The West Virginian. [volume] (Fairmont, W. Va.) 1914-1974, 1917-04-27

the United state Geological survey
OF the Department of the Interior has
developed some interesting facts
which viii doubtless be of consider.
able benefit to the oil industry. 1t
has long been recognized that oil and
gas are commonly associated with wa
ter, but of the chemical relation be-
tween the two little has been known.
It is now possible, as least in Cali
fornia, according to the Survey, to es-
Innate the position of oil and gas,
where present, from chemical analy-
sis Of the water yencountered by the
drill. Thus in drilling a wild cat"
we'll an indication of the presence or
absence of oil and gas below the water
may be had by Analysing the waters
successfully encountered, since inves-
legations have determined that the
deep-seated waters associated with oil
In California fields are different in
chemical composition from the waters
found near the surface as we'll as from
the deeper waters outside of the oil
fields: In some areas a significant
change in composition may be de-
tected as much as 1000 feet above the
oil. In others the upper limit of alter
alton may be within a few hundred
feet of the oil.
II is also possible to determine, at
least in a general way, the source Of
the water flooding an oil we'll. In the
Westside Coalinga field, for example,
the horizon of the water may thus be
determined rather definitely; in the
Midway=Sunset field, where the dis,
tinctions are less sharp, the success
Of this method will depend largely on
the number of authentic analysis that
are available for comparison.
In the oil fields of the San Joaquin
Valley water-bearing sands are gener-
ally encountered above, below, and in
many places in the oil measures, and
in these fields 1t is difficult to prevent
the water, which may be under high
pressure, from invading the oil sands
and thus running considerable tract
OF oil land. The United States Geologi-
cal Survey accordingly detailed G.
Sherburne Rogers to make study
of water conditions in these fields,
with special reference to the chemical
character of the waters. Some of
Mr.. Rogers's conclusions, drawn from
sturdy of several hundred analysis
N
follows:
/. Although some of the oil.field
waters as as salty as sea water, and
are probably true fossil sea water,
Others are not even slightly salty to
the taste. The distribution of salt is
controlled by the freedom of circula.
ton Of the waters, which is governed
chiefly by the geologic structure.
2. Although the surface and shallow
ground waters are strong sulphate or
gyp" waters, sulphate diminishes in
amount as the oil measures are APP
preached and finally disappears Out.
side the oil fields, however, large guam.
titles of sulphate are found in even
the deepest waters.
8. The waters a short distance
above the oil at many localities are
sulphur waters" containing the gas
hydrogen sulphide, but the shallow
waters and those in the oil measures
generally contain no sulphide.
Carbonates, which are subordin.
ate In the shallow waters, increase in
amouat as the oil zone is approach
ed. and II no chlorides are present con-
stitute the only dissolve salts in the
waters associated with the oil.
These conclusions appear to be we'll
ground for California, and probably
hold for other arid regions in which
the upper waters are sulphate or "al,
kali
The progressive alteration Of the wa
ter as oil is approached is so constant
and so striking in the area examined
that the conclusion that the oil and
water have reacted chemically can not
be avoided. 1t was suggested long
ago In the Russian oil fields that ny,
drocarbons are able to reduce sulphate
TO sulphide, andthat they themselves
are simultaneously oxidized to car.
bon dioxide or carbonate. The reac.
ton has not yet been checked in the
laboratory, however, and though es.
sentially correct Is probably much
more complicated than has been sup.
posed.
Some of the sulphide formed in the
reaction between the hydrocarbons
and the sulphate waters is undoubted.
~ oxidized to sulphur. Some OF this
sulphur is taken up again by the oil,
which makes the oil heavier and more
asphaltic. In the oil Fields of San
Joaquin Valley the oil that has been
most exposed to the action of the wa.