US2614981A - Process for inhibiting corrosion in oil wells - Google Patents

Description

Patented Oct. 21, 1952 UNITED I rue-s1 PROCESS FOR INHIBITING CORROSION IN. I OIL WELLS Delaware ,No Drawing. Application April 3, 1950, Serial No. 153,768

The present invention is directed to a method for inhibiting the corrosiveness to. corrodible metal surfaces of corrosive subsurface fluids containing carbon dioxide. vMore particularly, .the invention relates to a method for inhibiting the corrosivity of petroliferous well fluids containing carbon dioxide to corrodible ferrous metal conduits and attendant equipment through which the fluids are flowed and processed.

In many oil fields and gas-condensate flelds,

12 Claims. (Cl. 252-855) the production of fluids from subsurface formations is accompanied by extremely severe corrosion of the conduits and attendant equipment which is contacted by the fluid mixture being produced. In many cases it is found that the fluid mixture is acidic in nature and contains substantial amounts of carbon dioxide, a portion of which dissolves in water present in the fluids to form carbonic acid. These fluids, including the carbon dioxide, originate in the subsurface formations. In some cases the corrosion occurs throughout the conduits and attendant equipment through which the fluids are flowed and processed while in other cases the corrosion is limited primarily to rather restricted areas of the conduit and is often particularly severe in that portion of the conduit adjacent the well head. If corrosion, whether intensive or extensive, is permitted to continue unabated, the conduit and attendant equipment will become sufliciently damaged to require replacement. Not only is the actual cost of such replacement high, but other factors may be involved which further increase costs. For example, it may be necessary to kill a high pressure Well in order to make the necessary replacements. placements and repairs are being made, there is a loss in revenues due to having the well off production. Even of more importance than the high costs incurred as a result of corrosion, is the danger that a well will flow wild as a'result of the failure of the conduit or equipment due to corrosion. Such a result may be catastrophic.

It is therefore the main object of the present invention to provide a method whereby corrosion Furthermore, while re- 2 range of 300 to 550 F.preferab1y in the presence of an alkaline reacting catalyst.

Fatty acids which may suitably be used as the fatty material in the aforementioned reaction include those fatty acids having at least 12 and no more than 26'carbon atoms per molecule. As examples of such acids, mention may be made of oleic, ricinoleic, linoleic, linolenic, licanic, eleostearic, arachidonic, clupanodonic, lauric, myristic, arachidic, stearic palmitic, etc. The fatty oils which may be employed are those from which fatty acids having from 12 to 26 carbon atoms in the molecule can be derived. Fatty. oils which have been found to produce especially effective agents include tung oil, China-wood oil, oiticica oil, chaulmoogra oil, cottonseed oil, menhaden oil, linseed oil, castor oil, and the like. It will be understood, of course, that mixtures of individual members of the aforementioned class of oilsor mixtures of the individual members of the afore-' mentioned class of acids or mixtures including both oils and acids may be employed as the fatty material from which the corrosion inhibiting agent of thepresent invention is produced.

Various alkyl and/ or 'alkanol amines may suitably be employed'in the aforementioned reaction to produce the corrosion inhibiting reaction .product of the present invention. Examples of of corrodible ferrous metal surfaces by corrosive well fluids containing carbon dioxide is subalkanol amines which may be employed include triethanol amine, di-n-propanol amine, di-isoboth alkanol and alkyl groups. Examples of such alkyl-alkanol amines include di-ethyl,ethanol amine; ethyl,di-ethanol amine; ethyl,di-npropanol amine; di-ethyl,n-propanol amine;

ethyl,di-isopropanol amine; di-ethyLisopropanol amine; n-propyl,di-ethanol amine; isopropyLdiethanol amine; di-n-propyl,ethanol amine; di-

. isopropyl,ethanol amine; ethyl,di-butanol amine;

alkyl or alkanol amine at a temperature in the etc. While the amines employed'preferably contain a total of betweenfi and 18 carbon atoms in the alkyl and/or alkanol side chains, they may contain an even largernumberof carbon atoms in the side chains.

1 course, that mixtures of the. aforementioned It will be understood, of

cQF-FKCE amines may suitably be employed. Polymers of these amines,-- such as the polymers of tri-ethanol amine, may also suitably be employed.

When the fatty derivatives of the present invention are prepared'from a fatty oil, it is pref-,- erable that the fatty oil be present in the initial reaction mixture in a weight ratio of from about 1:1 to about 5:1 as compared to the alkyl or alkanol amine. When the fatty derivative is prepared from a fatty acid, the fatty acid is preferably present in the initial reaction mixture in a weight ratio of from about 0.5:1 to about 3:1 as compared to the amine.

The effectiveness as a corrosion inhibiting agent of the reaction product of fatty oils and/ or fatty acids with alkyl amines and/or alkanol amines depends upon the temperature at which the reaction is conducted. .If the reaction is conducted at a temperature below about 300 R, the resulting reaction product possesses little, if any, effectiveness as a' corrosioninhibiting agent for gaseoondensate -Iwell fluids containing. carbon dioxide. .On the other handyif the reaction is conducted at a temperature in excess of about 550 the reaction product obtained tends to be of very high solidification point and .of low solubility in the corrosive media. The reaction temperature selected will depend to some extent upon the particular fatty oil or acid employed and upon the particular amine employed. For example, when the corrosion inhibiting agent is prepared from triethanol amine and either tung oil, oiticica .oil, chaulmoogra oil, or, cottonseed oil in the presence of sodium hydroxide, a reaction temperature maintained for 2m 4.- hours in the range of 400 to 475 F. results in a product of especially desirable inhibition properties.

The extent of reaction, in addition to depending upon reaction temperature, also depends upon the time during which the reactiOn is permitted to continue. Ordinarily, effective agent may be prepared when the reactants are maintained at a temperature in the aforementioned range for a period of time in the range of from /2 t hours, a though the pre er ed time is in the ran e of 1 /2 to 4 hours.

As h ei bef men i ned an a ka n each ing catalyst, such as alkali metal hydroxides or carbonates, or mixtures thereof, is preferably employed. The fatty acids and amines will react to form the desired product withoutthe aid of a catalyst; the fatty oils, however, require the use of a catalyst to accelerate the reaction betweenthe oil and the amine. Examples of alkaline reacting catalysts are sodium hydroxide and sodium carbonate. The alkaline reacting catalyst concentrations ordinarily need not exceed about 3% by weight of the reactants although considerably lower concentrations may be successfully employed. For example, a concentration of 0.5% by weight of sodium hydroxide or sodium carbonate based upon the weight of the reactants has been found sufiicient to promote the. reaction. As a matter of fact, as little as about 0.05% of sodium hydroxide based upon the weight of the reactants has been found suflicient- The amount of fatty derivatives of the present invention employed toinhibit-the corrosion of ferrous metal surfaces by well fluid mixtures including moisture and carbon dioxide may be varied over a relatively wide range. However, it has been found that amounts within the range of 0.005% to 0.1% by volume of the fluid mixture give satisfactory results. Ordinarily, an amount within the range of 0.005% to 0.01% by volume will be sufficient.

When it is desired to protect from corrosion th conduit in the borehole as well as the attendant equipment, the fatty derivative or a solu-- tion thereof may be injected into the borehole 7 adjacent the subsurface formation from which the corrosive fluid, including carbon dioxide, is produced. Alternatively, the fatty derivative may be introduced directly into the conduit. A still further method of introducing the fatty de-' rivative into the fluids produced from the .subsunface formation involves introducing the fatty de-i rivative or a solution thereof into the annula space betweenthe casing and the tubing. Another method of introducing the fatty derivative. into the subsurface fluid consists of injecting the fatty derivative ora solution thereof into the subsurface reservoir through an adjacent well.

' Irrespective of the particularprocedure employed in introducing the fatty derivatives into the fluids in the well, the fatty derivative suppresses the] corrosivity of the fluids, thereby eliminating or reducing dama eto the conduit through which the fluids are produced and to attendant equip, ment through which the fluids are flowed.

The followingexamples will illustrate the elf-- fectiveness of the corrosion inhibitors hereinbefore described in inhibiting the corrosivityof a corrosive condensate Well fluid containing car-.

bon dioxide to corrodible ferrous metal surfaces.

EXAMPLE I product thus formed, 0.001 volume per cent was added to a beaker containing 200 cc. of corrosive Water from the gas-condensate field at Katy, Texas. This beaker, together with another beaker containing 200 cc. of water from the gascondensate field at Katy, Texas, placed in a desiccator: A mild carbon steel coupon was sub-' merged in the water in each of the beakers. The desiccator was then evacuated and carbon di oxide was added to the desiccator to a pressure of 1 m he Ea of the, coupons was reov f m th de ccato f r .2 da s, exposure under the aforementioned conditions and the extent of the corrosion of eachcoupon was a determined by measuring the loss inweight of the coupons. The results'of the tests are shown a in the following table:

Table I -Qonc. of Corrosion I Percent Inhibitor Inhibitor Rat'e'of grease i Vol. Per Coupons tion Over cent InJXr. Blank None Reaction Produ' or" 'Iri 9 0077 ethanolamine, Tun Oil, and e el i 1 .0. 0009 89,- J g m rm EXAMPLE II 35 grams of tung oil, 30 grams of triamylamine, and 2 grams of sodium hydroxide were heated together at a temperature of 392 to 432 F. for a period of 2 hours. The resulting reaction prodnot, when cooled, solidified at a temperature of 244 F. The eflectiveness of this reaction product I as an inhibitor was tested in the laboratory by using a concentration of 0.01 weight per cent in a 50:50 mixture of brine and condensate saturatedwith carbon dioxide. The brine and condensate were obtained from the gas-condensate field located at Katy, Texas. 100cc. of the aforementioned oil-brine mixture containing the inhibitor were placed in a sealed glass tube and a mild carbon steel coupon was suspendedjin' the tube. The coupon was immersed in the brineoil mixture 31 times per minute for a period of 14 days. The extent of the corrosion inhibition obtained was compared with results obtained when similar coupons were exposed under identical conditions to a carbon dioxide saturated 50:50 mixture of brine and condensate obtained from the Katy field, this last mentioned mixture containing no inhibitor. The results obtained are shown in Table II below:

The foregoing examples demonstrate the effectiveness of the inhibiting agent of the present invention in substantially eliminating the corrosivity of condensate well fluids containing carbon dioxide to corrodible ferrous metal surfaces.

Having fully described the present invention, what I desire to claim as new and useful and to secure by Letters Patent is:

1. A method for reducing the corrosiveness to corrodible ferrous metal of a corrosive petroliferous well fluid including moisture and carbon dioxide which comprises introducing into said fluid a corrosion inhibiting amount of the reaction product of a fatty material selected from the group consisting of fatty acids having no less than 12 and no more than 26 carbon atoms per molecule and a fatty, oil containing fatty acid radicals having noless than 12 and no more than 26 carbon atoms with an amine selected from the group consisting of alkyl and alkanol amines having a total of no less than 6 carbon atoms in the molecule, the reaction product being formed at a temperature in the range of 300 to 550 F. and in the presence of an alkaline reacting catalyst selected from the group consisting of alkali metal hydroxide and alkali metal carbonate, the weight ratio of fatty material to amine being in the range of 0.5:1 to about 5.0:1.

2. A method for reducing the corrosiveness to corrodible ferrous metal of a corrosive petroliferous well fluid including moisture and carbon dioxide which comprises introducing into said fluid a corrosion inhibiting amount of the reaction product of a fatty material selected from the group of fatty acids having no less than 12 and no more than 26 carbon atoms per molecule and a fatty oil containing fatty acid radicals having no less than-1'2 andno morethani26 car bon atoms with an amine selected from the group consisting of alkyl and alkanol amines having: a total of no less than fi and no more than-18 carbon atoms per molecule, the reaction product being formed byheating the-reactants for a period of from to 5 hours at a temperaturein the range of 300 to 550 F. in the presence of an alkaline reacting catalyst selected'from the group consisting of alkali metal hydroxide and alkali metal carbonate, the weight ratio of fatty material to amine being in the range of 0.5:1 to about 5.0:1.

3. A method in accordance with claimi ldn which the reaction product is added to the corrosive fluid in an amount in the range of 0.005%

v to 0.1 by volume of the fluid.

4. A method in accordance with claim 2 in which the reaction product is added to the corrosive fluid in an amount in the range of.0.005% to 0.1% by volume of the fluid.

5. A method for reducing the corrosiveness to corrodible ferrous metal of a corrosive petroliferous well fluid including moisture and carbon dioxide which comprises introducing into said fluid a corrosion inhibiting amount of the reaction product formed by heating a mixture of tung oil and triethanol amine at a temperature in the range of 300 to 550 F. for a period of from /g to 5 hours in the presence of an alkaline reacting catalyst selected from the group consisting of alkali metal hydroxide and alkali metal carbonate, the weight ratio of 'tung oil to tri-ethanol amine being in the range of l :1 to about 5:1.

6. A method in accordance with claim 5 in which said reaction product is added to the corrosive fluid in an amount in the range of 0.005% to 0.1 by volume of the fluid.

7. A method for reducing the corrosiveness to corrodible ferrous metal of a corrosive petroliferous well fluid including moisture and carbon dioxide which comprises introducing into said fluid a corrosion inhibiting amount of the reaction product formed by heating a mixture of /2 to5 hours in the'presence of an alkaline reacting catalyst selected from the group consist ing of alkali metal hydroxide and alkali metal carbonate, the weight ratio of tung oil to triamyl amine being in the range of 1:1 to about 5 1. g 8. A method in accordance with claim 7 in which the reaction product is added to the corrosive fluid in an amount in the range of 0.005% to 0.1% by volume of the fluid. v

9. A method for reducing the corrosiveness to corrodible ferrous metal of a corrosive petroliferous well fluid including moisture and carbon dioxide which comprises introducing into said fluid a corrosion inhibiting amount of the reaction product formed by heating a mixture of cottonseed oil and triethanol amine at a temperature in the range of 300 to 550 F. for a period from to 5 hours in the presence of an alkaline reacting catalyst selected from the group consistwhich the reaction product is added to the corrosive fluid in an amount in the range of 0.005% to 0.1% by volume of the fluid.

11. A method for reducing the corrosiveness to corrodible ferrous metal of a corrosive petrolifer- 7 OusrWelLfluid .includingmoistuwand lcarbpn die. oxide which comprises i introducing. into, ,said fiuid' a. corrosion inhibiting amount of the reaction product formed by 1heating a ,.mixture of menhaden oil and triethanol amine at a temperaturein the range of 300 to'550 F. for, a period of from to 5 hours in the presence of an alkaline reacting catalyst selectedfrom the group; consisting vof alkali metal hydroxide and alkali metal carbonate, the weight ratio of menhaclen oilto tri-ethanol amine being in the range ofizl toabout'a:1'.-;

12. A method in accordance with claim 11 in which the reaction product is added to the corrosive fluid inan amount in the range of10.005% tea-01% by volume of the fluid. v.

' MELBA L. LYTLE.

REFERENCES CITED 1 The following references are of record in the file of this patent:

mercial Solvents Corp.

Claims (1)

1. A METHOD FOR REDUCING THE CORROSIVENESS TO CORRODIBLE FERROUS METAL OF A CORROSIVE PETROLIFEROUS WELL FLUID INCLUDING MOISTURE AND CARBON DIOXIDE WHICH COMPRISES INTRODUCING INTO SAID FLUID A CORROSION INHIBITING AMOUNT OF THE REACTION PRODUCT OF A FATTY MATERIAL SELECTED FROM THE GROUP CONSISTING OF FATTY ACIDS HAVING NO LESS THAN 12 AND NO MORE THAN 26 CARBON ATOMS PER MOLECULE AND A FATTY OIL CONTAINING FATTY ACID RADICALS HAVING NO LESS THAN 12 AND NO MORE THAN 26 CARBON ATOMS WITH AN AMINE SELECTED FROM THE GROUP CONSISTING OF ALKYL AND ALKANOL AMINES HAVING A TOTAL OF NO LESS THAN 6 CARBON ATOMS IN THE MOLECULE, THE REACTION PRODUCT BEING FORMED AT A TEMPERATURE IN THE RANGE OF 300* TO 550* F. AND IN THE PRESENCE OF AN ALKALINE REACTING CATALYST SELECTED FROM THE GROUP CONSISTING OF ALKALI METAL HYDROXIDE AND ALKALI METAL CARBONATE, THE WEIGHT RATIO OF FATTY MATERIAL TO AMINE BEING IN THE RANGE OF 0.5:1 TO ABOUT 5.0:1.