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Патент USA US3072202

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United States Patent O?lice
1
.
,
3,072,192
Patented Jan. 8, 1963
2
as semi-polar organic corrosion inhibitors and inorganic
3,072,192
METHOD OF INHIBITING CORROSION IN
OIL PRODUCTION
Hendrik K. Van Poollen, Littleton, Colo., assignor t0
Marathon Oil Company, a corporation of Ohio
No Drawing. Filed Feb. 19, 1959, Ser. No. 794,255
6 Claims. (Cl. 166—42)
compositions, such as sodium dichromate and sodium
nitrite. In preferred practice these inhibitors are mixed
with a suitable lique?ed inert but slowly soluble material
which will congeal in the pellet forming stage and can
be controlled as to size so that the pellets are produced
in the same size range as the propping sand. It is not
necessary to have the inhibitor composition in solution
prior to congealing so long as it disintegrates in the forma
tion ?uids and pellets formed of compressed solids also
ducing corrosive effects on oil well equipment installed
may be employed.
in or associated with producing oil wells.
The quantity of pellets utilized in the treatment will
This invention is useful in various types of producing
vary with the amount of sand being used, the size of the
wells but has particular application to treatments utilized
fractured area being ?lled, and the productivity of the
in connection with oil well stimulation. The oil contains
ingredients possessing highly corrosive properties which 15 well. In many treatments where a considerable quantity
of sand is being used, an addition of pellets in an amount
attack the metallic surfaces in the well equipment and
approximating one percent by volume of the sand will
surface installations through which the oil is conducted,
be adequate under most conditions. Under extreme
treated and stored.
conditions as much as 10% might be required in such a
Among the methods utilized in oil well stimulations is
My invention relates to methods for preventing or re
a practice known as hydraulic fracturing or sand fractur
ing, in which a ?uent body of sand in graded sizes is
pumped or forced into an oil reservoir to render such
formation more permeable and to promote ?ow of oil
mixture, but any amount in excess thereof appears to
have no actual bene?t and only adds to the cost of the
treatment.
The sand-inhibitor mixture is distributed throughout
the fractured area according to the usual hydraulic frac
from the structure into the production well.
It has been known that corrosion inhibitor composi 25 turing procedure. As soon as the sand distribution is
completed pumping can begin and continues as long as
tions, if released in the structure to ?ow with the oil,
will retard the corrosive action to a considerable degree,
and it is bene?cial to have the inhibitor in place when
pumping begins.
required. The inhibitor commences functioning as pump
ing begins and continues in the same manner for a long
interval providing substantially the same degree of cor
The present invention represents a departure from prior 30 rosion control throughout the entire period.
In many instances it may be advantageous to introduce
inhibition methods, in utilizing corrosion inhibitors which
a substantial concentration of the inhibitor pellets into
are in solid form, are substantially insoluble in the car
the formation preceding the introduction and distribution
rier ?uid by which they are conducted into the formation,
of propping sand, in order to push the inhibitor far into
and go into solution slowly in the oil production of the
well, which usually has a substantial water con-tent. The 35 the formation. In such event, only a lean mixture of
inhibitor in the sand will su?ice, as the formation ?uids
inhibitor composition may be water soluble or oil soluble
will contain dissolved inhibitor on reaching the propping
and preferably is only slowly soluble in the formation
sand.
?uids of the oil stream being conducted through the well.
From the foregoing description it will be apparent that
A suitable composition for this purpose is described in
Rohrback et a1. Patent No. 2,6843 32, and the pellets may 40 this invention may be practiced with a wide selection of
be formed to meet size speci?cations or reduced and sized
to meet the size requirements of its intended use. A
chemicals as the inhibitor of the treatment, and the quan
tity of inhibitor used may vary substantially according
to the requirements of a given treatment. Changes and
modi?cations may be availed of within the spirit and scope
novel method is provided for distributing such composi
tions throughout the reservoir structure and corrosive
action is inhibited for a relatively long period due to the 45 of the invention as set forth in the hereunto appended
claims.
slow rate of dissolution.
I claim:
Accordingly it is an object of my invention to provide
1. The method of inhibiting corrosion in oil production
a simple, economical and e?icient method of inhibiting
from hydrocarbon producing reservoir formations pene
corrosion in metallic equipment utilized in oil production.
Another object of this invention is to provide a simple, 50 trated by a well, which comprises mixing a corrosion in
economical and e?icient method of distributing a corro
sion inhibiting composition in an oil producing structure
and for retaining such composition in the structure for a
hibitor composition in solidi?ed pellet form with a prop
ping agent in approximately the same size range, said
pellets being substantially insoluble in a carrier ?uid and
at least slowly soluble in formation ?uids, suspending the
A further object of the invention is to provide for the 55 mixture of pellets and propping agent in said carrier fluid,
delivering said mixture through a well bore to the bottom
distribution of a corrosion inhibiting composition through
of said well, initiating a fracturing of said formation at
out an oil bearing formation as an adjunct to a charge
the bottom of the well by increasing the pressure on said
of material being distributed throughout the formation
carrier ?uid to a degree sufficient to lift the overburden
for other purposes.
A typical procedure according to the present invention 60 and force said ?uid mixture into the formation, whereby it
is distributed through said formation outwardly from said
is to form solid inhibitor chemicals as pellets which dis
well, and withdrawing formation ?uids from the forma
solve slowly in formation ?uids. These pellets are sized
tion and through the well to induce a slow dissolution of
and mixed with propping sand in the same size ranges
the pellets by contact with the formation ?uids until the
until they are uniformly distributed in the sand. This
mixture is utilized as the propping sand of a hydraulic 65 inhibitor is completely dissolved therein.
2. The method of inhibiting corrosion in oil production
fracturing treatment and is pumped into cracks away from
from hydrocarbon producing reservoir formations pene
the well bore. The pellets are slowly soluble in the for
trated by a well, which comprises mixing a corrosion in
mation ?uids but supply a sui?cient inhibiting effect from
hibitor composition in congealed pellet form with a prop
the outset, and because the rate of dissolution is so slow,
ping agent in approximately the same size range, said pel
this effect persists for relatively long intervals.
lets being substantially insoluble in a carrier ?uid and at
Various compositions may be used as the inhibitor
least slowly soluble in formation ?uids, suspending the
material, as for example, the class of compositions known
relatively long period.
3
3,072,192
4
mixture of pellets and propping agent in said carrier ?uid,
tion from hydrocarbon producing reservoir formations
delivering said mixture through a well bore to the bottom
of said well, initiating a hydraulic fracturing of said for
mation at the bottom of the well by increasing the pres
penetrated by a well, which comprises mixing an oil solu
sure on said carrier ?uid to a degree su?icient to lift the
size range, said pellets being substantially insoluble in a
carrier ?uid and at least slowly soluble in formation ?uids,
suspending the mixture of pellets and propping agent in
said carrier ?uid, delivering said mixture through a well
bore to the bottom of said well, initiating a fracturing of
10 said formation at the bottom of the well by increasing
overburden and force said ?uid mixture into the forma
tion, whereby it is distributed through said formation
outwardly from said well, and withdrawing formation
?uids from the formation and through the well to induce
a slow disolution of the pellets by contact with the for
mation ?uids until the inhibitor is completely dissolved
therein.
3. The method of inhibiting corrosion in oil production
ble corrosion inhibitor composition in solidi?ed pellet
form with a propping agent in approximately the same
from hydrocarbon producing reservoir formations pene
the pressure on said carrier ?uid to a degree su?icient to
lift the overburden and force said ?uid mixture into the
formation, whereby it is distributed through said forma
tion outwardly from said well, and withdrawing forma
trated by a well, which comprises mixing a water solu 15 tion ?uids from the formation and through the well to
ble corrosion inhibitor composition in solidi?ed pellet
induce a slow dissolution of the pellets by contact with
form with a propping agent in approximately the same
the formation ?uids until the inhibitor is completely dis
size range, said pellets being substantially insoluble in a
solved therein.
carrier ?uid and at least slowly soluble in formation ?uids,
5. A method as de?ned in claim 1, in which the mix
suspending the mixture of pellets and propping agent in 20 ture of pellets and propping agent is in the proportion
said carrier fluid, delivering said mixture through a well
of 1 to 10% by volume of pellets in said agent.
bore to the bottom of said well, initiating a fracturing of
6. A method as de?ned in claim 1, in which the mix
,said formation at the bottom of the Well by increasing the
ture of pellets and propping agent is in the proportion of
pressure on said carrier ?uid to a degree su?icient to lift
the overburden and force said ?uid mix-ture into the for 25
mation, whereby it is ‘distributed through said formation
outwardly from said well, and withdrawing formation
?uids from the formation and through the well to induce
a slow dissolution of the pellets by contact with the for
mation ?uids until the inhibitor is completely dissolved 30
therein.
4. The method of inhibiting corrosion in oil produc
approximately 10% by volume of pellets in said agent.
References Cited in the ?le of this patent
UNITED STATES PATENTS
, 2,635,698
2,684,332
2,818,118
2,877,180
2,891,619
Rohrback et a1 ________ __ Apr. 21, 1953
Rohrback et al. _______ __ July
Dixon _______________ __ Dec.
Parks et a1. __________ __ Mar.
Sneary ______________ __ June
20,
31,
10,
23,
1954
1957
1959
1959
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