US2722462A - Drill pipe protector - Google Patents

Description

Nov. 1, 1955 N. K. TSCHIRLEY 2,722,462

DRILL PIPE PROTECTOR Filed March 20, 1952 Fig./.

22 Fl g 24 1 Norman K. Tschirley 1i INVENTOR.

United States Patent Office 2,722,462 Patented Nov. 1, 1955 DRILL PIPE PROTECTOR Norman K. Tschirley, McAllen, Tex. Application March 20, 1952, Serial No. 277,557 6 Claims. (Cl. 308-4) This invention relates to a drill pipe protector and particularly to an elastic collar fitted on a drill pipe to prevent Wear of the drill pipe coupling on the side of the hole or casing.

In the operation of rotary drilling rigs the rotary drill pipe extends downwardly through a casing and is generally provided with a plurality of sections which are held together by means of a coupling which is of considerably larger diameter than the normal diameter of the drill pipe. In operation of the pipe there is a tendency for the drill rod to whip in the casing or in the hole causing the couplings to wear against the side of the casing and also causing the drill bit to have a tendency to drill an erratic hole. It has heretofore been proposed to provide elastic collars on the drill pipes to eliminate contact be tween the couplings of the drill pipe and the side of the casing or hole and also to maintain the drill bit in substantially straight alignment with the casing. The heretofore used protectors have decreased the actual dimensions of the mud space between the drill pipe and the casing or the side of the hole and has resulted in serious circumstances. The increased pressure of the mud because of the restriction provided by the elastic collar frequently causes the mud to flow outwardly into the formation being drilled through so that not only it is mud lost together with the indications that could be received therefrom at the top of the Well but the mud that is lost in the formation may clog up the pores therein and prevent an otherwise good sand from bringing in a producing well. Also, the obstruction to the flow of the mud causes a back pressure at the mud outlet jets so that the jetting action of the mud in the drill bit is materially weakened.

The present invention provides an elastic collar of such formation that the total area between the collar and the casing is at no point less than the total area between the coupling in the drill pipe and the casing. This invention, therefore, produces a protective collar which in nowise limits the flow of the drill mud or produces back pressure in the well. The drill collar of the present invention, therefore, permits the mud to flow upwardly along the drill pipe without any undue restriction so that the mud does not flow into the formation or have high back pressure resulting in injury to the tools or the diminution of the drilling action.

The protector according to the present invention is provided with an elastorner collar snugly mounted on the drill pipe preferably adjacent to the coupling and having a normal diameter considerably less than the normal diameter of the coupling. A row of uniformly disposed projections or protrusions preferably of substantially hemispherical shape are mounted on the outer circumferential surface of the elastomer collar, the outermost point of these projections extending well beyond the maximum outside surface of the coupling. The relative proportions of the pipe casing, drill pipe coupling and clastomer collar, including the projections thereon, are such that at any point along the collar including a projection, the total cross-sectional area available for the passage of mud between the collar and the casing is substantially equal to the total cross-sectional area for the passage of said mud alongside the coupling.

It is accordingly an object of this invention to provide an elastic drill pipe protector.

It is a further object of this invention to provide a drill pipe protector which in nowise restricts the crosssectional area for mud flow.

A further object of this invention is to provide a drill pipe protector having a row of projections spirally therearound.

Other objects and many of the attendant advantages of this invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

Figure 1 is a vertical elevation partially in section of a drill rod and protective collar within a section of a well hole;

Figure 2 is a cross-section through the drill pipe coupling taken substantially on line 22 of Figure 1 showing the projections extending thereabove; and

Figure 3 is a cross-section taken substantially on the plane indicated by the line 3-3 of Figure l and indicating the difference in outside diameters between the elastic collar and the pipe coupling.

in the exemplary embodiment according to the invention a well pipe hole 10 is outlined by a casing 12 through which extends a rotary drill pipe having sections 14 and 16 connected together by the usual coupling 18. The coupling 18 defines a space 20 between the casing and the coupling through which the drill mud must return to the top of the well. It will thus be seen that the space 20 determines the freedom of flow of the drilling mud and particularly the pressure at the bottom of the Well so that unless the space is of sufiicient size there will be danger of high pressure at the bottom of the well. To prevent the coupling 18 from coming in contact with the casing 12, a collar 22 of elastomer material is placed on the drill pipe 14 adjacent to the coupling 18. The collar 22 is preferably a snug or tight fit on the drill pipe 14 so that there is little tendency of thecollar to slide or slip along the drill pipe. The normal outside diameter of the elastometer collar 22 is materially less than the normal outside diameter of the coupling 18 so that the.

space 24 between the collar and the casing is of greater width than the space 20 between the coupling and the casing 12. The protecting elements according to this invention now include a row of projections 26 arranged in spiral formation about the surface of the elastomer collar 22 and preferably of such dimensions that they extend materially above the outside diameter of the coupling 18 as is best seen in Figures 2 and 3. The projections 26 may be of any desired shape but are preferably substantially hemispherical and are so arranged that the transverse cross-sectional area of a projection 26 is equal to the difference in cross-sectional area between the outside diameter of the collar 22 and the outside diameter of the coupling 18. In other words, the total cross-sectional area through the drill pipe and collar 22, including a projection 26, is substantially equal to the total cross sectional area through the drill pipe and coupling 18. It will thus be seen that at any point along the collar 22, including a projection 26, the total cross-sectional area available for the passage of mud is substantially equal to the total cross-sectional area for passage of such mud between the coupling 18 and the casing 12.

It will thus be seen that the collar 22 plus its protecting projections 26 in nowise inhibit the flow or" the drilling mud over the normal inhibitions produced by the necessary couplings in the drill pipe. The protective collar can thus be applied to the drill pipe to maintain the pipe in substantial alignment in the central portion of the easing without causing excessive loss of mud into the formation through which the pipe passes or the reduction of drilling efficiency because of the high pressure of mud at the drill head.

-'While a preferred embodiment of the invention has been shown and described according to the present understanding thereof, it will be apparent to those skilled in the art that many changes and modifications can be made therein without departing from the true spirit of the invention.

Having described the invention, what is claimed as new is:

1. A string of drill pipe having lengths of pipe connected by enlarged couplings and operable in a well casing, a drill pipe and easing protector comprising a cylinder of elastomeric material tightly engaging the drill pipe, projections on the outer surface of the cylinder, said projections being uniformly distributed over the length and circumference of the cylinder simultaneously, the perpendicular distance from the axis of the drill pipe on which the cylinder is mounted to the extremity of any of the projections being greater than the perpendicular distance from the axis of the pipe to the outer surface of the coupling, the perpendicular distance from the axis of the pipe to the surface of the cylinder being less than the perpendicular distance from the axis of the pipe to the outer surface of the coupling, the total enclosed area surrounding the pipe and the protector including a pro jection, being substantially equal to the total enclosed area surrounding the pipe and coupling.

2. In combination, a well casing, a drill pipe having enlarged couplings and operating in said casing, a drill pipe and easing protector comprising a cylinder of elastomeric material sprung over the coupling and tightly gripping the drill pipe, the perpendicular distance from the axis of the pipe to the outer surface of the cylinder being less than the perpendicular distance from the axis of the pipe to the outer surface of the coupling; projec-tions on the outer surface of the cylinder, said projections being distributed uniformly over the length and circumference of said cylinder simultaneously whereby the enclosed area at any point over the length of the protector will be nearly equal to the enclosed area over the length of the coupling; the outermost point of said projections extending beyond the outer diameter of the coupling while providing at least as much clearance between the outside of the drill pipe and the inside of the casing as is provided between the pipe coupling and the casing.

3. In a string of drill pipe constituted of lengths of pipe with enlarged couplings and operating in a well casing, a drill pipe and easing protector combination comprising a cylinder of elastomeric material constructed to be sprung over the enlarged couplings of a drill pipe and to grip the drill pipe tightly, projections on the outer surface of the cylinder and distributed over the length and circumference of the cylinder simultaneously, the perpendicular distance from the axis of the pipe to the extremity of any of the projections on the cylinder being greater than the perpendicular distance from the axis of the pipe to the outer surface of the pipe coupling in the string of drill pipe, the circumscribed area over the length of the protector being from slightly less than to slightly greater than the circumscribed area over the length of the pipe coupling, the protector being a part of the string of drill pipe and rotatable inside the casing with at least as much clearance as is provided over the pipe coupling.

4. In combination a drill pipe having enlarged pipe couplings and a casing protector comprising, a cylinder of elastomeric material adapted to be sprung over the pipe couplings in a string of drill pipe and to grip the pipe tightly, the perpendicular distance from the axis of the drill pipe to the surface of the cylinder being permitted to equal but not exceed the perpendicular distance from the axis of the pipe to the outer surface of the pipe couplings, projections molded on the outer surface of the cylinder and being distributed over the length and circumference of said cylinder simultaneously so that the enclosed area at any point over the length of the protector will be nearly equal to the enclosed area over the length of the pipe couplings, and the tops of said projections to extend beyond the outer diameter of the pipe couplings while still allowing at least as much clearance between the outside of the drill string and the inside of a casing as is provided between the pipe coupling and the casing.

5. In combination, a cylindrical well casing, a rotary drill pipe operating inside said casing, an elastomeric cylinder mounted on the drill pipe and fitting inside the casing leaving at least as much clearance for circulation of drilling fluid as is left by the pipe couplings in the string of drill pipe, projections disposed upon the surface of the cylinder over its length so that as fluid is circulated through the casing one of the projections at a time will add to the restriction of fluid flow beyond the restriction offered by the elastomer cylinder, and disposed upon the surface of the cylinder over its circumference simultaneously so that the pipe couplings and easing will not contact each other when the drill pipe is rotated, raised or lowered inside said casing.

6. A device of the type described in claim 5, working as an integral part of a string of drill pipe and allowing at least as much clearance for the circulation of drilling fluid as is left by the couplings in the string of drill pipe regardless of the combination of drill pipe and casing sizes that might be used in cooperation to drill a given well.

References Cited in the file of this patent UNITED STATES PATENTS 1,894,519 McLaine Jan. 17, 1933 1,959,367 Kennedye May 22, 1934 2,049,265 Kinney July 28, 1936 2,166,116 Bettis July 18, 1939 2,252,978 Parkin Aug. 19, 1941 2,288,124 Creighton June 30, 1942

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