US2438673A - Well tool - Google Patents

Description

March 30, 1948. T, E, MCMAHAN 2,438,673

WELL TOOL Filed Feb. 20, 1945 Patented Mar. 30, 1948 UNITED STATES PATENT OFFICE WELL TOOL Thomas E. McMahan, Oja, Calif. Application February 20, 1945, Serial No. 57 8,820

` (c1. 16e-1s) 1 Claim.

This invention h-as to do with a well tool with laterally .Shiftable blades and it -is algeneral object of the invention to provide 'a tool of that type which is simple, eifect'ive, andl dependable.

The tool or construction of the present invention is designed to be rotated in a well and is useful, generally, in well operations as, for instance, for reaming, scraping, or like operations. For example, the construction of the present invention can be used to advantage' 'in well reamers or in Scrapers and it is particularly useful in Scrapers to be used within a casing orwell liner- This application is a continuation in part of my application entitled Bit forcleaning well casing, Serial- No. 535,599, filed May 15, 1944, now abandoned.

A typical cementi-ng oper-ation requires that a suitable Slug or body of cement beleft in the lower end portion'oi the casing being set vand when the setting period has terminated tools are run in the casing to drill out this slug of cement. Ordinary drilling bits can be used for this purpose, but are not Aaltogether eiective as they will not always remove all of the cement.

It is a general object of my present invention to provide a well tool with laterally operable or shiftable members, such as Scrapers or cutters, which members are actuated by fluid pressure. By my present invention I provide laterally shiftable members that may be cutter or scraper blades, and I operate those members into active cutting position by means of kiluid pressure.

-Another general object of my present invention is to provide :a tool lof the general character hereinabove referred to which employs the usual circulating fluid as the medium for actuating the cutters. By my present invention the circulating fluid employed to ush the cuttings from the Well also acts to expand the blades which act as cutters or Scrapers.

The various objects and features of my invention will be fully understood from the following detailed description of a typical preferred form and application of the invention, throughout which description reference is made to the accompanying drawings, in which:

Fig. 1 is a View showing a typical Well tool embodying the present invention, the tool being a combined bit and scraper, parts being broken away to illustrate the construction provided by the present invention;

Fig. 2 is an enlarged detailed transverse sectional view .taken as indicated by line 42 2 on Fig. r1.

In the drawings I show a well casing A containing a body or Slug of cement B and I show the tool D of the present invention on the lower end of an operating string S and being operated to remove the cement from the casing.

The tool which I have shown embodying the laterally shift-able members of the present invention involves, generally, an elongate body I0, cutting means il' on the lower end of the body designed to be advanced into the cement B and to cut away a substantial portion thereof, and cutting means I2 projecting laterally from the body above the means il to remove cement that may be left after the advance of the means Il or to cut or ream any formation at the side of the tool..

The cutting means l2 of the present invention comprises one or more blade-like members which maybe designed or fashioned to have the desired cutting or scraping action at the side of the tool.

The body lo is preferably an elongate member substantially round in cross section and is provided at its upper end with means for making connection with the string S which may be a string `or drill pipe, or the like. In thev case illustrated the body l ll is provided at its upper end with a threaded pin |14 for making connection with a box member 15e on the lower end of the string of drill pipe. A central longitudinal circulation opening l5 lextends through the body l0 `and suitably disposed discharge openings I6 are provided at the cutting means li so that circulating fluid discharge downwardly through the drill string S passes through the body I0 and issues at the lower end thereof, or at the means Il, to effectively flush away cuttings made by the means Il. Where the cutting means Il involves a plurality of blades, as will be hereinafter described, it is usually advantageous to provide a corresponding number of discharge openings for the circulating fluid so that each blade is effectively flushed. It is advantageous that the circulating iiuid issue at a high velocity in order to effectively keep the cutting parts clean and vto wash away the cuttings and, therefore, the combined areas oi the several discharge openings t6 is made less than the capacity of.' the opening `It', through the body. Through this relationship :of parts the 'openings i6 serve as a restriction and act to vbuild up pressure of circulating liuid within the body I0 which I utilize las will be hereinafter described.

The cutting means l l provided at the lower end of the body'may be varied considerably as circumstances require, or to satisfy the desires of the operator.A In the case .illustrated I have shown a drag type bit construction at thenlower end of the tool and this bit construction involves three cutting blades 20 spaced around the axis of the tool and projecting -downwardly from the lower end of the body I0. The blades have lower cutting edges 2| dressed or nished to effectively act on the formation or material to be cut. The cutting means as above described is a fixed or rigid cutting means and to facilitate free passage of the tube through the casing A, or through a like part, the blades 20 are limited as to their radial extent so that there is clearance between their outer sides 22 and the inner wall 23 of the casing. This clearance is made sufficient to allow for normal obstructions that may occur inl. the casing or that might tend to prevent pasf. sage of the tool if the fixed diameter of the tool were larger.

As a result of the proportioning the means acts to cut away the main bulk or body of cement B but leaves a thin wall or layer 24 oflcement' between .the outer sides 22 of the cutters and thewall 23 of the casing. If the bit is operating centrally in the Casing the layer 2 of cement will be a uniform thin wall such as is indicated at the right in Fig. 1 of the drawings. Thisthin wall of cement is, with ordinary tools, left `in 'the casing and' may seriously interfere wither-impair subsequent well operations.

The cutting means |2 is provided in the particular toolbeing illustrated as a means to scrape orcut away the layer 24 of cement left in the casing, and it is designed to do this by a scrapingaction w The .cutting means |2 actuated through -the construction provided by my present invention isshown as embodying a plurality of cutting blades, 'say for instance threeblades 3|) disposed longitudinally of the tool and equally spaced around the axis of the tool. The blades are carriedV in guideways 3|. provided in the body lil so that they are movable radially or voutward to engage vthe vwall 23 of the casing. The outer edge portions of the blades are sharpened or dressed to` have the 'desired cutting action. Y Inthe case illustrated the guideways 3| are located in ribs 33 which project from the exterior of the body and Vwhich extend longitudinally of the body. The guideways 3| are channel-like'openings extending into the body from the outer end por-V tions ofthe ribs and in the form of the invention illustrated the guideways have parallel flat side walls between which the blades 30 operate, The blades are slidably tted between vthe side walls of the guideways so that they are eiectively held and yet operate with suitable freedom.

Y In practice means are providedfor'retaining the blades in position in the guideways or for limitingoutward movement of the blades. In the particular construction illustrated lugs or ears 40 project from the ends of the vblades and stop blocksM are secured or xed in the ends of the guideways to overlie the ears, as clearly shown in Fig. 1 of the drawings. The ears and stops are related or proportioned so that the blades have the desired amount of free movement radially, this movement being such as to assure free operation of the blades to an out position where they will have the desired cutting or scaping action. The

stop or limiting means just described may vary However, it is practical to widely in practice. form the lugs or ears 40 integrally on the ends of thefblades and to make the stop blocks in the forni of separate parts arranged in place inthe ends/.0f .the guides to be secured.` inrvsitintr welding 42. s

just described. f

My present invention is primarily concerned with the construction whereby the blades or members 30 are operated to the extended position to have the desired cutting action. In accordance with my invention I provide one or more iiuid passages 50 from the uid circulation opening I5 wardly or to active working position. Since there j'mit-ted behind the members will normally tend to pressj orr urge them outwardly.

a back pressure built up in the circulation opening I5 provided in the body Ill for the reasons hereinabove pointed out, the pressure ad- '.l`oassure eiective operation of the members 30 and -to prevent leakage of circulating iluid at the members 30 I prefer to provide a sealing Vmeans in connection with each memberor blade 30. 'In the preferred form'of the invention I provide a strip -60 ofsealing material behind each member 30. Each sealing strip 60 preferably seats against the inner wall 6| of a blade and isproportioned so that there isa space 62 between the sealing strip and the bottom 63 ofthe guideway. This space is occupied by circulating fluid-intro.- duced through the passages 5|). AThe sealing means f or the sealing strip above referred to may be formed of "various Vmaterialszand may be of various constructions; However, YI prefer in practice toform it ofrubber or rubber-like material not attacked .by materials present in a well, and I prefer to form it so that'it lhas .sealing lips at its margins which serve to effectively prevent leakage of circulating fluid. In the .particular form of the invention illustrated the inner side 'I0 of the sealing strip is made concave in cross section whenviewed as shown in Fig. 2, so that it presents sealing lips 1| thatjeffectively bear against the sides of the guideway 3|.Y VSealing lips 72 are formed at the ends of the sealing strip to effectively seal against rthe ends 13 of the guideway- Y s i VIn order to facilitate retractionor depression of the blade members 30 as when the tool is being withdrawn from the Well, it is preferred to bevel or round the projecting corners 8|) ofthe blades and it is also desirable,l in practice, to round th'e ends 8| ofthe/ribs 33. l i; f

In operating the particulartool hereinabove describedthe cutting means cuts the major portion of the'. cement away and as this operation is being `Vperformed circulating fluid is constantly forced down through the drilling stringS to issue from the openings 6. The back pressure established in the passage or opening |5ii'sV exerted upon the blades 30 through the sealing strips 60 and consequently the bladesV are kept tight against the inner wall 23 of the casing. Y In a case where the invention'is employed fr tool other than. that above described rthe circulating pressure will maintain the members3|l inlanout position to ream`, sc'zra'pe,v or cut, as the case may be. v l

`With the tool illustrated the drilling and scrap-g y ing operation will proceed sovlong as the tool Yis cause the blades to be depressed, even though the circulation uid may be urging them out.

Having described only a typical preferred form and application of the invention, I do not wish to be limited or restricted to the specific details herein set forth, but Wish to reserve to myself any vari-ations or modications that may appear to those skilled in the art and fall Within th'e scope of the following claim.

Having described my invention, I claim:

A tool of the character described including an elongate body to be rotated by a well string, there being -a longitudinal fluid passage in the body and restricted outlet passages at the lower end of the body, a blade having an edge, a rib projecting from the side of the body forming a guideway carrying the bl-ade so its edge faces in the direction of rotation of th'e body, there being a Pas- 6 sage connecting the said fluid passage and the guideway, and a sealing member in the guideway behind the blade, the rib extending to the lower end of the body and there having an edge facing 5 in the direction of rotation of the body.

THOMAS E. MCMAHAN.

REFERENCES CITED The following references are of record in the 10 le of this patent:

UNITED STATES PATENTS

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