US2640735A - Stabilizer for drill collars and drill pipe - Google Patents

Description

June 2, 1953 F. A. sco'r'r l-:rAL

STABILIZER FOR DRILL coLLARs AND DRILL PIPEs 2 Sheets-Sheet l led Feb. 17, 1947 June 2, 1953 F. A. SCOTT ETAL 2,640,735

STABILIZER FOR DRILL COLLARS AND DRILL PIPES Filed Feb. 17,-1947 2 Sheets-Sheet 2 Fig. 4.

FLOYD l.. SCOTT FRED A. SCOTT INV ENTORS.

BY@ KM Patented June 2, 1953 2,640,735 of-Fries STABIEIZER DRILLv PIPE FredAScotLMdland, andfFloydLtfScothHouse fzon, Tex.,.zassignorszfto Hughes Tool Company, fHouston, .-Tex., ya... corporation: of'iDelawaref Application: Februaryfr ,"1947 Sera'FNo.4 I'7 29,142'

(Cl.;3ll8-4) '4 Claims.'

invention. relates/tothe artroflrotaryjiwell drillingfand. more.zpartieularlytothefstabilization of astring of.drill ..pipe"and/or drill.:collars during-.such drilling;

Inl the.. rotaryfmethod 'of vdrilling-wells ithe bore hole is. formed; bynattaching-fa bit uponthe lower end: of drillfstring, :such string. Aand `.bit V.being rotated bymeans of power applied vat itl-ie sur` face. Weight may. 'be applied toy the, .bit..by per.-

mitting thedrill string orstern, comprisinginter-k connectedrdrill pipe.- sections, to rest inpart upon the bit. In some cases, however, .aweightni` 40,000to 50,000.1105..v is needed for eilective drilling. In such a case it is impractical to: applyr .this weighttby;v meansl ofi the'isnperposedf drillr-stemias considerable flexing of s the -.stem.lthereby, occurs with resulting; damage. tofthestemaand produc'-Y tonof .a..crooked. hole.. To avoid thisfcondition, it :is .customary to.v providaaseriesof. drill. collars. adjacentL `the bitf and .these .drill collars fare relied upon toiprovide .-the..necessaryweightt upon th bit to` eifectadvancement thereof.

. `Various Afactors... involved in ...drillingvcause .in-.- stability in-.therotating drillstring, whether such string comprisesonly drill. vstem sections.. or, in.

combination therewith,.a plurality of drill collars.. Such instability.contributes greatly toga-ny tende) ency to produce a crooked holewand.alsogproduces destructive enect. upon the.,drill.-'string itself. .The present .invention ...is concerned. .with and itisan-.object ,of the. invention. toprovdega stabilizer. to be .used in. theldrillostringisothat in.- stabilitythereof-is minimized.. .Anothenbjectis toeprovideia stabilizer whereby the f a;

straight holeis ('eile'cted,` or. a theretfore crooked hole is straightened.'

Still another objectJof'ithe invention" is tofprovide a `drill stem! stabilizerfthatwll *dampenithef propagation ofwaves infthe sdrill stexnand"there b vnrinirnize` the'prdchiction `of alternatingstresses' which are- Asuperposed4 upon l" the' normal stresses withina d1illstem.

V'A'sti'll further object is tol "maintain'el-ements.

of the drillstem and. tool `fjointspnt"ofcontactj with a. sinronnding'casing or well bore wall wherebyabrasion-ofsuch elements is minimized;

Another object. of. the inventionl is. to, .provide-a stabilizer thatmay be inserted at any suitable point or pointsin a'drillstringysuch':device including af swiveled portion'resiliently engageab-lea vide za swiveling stabilizer for `drill stems .infwhich Y a; body1 ofi resilient. material rotatably` sizlrrounds a; journalportion of the. drill stem and presentsy outvvardlyr :extending integral .,projectionsf to. -en gage the surrounding"wa1ls.of the well...bore.

A still.' further. object of theinventionr-isrto provide aestabilizer including .relatively :rotatable partsf` theoutermost. of whichVA presents ioutwarde ly `iextending x resilient .-1 stabilizing projections.

The: foregoing. obj eats: together Vvwith other: objectswand advantages of theinvention ywil1...be

fully .apparent from ythefollowing description consideredy inconnection with Athe accompanying.

drawings in which:

Fig. el. a. vertical .elevational view' of foneorm oftheinvention: showing the normaliposition .of

the device when. in use inea` well bore;

.Figna rissa vertical elevational View ,of anzalternate form of:stabilizer-'comprising ajplura-lity. of short` sections;

Fig. 3 is a horizontal sectional viewtaken on the l-inef3--3` oflig..` 1

:Figf/i.; is-.a shortvertical sectionitaken on :line 4 4 of vlijst.

Whileztheterm .drilL-pipe is usedl-iereinit1isl to .be understood that .such term -comprehends 5a drill'-stringthat.v mayfcomprise drill pipeasectionsexclusively :or may include -1 drill. collars used in the .manner .above :indicated :The-invention vasx-shown. inFig. .1' of the draw-l ings;,comprisesA abody section .orfsub il, `provided with .pinand box terminalsf2v and-.Sf-soi-thatrthe stabilizer can bereadily connected -in a drill string between successive sections thereof. portion .4 of .thesub lis reduced-in orosssection thereby presenting upper-and-lower spaced shoulders '.fandii, the .assembly lsurrounding this.' reduced lportiontbeing. rotatablymounted. between theseshoulders.

liezassembly Tcomprises asmetalsheath I to which albody l l, of resilient. material, .such

as natural" or synthetic `rubber. or .the likeis united upon .itsinnervperiphery at I2. This assemblyiis'preferably formed in halves so that it can' be'readily'place'd' about' the vreduced portion 4 ofi the sub'v l *and then secu-red in 'place as'by welding-alongithe meeting edges I3 of the sheath I 0.

'li'ief'sheatht0 hasfaplura'lity of `openingsA l5` therein-.in staggered 'relation 'throughout its circumferenceffand fory a'xselected `.portion of lits length; Ti-iefffbody :il includes proectionsffl:

which. extendn outwardly l through .the a openings I5; .Although these 5 projections Acomprise-resilient'fmaterialyen.they possess fsuiilcient -inherentstiliness that their concerted action-when in..engagement with the surroundingfwallof a well bore, as shown at [l in Figsflfand .2,.is.,suf-

cient to produce desired stabilizing. of the .drill string of lwl'iichthe stabilizer'is. an element.

The stabilizer must 'necessarily be capable. of

axial movement'asit'is" lowerediinto a well or asI drilling' progresses. LFurtherrnore,A it `must *be also Ycapableofiizvassagethrouglri "restrictions-"that" The. central f bore.

may exist* within the vwell bore. The resilient nature of the projections It permits these projections to flex as necessary and thus permt such movement. To enhance flexibility preferably the projections I6 are provided with'.` central bores 20 which extend inwardly from the ends 2| of the projections for the major portion' of their length.

.- having a plurality of resilient outwardly extend- -ing projections thereon, and a sheath of rigid To further facilitate reduction inthe overall cross section of the stabilizer andpermit movement thereof past obstructions in the well,`

the body II is recessed at 22 within each of the openings I5 in the sheath I0. When a projection I6 is deiiected it may, when necessary, partially enter within such recess and in this manner the entire device may enter and pass through a restricted passage which is substantially the peripheral diameter of the sheath I9.

In order to minimize the contact area between the periphery of the sub I and the inner 10eriphery of the body I I, and also to facilitate the admission of well fiuids to lubricate the contacting surfaces between the sub and the swiveled assembly l, the inner periphery of the body II has longitudinally extending flattened areas 23,.

as best seen in Fig. 3. In a similar manner the ends of the body I I are sinuously relieved as indicated at'23', to provide spaced points of contact with shoulders 5 and 3 and lubrication for the thrust between the assembly 'I and the respective shoulders. This structure enables the assembly I to remain stationary within the well bore while the sub freely rotates therein as drilling progresses.

It is to be understood, of course, that during drilling a ushing nuid is pumped downwardly through the passage 24 within the stabilizer and thence, after passing through the bit therebelow, moved upwardly within the space 25 about the stabilizer as such fluid returns to the surface.

The operation of the device as thus far describedvis believed apparent from the foregoing description. By way of summary and further illustration it will be pointed out that a selected number of the stabilizer units are incorporatedY in the drill string as it is lowered into the well As deemed necessary, units may be successively interconnected and/or may be provided at spaced points in the drill stem. When the bit is upon bottom, drilling progresses in the conventional manner, it being understood that the projections I6 extend outwardly and engage the wall of the well bore. As above pointed out, the inherent stiffness of these projections produce the desired stabilizing effect.

To facilitate manufacture, repair and the Droduction of stabilizers of selected lengths, as well, to desirably distribute bearing stresses within the stabilizer structure, the device may be fabricated with a plurality of short assemblies I-surrounding the sub I as shown in Fig. 2. In this form of the invention the assemblies l are positioned within reduced areas on the sub whereby each assembly is rotatably mounted intermediate upper and lower shoulders 5 and 6'. Itseems apparent that such structure permits flexibility in constructing a stabilizer unit of a desired length and selectively positioning the stabilizer assemblies along such length.

Broadly, the invention comprehends a stabilizer for use in drill strings when drilling Wells by the rotary method, it being understood that such stabilizer shall dampen any movement of the drill stringtransversely of the axis of rota-l material 'fitting closely upon said body and having openings therein through which said projections pass for engagement with a surrounding wall to exert a stabilizing force upon the drill stem, the interior of said body having longitudinallyextending flattened areas to admit well iiuids between the body and the drill stem.

2. A stabilizer for drill stems comprising, a body of resilient material rotatably mounted upon atleast a portion of the drill stem and having a plurality of resilient outwardly extending projections thereon, and a sheath of rigid material fitting closely upon said body and having openings therein through which said projections pass for engagement with a surrounding wall to exert a stabilizing force upon the drill stem, said pr'ojectionsbeing hollow to permit flexing thereof as the drill stem and stabilizer move axially of an obstructed bore.

3. A stabilizer for drill stems comprising, a body of resilient material rotatably mounted upon at least a portion of the drill stem and having a plurality of resilient outwardly extending projections thereon, and a sheath of rigid material fitting closely upon said body and having openings therein through which said projections pass for engaging with a surrounding wall to exert a stabilizing force'upon the drill stem, the material of the body being recessed at said openings to enhance flexibility of the projections and to permit exing of the projections to a position substantially within the peripheral surface of the sheath.

4. A stabilizer for drill stems comprising, a sub for connection in the drill stem, spaced shoulders on said sub, -a body of resilient material rotatably surrounding said sub between said shoulders, a sheath of rigid material surrounding said resilient material and having a plurality of openings therein, and projections on said body extending outwardly through `said openings to resiliently engage a surrounding wall and exert a stabilizing force upon the drill stem, at least one of the end surfaces of said body being intermittently relieved radially to provide spaced points of contact with the adjacent shoulder whereby Well fluids are admitted to the shoulder and to the interior of the body.

FRED A. SCO'I'I. FLOYD L. SCOTT.

References Cited in the file of this patent UNITED STATES PATENTS

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