US3447839A - Welded drill blade stabilizer - Google Patents

Description

June 3, 1969 A. H. sALvAToRl 3,447,839

WELDED DRILL BLADE STABILIZER Filed Jan. 9, 1967 United States Patent O 3,447,839 WELDED DRILL BLADE STABILIZER Albert H. Salvatori, 4 Queens Gate Place, London SW. 7, England Filed Jan. 9, 1967, Ser. No. 608,140 Int. Cl. F16c 17/02, 31/02 U.S. Cl. 308-4 2 Claims ABSTRACT F THE DISCLOSURE This invention relates to well tools of the type for engaging the wall of a well bore and more particularly to `an improved blade type stabilizer attachable into a rotary drill string in lateral stabilizing relation with the drill string.

Drill string stabilizers are a well known Well tool which is made part of a drill string by inserting it between parts of a drilling string that are normally joined together, such as, for example, between a bit and a lower end of the drill collar or between the upper end of a drill collar and the lower end of a string of drill pipe. The device is such as to project outward to bear upon or engage the wall of the Well bore and serve as a fulcrum or guide in the drilling string. In rotary drilling operations wherein one or more stabilizers are used on the drill string and particularly on the drill collars far down in the well to center and stabilize the drill string in the hole, the lateral forces in compression and shear are very great. In addition to centering and stabilizing the drill string, such a well tool is sometimes placed near the drill bit to act as a fulcrum in directional drilling operations. The stabilizer must withstand such forces and still provide bypassage for circulation of drilling mud during the drilling operation.

Drill string stabilizers are of various types, one of the better known types being the blade type or drill blade type stabilizer, which comprises in general a body or a mandrel portion to which are affixed spiraled blades which extend from the body portion to the diameter of the well bore. The plurality of blades are so arranged about the circumference of the tool body that when in engagement with the wall of the well bore spaces for circulation of mud and removal of cuttings and debris from the Well are provided between the blades. Typically three such blades are utilized and are equally spaced circumferentially about the tool body. The blades are generally spiraled or set at an angle with respect to the verti cal axis of the drill string such that the plurality of the blades present a large arcuate bearing with the well bore wall as more fully described herein. Inasmuch as the stabilizer is subject to very great stresses in use, the radially extending blade must be securely fastened to the stabilizer body in order that the blades will not break loose and necessitate an expensive and time consuming lishing job. However, the blades must be securely aiiixed to the body and they should be mounted in a way permitting their easy removal and replacement since the blades of the stabilizer are subject to wear and deterioration in use. It is another requirement of such drill blade stabilizers that the blades will not rotate relative to the tool body, i.e., that the blades are aixed thereto in such manner that they rotate with the drill string.

In accordance with the prior art the radially extending blades of a drill blade stabilizer are affixed to the stabilizer body by forming a plurality of undercut grooves equal in number to the number of blades to be mounted on the tool body and by aiixing the blades in the undercut grooves in a removable manner as by forming transverse undercut grooves into which a stop member is inserted. Such construction is shown, for example, in U.S. Patent No. 2,834,579. Another and more simple method of axing the stabilizer blades to the body is by welding the blades directly thereon. This method has the primary advantage of simplicity and economy and also minimizes any possibility that the blades will be separated from the body and lost in the hole.

In prior art drill blade stabilizers a primary diliiculty of that type of stabilizer in which the blades are welded directly to the tool body lies in the fact that the body is an expensive piece of material and the welding to and removing from that body of circumferentially spaced blades soon renders the body unusable due to welding and removal damage. Additionally, the welding and removing of the blades from the body results in the creation of stresses in the body which soon weaken it beyond a usable safety factor.

It is a primary object of the present invention to provide an improved drill string stabilizer construction which is simple and economical to fabricate.

It is another object of the present invention to provide an improved stabilizer for drill strings in `which the part of the stabilizer Which is subjected to wear is easily replaceable in the eld.

It is another object of the present invention to provide a drill string stabilizer in which a single tool body can be utilized for stabilizing blades of different diameters.

It is another object of the present invention to provide a drill string stabilizer in which the drill blades of the stabilizer are lirmly aflixed to the body with no possibility of rotation with respect thereto.

The present invention provides =a novel drill blade stabilizer having sufiicient structural strength to act as a guide or fulcrum for centering means when inserted in a drill string and comprises .an oil tool body adapted to be inserted into a drill string with a plurality of circum- Fferentially spaced elongate Wall engaging members removably aixed to and extending radially from the tool body. The members extending from the exterior of the tool body are formed by providing longitudinally mating sections of a cylindrical sleeve which sleeve when assembled has an outside diameter approximately equal to the outside diameter of the tool body and an inside diameter approximately equal to a portion of the tool body which has been reduced in diameter by means of a longitudinally extending section of reduced diameter. The mating cylinders also include longitudinal protrusions which mate with longitudinally extending notches formed in `the body adjacent the reduced diameter section. The radially extending wall engaging members, hereinafter termed blades, are formed integrally with the mating cylindrical sections. The mating sections of the sleeve are welded together in assembled positions on the body without being welded to lthe body.

The -novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof will be better understood from the following Idescription considered in connection with the accompanying drawing in which a presently preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawing is for the purpose of illustration and description only, and is not intended as a definition of the limits of the invention.

In the drawing:

FIGURE 1 is a vertical section taken through the well bore showing a view in elevation of a presently preferred embodiment of a drill string stabilizer in accordance with the present invention and mounted in a drill string;

FIGURE 2 is an enlarged view in elevation of a portion of the presently preferred embodiment of a stabilizer in accordance with the present invention;

FIGURE 3 is a sectional view taken along line 3-3 of FIGURE 2; and,

FIGURE 4 is an exploded view showing the stabilizer of the present invention in disassembled condition.

Referring now to lthe -drtawing there is shown in FIG- URES 1 4 thereof, a presently preferred embodiment of a drill string stabilizer in accordance with the present invention. The drill string stabilizer is shown as assembled in an illustrative drill string in FIGURE 1 and is designated generally by the reference numeral 10. The stabilizer includes a tubular externally cylindrical vertioally extending tool body A which is connectible into a drill tool string by the usual upper and lower threaded ends 12 and 13, one of which would typically be a box end yand the other would be a pin end. Three well bore engaging members in the form of angularly extending stabilizer ribs, generally designated as B, are circumferentially spaced about and integrally aflixed to the outer surface of a sleeve C which is in turn mounted upon the body A. The blades extend radially outward from the body to a diameter sufficient to engage the wall 16 of the well bore to laterally stabilize and center the drill string. It is to be understood that the stabilizer may be connected into any portion of the drill string particularly between the drill collars for stabilizing guiding or other purposes. A central passage 17 extends longitudinally through the tool body A to communicate with similar passages in the elements of the string for flowing drilling mud therethrough. In the illustrative drill string shown in FIGURE l the stabilizer is connected into the drill string between a drill collar 17 which is in turn affixed to the bit 118 and a section of drill pipe 19 which is aixed to the upper end of the stabilizer body 11 and extends upwardly therefrom.

Referring now particularly lto FIGURES 2, 3, and 4 the stabilizer body A is a tubular elongate element preferably Iformed of steel with an outside diameter substantially equal to the outside diameter of the adjoining collars 18 or other elements in the drill string. In FIG- URE 2 the ends of the tool body have been omitted for clarity of the drawing, it being understood that in accordance with the description in connection with FIGURE 1, the -tool body 11 terminates in conventional threaded ends for insertion into the drill string. AS shown particularly in FIGURE 4 there is provided in the tool body a longitudinally extending portion of reduced diameter. This reduced diameter portion is designated as 20 in FIGURE 4 'and may occur at any position along the length of the tool body. The length of the section of reduced diameter is approximately equal to the length of the stabilizer sleeve which is somewhat greater in length than the blades which are in -turn of the desired length common to other types of drill blade stabilizers. Thus, in a typical stabilizer of one particular size the outside diameter of the body is 6% inches, the overall length is 60 inches, and the length of the sleeve is approximately 22 inches. The stabilizer blades on such a body would range in outside diameter from 7% inches to 97/s inches. Thus, in the illustrative tool body the section of reduced diameter of the body would be approximately equal to but greater than the length of the sleeve. The diameter of the reduced diameter section 20 of the body hereinafter termed the body groove 20, is approximately equal to the inside diameter of the sleeve in the 'assembled condition of the sleeve as discussed hereinafter. The body groove 20 thereby Idefines oppositely facing shoulders 21 and 22 as best shown in FIGURE 4 of the drawing. Extending longitudinally outwardly from the body groove 20 into the oppositely 'facing shoulders 21 and 22 are notches 23 and 214. Two such pairs of notches are provided in the presently preferred embodiment although only two are visible in the figures. : Notches 23 and 24 extend a substantial distance into the shoulders 21 and 22 and are approximately equal in depth to the depth of the body groove 20. The pairs of notches are approximately diametrically opposed in the present embodiment and each pair, i.e., 23 and 24, are in substantial longitudinal alignment as shown particularly in FIGURES 2 and 4. The notches are adapted to receive'mating protrusions on the lassembled sleeve to prevent rotation of the sleeve relative to the body as discussed more fully hereinafter. It will be apparent however, that various other configurations may be employed for preventing such rotation.

In accordance with the present invention, a plurality of blades or ribs C are provided to occur on the exterior of the sleeve B such that when assembled the sleeve C conforms in outside diameter to the body A and the blades or ribs project radially outward therefrom. The blades may vary in number, form and design, but in the presently preferred embodiment, three such ribs are spaced apart around the body and are pitched so that they are angularly disposed relative to the longitudinal axis of the body preferably at about 30 relative thereto. It is preferable that the several blades be straight elongate elements of considerable length and also of substantial width. The blades are spaced a substantial distance apart so that there are openings or channels between adjacent blades to provide adequate means for passage of uid that must circulate past the blades. It is to be understood that the term, blades, is one common to the art and is employed herein although meant to denote that the blades or ribs necessarily perform any cutting function in the well. It is their primary function as discussed hereinbefore, t0 prevent a bearing surface with the well bore. Accordingly, in the illustrative embodiment of the present invention, each blade is elongate in configuration and generally rectangular in cross-sectional configuration so that it has a substantially flat top surface 23. The orientation and configuration of the blades relative to the sleeve B and the tool body A is shown particularly in FIGURE 3. The blades C are permanently affixed to the sleeve B and in the present embodiment are so affixed by forming them integrally therewith. Referring now particularly to FIG- URE 4 the sleeve C is formed in two longitudinally mating sections designated 25 and 26. The sections are such that when assembled they form an elongate cylinder aS discussed hereinbefore having inside diameter approximately equal to the outside diameter of the tool body in the body groove 20 and an outside diameter approximately equal to the outside diameter of the tool body A. The mating sections 25 and 26 are so formed that the dividing line between the sections extends longitudinally through the sleeve between blades C which -are affixed thereon. The mating sections are also formed such that the dividing lines divide the sleeve into two portions each of which can be fitted over the tool body in the body groove 20, i.e., between the shoulders 21 and 22. Thus, the sleeve must be so divided that the distance between opposite edges of each section 25 or 26 are spaced apart by a distance greater than the diameter of the tool body in the body groove 20. This is apparent from the fact that the sleeve is so divided that it can be assembled about the tool body A in the groove section 20 and tted together to form a mating cylindrical sleeve. Thus when assembled the edge 27 of the sleeve section 25 mates with the edge 28 of the sleeve section 26 while the edge 29 of the sleeve section 25 mates with the edge 30 of the sleeve section 26. The protrusion 31 and 32 on each sleeve section are matable with the respective notch 23 and 24 in the tool body A.

When assembled on the tool body A, the two mating sections 25 and 26 of the sleeve C are aixed together to form the unitary sleeve cylinder upon the body A. In the presently preferred embodiment of the present inventhe assembly line edges 27 and 28 and the weld line 34 5 occurs between the assembly edges 29 and 30. The protrusions 31 and 32 mate with the notches 23 and 24 such that when the sleeve is assembled upon the tool body it is not welded thereto but is aiiirmly axed in the body groove 20 and prevented from rotating with respect to the tool body by the protrusions being mated with the notches. To disassemble the blades from the tool body A it is necessary only to remove weld material from the sleeve itself so that no removal damage occurs to the tool body which may be reused over a long period f use of the stabilizing tool.

Thus the present invention provides an improved sleeve type stabilizer consisting of a heavy duty body member around which is welded a prefabricated sleeve having the blades formed integrally thereon. The sleeve and body are so constructed that the mating iit prevents rotation of the sleeve yet at the same time eliminates any welding of the sleeve or blades to the body. The sleeve sections are preferably hard faced along the blade length. Assembly of the sleeve to the body thus merely involves clamping both pieces together around the body laying a small mild steel rod between each gap between the sleeves to prevent transfer of fusion of the weldment to the body and then welding the two halves of the sleeve assembly together. Thus, sleeves and blades of various sizes are easily replaceable in the iield. Considerably less welding is required than in prior art welded blade stabilizers and no hot bending or forming of blades to body contour is necessary as is typical of welded blade stabilizers of the type heretofore known to the art. The fact that no direct welding on the body itself occurs, prevents the formation of stresses which weaken the tool body or damage which occurs thereto due to welding and removal of the blades from the body.

What is claimed is:

1. A drill string stabilizer comprising:

an elongate tubular body, said body dening a longitudinally extending portion of reduced diameter with oppositely faced shoulders at the ends thereof;

a sleeve positioned about said tool body between said shoulders, said sleeve being comprised of two longitudinally mating sections, said sections being -Welded one to the other in the assembled position of said sleeve upon said body;

trusion from said sleeve extending into a mating indentation in the adjacent one of said shoulders.

2. A drill string stabilizer as dened in claim 1 in which the inside and outside diameter of said assembled sleeve is approximately equal to the outside diameter of l5 said reduced portion and the outside diameter of said tubular body respectively.

References Cited UNITED STATES PATENTS FOREIGN PATENTS Australia. Germany. Great Britain.

MARTIN SCHWADRON, Primary Examiner. L. I.. JOHNSON, Assistant Examiner.

U.S. Cl. X.R.

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