U.S. patent application number 10/357689 was filed with the patent office on 2003-06-19 for corrosion inhibitors for use in oil and gas wells and similar applications.
Invention is credited to Sandor, George Robert, Verma, Shyam Kumar.
Application Number | 20030114319 10/357689 |
Document ID | / |
Family ID | 26867545 |
Filed Date | 2003-06-19 |
United States Patent
Application |
20030114319 |
Kind Code |
A1 |
Verma, Shyam Kumar ; et
al. |
June 19, 2003 |
Corrosion inhibitors for use in oil and gas wells and similar
applications
Abstract
Anti-corrosion additives and processes useful for oil drilling
and similar applications. Heteropoly complex anions of transitional
metal elements can be added to an oil well drilling solution which
includes a metallic salt, optionally in combination with transition
metal compounds or compounds of the metallic elements of Groups
IIIa to VIa of the Periodic Table of Elements, to minimize
corrosion of systems within which the solution is used.
Inventors: |
Verma, Shyam Kumar;
(Gastonia, NC) ; Sandor, George Robert; (Gastonia,
NC) |
Correspondence
Address: |
MYERS BIGEL SIBLEY & SAJOVEC
PO BOX 37428
RALEIGH
NC
27627
US
|
Family ID: |
26867545 |
Appl. No.: |
10/357689 |
Filed: |
February 4, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10357689 |
Feb 4, 2003 |
|
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09713281 |
Nov 15, 2000 |
|
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60171895 |
Dec 23, 1999 |
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Current U.S.
Class: |
507/200 |
Current CPC
Class: |
C23F 11/185 20130101;
Y10S 507/939 20130101; C23F 11/187 20130101; C09K 8/54
20130101 |
Class at
Publication: |
507/200 |
International
Class: |
E21B 001/00 |
Claims
That which is claimed is:
1. A solution having corrosion inhibiting properties useful in oil
and gas well drilling systems and similar applications, the
solution comprising: an aqueous solution comprising at least one
transition metal salt, at least one alkaline earth metal salt, or a
mixture thereof; and at least one heteropoly complex anion of a
transition metal element present in an amount sufficient to provide
a corrosion inhibiting effect.
2. The solution of claim 1, wherein said transition metal salt
comprises one or more zinc halides.
3. The solution of claim 1, wherein said alkaline earth metal salt
comprises one or more calcium halides.
4. The solution of claim 1, wherein said solution comprises at
least one zinc halide and at least one calcium halide.
5. The solution of claim 4, wherein said solution comprises zinc
bromide, optionally zinc chloride, calcium bromide, and optionally
calcium chloride.
6. The solution of claim 1, said solution further comprising at
least one additional corrosion inhibiting additive in an amount
sufficient to provide a corrosion inhibiting effect.
7. The solution of claim 1, wherein said at least one heteropoly
complex anion comprises a compound selected from the group
consisting of [X.sub.aM.sub.bO.sub.c].sup.-n,
[X.sub.aZ.sub.dM.sub.bO.sub.c].sup.-n,
[X.sub.aZ.sub.dM.sub.bO.sub.cHe].sup.-n,
[X.sub.aM.sub.bO.sub.c(OH).sub.f- ].sup.-n,
[X.sub.aZ.sub.dM.sub.bO.sub.c(OH).sub.f].sup.-n, and mixtures
thereof, wherein: X and Z are central heteroatoms selected from the
group consisting of elements from Groups I-VIII of the Periodic
Table of Elements; a is 1 or 2; d is an integer from 0 to 4;
M.sub.bO.sub.c, M.sub.bO.sub.cH.sub.e, and M.sub.bO.sub.c(OH).sub.f
are oxoanions in which M is a transition metal element; b is an
integer from 5 to 22; c is an integer from 20 to 70; e is an
integer from 0 to 6; and f is an integer from 0 to 3; and n is the
charge of the anion.
8. The solution of claim 7, wherein: X is phosphorus, silicon,
manganese, tellurium or arsenic; and M is molybdenum or
tungsten.
9. The solution of claim 1, wherein said at least one heteropoly
complex anion is selected from the group consisting of
phosphomolybdates, silicon molybdates, manganese molybdates,
silicon tungstates, tellurium molybdates, arsenic molybdates, and
mixtures thereof.
10. The solution of claim 1, wherein said at least one heteropoly
complex anion comprises a phosphomolybdate of the formula
[PMo.sub.12O.sub.40].su- p.-3.
11. The solution of claim 6, wherein said additional corrosion
inhibiting additive comprises at least one transition metal
compound which is different from said transition metal salt and
from said heteropoly complex anion of a transition metal
element.
12. The solution of claim 11, wherein said additional corrosion
inhibiting additive comprises a transition metal which is different
from the transition metal of the heteropoly complex anion.
13. The solution of claim 11, wherein said additional corrosion
inhibiting additive is selected from the group consisting of
nitrates, halides, and oxides of transition metal elements, and
mixtures thereof.
14. The solution of claim 13, wherein said transition metal is
selected from the group consisting of cobalt, nickel, tungsten,
zirconium, manganese, chromium, and mixtures thereof.
15. The solution of claim 6, wherein said additional corrosion
inhibiting additive comprises at least one compound of the metallic
elements of Groups IIIa to VIa of the Periodic Table of
Elements.
16. The solution of claim 15, wherein said additional corrosion
inhibiting additive is selected from the group consisting of
oxides, sulfides, halides, nitrates, and mixtures thereof of
metallic elements of Group IIIa to VIa.
17. The solution of claim 16, wherein said additional corrosion
inhibiting additive is a halide of a metallic element of Groups
IIIa to VIa.
18. The solution of claim 17, wherein said halide is selected from
the group consisting of antimony bromide, germanium bromide,
arsenic bromide, and bismuth bromide, and mixtures thereof.
19. The solution of claim 15, wherein said additional corrosion
inhibiting additive comprises antimony as the metallic element of
Groups IIIa to VIa.
20. The solution of claim 1, wherein said solution comprises said
transition metal salt, said alkaline earth metal salt or mixture
thereof in an amount from about 1 to about 80 weight percent, based
on the total weight of the solution.
21. The solution of claim 20, wherein said solution comprises said
transition metal salt, said alkaline earth metal salt or mixture
thereof in an amount from about 20 to about 60 weight percent,
based on the total weight of the solution.
22. A solution having corrosion inhibiting properties useful in oil
and gas well drilling systems and similar applications, the
solution comprising: at least one salt selected from the group
consisting of first transition metal salts, alkaline earth metal
salts, and mixtures thereof; at least one heteropoly complex anion
of a transition metal element; and at least one additional
corrosion inhibiting agent selected from the group consisting of
transition metal salts which are different from said first
transition metal salts, salts of the metallic elements of Groups
IIIa to VIa of the Periodic Table of Elements, and mixtures
thereof, said heteropoly complex anion and said additional additive
present in an amount sufficient to provide a corrosion inhibiting
effect.
23. The solution of claim 22, wherein said first transition metal
salt comprises one or more zinc halides.
24. The solution of claim 22, wherein said alkaline earth metal
salt comprises one or more calcium halides.
25. The solution of claim 22, wherein said solution comprises at
least one zinc halide and at least one calcium halide.
26. The solution of claim 25, wherein said solution comprises zinc
bromide, optionally zinc chloride, calcium bromide, and optionally
calcium chloride.
27. The solution of claim 22, wherein said heteropoly complex anion
comprises a phosphomolybdate, and said additional additive
comprises at least one transition metal salt.
28. The solution of claim 27, wherein said additional additive
comprises at least one halide of cobalt, nickel, tungsten,
zirconium, manganese, chromium, and mixtures thereof.
29. The solution of claim 22, wherein said heteropoly complex anion
comprises a phosphomolybdate and said additional additive comprises
at least one salt of a metallic element of Group IIIa to VIa.
30. The solution of claim 29, wherein said additional additive
comprises a halide of the metallic elements of Group Va of the
Periodic Table of Elements.
31. The solution of claim 30, wherein said additional additive
comprises a compound selected from the group consisting of antimony
bromide (SbBr.sub.3), arsenic bromide, bismuth bromide and mixtures
thereof.
32. The solution of claim 22, wherein said heteropoly complex anion
is [PMo.sub.12O.sub.40].sup.-3.
33. The solution of claim 22, wherein said first transition metal
salts, alkaline earth metal salts, and mixtures thereof are present
in an amount from about 20 to about 60 weight percent, based on the
total weight of the solution.
34. An aqueous completion fluid for oil and gas well drilling
systems having corrosion inhibiting properties, comprising at least
one zinc halide, at least one calcium halide, or a mixture thereof;
at least one phosphomolybdate; and at least one halide of the
metallic elements of Group Va of the Periodic Table of Elements,
said phosphomolybdate and said Group Va halide present in an amount
sufficient to provide a corrosion inhibiting effect.
35. The aqueous completion fluid of claim 34, wherein said
phosphomolybdate is [PMo.sub.12O.sub.40].sup.-3, and said Group Va
halide is antimony bromide (SbBr.sub.3).
36. The aqueous completion fluid of claim 35, wherein said solution
comprises zinc bromide, optionally zinc chloride, calcium bromide,
and optionally calcium chloride.
37. A solution having corrosion inhibiting properties useful in oil
and gas well drilling systems and similar applications, the
solution comprising: an aqueous solution comprising at least one
transition metal salt, at least one alkaline earth metal salt, or a
mixture thereof; and at least one corrosion inhibiting agent
comprising at least one compound of the metallic elements of Groups
IIIa to VIa of the Periodic Table of Elements.
38. The solution of claim 37, wherein said transition metal salt
comprises one or more zinc halides.
39. The solution of claim 37, wherein said alkaline earth metal
salt comprises one or more calcium halides.
40. The solution of claim 37, wherein said solution comprises at
least one zinc halide and at least one calcium halide.
41. The solution of claim 40, wherein said solution comprises zinc
bromide, optionally zinc chloride, calcium bromide, and optionally
calcium chloride.
42. The solution of claim 37, wherein said corrosion inhibiting
agent is selected from the group consisting of oxides, sulfides,
halides, nitrates, and mixtures thereof of metallic elements of
Group IIIa to VIa.
43. The solution of claim 42, wherein said corrosion inhibiting
agent is a halide of a metallic element of Groups IIIa to VIa.
44. The solution of claim 43, wherein said corrosion inhibiting
agent comprises antimony.
45. The solution of claim 37, wherein said corrosion inhibiting
agent comprises at least one compound selected from the group
consisting of antimony bromide, germanium bromide, arsenic bromide,
and bismuth bromide, and mixtures thereof.
46. A solution having corrosion inhibiting properties useful in oil
and gas well drilling systems and similar applications, the
solution comprising at least one zinc halide, at least one calcium
halide, or a mixture thereof; and at least one halide of the
metallic elements of Group Va of the Periodic Table of Elements in
an amount sufficient to provide a corrosion inhibiting effect.
47. The solution of claim 46, wherein said Group Va halide is
antimony bromide (SbBr.sub.3).
48. The solution of claim 47, wherein said solution comprises zinc
bromide, optionally zinc chloride, calcium bromide, and optionally
calcium chloride.
49. A process for inhibiting the corrosion of metal surfaces in oil
and gas well drilling systems and similar systems employing an
aqueous completion fluid, the process comprising contacting the
metal surfaces with at least one heteropoly complex anion of a
transition metal element in an amount sufficient to provide a
corrosion inhibiting effect.
50. The process of claim 49, further comprising contacting said
metal surfaces with at least one additional additive having
corrosion inhibiting properties in an amount sufficient to provide
a corrosion inhibiting effect.
51. The process of claim 50, wherein said additional additive
comprising a compound selected from the group consisting of
transition metal compounds, compounds of the metallic elements of
Groups IIIa to VIa of the Periodic Table of Elements, and mixtures
thereof.
52. The process of claim 49, wherein said at least one heteropoly
complex anion comprises a compound selected from the group
consisting of [X.sub.aM.sub.bO.sub.c].sup.-n,
[X.sub.aZ.sub.dM.sub.bO.sub.c].sup.-n,
[X.sub.aZ.sub.dM.sub.bO.sub.cH.sub.e].sup.-n,
[X.sub.aM.sub.bO.sub.c(OH).- sub.f].sup.-n,
[X.sub.aZ.sub.dM.sub.bO.sub.c(OH).sub.f].sup.-n, and mixtures
thereof, wherein: X and Z are central heteroatoms selected from the
group consisting of elements from Groups I-VIII of the Periodic
Table of Elements; a is 1 or 2; d is an integer from 0 to 4;
M.sub.bO.sub.c, M.sub.bO.sub.cH.sub.e, and M.sub.bO.sub.c(OH).sub.f
are oxoanions in which M is a transition metal element; b is an
integer from 5 to 22; c is an integer from 20 to 70; e is an
integer from 0 to 6; and f is an integer from 0 to 3; and n is the
charge of the anion.
53. The process of claim 52, wherein: X is phosphorus, silicon,
manganese, tellurium or arsenic; and M is molybdenum or
tungsten.
54. The process of claim 49, wherein said at least one heteropoly
complex anion is selected from the group consisting of
phosphomolybdates, silicon molybdates, manganese molybdates,
silicon tungstates, tellurium molybdates, arsenic molybdates, and
mixtures thereof.
55. The process of claim 49, wherein said at least one heteropoly
complex anion comprises a phosphomolybdate of the formula
[PMo.sub.12O.sub.40].su- p.-3.
56. The process of claim 50, wherein said additional corrosion
inhibiting additive is selected from the group consisting of
nitrates, halides, and oxides of transition metal elements, and
mixtures thereof.
57. The process of claim 56, wherein said transition metal is
selected from the group consisting of cobalt, nickel, tungsten,
zirconium, manganese, chromium, and mixtures thereof.
58. The process of claim 57, wherein said additional corrosion
inhibiting additive is a transition metal halide.
59. The process of claim 50, wherein said at least one additional
corrosion inhibiting additive comprises at least one compound of
the metallic elements of Groups IIIa to VIa of the Periodic Table
of Elements.
60. The process of claim 59, wherein said additional corrosion
inhibiting additive is selected from the group consisting of
oxides, sulfides, halides, nitrates, and mixtures thereof of
metallic elements of Group IIIa to VIa.
61. The process of claim 60, wherein said additional corrosion
inhibiting additive is a halide.
62. The process of claim 61, wherein said halide is selected from
the group consisting of antimony bromide, germanium bromide,
arsenic bromide, and bismuth bromide, and mixtures thereof.
63. The process of claim 62, wherein said halide is antimony
halide.
64. The process of claim 49, wherein said at least one heteropoly
complex anion forms a protective layer on a metal surface.
65. The process of claim 49, wherein said metal surfaces are
exposed to temperatures up to about 550.degree. F.
66. A process for inhibiting the corrosion of metal surfaces in oil
and gas well drilling systems and similar systems employing an
aqueous completion fluid, the process comprising contacting the
metal surfaces with at least one at least one compound of the
metallic elements of Groups IIIa to VIa of the Periodic Table of
Elements in an amount sufficient to provide a corrosion inhibiting
effect.
67. The process of claim 66, wherein said compound is selected from
the group consisting of oxides, sulfides, halides, nitrates, and
mixtures thereof of metallic elements of Group IIIa to VIa.
68. The process of claim 67, wherein said compound is a halide.
69. The process of claim 68, wherein said compound comprises
antimony.
70. The process of claim 66, wherein said compound of the metallic
elements of Groups IIIa to VIa of the Periodic Table of Elements
forms a protective layer on a metal surface.
71. The process of claim 66, wherein said metal surfaces are
exposed to temperatures up to about 550.degree. F.
72. A process for inhibiting the corrosion of metal surfaces in oil
and gas well drilling systems and similar systems employing an
aqueous completion fluid, the process comprising providing in a oil
or gas well drilling system a corrosion inhibiting solution
comprising at least one metallic salt and at least one heteropoly
complex anion of a transition metal element, said at least one
heteropoly complex anion of a transition metal element present in
an amount sufficient to provide a corrosion inhibiting effect.
73. The process of claim 72, wherein said solution further
comprises at least one additional corrosion inhibiting additive
comprising a compound selected from the group consisting of
transition metal compounds, compounds of the metallic elements of
Groups IIIa to VIa of the Periodic Table of Elements, and mixtures
thereof, said at least one additional additive present in an amount
sufficient to provide a corrosion inhibiting effect.
74. The process of claim 72, wherein said at least one heteropoly
complex anion forms a protective layer on a metal surface.
75. The process of claim 72, wherein said solution is exposed to
temperatures up to about 550.degree. F.
76. The process of claim 72, wherein said solution further
comprises lithium nitrate and zinc halide.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of, and
claims priority from, commonly owned and assigned U.S. patent
application Ser. No. 09/713,281, filed Nov. 15, 2000, which claims
priority to U.S. provisional application Serial No. 60/171,895,
filed Dec. 23, 1999, the disclosures of which are incorporated by
reference herein in their entireties.
FIELD OF THE INVENTION
[0002] This invention relates generally to corrosion inhibitors,
and in particular to corrosion inhibitors and processes of using
the same to protect metal surfaces in oil and gas drilling
systems.
BACKGROUND OF THE INVENTION
[0003] Servicing fluids, also known as completion or packer fluids,
are used in many oil and natural gas wells for a variety of
purposes. Completion fluids used in oil and gas well drilling and
similar applications in oilfields include drilling muds, brines,
water, oil, and the like. Completion fluids can include inorganic
salts, such as halides of zinc, calcium, sodium and other alkali
elements, in concentrations ranging from trace amounts up to
saturation.
[0004] Corrosion is recognized as a problem in the development of
geoenergy sources, including oil and natural gas reserves,
geothermal and geopressured systems. The corrosion problems are
aggravated by the presence of acid gases such as hydrogen sulfide
and carbon dioxide and by the co-production of brine solutions. For
example, carbon steel is widely used in the construction of oil and
gas wells in oilfields. While a useful material for such
applications, carbon steel corrodes due to the presence of
electrolytes and water in many servicing or completion fluids. In
recent years, corrosion problems have become more severe as
production from deeper, high pressure and high temperature wells
has become more attractive, as these deeper formations can have
increased levels of acid gas fluids.
[0005] Additives can provide corrosion protection for metals used
in oil and gas drilling systems, such as carbon steel. However,
conventional additives do not always provide the desired degree of
corrosion protection, particularly at higher temperatures.
[0006] For example, corrosion inhibitors used in oil and gas
drilling operations have typically included organic compounds
containing nitrogen, sulfur and/or phosphorous. These corrosion
inhibitors protect metal surfaces at least in part by forming a
protective film on the metal surface. Thus, an important
consideration for corrosion protection in oil and gas drilling
systems is how well the corrosion inhibitor is transported to the
corroding surface within the oil or gas well system. Dispersibility
of the inhibitor in completion fluids, such as brine solutions,
also plays an important role in its corrosion protection
performance. Many other factors, such as stability of the
protective film and inhibitor concentration in the completion
fluid, are also important to provide enhanced corrosion protection.
Many current inhibitors, however, have limited stability,
particularly at higher temperatures, or exhibit poor
characteristics in the solution and therefor offer limited
protection.
SUMMARY OF THE INVENTION
[0007] The present invention provides corrosion protection for
metal surfaces present in oil and gas well drilling systems. One
embodiment of the invention includes brine solutions useful in oil
and gas well drilling systems and similar applications, for
example, as completion fluids. In one aspect of this embodiment of
the invention, the solutions include at least one heteropoly
complex anion of transition metal elements as a corrosion
inhibitor.
[0008] The invention also includes solutions that include a mixture
of at least one heteropoly complex anion of transition metal
elements with at least one additional corrosion inhibiting additive
or agent. For example, the solution can include a mixture of at
least one heteropoly complex anion of a transition metal element
and at least one other transition metal compound as corrosion
inhibitors. As another example, the solution can include a mixture
of at least one heteropoly complex anion of a transition metal
element and at least one compound of the metallic elements of the
groups IIIa to VIa of the Periodic Table of Elements as corrosion
inhibitors. Preferred compounds of the metallic elements of Group
IIIa to VIa include halides of Group Va, and more preferably
antimony halides, such as antimony bromide.
[0009] In another aspect of this embodiment of the invention, the
solutions can include at least one compound of a metallic element
of Group IIIa to VIa, and preferably of Group Va, of the Periodic
Table of Elements. Exemplary compounds include without limitation
oxides, sulfides, halides, nitrates, and the like, preferably
halides, of metallic elements of Group IIIa to VIa. Preferably the
solutions include halides, and more preferably antimony bromide
(SbBr.sub.3), as a corrosion inhibition additive.
[0010] The brine solutions of the invention containing the above
noted corrosion inhibitors can provide improved corrosion
protection for metal surfaces found in oil and gas drilling
systems. The noted corrosion inhibiting additives can be stable in
the solution phase, providing desired additive concentrations,
stability and improved dispersibility. Still further, use of the
solutions in oil and gas wells and other similar applications can
result in a protective layer containing magnetite (iron oxide)
formed on carbon steel. The inventors have found that a protective
layer which forms as a result of using the solutions of the
invention can be more corrosion resistant than the oxide layer
formed in the presence of conventional corrosion inhibitors, such
as lithium molybdate, in which magnetite film tends to be more
amorphous and less developed. In addition the solutions of the
invention can minimize or eliminate pitting of metal contacted with
the brines. The solutions are particularly useful at high
temperatures, approaching 550.degree. F. and higher.
[0011] The present invention also provides processes for inhibiting
corrosion metal surfaces present in oil and gas drilling systems
and similar applications using the above noted corrosion
inhibitors.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0012] The present invention will be described more fully
hereinafter in connection with illustrative embodiments of the
invention which are given so that the present disclosure will be
thorough and complete and will fully convey the scope of the
invention to those skilled in the art. However, it is to be
understood that this invention may be embodied in many different
forms and should not be construed as being limited to the specific
embodiments described and illustrated herein. Although specific
terms are used in the following description, these terms are merely
for purposes of illustration and are not intended to define or
limit the scope of the invention.
[0013] The present invention may be used to reduce the corrosive
effects of brines upon metals, and is particularly useful for
brines having a high concentration of metal halides, such as zinc
halide, often used in oil and gas well drilling, production and
storage. Metals which typically come into contact with the brines
include iron, steel (including carbon steel) and other ferrous
metals.
[0014] The solutions of the invention include any solution useful
in oil and gas well drilling systems and in similar applications,
such as solutions used in drilling, producing and storing oil and
gas from subterranean earth formations. The solutions typically
contain metal salts, such as but not limited to, transition metal
salts, alkali metal salts, alkaline earth metal salts, and mixtures
thereof. Exemplary salts include halides of zinc, calcium, and
mixtures thereof. For example, the solution can include zinc
halide, such as zinc bromide or zinc chloride or both, optionally
in combination with calcium bromide or calcium chloride or both.
The brine solution can include the salts in conventional amounts,
generally ranging from about 1% to about 80%, and preferably from
about 20% to about 60%, based on the total weight of the solution,
although as the skilled artisan will appreciate, amounts outside of
this range can be used as well.
[0015] Particularly preferred for use in the present invention are
solutions that include one or more halides of zinc and one or more
halides of calcium, and more preferably zinc bromide, with or
without zinc chloride, and calcium bromide, with or without calcium
chloride. Such solutions can include about 5 to about 40 percent by
weight zinc bromide; about 30 to about 60 percent by weight calcium
bromide; about 0 to about 22 percent by weight zinc chloride and/or
calcium chloride; and remainder water. For reference to exemplary
solutions useful in oil and gas well drilling applications, and
particularly deep high temperature and high pressure wells, see
U.S. Pat. Nos. 4,980,074, 4,304,677 and 4,292,183, the entire
disclosure of each of which is hereby incorporated in its entirety
by reference.
[0016] Other solutions useful in the present invention for oil and
gas well drilling applications include aqueous alkali hydroxide
solutions, such as aqueous solutions of sodium hydroxide. Such
solutions typically include the alkali hydroxide in an amount
ranging from about 10 to about 80% by weight, and preferably from
about 30 to about 60% by weight, although amounts outside of this
range may also be useful.
[0017] The heteropoly complex anions of transition metal elements
can be generally described as coordination-type salts and free
acids with a complex and high molecular weight anion. The
heteropoly complex anions include as a ligand or complexing agent
at least one transition metal atom which, as an ion in solution,
exhibits corrosion inhibiting properties in oil and gas drilling
systems. The heteropoly complex anions useful in the solutions of
the invention also are preferably substantially completely soluble
in brine solutions, so as to maximize the concentration of the
corrosion inhibiting ions in solution. The heteropoly anions
contain complexed transition metal atoms (such as Mo). Therefore,
the dissolved heteropoly anions can provide a higher level of
transition metal anions (Mo anions) in a solution, as compared to
simple transition metal oxides, such as molybdates like lithium
molybdate.
[0018] Any of the heteropoly complex anions known in the art can be
used in the invention, including compounds described in U.S. patent
application Ser. No. 08/876,126, filed Jun. 23, 1997, now U.S. Pat.
No. 6,004,475, issued Dec. 21, 1999, the entire disclosure of which
is incorporated herein by reference. Such complexes can be
generally represented by the following formulas:
[X.sub.aM.sub.bO.sub.c].sup.-n,
[X.sub.aZ.sub.dM.sub.bO.sub.c].sup.-n,
[X.sub.aZ.sub.dM.sub.bO.sub.cH.sub.e].sup.-n,
[X.sub.aM.sub.bO.sub.c(OH).sub.f].sup.-n, and
[X.sub.aZ.sub.dM.sub.bO.sub.c(OH).sub.f].sup.-n,
[0019] wherein:
[0020] X and Z are central heteroatoms from Groups I-VIII of the
Periodic Table of Elements;
[0021] the value of a varies and is 1 or 2;
[0022] the value of d varies and is an integer from 0 to 4;
[0023] M.sub.bO.sub.c, M.sub.bO.sub.cH.sub.e, and
M.sub.bO.sub.c(OH).sub.f are oxoanions in which M is a transition
metal element; the value of b varies, depending upon the number of
transition metal atoms present in the oxoanion and can be an
integer from 5 to 22, preferably 6 to 12; the value of c varies,
depending upon the number of oxygen atoms present in the oxoanion
attached to the transition metal and also capable of forming unique
structural groups with the central atoms, and is an integer from 20
to 70, preferably from 24 to 40; the value of e varies (for example
in the reduced heteropolyanion, the value of e varies depending
upon the reduction of the heteropolyanion) and is an integer from 0
to 6; and the value of f varies and is an integer from 0 to 3;
and
[0024] n is the charge of the anion and is the sum of the charges
on X, Z, M, O, H, and OH.
[0025] Although the above formulas are general representations of
the heteropoly complex anions useful in the invention, as will be
appreciated by the skilled artisan, other compounds can also be
included. Also as these formulas represent, in some heteropoly
complex anions, H atoms in addition to the O atoms have been
reported. Any of the various heteropoly complex anions known in the
art can be used in the invention, including compounds described by
G. A. Tsigdinos, Topics Curr. Chem., vol. 76, 5-64 (1978) and D. L.
Kepert, Comprehensive Inorganic Chemistry (A. F. Trofman et al.)
Oxford:Pergamon Press, vol. 4, pp. 607 (1973), the entire
disclosure of each of which is incorporated herein by
reference.
[0026] With regard to the central or heteroatom X, over 40
different elements (both metals and nonmetals) from Periodic Groups
I-VIII can function as central atoms in distinct heteropoly complex
anions. For example, X can be an elements selected from Groups IVB,
VB, VIB, VIIB, VIII, IB, IIB, IIIA, IVA, and VA of the Periodic
Table of Elements. Exemplary central atoms include, but are not
limited to, ions of phosphorus, silicon, manganese, arsenic, boron,
iron, tellurium, copper, zinc, aluminum, tin, zirconium, titanium,
vanadium, antimony, bismuth, chromium, gallium, germanium, and the
like.
[0027] M is a 2-18 hexavalent transition metal element atom, which
surrounds one or more central atoms X. The transition metal atom M
is selected from those elements which as ions in solution provide
corrosion inhibiting effect in oil and gas drilling systems.
Preferably the transition metal element M in the oxoanion is
derived from molybdate or tungstate. Other transition metal
elements can also be present, as represented in the formula as Z,
such as but not limited to, an element selected from Groups IVB,
VB, VIB, VIIB, VIII, IB, IIB, IIIA, IVA, and VA of the Periodic
Table of Elements. Exemplary elements include without limitation
manganese, cobalt, nickel, copper, zinc, vanadium, niobium,
tantalum, gallium, germanium, arsenic, antimony, bismuth,
tellurium, and the like and other transition elements.
[0028] Exemplary heteropoly complex anions include, but are not
limited to, phosphomolybdates, such as but not limited to,
[PMo.sub.12O.sub.40].sup.-3, wherein P.sup.+5 is the central atom
or heteroatom, [PMo.sup.10V.sub.2O.sub.40].sup.-5 and the like;
silicon molybdates, such as but not limited to,
[SiMo.sub.11NiO.sub.40H.sub.2].su- p.-6, wherein Si.sup.+4 is the
central atom; manganese molybdates, such as but not limited to,
[MnMo.sub.9O.sub.321].sup.6, wherein Mn.sup.+4 is the central atom;
silicon tungstates, such as but not limited to,
[SiW.sub.12O.sub.40].sup.-4, wherein Si.sup.+4 is the central atom;
tellurium molybdates, such as but not limited to,
[TeMo.sub.6O.sub.24].su- p.-6, wherein Te.sup.+6 is the central
atom; arsenic molybdates, such as but not limited to,
[As.sub.2MO.sub.18O.sub.62].sup.-6, wherein As.sup.+5 is the
central atom; manganese niobiates, such as but not limited to,
[MnNb12O.sub.36].sup.-12, wherein Mn.sup.+4 is the central atom;
and the like, and mixtures thereof. Currently preferred heteropoly
complex anions are phosphomolybdates.
[0029] The heteropoly complex anions which have been structurally
characterized can be divided into the broad groups, depending upon
the heteroatom [X], transition metal atom [M] stoichiometry, and
upon the coordination number of the heteroatom (that is, the number
of points at which M is attached to the heteroatom in the complex).
The heteropoly complex anions can be classified according to the
ratio of the number of the central atoms to the peripheral
molybdenum or other such atoms. For example, the different types of
known heteropoly complex anions of molybdate show the following X:M
ratio with one or more central atoms: X:M=1:12, 1:11, 1:10, 1:9,
1:6, 2:10, 2:17, 2:5, 4:12, 1m:6m (m unknown) and 1:1 heteropoly
complex anions. The known tungstates include all of the above in
addition to 2:18, 2:17 and 2:4:18.
[0030] In a preferred embodiment of the invention, the transition
metal of the heteropoly complex anion is molybdenum or tungsten,
and more preferably molybdenum. A particularly preferred solution
includes the heteropoly complex anion
[PMo.sub.12O.sub.40].sup.-3.
[0031] The solutions of the invention can also include one or more
additional corrosion inhibiting additives or agents in combination
with the heteropoly complex anion. For example, the solution can
include another transition metal additive having corrosion
inhibiting properties. Generally the corrosion inhibiting
transition metal additive is a transition metal salt that is
different from the transition metal salts such as the zinc halides
described above. Useful transition metal additives having corrosion
inhibiting properties include compounds capable of providing the
transition metal element as ions in aqueous brine solutions for
complexing with the chosen heteropoly anion. The transition metal
element of the transition metal additive can be the same or
different from the transition metal of the heteropoly anion
complex. Exemplary transition metal additives include nitrates,
halides, oxides, and the like, preferably halides, of transition
metal elements such as cobalt, nickel, tungsten, zirconium,
manganese, chromium, and the like. The solutions of the invention
can also include mixtures of such corrosion inhibiting transition
metal additives. See U.S. Pat. No. 6,004,476, issued Dec. 21, 1999,
the entire disclosure of which is hereby incorporated by
reference.
[0032] Other additional corrosion inhibiting additives useful alone
or in combination with the heteropoly complex anion include
corrosion inhibiting compounds of the metallic elements of Groups
IIIa to VIa of the Periodic Table of Elements. Such compounds are
also selected from compounds capable of providing the metallic
elements of Group IIIa to VIa as ions in brine solutions. Exemplary
compounds of the metallic elements of Groups IIIa to VIa include
oxides, sulfides, halides, nitrates, and the like, preferably
halides, of metallic elements of Group IIIa to VIa, such as
antimony, germanium, and the like. See U.S. Pat. No. 6,004,476,
noted above.
[0033] U.S. Pat. No. 6,033,595, issued Mar. 7, 2000, the entire
disclosure of which is hereby incorporated by reference, describes
halides of metallic elements of Group Va of the Periodic Table of
Elements which can be particularly useful in the invention.
Exemplary halides of Group Va metallic elements (i.e., arsenic,
antimony, and bismuth) include antimony bromide, arsenic bromide,
and bismuth bromide, and the like and mixtures thereof. Other
halides can also be useful, such as chloride or. iodide, although
bromides are currently preferred.
[0034] The heteropoly complex anions, transition metal additives,
compounds of metallic elements of Groups IIIa to VIa, including
compounds of the Group Va metallic elements, are present in the
compositions of the invention in amounts sufficient to provide the
desired corrosion inhibiting effect. This amount can vary depending
upon various factors, such as the solubility of the compounds in
the brine solution, the nature of the ions, temperatures in the oil
well or other similar application, concentration of brine in
aqueous brine solution, metals used in the construction of the oil
well, the presence of air, and the like. Preferably, the aqueous
brine solutions of the invention include at least one heteropoly
complex anion in an amount ranging from about 50 parts per million
(ppm) to about 5000 ppm, more preferably about 50 ppm to about 500
ppm. Transition metal compounds or compounds of the metallic
elements of Group IIIa to VIa can be present in the solutions in
amounts ranging from about 10 parts per million (ppm) to about 200
ppm. However, compounds of the metallic elements of Group Va can be
present in an amount ranging from about 50 parts per million (ppm)
to about 5000 ppm. The corrosion inhibiting agents can also be
useful in amounts outside of these ranges, so long as the agent is
present in an amount sufficient to provide corrosion inhibition
properties.
[0035] Further, the solution can include other corrosion
inhibitors, such as but not limited to lithium nitrate, molybdate
and/or chromate in conventional amounts. Other agents
conventionally found in completion fluids can also be present such
as but not limited to bactericides, scale preventives, algaecides,
emulsifiers, demulsifiers, water and other solvents or diluents,
e.g., hydrocarbons, alcohols, and the like.
[0036] The present invention also provides processes for inhibiting
corrosion of metals, particularly in oil and gas well drilling,
production and storage systems, resulting from the presence of one
or more metallic salts, such as zinc halide. The solutions of the
invention find particular application for the protection of metal
equipment, pipes, tubing, and the like of oil and gas wells.
[0037] In the process of the invention, the above described
corrosion inhibiting additives singly or in combination are fed or
circulated in the oil or gas well to contact the walls of casings,
tubing, and other well components such as wellhead fittings,
connections, meters, storage tanks, flow lines handling the
corrosive fluid, and other metallic elements employed therein. The
additive(s) can be added to the oil or gas drilling system by
adding the corrosion inhibitors to brine solutions, which are then
employed in the oil and gas drilling system under conditions and in
amounts sufficient to provide a corrosion inhibiting effect. As the
skilled artisan will appreciate, the environment or conditions,
such as temperature and/or pressure, can vary. Typically, the
temperatures can be as high as 550.degree. F., and higher. The
additives, in brine solutions, are particularly advantageous for
high temperature applications.
[0038] Many modifications and other embodiments of the invention
will come to mind to one skilled in the art to which this invention
pertains having the benefit of the teachings presented in the
foregoing descriptions. Therefore, it is to be understood that the
invention is not to be limited to the specific embodiments
disclosed and that modifications and other embodiments are intended
to be included within the scope of the appended claims. Although
specific terms are employed herein, they are used in a generic and
descriptive sense only and not for purposes of limitation.
* * * * *