Note: Descriptions are shown in the official language in which they were submitted.
2~3~35
CORROSION lN~IBITION U~lNG MERCURY lN~ENSIFIERS
Cross-Reference to Related Application
This applic~tion is related to pending U.S. patent application Seri~l
5 No. 07/226,468 filed on August 1,1988, which pertains to fluids containing
a soluble copper metal salt for treatment of subterranean wells for the
enhancement of production therefrom.
Field of the Invention
The invention relates to methods for the prevention of the
corrosion of steels exposed to acid environments, and in one aspect, more
particularly relates to chemical additives that might be employed in the
acid medium to inhibit the corrosion of steel surfaces in contact therewith.
Background of the Inven ion
It is well known that steel surfaces will corrode in the presence of
acid environments. While the rate at which corrosion will occur depends
on a nurnber of factors, such as the steel alloy itself, the strength and type
of acid, the temperature of the environment, the length of contact, etc.,
~0 some sort of corrosion invariably occurs. Alloy technology has provided
materials to withstand the incidental contact of steel with acid, but the
corrosion problem is particularly aggravated when there is no choice but
to contact steel with acid, as in the case of chemical processing where acids
are employed. In instances where the acid is not required to remain pure
25 and where the contact is inevitable, attention has turned eoward providin~
corrosion inhibitors in the acid medium itself to prevent corrosion of the
steel surfaces that it must come into contact with, yet still deliver the acid
to its ultimate destination. It would be advantageous if a new corrosion
inhibitor were discovered that would be an improvement over the
30 presently known systems. Por example, a corrosion inhibitor providing a
large corrosion inhibiting effect for a small proportion used would be
advantageous. Additionally, there are presently no known effective high
temperature HCl corrosion inhibitors for chrome steels such as Chrome 13
(Cr 13) and 2205 cluplex.
2 ~ 3 ~
A specific environment in which an improved corrosion inhibitor
~vould be appreciated is in the oil patch. It is well known that during the
production life of an oil or gas well, the production zone within the well
may be chemically treated or otherwise stirnulated to enhance the
economical production lifetime of ~he well. A common way of doing this
is by acid fracturing or matrix acidlzing, whlereby a highly acidic solution,
generally having a pH of less than about 1, but which may be as high as
about 6.9 is injected into the well. Because of the acidic nature of the
treatment fluid, the production or workover corlduit which is utilized in
the well in such applications encounters considerable acidic corrosion, in
the forms of surface pitting, embrittlement, loss of metal component and
the like.
In earlier years of producing subterranean wells, the vast majority
of production and workover conduits which were utilized either
temporarily or permanently in the well and through which a treatment or
stimulation fluid was introduced into the well comprised carbon steels,
such as J-55, P-105, N-80 and the like. Recently, due primarily to the
drilling and completion of many subterranean wells through formations
which contain high concentrations of corrosive lluids such as hydrogen
sulfide, carbon dioxide, brine, and combinations of these constituents, the
production and workover conduits for use in the wells have been made of
hi~h alloy steels. The high alloy steels, such as those employed herein in
the description of the invention, include chrome steels such as 13 chrome
and 2205 duplex steels and the like.
Stainless steels, first commercially developed in the 1920s, obtain
their corrosion resistance by incorporation of a surface oxide film or
adsorbed oxygen, of about 10 to 100 angstroms thickness. These stainless
steels may be classified by their general structure and properties as: (1)
martensitic; (2) ferritic; (3) austenitic (4) duplex; and (5) precipitation-
hardening steels.
Martensitic alloy steels are magnetic and are hardenable by heat
treating procedures. In subterranean well environments, they may be used
for mild corrosion and high temperature service. Typical of such
martensitic alloys is UN~ S41000 (alloy 410) which contains from about
11.5% to about 13.5% chromium, about 0.15% carbon and no nickel.
3 ~ v ~
Ferritic alloys are similar to martensitic alloys in that they, also, are
magnetic. However, ferritic alloys are not hardenable by heat treatment
and have corrosion resistance between alloys 410 and 30~. They are also
immune to chloride stress corrosion acking and have a ductile t~ brittle
5 transition temperature which somewhat limits their use in subterranean
oil well environments. Exemplary of such ferritic all~ys is UNS S44735,
which contains from about ~8.0 to about 30.0% chrome, about 1% nickel,
between about 3.6% to about 4% molybdenum, and trace amounts of
copper, nitrogen, titanium and niobium.
10Austenitic stainless steels are non-magnetic and hardenable by cold
work, and, like ferritic alloys, are not hardenable by heat trea~nent. Typical
of such stainless steels is llNS S31603 (alloy 316L), which contains from
about 16 to about 18% chrome; from about 10 to about 14% nickel, with
traces of copper and molybdenum. Also typical of such austenitic stainless
15steels is UNS N08020 (alloy ~0); UNS N08825 (alloy 825); and UNS N08904
(alloy 904L), which contains from about 19 to about 23% chrome, from
about Z3 to about 45% nicke}, and from about 2 and about 5%
molybdenum, with small percentages of copper along with other
elements. Variants of these steels, such as S31254, N08026 and N08925,
20 which contain up to about 6% molybdenum, are also classified as
austenitic stainless ste~ls and have high chloride resistance, and are
particularly effective when used in and exposed to such environments.
Duplex steels combine ferrite and austenitic steels and have 2 to 3
times a yield strength of the austenitic stainless steels. A duplex stainless
25 steel family is resistant to pitting and crevice corrosion and has
significantly better CSCC resistance, than do the 3ûO ser;es stainless steel
products. Such steels have favorable toughness and ductility properties,
with a coefficient o~ expansion nearer to that of carbon steel, thus reducing
stress problems. Heat transfer in such stainless steels is about ~5% greater
30 than that of the austenitic steels.
Precipitation-hardened stainless steels attribute their high strength
to the precipitation of a constituent from a super-saturated solid solution
through a rela~ively simple heat treatment but do not encounter a loss in
resistance to corrosion or ductility. These steels may be heat treated.
35 Typical of such steels are UNS S17~00 (17~ PH) and I~NS S15700 (PH 1~7
4 2 ~ 3 ~
Mo), which contains from about 14 to about ~6% chromium, and from 2 to
about 3% molybdenum, with from about 6.5% to about 7.8% nickel.
Other high alloy steels indude those having high nickel content.
Typical of such high nickel alloys are UNS N10276 (alloy C-276); UNS
N06625 (alloy 625); and UNS N06110. These high nickel alloy materials are
used to prepare tubular goods for subterranean wells, and other
components for use within subterranean wells where such use is expected
to encounter extr~mely corrosive environments. The high nickel alloys
have high tolerance to extremely hostile environments and typically
contain about 60% r~ickel, from about 15 to about 20% chromium, and
from about 9 to about 16% molybdenum.
U.S. Pat. No. 3,773,465 presents a typical teaching with respect to
treatInent of low alloy, or N-80-type production conduits with intensified
acid corrosion inhibitor compositions, and discloses the use of cuprous
iodide in such treatment. Halohydroxylalkylthio-substituted and
dihydroxyalkylthio-substituted polycarboxylic acids and alkali metal salts
thereof are taught as effective corrosion inhibitors for various metal
surfaces in U.S. Pat. No. 4,670,163. In one embodiment, mineral acid
compositions such as aqueous hydrochloric acid metal cleaning solutions
exhibit diminished corrosiveness when corrosion inhibiting additives of
the invention are present in the compositions.
U.S. Pat. No. 4,498,997 relates to a method of acidizing a
subterranean formation or well bore employing an acidic solution
containing a corrosion inhibitor composition having an inhibiting
effective amount of an acetylenic alcohol, a quaternary ammonium
compound, an aromatic hydrocarbon and an antimony compound
intensifier. Acetylenic compounds as inhibitors are also noted as effective
by P.A. Burlce, et al. in "Corrosion of Chromium Steels in Inhibited
Acids," Corros~on/87, Paper No. 41, National Association of Corrosion
Engineers, San Francisco, California, 1987. U.S. Pat. No. 4,552,672 describes
an improved system over the one of the '997 patent, where the improved
system also contains a stabilizer to substantially prevent precipitation of
solubilized antimony-containing compounds from the aqueous solution.
Related to the '997 and '672 patents is the discussion of proprietary blends
~5 of acetylenic alc~ols, dispersants, nd heterocyclic quaternized amines,
.
with or without formamide and inorganic salts which are examined for
their corrosion inhibition properties in ~1.1,. Walker, et al~, "Inhibition of
High Alloy Tubulars II: Effect of Fluoride Ion and Acid Strength,"
Corrosion/88, Paper No. 189, National Association of Corrosion Engineers,
St. Louis Missouri, 1988.
Further of irlterest is U.S. Pat. No. 4,~83,954 which describes a
method and composition for stimulating subterranean formations
containing iron deposits, although it is not related to corrosion inhibition
systems. The composition comprises an adrnixture of (i) at least one
member selected from the group consisting of hydroxylamine
hydrochloride, hydroxylamine hydrobromide, hydroxylamine sulfate,
hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine
sulfate, hydrazine rnonobromide, hydrazine dibromide, hydrazine
monoiodide, hydrazine diiodide and hydroquinone together with ~ii) at
least one member selected from the group consisting of glucono-~-lactone,
citric acid, salts of citric acid, ethylenediaminetetraacetic acid, salts of
ethylenediaminetetraacetic acid, nitrilotriacetic acid, salts of nitrilotriacetic
acid, hydroxyethylethylenediaminetriacetic acid and salts of hydroxyethyl-
ethylenediaminetriacetic acid, and (iii) a catalytic amount of a solubilized
salt of a compound capable of providing cupric, cuprous, nickel, zinc ions
or rnixtures thereof. The method involves contacting the formation in a
manner and amount to sequester iron. It is noted that when the treating
fluid is used in a formation that is substantially non-acidic that the
compounds of group (ii), above, can be omitted.
It would be desirable if a new corrosion inhibitor or additive thereto
could be discovered which would be an improvement over present
techniques. The present invention relates to the use of an acid soluble
mercury metal salt as an intensifier alone or together with a cuprous
halide, in an acid corrosion inhibitor to retard the corrosion of steel,
particularly chrome steel surfaces in acid environments.
U.S. Pat. No. 3,954,636 relates to a composition and method for the
acid stimulation of subterranean formations, where the composition
comprises a mixture of an acid which solubilizes at least a portion of the
formation, an alcohol ;n which the acid and carbon dioxide are soluble,
and a small proportion of water and carbon dioxide. The patent off-
6 2 ~
handedly mentions that a standard corrosion inhibitor and cupric chloride
may be added to the mixture, but fails to indicate the purpose and details
behind the cupric chloride addition.
Two methods for inhibiting stress cracking in stainless steel using
mercury are set forth in U.S. Pat. Nos. 3,8~0,585 and 4,004,055. Both patents
contain a discussion about how what is commonly called "stress corrosion
cracking" is not believed by the inventors to involve much of a
"corrosion" factor~ The 585 patent teaches a method of inhibiting stress
cracking in stainless steel articles exposed to a chloride-ion containing
fluid environment in which the surface of the stainless steel article is
contacted with a trace amount of an inorganic metal salt, such as mercuric
nitrate, or with the metal corresponding to the cation of the salt, such as
mercury. This is to enlarge the anodic areas on the surface and inease the
uniformity of the electrical potential of the surface thereby eliminating
concentrated non-uniform attack on the surface and attendant cracking.
The method of the '055 patent also relates to inhibiting the stress cracking
of stainless steel exposed to a chloride-ion fluid environment where the
surface of the stainless steel is coated with at least a trace amount of
metallic mercury. The invention therein also contemplates the
mercury/stainless steel amalgam.
Summary of the Invention
Accordingly, it is an object of the present invention to provide an
improved intensifier for use in corrosion inhibitors that is effective in
inhibiting the corrosion of steel surfaces in acid environments.
It is another object of the present invention to provide a corrosion
inhibitor intensifier that may be employed in very low proportions.
It is yet another object of the invention to provide an improved
corrosion inhibitor intensifier that may be readily incorporated into
conventional corrosion inhibitors used in acid injection systems to
enhance production from subterranean formations.
In carrying out these and other objects of the invention, ~ere is
provided, in one form, a corrosion inhibitor composition for inhi~iting
the corrosion of steel in the presence of an acidic medium which has an
effective amount of an acid soluble mercury metal salt intensifier; and at
7 ~3~
leas~ one component selected from the group of corrosion inhibitor
components consisting of an ~cetylenic alcohol, a quaternary ammonium
compound, an aromatic hyd~ocarbon and mixtures thereof.
Detailed Desc~iption of the Invention
It has been discovered that extremely small amounts of an acid
soluble mercury metal salt, such as a mercury halide, for instance mercuric
chloride, is surprisingly effective in inhibitlng corrosion of steel surfaces
when employed together with corrosion inhibitors. Although it is
appreciated that metallic mercury and mercury compounds are
undesirable to release into the environment at certain levels, it is further
surprisingly noted that the proportions necessary for the implementation
of the present invention are below those levels. Data are presented herein
for the spent acid residuals showing representative low levels of mercury.
The acid soluble mercuric metal salt intensifier of the present
invention may be used alone or in conjunction with a co-intensifier, such
as an acid soluble copper metal salt, for example, a cuprous halide. It will
be appreciated that the intensifier of tlus invention may be used with
conventional corrosion inhibitors such as those described below, in any
application where a steel surface, such as stainless steel, high alloy or other
steel, is exposed to an acid environment. While the specific implementa-
tion of this invention is described in the context of the oil patch, the
invention may certainly find uses in other applications where it is
desirable to reduce corrosion, such as chemical processes that necessarily
~5 require the contact of adds with conduits, fittings, and other equipment.
In the implementation of the invention in the production of fluids
from subterranean reservoirs, a fluid is introduced through a high alloy
steel member or conduit positioned within the well. The fluid is an acidic
injection medium and an acid corrosion inhibitor, which is intensified by
the introduction into the t~eatment fluid and contact with the steel
member of an acid soluble mercuric metal salt, which may be mercuric
chloride, alone or together with a cuprous halide, such as cuprous
chloride. The invention also encompasses a method of treating a well for
enhancement of production within a production ~one by introduction
into the steel conduit an intensified acid corrosion inhibitor composition.
~t ~
The fluid which is con~emplated for use in one aspect of the present
invention for treatment of a subterranean well for enhancement of
production will be aqueous based; that is, it will be formed using sea water
available at the well location, a brine, tap water or similar fluid. The
amount of fluid used for the treatment will vary, of course, from well to
well, and will be based upon the particular application at hand, and the
amount thereof is not particularly critical to the method of the present
invention. It will be appreciated that one skilled in the art of corrosion
inhibition will be able to adapt the teacllings of this invention to
applications outside the realm of oil and gas recovery, such as the area of
chemical processing, with only routine experimentation.
The high alloy steel member which is introduced into the well may
be provided either in the form of a section or string of workover tubin~, or
may be permanently implaced production tubing. It may also include, as
opposed to tubing p~r se, any high alloy steel surface, such as the lining of
down hole pumps, gas separators, packer mandrels, tubing hangers, safety
valves, side pocket mandrels, wire line tools and the like. In any event,
the phrase "high alloy steel conduit" is meant to generally refer to oil
country tubular goods or metal surfaces of down hole equipment of a
stainless steel, as described above. Preferably, such high alloy steel
members will be provided in the form of 2205 steel, which generally
contains about 22% by weight chrome and about 5% by weight nickel, with
the balance of the materials varying depending upon the source of the
conduit or surface of the member. Alternatively, high alloy steel conduits
~5 may also be formed of tubing joints having about 13% by weight chrome.
This tubin~ normally is provided in 30 foot to 60 foot sections or "joints"
which are threadedly secured to one another and introduced into the well
to form a string of tubular conduit which has its lower end positioned
within a production zone, or location, in the well to be treated.
If this tubing is provided in the form of a work-string, it may be
retrieved from the well. If the tubing is production casing, it will be
cemented in place at some time during the early life of the well, ~nd before
treatInent of the subterranean well zone. If the steel is used in down hole
equipment of a non-conduit nature, it may be permanently placed, or may
be retrievable.
~ ~ 3 r~
The treatment fluid has ~s a primary additive an acidic injection
medium which may be any compatible acid, such as hydrochloric, formic,
citric, hydrofluoric, acetic, and mixtures thereof. The fluid with the acid
injection medium therein should have a pH of no greater than about 6.9.
The treatment fluid also contemplates incorporation of an acid
corrosion inhibitor which typically will be provided in treatment
concentrations of from about 1,000 ppm, based upon the weight of the
entire treatrnent fluid to about 60,000 ppm of such weight. Of course, the
treatment level of the acid corrosion inhibitor will vary depending upon
the particular physical characteristics of the well, the high alloy steel
conduit, temperature and pressure considerations, the selected acidic
injection medium, and the like.
The acid corrosion inhibitor to be combined with the acidic
injection medium and the intensifier can be any acetylenic compound
such as an acetylenic alcohol; a nitrogen compound, such as a quaternary
ammonium compound; and aromatic hydrocarbon or mixtures thereof, as
is known to those skilled in the art. For example, acid corrosion inhibitors
as made and described in U.S. Pat. Nos. 3,514,410; 3,404,094; 3,107,~1;
2,~93,863; and 3,382,179; may be utilized in accordance with the present
invention.
Exarnples of acetylenic compounds which may be used include
hexynol, dimethyl hexynol, diethyl hexynediel, dimethyl hexynediol,
dimethyl oxtynediol, methyl butynol, methyl pentynol, ethynyl
cyclohexynol, 2~thyl hexynol, phenyl butynol, and ditertiary acetylenic
glycol.
Other acetylenic compounds which can be employed in accordance
with the present invention include, but are not limited to, butynediol, 1-
ethynylcyclohexanol, 3-methyl-1-nonyn-3-ol, 2-methyl-3-butyn-2-ol, also 1-
propyn-~ol, 1-butyn-~ol, 1-pentyn-3-ol, 1-heptyn-3-ol, 1-octyn-3-ol, 1-
nonyn-3-ol, 1-decyn-~ol, 1-(2,4,6-trimethyl-3 cyclohexenyl~-3-propyne-1-ol,
and in general acetylenic compounds having the general forrnula:
,
lo ~ 3 ~
~1
HC- Cf-R2
R3
wherein Rl is -H, ~H, or an alkyl radical; R2 is -H, or an alkyl, phenyl,
substituted phenyl or hydroxy-allcyl radical; and R3 is-H or an alkyl,
5 phenyl, substituted phenyl or hydroxyalkyl radical.
Acetylenic sulfides having the general formula
HC-C-R-~R~_CH
can also be employed in the present invention in lieu of acetylenic
alcohols. Examples of these are dipropargyl sulfide, bis-(1-methyl-2-
10 propynyl)sulfide and bis-(2-ethynyl-2-propyl)sulfide.
The nitrogen or ammonia compounds that can be employed in
accordance with the present invention include, but are not limited to,
those amines having from one to twenty-four carbon atoms in each alkyl
moiety as well as the six-membered heterocyclic amines, for example, alkyl
15 pyridines, crude quinolines and mixtures thereof. This includes such
amines as ethylarnine, diethylamine, triethylamine, propylamine,
dipropylamine, tripropylamine, mono-, di- and tripentylamine, mono-,
di- and trihexylamine and isomers of these such as isopropylamine,
tertiary-butylamine, etc. This also includes alk~l pyridines having from
~0 one to five nuclear alkyl substituents per pyridine moiety, such alkyl
substituents having from one to 12 carbon atoms and preferably those
having an average of six carbon atoms per pyridine moiety, such as a
mixture of high boiling tertiary-nitrogen-heterocyclic compounds, such as
~P (high alkyl pyridines), Reilly 1~20 base and alkyl pyridines H3. Other
25 nitrogen compounds include the crude quinolines having a variety of
substituents.
The inhibitor may also contain a number of other constituents,
such as nonyl phenol adducts and tallow amine adducts, tall oil adducts,
such as surfactants. Oil wetting components, such as heavy aromatic
30 solvents, may also be present.
The third component of the treatmlent fluid of the present
invention is an intensifier for the acid corrosion inhibitor. The intensifier
may be added to the treatment fluid independently and separately of the
acid corrosion inhibitor. Alternatively, the intensifier may be a
component part of the acid corrosion inh;bitor. In either event, the
intensifier is provided for purposes of assisting, aiding and amplifying the
corrosion inhibition effects of the acid corrosion inhibitor.
The intensifier contemplated for use in the present invention is any
acid soluble mercury metal salt, such as a mercuric halide, and is most
preferably a member selected from the class consisting of mercuric
chloride, mercuric acetate, mercuric oxides, and mercuric nitrate. Group
Va Elemental Series metals are useful in the intensifiers of this invention,
besides mercury. It is generally preferred that mercuric chloride be used,
although the selected intensifier will depend upon the particular
application at hand, the steel surface used, temperature and pressure
factors, the particular selected acid corrosion inhibitor, the acid utilized,
and the water used to form the treatment fluid. Those skilled in the art
will be able to select the best intensifier for the particular application at
hand by pre-testing techniques as utilized in the working examples, below.
~gain, the amount of intensifier incorporated in the acid injection
medium with the acid corrosion inhibitor will vary, depending on the
parameters described above, but will typically be no less than about 0.05
pound per thousand gallons of acidic injection medium, as an example
only. Although there is no upper limit to the amount of intensifier
employed, it may be uneconomic to use more than about 4 or 5 pounds
per thousand gallons of acid injection medium, since it is expected that no
significant increase in benefit may be obtained above that level. In one
optimized embodiment, the acid soluble mercury metal salt should be
present in an amount of at least 0.30 weight %, based on the inhibitor.
Other optional co-intensifiers include acid soluble copper metal
salts, such as a cuprous halide, and is preferably a member selected from
the class consisting of cuprous chloride, cupric formate, copper acetate,
and cuprous nitrate. Generally, cuprous chloride is preferred. There is
evidence under certain conditions that the combination of cuprous
chloride with mercuric chloride gives a synergistic effect and an
12
improvement in corrosion inhibition that is greater th~t the use of each
compound used separately. Other optionai co-intensifiers that may be
employed include acid soluble bismuth metal salts and antimony metal
salts similar to the copper metal salts described above.
As noted, very small proportions of the acid soluble mercury metal
salt need be used. Using the acid corrosion inhibitor as a basis, the
preferred amount need only be 0.30 wt.%. The preferred amounts of the
copper metal salt, bismuth metal salt and antimony metal salt sh~uld be at
least 0.6 wt.% based on the acid corrosion inhibitor. It will be understood
that these preferred ranges are not limiting, but simply exemplary. It is one
of the most unusual aspects of the present invention that the intensifier
may be used in extremely small amounts, even those mentioned above,
and yet still be effective. The optimal amount for a particular application
will depend on a number of factors including, but not limited to
temperature of the acidic medium, the nature of the steel exposed in the
medium, etc., and one skilled in the art may determine such levels after
merely routine experimentation.
The invention will be further illustrated with reference to the
following illustrative examples.
E)CA~LES 1-104
Corrosion rate tests were performed on test coupons of N-80 carbon
steel, chrome 13 and 2205 duplex steels in a simulated treatment f~uid
comprising water containing hydrochloric acid, with the acidic injection
medium being provided in the form of 100 ml 15% hydrochloric acid
(HCl). To the treatment fluid with the acidic injection medium provided
therein were added the indicated gallons per thousand gallons (gpt) of
fluid selected, and commercially available inhibitors, "A", "B" or "C". The
generic composition of such sample inhibitors can generally be described
as follows:
Inhibitor (:~eneric Description
A Heterocyclic quaternary product
B Mannich reaction product-
13 ~ 3 ~
C Heterocyclic quaternary product with small
amount of cuprous chloride and mercuric
chloride built into it (see Table VIII)
After introduction of the selected inhibitor to the treatment fluid,
the indicated intensifiers were added in the indicated amounts.
Alternatively, the intensifiers could be added earlier. The simulated
treatment fluid with the respective acid corrosion inhibitor and intensifier
additions were then placed into high temperature and high pressure
corrosion test cells to which were added the test coupons of the indicated
steels. The coupons were permitted to remain in the simulated treatment
fluid for six hours at a pressure between 4,000 and 5,000 psi. Thereafter, the
coupons were removed from the test cell, neutralized, scrubbed and
weighed for weight loss described in pounds per sq. ft. (lb./ft2). Of course,
the lower the weight loss, the more effective the corrosion inhibitor and
the intensifier in preventing corrosion. The effect with and without
optional antimony salts and bismuth salts is also explored.
Special attertion is directed to Examples 9, 10, 15, 21, 24, and 26
which show exceptional corrosion inhibition ability for all tested steels. At
the higher temperature of 350F, Ex~nples 33, 34, 38, 39 and 41 show
exceptional results for the 2205 duplex steel. See also the results obtained
with corrosion inhibitor C in Tables VII and VIII.
Shown in Table I is the effective corrosion control of N^B0 and Cr 13
steels using 4 gpt of inhibitor A and 0.012 gms./100 ml acid of CuCl and
0.006 gms./100 ml acid of HgC12, as seen in Example 6. See also Examples 7,
8, 9 and 10 using increasing amounts of HgC12. An effective inhibitor of
2205 duplex steel is obtained in Example 10 using 0.010 gms. of HgCl2.
Effective control of 2205 corrosion is also seen using 6 gpt of inhibitor A,
- only 0.003 gms. HgCl2 and 0.08 gms. of CuCl, as seen in Example ~2; see
also Examples 23-27.
14 ~3~
TABLE I
Corrosion Rates at 250~ Using Corrosion Inhibitor A
gpt gms/100 ml 15% HCl lbs/ft2 Corrosion Rate
Ex. cor. ih. A CuCI ~2 SbCl~ 13iCl~ N-80 Crl3 2205
4 ~ 0.482 0.507 1.019
2 4 - 0.01 - - 0.013 0.008 0.084
3 4 0.06 - - - 0.026 0.239 0.714
4 4 0.004 0.002 - - 0.067 0.1~0 0.066
4 0.008 0.004 - - 0.012 0.068 0.040
6 4 0.012 0.006 - - 0.023 0.013 0.158
7 4 0.016 0.008 - - 0.005 0.007 0.066
8 4 0.020 0.010 - - 0.005 0.005 0.073
9 ds 0.030 Q.010 - - 0.004 0.004 0.052
4 0.040 0.010 - - 0.003 0.004 0.036
11 4 0.040 0.010 0.040 - 0.016 0.012 0.081
12 4 0.0~0 0.010 - 0.040 0.262 0.016 0.025
13 4 0.060 0.010 - - 0.004 0.005 0.079
14 4 0.060 0.010 0.060 - 0.008 0.082 0.053
4 0.060 0.010 - 0.060 0.025 0.025 0.022
16 6 0.005 - - - 0.674 0.265
17 9 0.004 - - - 0.864 0.095
18 10 0.005 - - - 0.877 0.058
19 6 0.003 0~040 ~ 0.050
8 0.004 0.040 - - - - 0.046
21 10 0.005 0.040 - - - - 0.046
22 6 0.003 0.080 - - - - 0.033
23 8 0.004 0.080 - - - - 0.031
24 10 0.005 0.080 - - - - 0.025
6 0.0~3 0.120 - - - - 0.032
` 26 8 û.004 0.120 - - - - 0.032
27 10 0.005 0.120 - - - - 0.020
28 ~ 0.003 0.005 0.040 - - - O.û19
29 8 0.004 0.007 0.080 - - - 0.009
0.005 0.009 0.120 - - - 0.018
TABLE II
Corrosion Rates at 300F Using Corrosion Inhibitor A
gpt gms/100 ml 15% HCL lbslft- Corrosion Rale
Ex. cor. ih. A CuCl H~CI? SbCl~ BiCl~ N-80 Crl3 2205
31 20 - - - - 0.~0 0.950 0.989
32 20 0.010 0.005 - - 0.832 0.776 0.925
33 20 0.0~0 0.010 - - 0.183 0.374 0.395
34 20 0.040 0.020 - - 0.04g 0.113 0.226
0.0~0 0.020 - - 0.043 0.112 0.168
~6 20 0.060 0.020 0.~20 - 0.018 0.024 0.0~4
37 20 0.060 0.020 - 0.120 0.136 0.881 0.136
38 20 0.120 0.020 - - 0.023 0.298 0.123
39 20 0.240 0.020 0.240 - 0.010 0.019 0.015
0.240 0.020 - 0.240 0.03~ 0.130 0.039
41 20 0.240 - - - 0.248 0.976 0.181
42 20 0.080 0.010 0.120 - 0.095 0.402 0.025
43 20 0.080 0.010 - 0.180 0.079 0.118 0.124
44 20 0.020 0.010 0.120 - 0.020 0.037 0.056
0.020 0.010 0.180 - 0.054 0.044 0.055
46 20 0.020 0.010 0.240 - 0.126 0.047 0.040
- 47 20 0~720 0.010 - - 0.013 0.011 0.068
48 20 - 0.010 - - - 0.652
Effective corrosion control of N80 steel is provided using 20 gpt of
5 inhibitor A, 0.04 gms. CuCl and 0.02 gms. HgC12 as seen in Example 34; see
also Example 35. ~:urther, effective corrosion control of N-80 and Cr 13 and
fair control for 2205 may be obtained by using 20 gpt of inhibitor A, 0.01
gms. HgC12 and 0.72 gms CuCl, in accordance with Example 47.
16
TABLE m
Corrosi~n Rates at 350F Using Corrosion Inhibitor A
gpt gms/100 ml 15% HCI Ibs/ft_Corrosion Rate
Ex. cor. ih. A CuCl HgCl? SbCl~ E~iCl~ N-80 Crl3 2205
49 20 - - - - 0.839 0.887 0.975
0.020 0.010 - - 0.~42 0.495 0.950
51 20 0.020 0.010 0.240 - 0.841 0.203 0.022
52 20 0.120 0.010 0.120 - 0.691 0.231 0.019
53 20 0.120 0.010 0.240 - 0.466 0.169 0.058
54 20 0.120 0.020 - - 0.860 0.129 0.940
0.240 0.020 - - 0.~71 0.116 0.941
56 20 0.240 0.020 0.120 - 0.381 0.121 0.052
57 20 0.240 0.020 0.240 - 0.363 0.089 0.036
58 20 ~.240 0.020 - 0.240 0.867 0.139 0.346
59 20 - 0.020 0.240 - 0.848 0.361 0.130
S0 20 1.500 0.020 - - 0.153 0.941 0.648
61 20 1.500 0.030 - - 0.115 0.926 0.434
62 20 1.500 0.040 - - 0.129 0.943 0.428
63 20 0.040 0.020 0.500 - 0.025
S4 20 0.060 0.030 0.500 - 0.012
0.080 0.040 0.500 - 0.016
16
17 S~3~ i3
TABLE IV
Corrosion Rates at 250F Using Corrosion Inhibitor B
gpt gms/100 ml 15% HCI _ lbs/ft_ Corrosion Rate
Ex. cor. ih. B HgSk CuCl SbCl~ BiCl~ N 80 Cr l3 2205
66 10 - - - - 0.209 0.306 0.909
67 4 0.010 - - - 0.029 0.116 0.278
68 4 0.010 0.040 - - 0.018 0.076 0.090
69 d~ 0.006 0.012 - - 0.023 0.076 0.112
4 0.006 0.040 - - 0.015 0.081 0.075
71 4 - - 0.040 - 0.015 0.036 0.667
72 4 - 0.040 0.040 - 0.012 0.097 0.614
73 4 0.010 0.040 0.040 - 0.014 0.076 0.034
74 4 0.010 0.060 - 0.060 ~1.027 0.151 0.061
4 0.010 0.040 - 0.040 0.015 0.118 0.067
As shown in Table IV, effective corrosion control of N-80 is
5 obtained using 4 gpt of inhibitor B, 0.01 gms. of HgC12 and 0.04 gms. CuCl
as seen in Example 68, and fair to poor control of Cr 13 and 2205. See also
Examples 69 and 70.
TABLE V
Corrosion Rates at 300F Using Corrosion Inhibitor B
gpt ms/100 ml 15% HCl lbs/ft2 Corrosion Rate
Ex. cor. ih. B ~1~ CuCl SbCl~ BiCl~ N-80 Crl3 2205
76 20 - - - - 0.878 0.920 1.013
77 20 0.02 0.720 - - 0.060 0.018 0.125
78 20 0.020 0.060 0.120 - 0.131 0.285 0.260
79 20 0.020 0.240 - û.240 0.253 0.808 0.187
0.050 - - - 0.840 o.no 0.946
Effective conkol of Cr 13 corrosion is available using 20 gpt of
inhibitor B, o o2 gms HgC12, 0.72 gms CuCl, with fair control of N-80 and
poor control of 2205, according to Example 77.
17
18 ~J ~ 3
TABLE VI
Corrosion Rates at 350F Using Corrosion Inhibitor B
gpt gms/100 ml 15% HCI Ih~L~ COr ~;o~
Ex. cor. ih. B ~ CuCI ~ ~ N-80 Cr 13 2205
81 20 - - - - 0.868 O.g37 0.965
~2 20 0.080 - - - 0.848 0.801 0.976
83 20 0.050 0.500 - - 0.841 0.918 0.832
84 20 0.020 0.050 0.500 - 0.108 0.04~ 0.567
û.020 0.050 - 0.500 0.~64 0.959 0.951
The Examples of Table VI indicate no effective control with
5 inhibitor B at 350F.
TABLE VII
Corrosion Rates at 350F and 4,000 - 5,000 psi in 15% HCI
Using Corrosion Inhibitor A, B and C
gms/100 ml 15% HCI ~ Corros,on Rale
Ex. Inhibitor ~pt, inh. CuCl ~ Cr 13 2205
86 A 40 1.500 0.020 0.039 0.363
87 A 50 1.500 0.020 0.040 0.479
88 B 40 1.500 0.020 0.909 0.429
89 B 50 1.500 0.020 0.912 0.472
C 40 1.4 - 0.054 0.030
91 C 50 1.4 - 0.034 0.025
Particular attention should be given to the excellent results obtained
using the intensifier of this invention with corrosion inhibitor C as seen
in Examples 90 and 91 and 92-104.
EXAMPLES 92-104
Because weight loss is not the only test criteria for determining the
ability of a given corrosion inhibitor to function satisfactorily in protecting
a metal surface, the coupons were also tested and evaluated for possible
pitting caused by exposure to the acidic environment of the simulated
20 treatment fluid. Aft~er the coupons were removed from the respective test
18
19 ~ ~ 3 ~ !~ 3 ~
cell, pitting was visually observed using a 10 point scale, with 9 defining
the most unsatisfactory result, and indic~ting extreme pitting and/or
delamination. A rating of 0 with respect to pitting was utilized if the
coupon, when compared to an untested coupon, appeared approximately
5 the same as the untested coupon. When a rating of 9 was found on any
coupon, pitting and/or delamina~on had occurred over at least 50% of the
surface area of the coupon. A rating of 1, 2 or 3 indicates that the coupon is
free of pits and delamination, but is disc~lored with increasing
discoloration as the number increases. The results of th~s test, as well as
weight loss on additional experiments are set forth in Table vm.
TABLE VIII
Corrosion Rates and Pitting Using
Inhibitor C and 2205 Duplex Steel
(Inhibitor C contains approx. ~HgC12 and approx. ~CuCl.) O~
2205 Duplex . O- t2 ~83
gpt of grams of Je
InhibitorC in CuCI in Total Pittin~
Ex. ~5% HCI 15% HCI F Hrs. Hrs. Ibs/fl2 rat~ng
92 20 0.72 325 6 8 0.048
93 30 0.72 325 6 8 0.032
9~ 40 0.72 325 6 8 0.039 2
9S 30 0.72 350 2 4 0.027
96 40 0.72 350 3 5 0.035
97 30 1.44 350 4 6 0.054 3
98 40 1.44 350 4 6 0.031
99 40 1.44 350 5 7 0.036
100 40 1.4~ 350 6 8 0.043 3
101 50 1.44 350 6 8 0.029
102 60 1.44 375 3 5.5 0.055 2
103 60 1.44 400 ~ 4 0.081 7
104 30 1.44 400 0 3 ~.037
20 ~ f~3
SAMPLES 1-12
Samples 1-12 concern the contents of spent acid residuals following
an acidizing treatment. They verify that there is minimal mercury
feedbac,c present utilizing the low quantities of the present invention.
Such low levels would permit use of the intensifiers of the present
invention with assurance of negligible and insignificant envirorunental
consequences.
Sample 1: Sample of aqueous inhibited acid before corrosion test.
Sample 2: Sample of aqueous inhibited acid before corrosion test and after
neutralization with oyster shells and crude filtration to
remove the unreacted shells and residue.
Sample 3: Sample of deionized water.
Samples 4, 7 and 10: Samples of the aqueous inhibited acid after the
corrosion test.
Samples 5, 8 and 11: Samples of the parrafinic oil covering the inhibited
acid after the corrosion test.
Samples 6, 9 and 12: Samples of the aqueous inhibited acid after corrosion
test and neutralization with oyster shells and crude
filtration to remove the unreacted shells and residue.
Series I
Test Conditions: 20 gpt corrosion inhibitor C, 15% HCl
Room temperature mixture
~5
Sample 1Sample 2
Metal ~ (ppm)
Cr <0.4 <0.4
~u 93.490.2
Pe 1.1385.7
Hg 50.7<0.1
N i <0.251O.Z73
g~ <0.392~0.392
21
Series II
Test Conditions: Lab blank; deionized water
Sample 3
Metal '~E?pm)
G ~0.4
Cu ~0.4
Fe <0.2
Hg <0.1
N i ~0.25
- Sb <0.392
Series III
Test Conditions: 20 gpt corrosion inhibitor C,
SS-2205 Steel, 15% HCl
6 Hours at 300F, 4000 psi
Sample 4 Sample 5 Sample 5
Metal (ppm) (ppm) (ppm)
Cr 940 7.7 784
Cu 110 0.98 104
Fe 7320 8.3 6200
Hg 5.1 0.57 ~0.1
N i 470 1.4 470
go <0.392 <2.0 <0.3~2
.. .
22 -~J
Series IV
Test Conditions: 20 gpt corrosion inhibitor C, 60 Ib/mgal CuCI,
S~2205 steel coupons, 15% HCl
6 Hours at 300F, 4000 psi
Sample 7 Sample 8 Sample 9
Metal (ppm) (ppm) ~ppm?
Cr 211 1.60 178
Cu 5500 19.1 5850
Fe 884 3.8 791
Hg 8.7 0.36 <0.1
Ni 53.2 ~1.30 48.8
<0.392 <2.0 ~0.392
Series V
Test Conditions: 20 gpt corrosion inhibitor C, 5 Ib/mgal CuCl,
15 Ib/mgal SbCl3, S~2205 steel coupons, 15% HCl
6 Hours at 300F, 4000 psi
Sample 10 Sample 11 Sample 12
Metal (ppm) ~ (ppm)
G 163 c0.2 116
Cu 459 <0.2 38.1
Fe 1780 2.70 1360
Hg 5.0 0.36 <0.1
Ni 57.5 <1.3 43.5
g~ 359.0 258.û
Many modifications may be made in the present invention without
departing from spirit and scope thereof which are defined only by the
appended claims. For example, a particular c~intensifier or combination
of intensifiers not explicitly recited herein, but which falls within the
15 claims may prove to have advantageous characteristics.
