US3268274A - Spiral blade stabilizer - Google Patents

Description

3, 1966 J. E. ORTLOFF ET AL 3,2682% SPIRAL BLADE STABILIZER 2 Sheets-Sheet Filed May 25, 1964 William D. Smiley John E. Orlloff I NVENTOR S BY %.w-. E. Q;

ATTORNEY Aug. 23, 1966 J. E. ORTLOF'F ET AL 3,2682% SPIRAL BLADE STABILIZ-ER 2 Sheets-Sheet 2 Filed May 25, 1964 FIG. 4

FIG. 3

William D. Smiley John E. Orf/off INVENTORS BY E. Q;

ATTORNEY United States Patent 3,268,274 SPIRAL BLADE STABILIZER John E. Ortloif and William D. Smiley, Tulsa, Okla,

assignors, by mesne assignments, to Esso Production Research Company, Houston, Tex., a corporation of Delaware Filed May 25, 1964, Ser. No. 369,735 7 Claims. (Cl. 308-4) The present invention relates to rotary drilling equipment and is particularly concerned with improved drill string stabilizers useful in drilling oil wells, gas wells and similar boreholes.

Stabilizers are widely used to center the drill string in the hole during oil field rotary drilling operations. The typical stabilizer employed for this purpose consists of a tubular sub fitted with rigid external ribs which bear against the borehole wall as the drill string rotates. Because of abrasion which occurs when the ribs move in contact with the wall, tungsten carbide or a similar refractory material is generally applied to the outermost rib surfaces by means of an electric are or oxyacetylene torch. This improves stabilizer life but is not wholly satisfactory. Experience has shown that materials thus applied generally have rough outer surfaces which may cause excessive wear of the casing and other equipment in the borehole, that they often contain flaws due to slag or gas inclusions and are usually highly stressed because of differences in thermal expansion, and that such materials are generally softened or degraded as they are welded in place. In addition, the large rough particles of tungsten carbide applied by the welding process protrude from the weld metal and break relatively easily under impact as the blades contact the borehole wall. As a result of these and related difficulties, conventional stabilizers wear undersize quickly and generally have to be rebuilt at frequent intervals to maintain their effectiveness.

The present invention provides a new and improved stabilizer which eliminates many of the difiiculties encountered with stabilizers available in the past. The stabilizer of the invention is characterized by spiral segmented ribs which extend longitudinally over the major portion of the tool surface. Each rib segment is hardfaced on its outer surface with closely spaced blocks of tungsten carbide, with spheroidal granules of tungsten carbide or with a similar material set in a suitable matrix. It has been found that such stabilizers can readily be fabricated with smooth outer surfaces which will not severely damage the casing or other equipment in the bore hole, that the segmented ribs are surprisingly resistant to wear and abrasion, and that such stabilizers generally have a useful life at least three times that of the conventional tool.

The nature and objects of the invention can best be understood by referring to the following detailed description of the improved stabilizer and to the accompanying drawing, in which:

FIGURE 1 is a vertical elevation, partially in section, of one embodiment of the stabilizer which includes segmented ribs bonded directly to the tool body;

FIGURE 2 is an enlarged cross-section through a rib segment taken along the line 22 in FIGURE 1;

FIGURE 3 is a vertical elevation, partially in section, of an alternate embodiment of the invention in which the rib segments are formed on sleeves attached to the tool body; and

FIGURE 4 is a cross-sectional view through the stabilizer of FIGURE 3 taken about the line 44.

The stabilizer shown in FIGURE 1 of the drawing includes an elongated tubular body 11 provided with an 3,268,274 Patented August 23, 1966 A.P.I. tool joint box at its upper end and with an A.P.1. tool joint pin 12 at its lower end. These permit connection of the tool at an intermediate position in a conven tional rotary drill string. Other connecting means may be utilized in lieu of the box and pin if desired. An internal passageway, not shown in the drawing, extends through the body to permit the circulation of drilling fluid. Spiral ribs 15, 16 and 17 are mounted on the outer surface of body 11 and are spaced at intervals of about the body periphery. As indicated by reference numerals 15a, 15b and 15c, each rib is made up of three longitudinal segments which are separated from one another to form a discontinuous spiral extending about the body through an angle of about 120. This use of segmented ribs minimizes difficulties encountered due to differences in the coefficients of thermal expansion of the rib metal and hardfacing material, limits the adverse effect of failure of the carbide at a particular point, reduces abrasion caused by the entrapment of particles between the rib surface and the borehole wall, and permits fabrication of the tool in sizes which would not otherwise be feasible.

The rib structure is shown more clearly in FIGURE 2 of the drawing. As shown in FIGURE 2, each rib includes a supporting member 18 of steel, aluminum or similar metal containing a channel in its outer surface. This channel is filled with a matrix 19 formed of closely spaced powder granules of tungsten carbide or a similar refractory hard metal carbide bonded together with a metallic binder. Suitable binders include cast iron, iron nickel alloys, copper-nickel alloys, copper-nickel-tin alloys, copper-nickel-manganese alloys, iron-nickel-manganese alloys, S-Monel and other alloys having melting points in the range between about 1500 F. and about 2500 F. and the ability in the molten state to wet the refractory hard metal carbide granules employed. Cubes, cylinders or similar pieces 20 of tungsten carbide, titanium carbide, tantalum carbide, tungsten carbide-titanium carbide, or a similar refractory hard metal carbide are embedded in the matrix in a regular pattern so that each piece presents a smooth outer face. The use of cemented tungsten carbide containing from about 3 to about 15% cobalt as the cementing agent is preferred. The cubes or other carbide bodies will normally be between about one-eighth and about one-half inch in size and should be spaced from' about one-sixteenth to about one-fourth inch apart. This permits the concentration of a large quantity of carbide at the outer surface of the rib and yet avoids difiiculties encountered when a continuous or substantially continu-' ous facing of carbide is used. The matrix between the carbide bodies is sufficiently ductile to resist fracturing under high impact loading and is hard and erosion resistant because of the carbide powder granules contained therein. The powder granules also increase the strength of the matrix so that there is little chance of dislodging the carbide cubes or similar bodies even though a Wide spacing is used. The hardfacing material may extend a short distance above the surface of the surrounding rib body if desired but this is not essential.

The ribs employed on the stabilizer of the invention may be fabricated by first preparing a carbon or ceramic mold containing a cavity shaped to receive a rib segment. The mold should be designed so that the channel in the outer surface of the rib body can be placed adjacent a surface to which the carbide cubes or similar bodies can be glued or otherwise affixed and should be provided with a port through which the binder metal can be introduced. Cubes, cylinders or other bodies of tungsten carbide, tantalum carbide, titanium carbide, molybdenum carbide, tungsten carbide-titanium carbide or a similar refractory hard metal carbide having smooth outer faces are mounted on this surface in the desired pattern. The rib body is then placed in the mold so that the cubes or other bodies extend into the channel. The space surrounding the cubes is packed with powdered tungsten carbide or the like between about 100 mesh and about 400 mesh in size. The powder utilized may be either angular powder prepared by crushing pieces of cast, tungsten carbide or spheroidal powder obtained by melting tungsten carbide and cooling the resultant droplets in a gas stream. The mold may be vibrated and pressed at moderate pressures to compact the powder and reduce porosity if desired.

After the mold has thus been prepared, it is placed in a furnace and heated to a predetermined infiltration temperat-ure in the range between about 2000 F. and about 2600 F. The temperature selected will depend primarily upon the melting point and infiltration characteristics of the binder metal utilized. Temperatures at least 100 F. above the melting point of the binder are generally necessary. After the mold has reached the infiltration temperature, a molten binder alloy previously heated to the same temperature is introduced through the port and allowed to infiltrate into the interstices between the carbide bodies, powder granules, and rib body. The molten binder wets and alloys with the carbide and steel. The mold is held at the infiltration temperature for a period of from about 3 minutes to about minutes or longer and is then removed from the furnace and allowed to cool. It is preferred that the mold be cooled rapidly until a temperature below the melting point of the binder alloy is reached and that thereafter it be cooled slowly to room temperature in order to avoid adversely affecting the grain structure of the steel. After the rib has reached room temperature, it may be removed from the mold and machined or sand blasted to remove any excess binder metal.

The rib segments thus prepared are welded in place as shown in FIGURES 1 and 2 of the drawing. This may be done by first tack welding the segments in the proper position and running narrow beads on each piece. The stabilizer body is then heated to a temperature of about 500 F. and fillet welds are built up to the desired size. It is generally advisable to alternate between pieces to prevent excessive build up of heat. After the welds have been completed, the stabilizers should be slowly cooled to room temperature. It will be understood that the above procedures may be varied somewhat depending upon the particular materials from which the stabilizer body and ribs are made but that a procedure similar to that outlined will generally be followed.

In lieu of bonding the hard surfacing material to the body of the rib segment as described above, a pad containing the tungsten carbide cubes or similar bodies, the carbide powder granules, and the binder metal may be produced by infiltration and thereafter bonded to the outer surface of the rib body by a welding or brazing technique. This latter method is advantageous under certain conditions but has disadvantages in that a less satisfactory bond is generally secured. It is therefore preferred to form the hardfacing material in contact with the rib as described previously.

If spheroidal tungsten carbide powder is utilized in place of angular powder in fabricating the ribs, the cubes or similar particles of tungsten carbide or the like may be omitted. Tests have shown that spheroidal powder granules properly prepared are harder than corresponding angular granules and that the use of spheroidal granules between about 100 and about 400 mesh on the Tyler screen scale permits the formation of rib surfaces which are smooth and highly resistant to abrasion and impact. The fabrication methods employed with the spheroidal powder are similar to those used with the angular powder and cubes or other particles.

FIGURES'S and 4 of the drawing depict an alternate embodiment of the invention in which the stabilizer ribs are formed on sleeves mounted on the body. This embodiment is similar to that described earlier in that it includes an elongated tubular body 30 provided with an A.P.I. box at its upper end and an A.P.I. pin 31 at its lower end. An internal passageway permits the circulation of drilling fluid through the apparatus. Sleeves 34, 35 and 36 are mounted on the outer surface of the body and are welded or brazed in place as shown. The sleeves extend longitudinally over only part of the body so that sufiicient space is left near the box and pin to permit engagement of the tool with the tongs normally used in rotary drilling operations. Each sleeve contains 3 integral ribs spaced at 120 intervals about the tool periphery. These ribs are indicated on sleeve 34 by reference numeral- s 37, 38 and 39. The rib segments on the sleeve are aligned to form discontinuous ribs which extend about the body through angles of about 120. This use of integral sleeves and ribs as shown simplifies fabrication of the tool and facilitates the making up of stabilizers of various lengths. The integral rib segments of the apparatus shown in FIGURES 3 and 4 of the drawing are hardfaced with a material similar to that described earlier. Cubes or similar particles 40 of cemented tungsten carbide or the like may be embedded in a surrounding matrix composed of cast tungsten carbide powder and a binder alloy or, alternately, the material may consist of spheroidal tungsten carbide granules bonded together with a binder alloy.

The hardfacing material, ribs and supporting sleeve are fabricated as a unit in a graphite mold machined to the desired shape. Cubes or similar sintered carbide bodies may be glued to the mold surfaces corresponding to the outer rib faces. Tungsten carbide powder between about and about 400 Tyler mesh size, either angular or spheroidal, can then be packed into the rib cavities about the cubes. A small amount of wax or other organic binder may be added to the powder to assist in holding it in place if desired. After the mold and its contents have been heated to the infiltration temperature in a furnace, a molten iron nickel alloy containing about 10% nickel or a similar binder metal previously heated to the infiltration temperature is permitted to flow into the annular space in the mold and infiltrate into the interstices between the carbide powder granules and cubes. The mold is then removed from the furnace and allowed to cool. The exposure of the cubes to the molten binder should be limited to 30 minutes or less, preferably less than about 15 minutes, so that the original hardness of the carbide is not lost. The finished casting thus consists of a sleeve of the binder metal having integral ribs with carbide cubes surrounded by tungsten carbide granules at the outer rib surfaces. This casting is then slipped over the stabilizer body and welded in place. If desired, two sleeves can be Welded in place, one at either end of the tool body rather than three at the center of the body as shown leaving space for the tongs between two adjacent sleeves. In some cases it may also be desirable to secure the sleeves on the body by means of collars held in place at either end so that the sleeves themselves are free to rotate with respect to the body. This reduces relative motion between the rib surfaces and the borehole wall and may thus further extend stabilizer life. These and other modifications will be readily apparent to those skilled in the art.

The advantages of the stabilizers of the invention over conventional tools are shown by the results of comparative tests carried out during an extended oil field drilling program. Tests of conventional stabilizers hard-faced with tungsten carbide applied by means of a welding torch showed that such stabilizers normally were severely worn after only a few thousand feet and had to be rebuilt after each well. Tests with a stabilizer of the type shown in FIGURES 1 and 2 of the drawing were then carried out in the same area under comparable conditions. This stabilizer was used in three different wells. The total depth was about three times that drilled with the conventional stabilizers. Upon completion of the third well, it was found that the stabilizer ribs showed essenially 19 gns Of wear. The gage diameters were essentially unchanged. There was no evidence of fracturing or failure of the hard surfacing material on the rib surfaces. No difiiculties due to excessive wear of the surface casing were encountered. This improved performance significantly reduces the cost of using stabilizers to control borehole deviation.

What is claimed is:

1. A drill string stabilizer which comprises:

(a) a tubular body member provided with means near the upper and lower ends thereof for connecting said body member at an intermediate position in a rotary drill string;

(b) a plurality of spiral ribs extending outwardly beyond said body member at spaced intervals about the periphery thereof, said ribs being made up of longitudinal segments arranged in spaced end-to-end relationship; and,

(c) a hardfacing material bonded to said rib segments to form smooth outer surfaces, said hardfacing material comprising refractory hardmetal carbide powder granules between about 100 and about 400 mesh on the Tyler screen scale bonded together with a metallic binder having a melting point between about 1500 F. and about 2500 F. and in the molten state having the ability to wet said powder granules.

2. A stabilizer as defined by claim 1 wherein said powder granules are spheroidal granules of tungsten carbide.

3. A stabilizer as defined by claim 1 wherein said rib segments are mounted on sleeves which are in turn mounted on said body member.

4. A drill string stabilizer which comprises:

(a) a tubular body member provided with means near the upper and lower ends thereof for connecting said body member at an intermediate position in a rotary drill string;

(b) a plurality of elongated rib segments bonded in place on the outer surface of said body member to form spiral ribs extending part way around said body member at spaced intervals about the periphery thereof, each of said ribs being composed of at least two segments mounted in spaced end-to-end relationship; and,

'(c) a hardfacing material bonded to the outer faces of said rib segments to form smooth outer surfaces, said hardfacing material comprising a plurality of preformed bodies of cemented hardmetal carbide having smooth outer faces between about inch and about inch in size spaced from about to about 4 inch apart in a regular pattern, refractory hardmetal carbide powder granules between about 100 and about 400 Tyler mesh between said preformed bodies, and a metallic binder having a melting point between about 1500 F. and about 2500 F. and the ability to wet said preformed bodies and powder granules in the molten state bonding said bodies and granules together.

5. A drill string stabilizer which comprises:

(a) a tubular body member provided with means near the upper and lower ends thereof for connecting said body member at an intermediate point in a rotary drill string;

(b) a plurality of sleeves mounted on said body member at vertically spaced intervals, said sleeves having external rib segments on the outer surfaces thereof and said rib segments on adjacent sleeves being aligned to form discontinuous spiral ribs; and,

(c) a hardfacing material bonded to said rib segments to form smooth outer surfaces, said hardfacing material comprising refractory hardmetal powder granules between about and about 400 mesh on the Tyler screen scale bonded together with a metallic binder having a melting point between about 1500 F. and about 2500 F. and in the molten state having the ability to wet said powder granules.

6. A drill string stabilizer which comprises:

(a) a tubular body member provided with means near the upper and lower ends thereof for connecting said body member at an intermediate position in a rotary drill string;

(b) a plurality of rib segments welded to the outer surface of said body member to form discontinuous spiral ribs located at intervals of about about the periphery of said body member and extending through angles of about 120; and,

(c) a hardfacing material bonded to the outer faces of said rib segments to form smooth outer surfaces, said .hardfacing material comprising spheroidal tungsten carbide granules between about 100 and about 400 mesh on the Tyler screen scale bonded together with a copper-nickel alloy having a melting point between about 1500 F. and about 2500 F. and in the molten state having the ability to wet said powder granules.

7. A stabilizer as defined by claim 6 wherein said hardfacing material includes cubes of cobalt-cemented tungsten carbide between about A; and about /2 inch in size.

References Cited by the Examiner UNITED STATES PATENTS 2,248,530 8/1941 Granger 308241 2,657,907 ll/1953 Cochran l66241 2,667,930 2/ 1954 Saurenmon l66173 3,054,647 9/ 1962 Rosenberg 308-4 DAVID J. WILLIAMOWSKY, Primary Examiner. L. L. JOHNSON, Assistant Examiner.

Claims (1)

1. A DRILL STRING STABILIZER WHICH COMPRISES: (A) A TUBULAR BODY MEMBER PROVIDED WITH MEANS NEAR THE UPPER AND LOWER ENDS THEREOF FOR CONNECTING SAID BODY MEMBER AT AN INTERMEDIATE POSITION IN A ROTARY DRILL STRING; (B) A PLURALITY OF SPIRAL RIBS EXTENDING OUTWARDLY BEYOND SAID BODY MEMBER AT SPACED INTERVALS ABOUT THE PERIPHERY THEREOF, SAID RIBS BEING MADE UP OF LONGITUDINAL SEGMENTS ARRANGED IN SPACED END-TO-END RELATIONSHIP; AND (C) A HARDFACING MATERIAL BONDED TO SAID RIB SEGMENTS TO FORM SMOOTH OUTER SURFACES, SAID HARDFACING MATERIAL COMPRISING REFRACTORY HARDMETAL CARBIDE POWDER GRANULES BETWEEN ABOUT 100 AND ABOUT 400 MESH ON THE TYLER SCREEN SCALE BONDED TOGETHER WITH A METALLIC BINDER HAVING A MELTING POINT BETWEEN ABOUT 1500*F. AND ABOUT 2500*F. AND IN THE MOLTEN STATE HAVING THE ABILITY TO WET SAID POWDER GRANULES.

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