Corrosion inhibitor

Details Corrosion inhibitor Corrosion inhibitor

2002-06-21

2003-01-28

Anthony, Joseph D. (Department: 1714)

Compositions

Preservative agents

Anti-corrosion

C252S388000, C507S266000, C510S258000, C510S267000, C134S003000, C134S022140, C134S022190, C422S012000, C106S014130

Reexamination Certificate

active

06511613

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to methods and compositions for inhibiting corrosion of metals, and, in one aspect, more particularly relates to methods and compositions for inhibiting corrosion of metals in acid environments where the acid contains halogen, such as hydrochloric acid, hydrofluoric acid, and the like.
BACKGROUND OF THE INVENTION
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 number of factors, such as the steel alloy itself, the strength and type of acid, the temperature of the environment, the length of contact, etc., some sort of corrosion invariably occurs. Alloy technology has provided materials to withstand the incidental contact of steel with add, 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 acid is not required to remain pure and where the contact is inevitable, attention has turned toward providing 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 presently known systems. For example, a corrosion inhibitor providing a large corrosion inhibiting effect for a small proportion used would be advantageous.
A specific environment in which an improved corrosion inhibitor would 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 stimulated to enhance the economical production lifetime of the well. A common way of doing this is by acid fracturing or matrix acidizing, whereby 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. Spent acid in return fluids may have a pH of around 3-6.9, and organic acids used in acidizing include formic acid and acetic acid, each of which have a pH below 6.9. Because of the acidic nature of the treatment fluid, the production or workover conduit 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 comprised carbon steels; they were utilized either temporarily or permanently in the well, and treatment and/or stimulation fluids were introduced through them into the well. Recently, due primarily to the drilling and completion of many subterranean wells through formations which contain high concentrations of corrosive fluids 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 high alloy steels. The high alloy steels include chrome steels, duplex steels, stainless steels, martensitic alloy steels, ferritic alloy steels, austenitic stainless steels, precipitation-hardened stainless steels, high nickel content steels, and the like.
Corrosion inhibitors containing iodine and other halogens are known. For example, U.S. Pat. No. 2,989,568 relates to the preparation of halogenated acetylenic alcohols containing chlorine or bromine. Such compounds are described as useful as corrosion stabilizers for chlorinated solvents such as trichloroethylene and as inhibitors in plating baths.
The effects of inorganic anions, organic compounds, and combinations of the two on corrosion of mild steel in various acids were determined by N. Hackerman, et al. as described in “Effects of Anions on Corrosion Inhibition by Organic Compounds,”
Journal of the Electrochemical Society,
Vol. 113, No. 7, July 1966, pp. 677-81. From corrosion rates of steel in adds, the order of the degree of adsorption of anions was concluded to be: I
−
>Br
−
>Cl
−
>SO
4
=>ClO
4
−
.
U.S. Pat. No. 3,686,129 mentions that hydrogen embrittlement which normally occurs when high strength metal parts are immersed in acid-cleaning solution, is minimized or eliminated by adding certain combinations of (1) mono-alkynols and (2) iodine compounds which are either iodo-alkenols or suppliers of iodide ion.
Inhibited treating acids for use in contact with ferrous surfaces at temperatures of from about 150° F. to about 450° F. are described in U.S. Pat. No. 3,773,465. Cuprous iodide is present in a concentration of from about 25 ppm to about 25,000 ppm by weight of the treating acid.
U.S. Pat. No. 3,816,322 describes that iron surfaces are protected against corrosion by aqueous acidic solutions containing a polyhydric compound or derivative thereof by dispersing into the corrosive solution which will contact the metal surface an effective amount of a heterocyclic amine, an acetylenic alcohol, and an ionizable iodine containing compound.
There remains a need for new, stable corrosion inhibitors and methods therefor which would work in halogen acid environments for a wide variety of steels. For example, iodine alone formulated with conventional corrosion inhibitor ingredients can enhance halogen acid corrosion control primarily of chrome steels, but also carbon steels. However, with time, iodine corrosion inhibitors tend to become less effective. In one non-limiting theory, it is believed that the iodine slowly reacts with organic materials, or at least the organic materials are the cause for formulation degradation.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide compositions of matter effective in the inhibition of corrosion in halogen acid environments.
It is another object of the present invention to provide compositions for minimizing corrosion in halogen acid situations, which compositions may be easily made.
It is yet another object of the invention to provide methods and compositions for suppressing the corrosion of steels in halogen acid environments which can be readily implemented using conventional equipment.
Still another object of the invention is to provide an iodine-containing halogen acid corrosion inhibitor which is stable over time.
In carrying out these and other objects of the invention, there is provided, in one form, a method for inhibiting the corrosion of metals in contact with an acidic liquid medium which involves providing a liquid medium containing an acid, and then adding to the liquid medium an effective amount of a corrosion inhibitor comprising a reaction product of iodine and propargyl alcohol. Other ingredients may be added, of course.
DETAILED DESCRIPTION OF THE INVENTION
It has been discovered that the reaction product of iodine in an excess of pargyl alcohol gives compound (I):
That is, 2,3di-iodo-2-propen-1-ol in propargyl alcohol. The resulting product is propargyl alcohol white and it is acid soluble. As will be shown, it is a useful ingredient used to prepare a halogen acid corrosion inhibitors, and mixed halogen acid/organic acid corrosion inhibitors, such as combinations of acetic acid and HF, and/or formic acid/HF. The halogen acid environments where the invention is useful encompass acid environments where the acid includes, but is not limited to, hydrochloric acid, hydrofluoric acid, formic acid, acetic acid, and mixtures thereof. Intermediate compound (I) has been found to have excellent stability, thus avoiding degradation over time. Compound (I) is an intermediate which is used in an inhibitor composition.
In one preferred embodiment of the invention the intermediate corrosion inhibitor (I) is made by reacting from about 6 parts by weight of propargyl alcohol to about 1 part by weight of iodine. In a broad range, the weight ratio range of propargyl alcohol to iodine is from about 1.1:1 to about 12:1. In a preferred embodiment of t

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