Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1941-04-05
new PENDROY


rizons: the Moulton sand, the Cut
Bank sand and the Ellis-Madisor
contact. Completed with three-inch
hole, II was impossible 10 make an
adequate test and II was abandon
ed
Oil In MOulton
The MoultOn sand was from,
1880 to PASS, with oil and gas IN
the top II feet. This is believed TO
be the producing horizon Of the
Lander pool and IL produces gas IN
the north end of Cut Bank gas
field. II is one OF the upper mem
bers of the Sunburst sand series.
The lower Cut Bank sand. from
1852 TO 1855 carried high gravity
oil throughout. II was impossible
20 make an adequate test although
the stump was covered with oil while
the Bit was passing through the
sand.
The greatest production came
from 2S44 to 2S46, eight feet be-
low the top OF the Madison lime. 1t
made 25 barrels of oil the first
day. following acidization, after re-
covery OF the treating fluid, but IL
developed water Unable TO do any
thing with so small a hole. the
Zodiac people attempted TO bridge
back and shoot the Cut Bank and
MOulton sands but the small shot
Of nitro glycerin merely punctured
the casing and did not penetrate
the formation and only drilling mud
came into the hole
Closer To Fault
The new test is considerably
higher on structure as 1t is close.
to the fault. the exact location of
which has been established by sells
mic survey. The location recon-
mended Dy Larry Freeman OF the
Holland Research corporation was
a full quarter mile closer to the
fault than the Zodiac well. but Tar
rant chose 66O-foot location since
ne is quite positive of production
anywhere close to the Zodiac well.
Important Feature
Development of commercial pro-
duction at this location win be fol-
lowed by the drilling of three or
four structural noses plunging in
a northwesterly direction from the
Pendroy faHlt-the most outstand-
ing structural feature that has
been discovered in the central
Sweetgrass Arch. The fault is known
to have a displacement OF as much
as 500 feet. extending from north
east to southwest across the PEN
droy area and explaining the varied
results OF drilling of several wells.
The Zodiac-Gulf States companies
drilled two wells, one on the up
throw side and the other on the
downthrow side, to definitely es-
taolish the accuracy of the SETS
mic survey. The test on the up
throw side was intended to test
the Devonian but the hole was lost
at the top Of the Madison lime.
Drilled Through Fault
According to E. Byers Emrick, dis
cover of the structure and an Of
ficer Of hhe Zodiac, there was on
ly 1895 feet OF Colorado shale en-
eountered in the Gu1f States well,
whereas the average thickness of
the Colorado in the area is 1880
feet. The drill crossed the fault
from the downthrow side to the
upthrow side Of the Colorado shaIe.
This location was necessary, in or
der to tap the Devonian high"
mapped on the southeast side of
the fault. The faulted condition
is believed responsible for the ex-
sessiVe caving which forced the
abandonment of the hole, losing
-wo strings of tools.
The first well drilled in the area
was that of Gypsy Oil company
which had showing Of
III at the Madison contact.
t was too low on structure to pro-
luce, according to Emrick, although
'thers believe that had acidizatiou |
been known at the time of the |
irilling OF the Gypsy well, il might
rave been made into a CONNER |
ial producer.
Tarrant is prepared to complete. |
y test all the three horizons. He
particularly interested in the |
possibility of a high gravity oil /
'ooi in the Cut Bank sands in loo
Liked pools along the fault. The
ault provides south closures for the
everal structural noses.