Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Maintaining environment nondestructive to metal
Reexamination Certificate
1999-10-12
2002-08-13
McKane, Elizabeth (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Maintaining environment nondestructive to metal
C585S950000, C252S394000, C252S396000
Reexamination Certificate
active
06432355
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to corrosion inhibition, and, more particularly, to a process of corrosion inhibition of a steel pipeline during transport of water and gas, or water and oil, or mixtures thereof, therethrough.
2. Description of the Prior Art
U.S. Pat. No. 4,174,370 described the use of certain pyridine compounds for inhibiting the corrosion of metals, particularly the prevention of corrosion of pipe which is on contact with a corrosive oil-containing medium, as, for example, in oil wells producing corrosive oil or oil-brine mixtures.
U.S. Pat. No. 5,723,524 describes compositions for retarding the formation of gas hydrates in a gas/water system.
Accordingly, it is an object of this invention to provide a new and improved corrosion inhibitor, particularly for use in pipelines carrying a gas and liquid, such as natural gas and water.
Another object herein is to provide a corrosion inhibitor composition having dual functionalities as both a corrosion inhibitor and as a gas hydrate inhibitor in natural gas-containing wells.
These and other objects and features of the invention will be made apparent from the following.
SUMMARY OF THE INVENTION
What is described herein is a single phase composition for effectively inhibiting the corrosion of pipeline conduits, and for preventing or retarding the formation or agglomeration of gas hydrates, during the transport of a fluid comprising water and a hydrocarbon, through the conduit. The composition comprises a copolymer of (a) vinyl caprolactam and (b) vinyl pyridine; optionally, a terpolymer with vinyl pyrrolidone, preferably wherein the vinyl pyridine is the 2- or 4-vinyl pyridine, optionally quaternized, e.g. with a C
1
-C
18
alkyl halide, e.g. the iodide, bromide, chloride or fluoride; having a cloud point of >10° C., preferably >15° C.
Most preferably, the composition is made in a polymerization solvent which is a glycol ether, containing an alkoxy group having at least 3 carbon atoms, and most preferably, which is 2-butoxyethanol (BGE); and includes also a carrier solvent different from the polymerization solvent, preferably, monoethylene glycol (MEG).
In a preferred embodiment of the invention, the vinyl caprolactam monomer comprises about 70-97% of the polymer, and has a molecular weight of about 500 to 2500.
DETAILED DESCRIPTION OF THE INVENTION
Corrosion Inhibition
This function of this invention relates to the use of the copolymer in inhibiting the corrosion of metals, most particularly iron, steel and ferrous alloys. These copolymer compounds can be used in a wide variety of applications and systems where iron, steel and ferrous alloys are affected by corrosion. They may be employed for inhibiting corrosion in processes which require a protective or passivating coating as by dissolution in the medium which comes in contact with the metal. They can be used in preventing atmospheric corrosion, underwater corrosion, corrosion in steam and hot water systems, corrosion in chemical industries, underground corrosion, etc.
The corrosion inhibitors contemplated herein find special utility in the prevention of corrosion of pipe or equipment which is on contact with a corrosive oil-containing medium, as, for example, in oil wells producing corosive oil or oil-brine mixtures, in refineries, and the like. These inhibitors may, however, be used in other systems or applications. They appear to possess properties which impart to metals resistance to attack by a variety of corrosive agents, such as brines, weak inorganic acids, organic acids, CO
2
, H
2
S, air or oxygen, etc.
The present process finds particular utility in the protection of metal equipment of oil and gas wells, especially those containing or producing an acidic constituent such as H
2
S, CO
2
, air or oxygen, organic acids and the like. For the protection of such wells, the reagent, either undiluted or dissolved in a suitable solvent, is fed down the annulus of the well between the casing and producing tubing where it becomes commingled with the fluid in the well and is pumped or flowed from the well with these fluids, thus contacting the inner wall of the casing, the outer and inner wall of tubing, and the inner surface of all wellhead fittings, connections and flow lines handling the corrosive fluid.
Where the inhibitor composition is a liquid, it is conventionally fed into the well annalus by means of a motor driven chemical injector pump, or it may be dumped periodically (e.g., once every day or two) into the annulus by means of a so-called “boll weevil” device or similar arrangement. Where the inhibitor is a solid, it may be dropped into the well as a solid lump or stock, it may be blown in as a powder with gas, or it may be washed in with a small stream of the well fluids or other liquid. Where there is gas pressure on the casing, it is necessary of course, to employ any of these treating methods through a pressure equalizing chamber equipped to allow introduction of reagent into the chamber, equalization of pressure between chamber and casing, and travel of reagent from chamber to well casing.
For injection into the well annulus, the corrosion inhibitor is usually employed as a solution in a suitable solvent. The selection of solvent will depend much upon the specific reagent being used and its solubility characteristics.
For example, for the protection of gas wells and gas-condensate wells, the amount of corrosion inhibitor used might range between about ¼ to 3 lbs per million cubic feet of gas produced, depending upon the amounts and composition of corrosive agents in the gas and the amount of liquid hydrocarbon and water produced. However, on no case does the amount of inhibitor required appear to be stoichiometrically related to the amount of acids produced by a well, since protection is obtained with much less corrosion inhibitor than usually would be required for neutralization of the acids produced.
These reagents can also be used in the prevention of corrosion in the secondary recovery of petroleum by water flooding and in the disposal of waste water and brine from oil and gas wells. Still more particularly, they can be used in a process of preventing corrosion in water flooding and in the disposal of waste water and brine from oil and gas wells which is characterized by injecting into an underground formation an aqueous solution containing minor amounts of the compositions of this invention, in sufficient amounts to prevent the corrosion of metals employed in such operation.
When an oil well ceases to flow by the natural pressure in the formation and/or substantial quantities of oil can no longer be obtained by the usual pumping methods, various processes are sometimes used for the treatment of the oil-bearing formation in order to increase the flow of oil. These processea re usually described as secondary recovery processes. One such process which is used quite frequently is the water flooding process wherein wter is pumped under pressure into what is called an “injection well” nd oil, along with quantities of water, that have been displaced from the formation, are pumped out of an adjacent well usually referred to as a “producing well”. The oil which is pumped from the producing well is then separated from the water that has been pumped from the producing well and the water is pumped to a storage reservoir from which it can again be pumped into the injection well. Supplementary water from other sources may also be used in conjunction with the produced water. When the storage reservoir is open to the atmosphere and the oil is subject to aeration this type of water flooding system is referred to herein as an “open water flooding system”. If the water is recirculated in a closed system without substantial aeration, the secondary recovery method is referred to herein as a “closed water flooding system”.
Because of the corrosive nature of oil field brines, to economically produce oil by water flooding, it is necessary to prevent or reduce corrosion since corrosion increases the cost thereof
Bakeev Kirill N.
Chuang Jui-Chang
Drzewinski Michael A.
Graham David E.
Winkler Thomas
Davis William J.
ISP Investments Inc.
Katz Walter
Maue Marilyn J.
McKane Elizabeth
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