Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1941-02-22

We have discussed these theories with
many biologists and have read every
geological report we could find. We
read with interest one report by DR.. San
derson, Of Calgary, on the Ellis forma-
ton in the Sweetgrass Hills in which
that eminent authority said that there
was adequate material dn the Ellis to
form petroleum. That seemed to in
dictate that the Ellis-Madison contact oil
might have been distilled from the Ell
lis shales for, it appears, the so-calied
'fblack lime OF the Ellis is mostly shale,
although it reacts like lime under hy-
drochloric acid.
But when we watched a drill pound
ing through % feet of limestone that
was described by the driller as harder
than the hinges of He'll and thereafter
saw the hole fill with 3S gravity crude,
we began wondering how that Ellis oil
could have penetrated DOWNWARD
through 20 feet of hard lime: how it
could invade a strata that has heavy
water pressure holding the oil in place.
In fact, it simply can't be done.
Then we saw Turner Valley field
producing from another "break" 400
feet deeper near the bottom of the lime.
We searched the logs of wells drilled
through the Madison lime in Kevin-Sun-
burst field and discovered that the TuT-
ner Valley break is present in Kelvin,
only it was never acidized. That is an in
teresting prospect for the future deep
drilling in northern Montana.
Surely Turner Valleys crude is too
far down in the lime to have migrated
down from the Ellis. Also we know posi-
lively that the hard, massive Madison
lime does not contain enough hydro
earbons to form as much oil as is found
in any Of those Turner Valley wells
not to mention the famous Kelvin wells
which have produced ten times as much
oil as an equivalent normal sand" area
might have produced.
Then 1t must have come FROM BE-
LOW. But 1t is not that simple.
We know, of course, that the massive
Madison limestone does not BEND, as
do the plastic shales. The brittle lines
crack and fracture, under the stresses of
mountain building. AS a result we may
find a structure which looks like a
as shown by the dip of the
shales, while the massive limestones I'M
derneath, likewise upwarped, are crack
ed and fractured from top to bottom
with no serious displacement in any one
of the fractures.
Starting from that theory, we were
very much interested in recent refer
ence to a paper by K c. Head, emf
nent geologist who was quoted with re-
gard to deep drilling. We read this COM
plete paper very carefully and found his
theory as to the upward migration of
oil from lower horizons. Also he ex-
planned why the deeper we drill, the
higher the gravity of the oil. We were
formerly educated to believe that the
deeper we drilled, the heavier the oil.
The theory was that the lighter ends
upward, leaving the residual oil
below. Head cancels out that theory by
saying that at greater depth the heat
and pressure convert crude oil into light
oil-if deep enough-into a gasoline
laden gas That theory worked out pref
ty we'll in Turner Valley as well as in
Kettleman Hills, years after Head pro-
nounced the theory.
Discussing first the possibility OF oil
at 10, 900 feet or deeper he asked
ITO begin with. would the temperature
and pressure permit the oil to exist
At a depth of 10000 feet or more be-
low the surface? The pressure should
be about 1880 pounds to the square
nch, for 1t has been noted that the So
,alled rock pressure" in newly opened
fields commonly correspond closely to
he pressure that would be due TO
column of water reaching from the oil to
The surface of the ground.
ut is not uncommonly less than this