US2846385A

US2846385A - Prevention of corrosion in wells

Info

Publication number: US2846385A
Application number: US461566A
Authority: US
Inventors: Rudolph C Buchan
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1954-10-11
Filing date: 1954-10-11
Publication date: 1958-08-05
Anticipated expiration: 1975-08-05

Description

Aug. 5, 1958 R. c. BUCHAN 6,

PREVENTION OF CORROSION IN WELLS Filed Oct. 11. 1954 Rudolph 6. Baa/ran,

BY A;

IN V EN TOR.

United States Paten PREVENTION-F'CGRROSION'IN'WELLS :Rudolph .C..-.. Buchan; Houston, Terr -1 assignor, by memo assignments, .to. Esso: .Researchand Engineering Com= .panyIElizabe'th, N.. J a. corporation. of Delaware Application October 11,- 1954; Serial-N0-. 4'61",566

-5. Claims. (Cl.:204--148) The present :invention is. directed to a method for preeventing: corrosioninuwells. More particularly/the =invention is concerned with protecting asteel well casing from corrosion-by corrosivewellifluids. In its more specific--aspects,: the invention isdirected to a'me'thod forprotectinga-steel well casingfrom corrosion by corrosive well-*fluids forming-a *stagnantbodyinthe casing.

The present invention may-be=briefly described-as a method for protecting a steel well casing from corrosion by corrosive=well*'fluids-in contact therewith in which a tubing is arranged :having its :loweropen end at a level -a.subst-antial distance above a zone.trom..which said corrosive well'fluids are produced. IA, st-agnantbody of said corrosive well'fluids is in contact withjthe steel -casing. The-methodparticularly"comprises lowering a 'retrievable, saerificial metal tubular member; smaller in diameter-than the-tubing, through-the tubinguntil' the tubular 'member projects--a-substantial =dist-ance from the .lower .open-end of thetubing and-extends from the-open end of the tubing to.thezonetromvwhich the corrosive well fluids are produced. The sacrificial metal tubular --mem'ber-.is =anodic- -to-' steel arid is *electrically connected to the tubing. The tubular member is maintained in the tubing and casing while the corrosive fluids are produced such that the casing is protected from corrosion by the corrosive fluids and the tubular member is corroded instead.

The sacrificial metal making up the tubular member may be zinc, magnesium, aluminum and/or alloys of,

these materials, and the like.

The invention contemplates the removal of the tubular member periodically from the tubing, while the tubing remains in place, for determination of the extent of corrosion taking place in the well. The corrosive nature of the well fluids willbe indicated by corrosion of the sacrificial metal and is further contemplated that as the sacrificial metal tubular member is corroded it may be i replaced by another tubular member of a metal anodic to steel.

The present invention will be further illustrated by reference to the drawing in which the single figure discloses apparatus illustrating a preferred mode.

Referring now to the drawing, numeral 11 designates a well bore drilled in the earth to penetrate a plurality of hydrocarbon

productive intervals

12, 13, and 14 which may be separated from each other by non-productive intervals of zones 15 and 16.

In this particular instance, the well bore 11 has a steel casing 17 arranged therein which is cemented in place with primary cement 18. The casing 17 has a tubing 19 arranged therein with its lower open end 20 above the hydrocarbon productive interval 12. There is provided, for closing the annulus A between the casing 17 and the tubing 19 a packer 21 which may be a packer such as illustrated in the 20th edition of the Composite Catalog on pages 875 and 876 or on pages 496 and 497 of the catalog, supra, which illustrated Fatented Aug. 5, 1958 'type illustrated on'pages"875"and-"876 of the catalog,

supra, is schematically shown, such packer comprising upper and 'lower; expandable cup members 1.and Zfixed to retaining rings"3" andfl4, respectively. "The retaining ring 3 is slidable'with respect t0the.tubing.17 and is inwardly; downwardly tapered against the lower end there- ,of for bearing "engagement with slipsfS to" force such slips "5 into'engagement with the casing"17, as-i'shown.

A "stagnant zone .Z'of' corrosive well fluidsthus-exists below the packer 21"which maywapiidly .c'orrode;the casing.

In the practice of .the present' invention, an. elongated tubular member 22' "is. lowered through the" tubing 19,

such ason awire' line,not"shown,iand secured and/or supported in a'lan'dirignipple, such as 22a, whichj'may be a 'landing nipple,"such.as.described in'thel Composite 20-' "member 22"which"is constructedof sacrificial imetal'of the :naturedescribed supra is' electrically connected to the tubing 19 by-me-ans" 23 s which "may comprise 'the' land- Catalogue,"'supra,:at*page'4000. "The tubular extension ing nipple -22w but which will include auuit'a'blemetal to metal band.

The tubularrextension member 22 extends with' its fluids which may include hydrocarbons--..-and:salt-@water.

.aThe,. salt--water: maynbe corrosive due to .the presence of corrosive salts, sulfides, such as..hydrogen.sulfide,z-.metal sulfides, and the. ilikfifl and-due..to.the.presence,of organic acids, and carbon dioxide: and .the .like. ..The.corrosive .fluids including hydrocarbons ordinarily will proceed upwardly through the tubular member 22 and upwardly through the tubing 19 following'the path described by the arrows and to a zone Z where a relatively stagnant body of corrosive well fluids will exist which will corrode the casing 17.

In accordance with the present invention, with a sacrificial metal tubular member 22 of the nature described supra anodic to the steel casing 17 extending from the tubing 19, the steel casing 17 is not corroded by corrosive fluid in the zone Z above the lower end of the tubular member 22 and the sacrificial metal tubular member 22 is corroded, thereby protecting the casing 17 from corrosion.

From time to time the tubular member 22 may be retrived from the tubing 19 while the tubing 19 is maintained in place and the tubular member 22 withdrawn to the well head by engaging the fishing neck 25 with a fishing tool carried on a wire line, not shown, and the extent of corrosion of the tubular member 22 determined by inspection. Theinspection will also reveal the corrosiveness of the corrosive fluid in the zone Z. If it is determined that corrosion is being suffered by the corrodible tubular member 22 to the extent that its utility is destroyed, the tubular member 22 may be replaced by another sacrificial metal tubular member constructed of a metal anodic to a steel casing 17.

It may be seen from the foregoing description taken with the drawing that the present invention is of great min, as desired. However, it would be preferred to construct the tubular member 22 of the sacrificial metal due to its lightness and due to ease in manipulation and protection of the casing 17.

The nature and objects of the present invention having been completely described and illustrated, what i wish to claim as new and useful and to secure by Letters Patent is:

1. A method for protecting a portion of a steel well casing adjacent a hydrocarbon producing formation from corrosion by a stagnant body of corrosive fluids accumulated in said portion of said casing by production from said formation into said casing, said casing having a tubing arranged therein with the lower end of said tubing above said stagnant body of corrosive fluids in said portion of said casing, which method comprises the steps of metallically, annularly interconnecting said tubing with said casing adjacent said lower end of said tubing to thereby establish an electrical interconnection between said casing and said tubing adjacent said lower end of said tubing, lowering a retrievable sacrificial metal tubular member smaller in diameter than said tubing through said tubing until said tubular member projects a substantial distance from the lower end of said tubing and extends to said portion of said casing containing said corrosive well fluids, said sacrificial metal being anodic to steel, whereby a galvanic action is established in said portion of said casing adjacent said producing formation, and maintaining said tubular member in said tubing and easing while said corrosive fluids are produced, whereby said portion of said casing is protected from corrosion by said corrosive fluids and said sacrificial member is corroded.

2. A method in accordance with claim 1 wherein the sacrificial metal is zinc.

3. A method in accordance with claim 1 wherein the sacrificial metal is magnesium.

4. A method in accordance with claim 1 wherein the sacrificial metal is aluminum.

5. A method for protecting a portion of a steel well casing adjacent a hydrocarbon producing formation from corrosion by a stagnant body of corrosive fluids accumulated in said portion of said casing by production from said formation into said casing, said casing having a tubing arranged therein with the lower end of said tubing above said stagnant body of corrosive fluids in said portion of said casing, which method comprises the steps of closing the annulus between said tubing and said casing adjacent the lower end of said tubing and metallically, annularly interconnecting said tubing with said casing adjacent said lower end of said tubing to thereby establish an electrical interconnection between said casing and said tubing adjacent said lower end of said tubing, lowering a retrievable sacrificial zinc tubular member smaller in diameter than said tubing through said tubing until said tubular member projects a substantial distance from the lower end of said tubing and extends to said portion of said casing containing said stagnant body of said corrosive well fluids, whereby a galvanic action is established in said body of said casing adjacent said producing formation, and maintaining said tubular member in said tubing and casing while said corrosive fluids are produced, whereby said portion of said casing is protected from corrosion by said corrosive fluids and said sacrificial member is corroded.

References Cited in the file of this patent UNITED STATES PATENTS 1,608,709 Mills Nov. 30, 1926 1,804,078 Baden May 5, 1931 2,149,617 Menaul Mar. 7, 1939 2,155,370 Hall et al. Apr. 18, 1939 2,244,322 Zoller et a1 June 3, 1944 2,401,546 Brown June 4, 1946 2,665,759 Childers Jan; 12, 1954 FOREIGN PATENTS 523,618 Great Britain July 19, 1940

Claims

1. A METHOD FOR PROTECTING A PORTION OF A STEEL WELL CASING ADJACENT A HYDROCARBON PRODUCING FORMATION FROM CORROSION BY A STAGNANT BODY OF CORROSIVE FLUIDS ACCUMULATED IN SAID PORTION OF SAID CASING BY PRODUCTION FROM SAID FORMATION INTO SAID CASING, SAID CASING HAVING A TUBING ARRANGED THEREIN WITH THE LOWER END OF SAID TUBING ABOVE SAID STAGNANT BODY OF CORROSIVE FLUIDS IN SAID PORTION OF SAID CASING, WHICH METHOD COMPRISES THE STEPS OF METALLICALLY, ANNULARLY INTERCONNECTING SAID TUBING WITH SAID CASING ADJACENT SAID LOWER END OF SAID TUBING TO THEREBY ESTABLISH AN ELECTRICAL INTERCONNECTION BETWEEN SAID CASING AND SAID TUBING ADJACENT SAID LOWER END OF SAID TUBING, LOWERING A RETRIEVABLE SACRIFICIAL METAL TUBULAR MEMBER SMALLER IN DIAMETER THAN SAID TUBING THROUGH SAID TUBING UNTIL SAID TUBULAR MEMBER PROJECTS A SUBSTANTIAL DISTANCE FROM THE LOWER END OF SAID TUBING AND EXTENDS TO SAID PORTION OF SAID CASING CONTAINING SAID CORROSIVE WELL FLUIDS, SAID SACRIFICIAL METAL BEING ANODIC TO STEEL, WHEREBY A GALVANIC ACTION IS ESTABLISHED IN SAID PORTION OF SAID CASING ADJACENT SAID PRODUCING FORMATION, AND MAINTAINING SAID TUBULAR MEMBER IN SAID TUBING AND CASING WHILE SAID CORROSIVE FLUIDS ARE PRODUCED, WHEREBY SAID PORTION OF SAID CASING IS PROTECTED FROM CORROSION BY SAID CORROSIVE FLUIDS AND SAID SACRIFICIAL MEMBER IS CORRODED.