Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Maintaining environment nondestructive to metal
Reexamination Certificate
1998-06-19
2001-01-30
McKane, Elizabeth (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Maintaining environment nondestructive to metal
C252S390000, C252S393000, C252S394000
Reexamination Certificate
active
06180057
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to corrosion inhibiting compositions and methods for inhibiting the corrosion of metal surfaces by corrosive aqueous fluids.
2. Description of the Prior Art
Subterranean hydrocarbon containing formations penetrated by well bores are often treated with aqueous acids to stimulate the production of hydrocarbons therefrom. One such treatment generally referred to as “acidizing” involves the introduction of an aqueous acid solution into a subterranean formation under pressure so that the acid solution flows through the pore spaces of the formation. The acid reacts with acid soluble materials contained in the formation thereby increasing the size of the pore spaces and increasing the permeability of the formation. Another production stimulation treatment known as “fracture-acidizing” involves the formation of one or more fractures in the formation and the introduction of an aqueous acid solution into the fractures to etch the fracture faces whereby channels are formed therein when the fractures close. The acid also enlarges the pore spaces in the fracture faces and in the formation.
While acidizing and fracture-acidizing well stimulation treatments have been performed successfully for many years, a continuous problem which accompanies the treatments is the corrosion of metal surfaces in pumps, tubular goods and equipment used to introduce aqueous acid solutions into the subterranean formations to be treated. The expense associated with repairing or replacing corrosion damaged tubular goods and equipment can be very high. The corrosion of tubular goods and down-hole equipment is increased by the elevated temperatures encountered in deep formations, and the corrosion results in at least the partial neutralization of the acid before it reacts with acid-soluble materials in the formations.
Aqueous acid solutions are also utilized in a variety of other industrial applications to contact and react with acid soluble materials. In such applications, metal surfaces are necessarily also contacted with the acid and any corrosion of the metal surfaces is highly undesirable. In addition, other corrosive fluids such as aqueous alkaline solutions, heavy brines, petroleum streams containing acidic materials and the like are commonly transported through and corrode metal surfaces in tubular goods, pipelines and pumping equipment.
A variety of metal corrosion inhibiting compositions and formulations which can be added to aqueous corrosive fluids have been developed and used heretofore. While such compositions and formulations have achieved varying degrees of success in preventing corrosion of metal surfaces, there is a continuing need for improved metal corrosion inhibiting compositions which are effective when combined with aqueous corrosive fluids of the types described above and which provide greater and more reliable corrosion inhibition than has heretofore been possible.
SUMMARY OF THE INVENTION
The present invention provides corrosion inhibiting compositions which when added to a corrosive aqueous fluid inhibit the corrosion of metal surfaces contacted thereby, metal corrosion inhibited aqueous acid compositions and methods of using the compositions which meet the needs described above and overcome the deficiencies of the prior art.
The compositions and methods of the present invention are based on the discovery that certain aldehyde oligomers formed by the condensation reaction of benzaldehyde and acetaldehyde provide unexpected increased corrosion inhibition when added to corrosive aqueous fluids as compared to prior art corrosion inhibiting compositions including aldehydes. Surprisingly, the aldehyde oligomers of this invention can be utilized directly in corrosive aqueous fluids without the use of a dispersing surfactant or mutual solvent. However, in preferred corrosion inhibiting compositions of this invention, a dispersing surfactant or a mutual solvent or both are included in the compositions.
A composition for inhibiting the corrosion of metal surfaces when added to a corrosive aqueous fluid of this invention basically comprises one or more aldehyde oligomers and derivatives thereof having the general formula
wherein:
R
1
is phenyl or a phenyl group substituted with one or more of the groups methyl, hydroxyl, methoxy or other substituent which does not have an adverse effect,
R
2
and R
3
are individually hydrogen, a saturated or unsaturated aliphatic group having from 1 to about 12 carbon atoms, an aryl group or other substituent which does not have an adverse effect,
R
4
is hydrogen, —(NH—CH
2
—CH
2
—)
m
—NH—CH
2
CH
2
NH
2
where m is 0 or an integer in the range of from 1 to 5, a tris(2-aminoethyl)amine group or other substituent which does not have an adverse effect,
n is an integer in the range of from 2 to 7, and
X is oxygen, NH or other N-substituent which does not have an adverse effect.
As mentioned, the above described corrosion inhibiting composition can include a dispersing surfactant or a mutual solvent, or both, and in addition, one or more quaternary ammonium compounds, one or more corrosion inhibitor activators and other components commonly utilized in corrosion inhibiting formulations.
Metal corrosion inhibited aqueous acid compositions are also provided by this invention which are comprised of water, an acid selected from the group consisting of inorganic acids, organic acids and mixtures thereof and at least one aldehyde oligomer of the type described above.
In accordance with the methods of this invention, the corrosion of metal surfaces by a corrosive aqueous fluid is inhibited by combining a corrosion inhibiting composition including one or more of the above described aldehyde oligomers therewith.
It is, therefore, a general object of the present invention to provide improved corrosion inhibiting compositions and methods.
Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows.
DESCRIPTION OF PREFERRED EMBODIMENTS
The present invention provides improved corrosion inhibiting compositions which when combined with a corrosive aqueous fluid inhibit the corrosion of metal surfaces contacted thereby, improved corrosion inhibited aqueous acid compositions and improved methods of inhibiting the corrosion of metal surfaces by a corrosive aqueous fluid using the compositions.
The corrosion inhibiting compositions of the present invention are basically comprised of one or more aldehyde oligomers formed by the condensation reaction between benzaldehyde and acetaldehyde. It has been discovered that such oligomers provide surprisingly improved protection to metal surfaces from corrosion by corrosive aqueous fluids when one or more of the oligomers are combined with the corrosive aqueous fluids.
The aldehyde oligomers formed by the above described reaction which provide improved corrosion protection to metal surfaces in accordance with the present invention have the general formula
R
1
is phenyl or a phenyl group substituted with one or more of the groups methyl, hydroxyl, methoxy or other substituent which does not have an adverse effect,
R
2
and R
3
are individually hydrogen, a saturated or unsaturated aliphatic group having from 1 to about 12 carbon atoms, an aryl group or other substituent which does not have an adverse effect,
R
4
is hydrogen, —(NH—CH
2
—CH
2
—)
m
—NH—CH
2
CH
2
NH
2
where m is 0 or an integer in the range of from 1 to 5, a tris(2-aminoethyl)amine group or other substituent which does not have an adverse effect,
n is an integer in the range of from 2 to 7, and
X is oxygen, NH or other N- substituent which does not have an adverse effect.
The substituents which do not have an adverse effect referred to above are those substituents which do not adversely interfere with the corrosion protection provided by the aldehyde oligomers and/or add to the corrosion protection provided. Examples of such substituents are halides, hydro
Cassidy Juanita M.
Funkhouser Gary P.
Taylor Grahame N.
Williams Dennis A.
Dougherty, Jr. C. Clark
Kent Robert A.
McKane Elizabeth
Nalco/Exxon Energy Chemicals L.P.
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