from a
bed within SO feet of the top of the Madi-
son, and one well in Sec 17-35N-2W, had
an initial daily production of 5000 barrels
from a bed about 86 feet below the top of
the Madison limestone"
We interrupt here to point out that back
in the first decade of production in Kelvin
field the producing horizon was referred to
as the Ellis sand" It is now definitely
known that the producing horizon does not
belong to the Ellis or JauraSsic age and in
fact is not a sand. It is erosional wash"
weathered ON the top of the lime at the
end of the Ndississippian period
Thereafter follows the paragraph first
quoted in which Mr.. Collier seeks to explain
the erratic distribution of the oil This
theory has been pretty well proven in Kelvin
field but operators have been SO bound by
precedent that few have ventured beyond
the horizons prospected by their neighbors
One pioneer is A. E. Crumley who con-
tinued on down into the lime and developed
a second break" which became known as
the "Crumley sand" Again, it is not sand,
but a weathered lime which fortunately
responds to acidization Below that is the
"Lashbaugh sand"-the horizon opened by
L. b. ONef in one well on the Lashbaugh
farm, that being the well referred to by
Mr.. Collier as having found 3.O00-bbl pro-
duction from a bed about IS feet below the
top Of the Madison limestone
The Reagan horizon is a 20-foot strata of
porous lime material starting 20 feet below
the top of the lime and extending to 80 feet
below the top Of the lime Whether that
corresponds to the 'Lashbaugh sand" none
can now guess 1t carried water at the base
of the formation, as might be expected
The hydrostatic head appeared to be 27OO
feet at the Reagan location. The height Of
the water is interesting in that 1t perhaps
indicates the height to which this oil may
have been carried elsewhere in the Cut Bank
district OF the Sweetgrass Arch. The Rea-
gan well is about 1900 feet lower structural
ly than the nearest producing pools of
Kelvin field so a 27O0-foot head of water
should provide adequate hydrostatic pres
sure to trap oil in any fold that may exist
between the Twin Rivers Nose and the
Kelvin field.
And speaking of water, we find this dis
cussion by Mr.. Collier:
WATERS ASSOCIATED WITH THE OIL
The waters associated with the oil in the
Kevin-Sunburst field are believed to have
been relatively stationary since the accurnu-
lation of the oil, such lack of circulation
being perhaps due to the great Lewis thrust
fault along the Rocky Mountain front,
about rs miles to the west. or to the inter-
mediate belt of highly folded and faulted
rock, either OF which may have sealed the
strata of the Sweetgrass arch against the
invasion of surface water from the west
Some waters may have invaded the
Kevin-Sunburst field from the Little Belt
Mountains on the south, part of this water
perhaps flowing northwestward along the
west side Of the Teton Ridge anticline to
the Conrad saddle and then eastward across
the arch. Owing to the varying porosity Of
the basal sand" of the Ellis formation it