Montana oil and mining journal. [volume] (Great Falls, Mont.) 1931-1953, 1940-08-24
THERMOCHEMISTRY


CONTINUED from Page One)
conditions under pressure and tenn
perature in the laboratory. Flow
ing wells, with which IL was pos
lsible TO quickly reverse the flow Of
acid from the formation, gave more
data on reaction time.
DOIOmite Reacts Slowly
This work, summed up. establish
ed the following points
Rate OF reaction is slowed up
by pressure alone when a gas is
evolved
Dolomite such as the Permian
formation has the slowest reaction
time. This slow reaction time Of
Dolomite under pressure in field
operation gives a reaction time Of
80 minutes with 500 OF a 15eo
acid solution neutralized.
other forma tions will neutralize
acid in less time than above.
shorter time interval OF acid
in the formation does not prevent
secondary precipitation due to
presence of Gypsum.
No More Speed Needed
The above results OF research
are true under conditions where
no emulsion is formed between ac-
Id and oil from the formation Be
cause of the necessary time involv
ed in reversing the flow or put
ting a well on the pump in the
field. it can be seen that there is no
necessity for speeding up the rate
of reaction of the acid.
AS there are many treatments
now being made in the field with
plain acid. there are still erratic
results both in quantity and quail
ity OF oil. These are caused chiefly,
from a chemical angle. by ignor
ance of the lately discovered abil-
stable emulsion. the properties of |
which have been previously discuss |
ed. and using a specified remedy !
in each case.
These poor results and confusion |
of thought have led to a recurring !
belief in the efficiency of heat, to-
gether with new methods of crea-
tion and application. Unhappily, 1t |
is not considered that heat has alb
solutely NO effect upon emulsion
prevention or upon breaking an
formed between the acid /
and oil, and WHICH PROVES TO !,
BE STABLE
Use Magnesium Metal
One method being tried at pres
ent to create heat in a we'll is
by introducing of magnesium met
al and subsequent passage of acid
over it, depending upon the heat
Of the reaction to heat up the for
nation locally.
One basic fact in connection with
this method has either been ignor-
ed or is unknown. This is the eff
feet OF pressure upon the reaction
time.
At atmospheric pressure the re-
action is very fast and much heat
S evolved. Milliard's Physical Uni
yersity gives the heat of reaction
as producing 1925 B. T. u per
b. of Magnesium The temperature
Use will depend upon the volume
If solution to be heated and the
line given for the reaction to
AXE place. 4
At ordinary pressure. about 40 q,
sal. of 800 acid will consume %
BIS Of magnesium in 10 minutes e
With a theoretical temperature in ;
rease of 7S4o F. The actual tenn g
,erature increase due to evapora- {
ion and condensation of steam {
would not be much above 212' F. Ia
Under pressure of 1000 lbs. or /
more it will take % times as long d
or the reaction to take place. t
Factors OF Heat n
During this process, a well must l.
,e able to hold the acid in place {
or definite length of time for
he reaction to complete itself, and t
or a temperature increase to Oc- n
ur with the smallest possible vol a
me of acid beyond the theoretical b
mount. The actual temperature rise n
7ill be a function of time, vol v
me and strength of acid involved 2
nd the weight of magnesium con- 3
umed. 4
Thus if 1000 gal of 23%o acid a
rere put into the formation in 80 B
minutes and the fluid head due to /,
yell depth gave 1000 lbs. pres 8
ure or more, only 159o of the mag a
esium would be consumed in this s.
me. If the acid acted at atmos- v
heric pressure. or If the 1000 Il
al. just consumed the magnes Il
I'm present, the theoretical tenn 81
erature rise of the solution would ii
e:
8325 80