Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1937-11-13

" ALLURE of some wells to respond
to acidization, while nearby wells
are acidized into big producers has
been the subject of much discussion in
Kevin-Sunburst field this fall among OPP
orators who regard acidiZation as i'm
portant an operation as the drilling of
the well itself. foolish economics or
shortcuts in acidization are being aban-
dOned by better operators, likewise many
experimental methods have been aban-
doned in favor of methods which have
proven successful in a majority of cases.
Heavy shots, as a rule, have not prov
en- successful although it is possible that
further experimentation viii reveal that
wells which failed to respond TO large
shots might not have responded at all
TO customary 500-gallon shots and like
wise wells which have been greatly in
creased by 5OO-gallons, shots might have
been made into really large wells with
larger shots However, enthusiasm about
the Midcontinent practice of multi
thousand gallon treatments has greatly
waned.
One factor that has developed is more
careful laboratory work. Formerly little
attention was paid to the character of
the lime and the acid mixture was vir-
tually the same-depending on the in
vidual idea of the operator-for every
well. Now the operators take careful
samples of the drill cuttings and deter
mine the reaction of the lime to acid.
1t has been found that weaker solutions
of acid do best in some lime while
stronger solutions do best in others. Too
strong acid base proven harmful in many
instances. At the same time, too-rapid
travel of the acid, with harmful effects,
has caused the development of a techni-
que whereby a substance has been in
troduced to slow up the travel of the
acid in the old flow-channels, forcing
H. ~ rFpfn
the limestone. This substance is
Dowell product known as jell. 1t is used
on old wells rather than new producers
wherein the chief problems have arisen
Kelvin operators are again convinced
that porosity of the lime has much to
do with he success, with or aci-
dization, of any lime well. The
was offeres by wells on the Carl
son farm in Section %. These wells
showed more oil than the average well,
before acidization After acidzation they
dried up completely Yet less than a
quarter of a mile east Of the Carlson
made $50 barrels initially without acidi-
cation. On the Carlson farm the for
nation seemed to tighten up when the
acid was applied. 1t was impossible to
force the acid back into the formation.
Dfscontinuous porosity in lines has
been carefully studied by the biologists
of Dowell, Inc. and an instance of dis
continuous porosity in the upper Monroe
limestone in parts if the Vernon pool.
Isabella county, Michigan, is attributed
to secondary deposition of flourdte, ac-
cording to P. E. Fitzgerald, formerly OF
Shelby, and o. A. Thomas The erratic
behavior of wells in that pool were ex-
planned by the precipitation of the fluor-
lite with the infiltration of oil, with the
result than many of the crystals are char
acterized by hydrocarbon inclusions. 1t
is not unlikely that secondary deposits
of other minerals such as calcite, celestite
and barite may account for continuous
porosity booming discontinuous or even
becoming discontinuous or even
destroyed. Some such condi-
Where wells have drilled from the
black lime directly into the massive white
lime of the Madison, even with a slight
showing at the top, it has been found
that the lime is not likely to give much
oil after acidization. 1t must have por-
osity. 1t is believed that utilization Of
groundwaters into the limestone, these
waters carrying organic acids, is respon-
sible for the porous material found at