Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1936-05-09

success in the Del Bonita well is doubt
full. Mechanical difficulties are which
made an adequate test impossible after
the shooting. None is convinced that
heavy nitro gIycerine shot might not
make another Lander gusher out of the
Del Bonita. However, that cannot be done
in this hole.
- r greater significance, however, is
the flow of oil and gas from a hor-
lion in the basal Ellis. There is
no production in Cut Bank field in this
horizon. Cut Bank wells stop at the
top of the Ellis. The Del Bonita well
had no Cut Bank sand, which is found
in place just above the Ellis, so con-
tinued on down, aiming to test the top
of the Madison lime-the Kevin-Sunburst
producing horizon. Near the base of the
Ellis, in lime formation, it began to
show gas and then oil. 1t was "sweet"
gas and "sweet" oil, unlike the sulphur
laden products of the Madison lime.
Fearing the development of water, the
Del Bonita people drilled ahead cautiously.
They treated with acid and then drilled
a little deeper, treating a second time.
The result of acidization was not de-
finitely determined. The flow of gas I'M
creased and after the second acid treat
ment, the well flowed more than 100
barrels per day. Biologists doubt that
the drill has yet reached the Madison
lime. Further drilling viii determine
not only the geological facts but may
open mp oil production propOrtionate to
the gas pressure which has greatly handt-
capped this operation ever since the lime
was encountered.
AT the present time, the well is re-
ported to be making about 2,OOO,OO0
cubic feet of gas and blowing about %
barrels of high gravity oil per day. We
have sample of this oil. 1t is paraffin
base oil, unlike any Madison lime oil
we have even seen. It cOngeals when
cold. When warm IL blows the stopper
off the bottle.
The significance of the Del Bonita well
will shortly be applied to Montana with
the coming completion of the test well
on Dunbar structure. Dunbar is the
first fold or reversal west of Cut Bank
field. 1t does not qualify, like Del
Bonita, as deep drilling, for production
should be found at around S4OO feet,
whereas the Del Bonita well is 5,1OO
feet deep.
Dunbar structure is a better STRUCTURE
than is Cut Bank. Biologists were never
able to close Cut Bank structure on the
East-nor has it ever been closed. How
ever, oil is trapped in Cut Bank as a
result Of lensing OF sands, rather than the
customary reversal of the fold. In other
words, the ideal structure is shaped like
an inverted dish. on floating ON top of
circulating underground water is caught
in the trap so formed. But i'm the case
OF Cut Bank, one side is knocked out of
the inverted celery dish-cOntinuing the
then the oil would have
escaped into the thigh" of the structure
east OF Kelvin had 1t not been trapped
In the edge of an ancient ocean beach
which tapers out and ends before it gets
as far eastward as Kelvin.
Dunbar has reversal or perhaps a
fIattening'' of the beds, which should
serve as a trap for oil that might migrate
upward onto the Arch and into Cut
Bank field. Dunbar has a chance for
productiOn-in the Sum
BURST sand. None knows the true sig
lificance of the Lander wen.
The presence of the Cut Bank sand in
dunbar is generally accepted as fact.
{ win likely be considerably thicker at
his point than i'm the Cut Bank field,