US2453882A

US2453882A - Inhibiting corrosion in wells

Info

Publication number: US2453882A
Application number: US643207A
Authority: US
Inventors: Prentiss S Viles; Elza Q Camp
Original assignee: Standard Oil Development Co
Current assignee: Standard Oil Development Co
Priority date: 1946-01-24
Filing date: 1946-01-24
Publication date: 1948-11-16
Anticipated expiration: 1965-11-16

Description

Patented Nov. 16, 1948 aisassa INHIBITINGI'COBROSION 1N WELLS Prentiss S. Viles and Elza Q. Camp, Goose Creek, Tex., assignors to StandardOil Development Company, a corporation of Delaware No Drawing.

Application January 24, 1946, Serial No. 643,207. 1

6 claims. ((31. 252-4555 The present inventionis directed to the production of fluids from underground formations. More particularly, the invention is directed to protecting the conduits and attendant equipment, through which fluids from subsurface formations are flowed and processed, from corrosion by materials occurring in or are introduced into fluids originating in subsurface format1ons.

In many oil, gas, and condensate fields, the production of fluid from subsurface formations is accompanied by extremely severe corrosion of the conduits and attendant equipment which comes into contact with the fluid mixture being produced. In many cases it is found that the fluid mixture is acidic in nature and comprises substantial amounts of carbon dioxide, a portion of which dissolves in water present to form carbonic acid. In addition to the carbon dioxide other materials which are present in the corrosive mixture may include organic acids. inorganic acids, inorganic salts and acidic sulfur compounds. These corrosive substances occur in or are introduced into the fluids originating in the subsurface formations. In some cases the corro sion occurs throughout the conduits and attendant equipment through which the fluids from the subsurface formations are flowed and processed.

In other cases the corrosionis limited primarily to portions of the conduits near the surface of the wells and to the well-head and attendant equipment. In all cases it has been necessary to make extensive replacements of equipment that has failed as a result of corrosion. This not only limits production, but is extremely expensive, particularly in those cases in which it is necessary to kill a high pressure well in order to make repairs and to replace corroded equipment. In addition to the high costs of making repairs to well equipment, there is a marked loss in revenues due to having a well off production and to the necessity of having ,to maintain additional wells and sources of supply to meet production requirements during periods in which a Well is off production for repairs as a result of corrosion. Further, there is constant danger that a Well will flow wild as a result of the failure of equipment due to corrosion. In cases of this kind, enormous losses are incurred.

It is, therefore, the main object of the present invention to provide a method whereby corrosion is substantially eliminated or inhibited in the conduits and attendant equipment through which fluids from subsurface formations are flowed and processed,

In accordance with the present invention,

acidic corrosion of metallic surfaces is inhibited or substantially eliminated by adding small amounts of sulfur to fluids produced from sub surface formations which are acidic in nature and include carbon dioxide. l

The amount of sulfur employed toinhibit the corrosion of the ferrous metal surfaces by the fluid mixtures produced from subsurface formations may be varied over a wide range and satisfactory results obtained. Inasmuch as sulfur is usually an undesirable constituent in. the hydrocarbon fluid being obtained, it is preferable to employ only small amounts of the sulfur to inhibit the corrosion but in some cases the use of large amounts of sulfur may be desirable or necessary and in such instances the sulfur may be added in amounts up to 3% by weight based on the weight of fluid mixture produced from the subsurface formation. I-Iowever, it will usually be found that minor amounts of sulfur will be effective for inhibiting corrosion of the ferrous metal surfaces and, accordingly, under many operating conditions the sulfur used for effectively inhibiting corrosion may be .1% or even as low as .01'%

by weight of the fluid mixture being produced.

It may be found that after an effective amount of sulfur has been employed to inhibit corrosion.

of the ferrous metal surfaces, a lower amount maintained in the fluid mixture will be effective thereafter to maintain the inhibiting effect. Accordingly, a substantial amount of sulfur as of the order of 1% by weight of the fluid produced, may be employed for a period sufficient to cause corrosion of the ferrous metal surfaces to be effectively inhibited and thereafter much smaller amounts, as of the order of .01% of sulfur based on the weight of the fluid produced, may be employed to maintain the inhibited condition of the metallic surfaces.

It will be found convenient to suspend or dissolve the sulfur in a suitable vehicle before introducing it into the fluid mixture. The resultant suspension or solution may then be conveniently injected into the borehole adjacent the subsurface formation from which the fluid is produced or may be introduced into the conduit through which the fluid mixture flows from the subsurface formation to the surface of the earth. Another method of employing the inhibiting agent is by injecting the suspension or solution into the subsurface reservoir by employing an adjacent well; it will be apparent that when adding the inhibiting agent in accordance with this Drocedure, the fluid entering the borehole of the producing well will comprise th'e inhibiting agent.

Test pieces of carbon steelwere immersed in water solutions under a pressure of 100"lb's, per

sq. in. gauge of carbon dioxide and thez-test pieces were maintained under this pressure for anzi'n terval of 24 hrs. and at a temperatureof 1'70! F. The carbon dioxide was admitted to the system through a pressure regulator valve thus maintaining a constantpressure of carbon di'ox I id'e'-onthe system so that the water solutions in which thea'carbon steel test specimens wereimmersed':.we're" saturated with carbon dioxide at the temperatures and pressures at' wh'ich -thetests were conducted? One of the solutionswas employediash-sa. blanlvwith i-no inhibiting material added-"while another. 1 solution has: added thereto anainhibitingmaterial comprising elemental sulfur dissolved in hydrocarbons in an amount of 1 'sulfur:and!20:%hydrocarbons by-weight in the solutiom. The results obtained? by --the"t'e'sts'- are shown'mmherfol'lowing' table:

Table.

1 h Reduction of Corrosion InhibitingMater'ial. Rate, Inches gggigfig I perYear Per Cent None 0. 2250 Free-sulfur'dissolvcd iii-Hydrocarbons 0.0405 82.1

It? will be. observed from. the data-presented in. the foregoing. table; that, the addition of; a smal1.-

amount of ,elemental sulfur effects-a markedrreduction in the,.tendency ofacorrosive water-solu tion to corrodecarbon steel.

The; nature and objects of the present invention having been fully described and illustrated, what We 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 fluid including moisture and carbon dioxide which comprises introducing into said fluid a corrosion inhibiting'amount of elemental sulfur.

2. A method in accordance with claim 1 in which the elemental sulfur added to the corrosive fluid is. in an. amount up to 3% by weight of the fluid.

3;:A methodaccordance with claim 1 in which the elemental sulfur introduced into said fluid is in the range of 0.01% to 1% by weight of 4;:-A=:method for reducing the corrosiveness to corrodible ferrous metal of a corrosive fluid including a major portion of hydrocarbons and a minor portion of moisture and carbon dioxide whichicomprisesintroducing into said fiuidacorrosion inhibiting-amount of elemental'sulfur.

5. A method in accordance with claim 4 in which, said ferrous metal is a conduit through which said corrosive fluid is withdrawn from a subsurface formationand in which said elemental sulfuris introduced directly into said conduit.

6.- A method in accordance with claim 4 in;

which theelemental sulfur introducedinto said fluid is in the range of"0.0 to 1% by weight of the fluid.

PRENTISS S. VILES. ELZA'Q. CAMP;

REFERENCES CITED 'I.l"'1e-following references are of'record'in the file ofz'this patent:

UNITED STATES PATENTS Number Name Date 1,829,705" Walker I Oct. 27, 1931 1,873,084 Walker II .Aug. 23, 1932 2,147,155 Gardner Feb. 14, 1939 2,222,431 Colin Nov. 19, 1940 2,258,806 Pier etral; Oct. 14, 1941? OTHER REFERENCES Industrial and-Engineering Chemistry, vol. 38, pp.. 10. and 14, Jan. 16,- 1946.