US3147536A

US3147536A - Apparatus for milling tubular strings in well bores

Info

Publication number: US3147536A
Application number: US148172A
Authority: US
Inventors: David E Lamphere
Original assignee: Individual
Current assignee: Individual
Priority date: 1961-10-27
Filing date: 1961-10-27
Publication date: 1964-09-08
Anticipated expiration: 1981-09-08

Description

Sept. 8, 1964 D. E. LAMPHERE 3,147,536

APPARATUS FOR MILLING TUBULAR STRINGS IN WELL BORES Filed Oct. 27, 1961 2 Sheets-Sheei. l

4free/Vey.

Sept. 8, 1964 D. E. LAMPHRE 3,147,535

APPARATUS FOR MILLING TUBULAR STRINGS IN WELL BORES Filed oct. 27, 1961 2 sheets-sheet 2 lNVEN TOR.

rroe ES.

United States Patent O David E. Lamphere, Fullerton, Calif., assignor, assignments, of three-fifths to Archer W. i and one-fifth to .lean K. Lamplrere, both of F llerton, Calif., and one-iifth to Archer W. Kammerer, Jr.,

Houston, Tex.

Filed Oct. 27, 1961, Ser. No. 148,172 Claims. (Cl. 29-1tl6) The present invention relates to subsurface well bore appar-atus, and more particularly to apparatus for milling away liners, casings, and similar conduit strings, while disposed in well bores.

Milling apparatus for cutting and milling away conduit strings in well bores have been proposed, the apparatus including circumferentially spaced sets of longitudinally aligned blades or blade segments separated from one another by a gap or slot, so that .a worn blade or segment breaks off near the end of its useful life and can be circulated out of the well bore. The laligned blade or segment there/above is then spaced above the end of the conduit string by a distance at least equaling the longitudinal extent of the gap or slot. It cannot come into play to perform its milling action on the conduit string until other circumferentially spaced blades of the apparatus have been worn away sufficiently to allow lowering of the apparatus along the conduit string. As a result, only some of the circumferentially spaced blades are sometimes effective for milling action on the conduit string, retarding the rate of milling land also tending to decrease the useful life of the entire apparatus. It is also a fact that the aligned blade or segment above the severed part initially therebelow is not immediately eifective to mill away the conduit string upon engaging it, since it, at rst, tends to slide around the conduit string unitl a sharp leading blade edge is formed by the abrading action of the conduit string on its lower end. The necessity for the sharp leading blade edge to be formed also increases the time required to mill away the conduit string.

Accordingly, an object of the ypresent invention is to provide milling apparatus for cutting away a conduit string disposed in a well bore, which is capable of performing its milling action in a more rapid manner, and which possesses an increased effective life.

Another object of the invention is to provide milling apparatus for cutting away a conduit string disposed in a well bore and which includes longitudinally aligned cutter blades or blade segments, there being a sharp cutting edge or portion on an upper blade or segment immediately available for action upon the conduit string after a lower blade or segment has worn away or broken off.

A further object of the invention is to provide milling apparatus for cutting away a conduit string in a well bore and which includes longitudinally aligned blades or segments, there being hardfacing material available for milling `action on the conduit string disposed across the slots, grooves or gaps separating the blades or segments, thereby increasing the milling life of the tool and diminishing the time required to mill away a desired length of the conduit string.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several forms in which it may be embodied. Such forms are shown in the drawings vaccompanying and forming part of the present specification. These forms will now be described in detail for `the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is n ot to be taken in a limiting sense, since ICC the scope of the invention is best dened by the appended claims.

Referring to the drawings:

FIGURE l is a side elevational view, the parts broken away, or" a milling apparatus disposed in a well bore and operating lupon a conduit strin-g located therewithim FIG. 2 is an enlarged longitudinal section of a portion of the yapparatus disclosed in FIG. l, after part of the apparatus has worn away ythrough use;

FIG. 3 is a cross-section taken along the line 3-3 on FIG. l;

FIG. 4 is a side elevational view of a modified form of milling apparatus;

FIG. 5 is a side elevational view of still another embodiment of the invention;

FIG. 6 is a side elevational view of still another species of the invention.

In the form of invention illustrated in FIGS. 1 to 3, inclusive, the apparatus A is a milling tool embodying a tubular body 10 having an upper threaded connection 1l, such as -a threaded box, for threaded attachment to the companion pin end 12 of a string of drill pipe B extending to the -top of the wel-l bore C. The milling apparatus is particularly designed for milling or cutting away a tubular string D disposed in the well bore, such as a string of casing, liner or tubing. The tubular body 10 has a central passage 13 therethrough for receiving drilling fluid pumped down the drill pipe B, this duid discharging through one or more ports or nozzles 14 in a lower pilot bit portion or guide 15 integral with the body 1t), carrying the cuttings from the drilling region 11pwardly through the annulus E -around the drill pipe to the top of the well bore. The pilot or guide portion 15 preferably has an effective diameter slightly less than the inside diameter of the conduit string D to be disintegrated, in order to appropriately center the tool A therewithin.

The tubular conduit D, such as a liner or casing, is milled away by the action of circumferentially spaced sets of cutter blades 16 integral with or otherwise suitably secured to the body 10 of the tool and extending generally radially thereof. Each set 16 preferably includes a plurality of longitudinally aligned blade elements or

segments

17, 18, adjacent segments being separated by a transverse gap, slot or groove 19, which may be inclined in an upward and inward direction from the outer longitud-inal surface 20 of each blade toward the axis of the tubular body. In effect, each set 16 constitutes a single blade separated into

segments

17 or 18 by the gaps, slots or grooves 19. Each blade 16 merges into a rib or pilot portion 21 that will conform closely to the inner wall of the tubular conduit D to be milled away, in order to assist in centering the tool with respect to the tubular conduit string. Above the centering portion 21 is the lowermost part 22 of each blade, which also preferably tapers upwardly and inwardly, and which is adapted to engage the upwardly facing end F of the tubular conduit to perform a milling action thereon.

The leading face 23 of each set of blades is hardfaced by welding or brazing suitable hardfacing material 24 thereto. The hardfacing material may, by way of example, be sintered tungsten carbide particles, tungsten carbide, titanium carbide, or the like, which are welded, brazed or otherwise deposited on the leading faces in a known manner, and which extend from the lowerrnost ends 22 of the milling blade members preferably to their uppermost ends 25. The lowermost ends 22 of the blade 16 all lie in the sarne position, that is, circumferentially aligned, so as to be capable of simultaneously operating upon the upper end F of the tubular conduit D Fbe disintegrated.

In the operation of the apparatus A, it is lowered in the well bore on the lower end of the string of drill pipe B until the pilot or

guide porti'on

15, 21 enters the tubular Conduit D and the lower ends 22 of the blades 16 engages the upper end F of the tubular conduit. The drill pipe B and the apparatus A are then rotated at a proper speed, suitable drilling weight `being imposed on the apparatus to force the lower ends 22 of the blades against the upper end F of the tubular member. The hardfacing material 24 on the leading faces 23 of the blades acts upon the steel, or other material, of which the tubular string is made and reduces the same to cuttings, the cuttings being carried away by thedrilling mud or other drilling iluid pumped down the drilling string B and through the central passage 13 of the apparatus body 10, discharging from the ports and nozzles 14. The mud and cuttings ow upwardly through the arcuate spaces between the circumferentially spaced blades 16 and then around the drill pipe B to the top of the well bore C.

The blades 16 cut the tubular conduit D away in a downward direction. As milling away of the tubular conduit D proceeds, the latter itself cuts longitudinal grooves 30 in the blades 16. Since the cutter blades have the hardfacing material 24 applied to them over substantially the entire surface of their leading faces 23, there is always hardfacing material on a blade available for action upon the upper end F of the tubular conduit. As the tubular conduit D cuts substantially through a

blade segment

17 or 18, the outer part 31 of such segment breaks off or away (FIG. 2). However, it is of insufficient size to interfere with the continued milling action of the apparatus on the tubular conduit D and will be flushed by the drilling iluid in an upward direction around the dr-ill pipe B to the top of the well bore C. As each

segment

17 or 18 breaks away, the next segment or blade element thereabove engages the upper endF of the conduit string and will continue the milling action upon the conduit string to cut it away in a downward direction.

In the form of invention illustrated in FIGS. 1 to 3, the gaps, slots or grooves 19 in the longitudinally extending blade sets 16 are staggered with respect to one another,

so that when one blade segment, such as segment 18, is cut away by the action of the conduit string, a blade segment of another set, such as segment 17, circumferentially spaced therefrom, is still effective for operation upon the conduit string. The blades 16 of the apparatus, therefore, will not tend to flare the conduit string outwardly, which would interfere with continued disintegration of the latter by the milling apparatus A. Such a general arrangement is illustrated and described in Patent No. 2,855,994, to Archer Vl. Kammerer, Jr., patented October 14, 195 8, for Milling Apparatus. Although the milling apparatus illustrated inthe patent is very effective in milling away a conduit string, such as a liner disposed in a well bore, the` longitudinal gap or space 19 between aligned

blade segments

17 or 18 means that an upper segment cannot begin its milling operation after a lower segment has been worn away and removed until a sufcient length of the conduit string has been milled away by other blades and longitudinal grooves Si) worn therein as to bring the lowermost end of an upper segment into contact with the conduit string. Moreover, it is found that the lower ends of the upper segments may not be sharp and immediately effective to perform a milling action on the conduit string. The body of metal of a blade V16, which is normally steel, must first be worn away by the upper end F of the conduit string before the hardfacing material 24 is in a sharp state, to begin its cutting action on the conduit string.

The aforenoted difficulty is overcome in the present case by extending the hardfacing material 24 applied to the leading face 23 of each blade 16 across the slot or vgroove 19 between aligned blade segments. Thus, as a lower segment 17 or 1S breaks away, suflicient hardfacing material 24a still adheres to an upper segment that was aligned therewith, and depends below the body metal of `the upper segment as to, in elect, bridge the gap, groove or slot 19 and be promptly effective for accomplishing a milling action upon the upper end F of the liner D, or other conduit string. Moreover, since the hardfacing material 24a is extending below the body metal of the blade, which is usually steel, it is in a sharp condition and promptly effective for disintegrating the conduit string D. As the conduit string wears the groove 30 upwardly through the depending hardfacing material 24a, it will eventually engage the body metal of the segment thereabove and continue to wear such body metal away to a greater extent than the hardfacing material, since the body metal is softer. The hardfacing material 24 always extends slightly below the body metal, presenting a sharp cutting surface for action upon the upper end F of the conduit string.

rThe form of invention disclosed in FIG. 4 is substantially the same as shown in FIGS. 1 to 3, inclusive. However, the transverse slots or grooves 19a do not extend completely through the body metal of each blade 16, in order to separate it into aligned

segments

17 or 18. Instead, each groove or slot 19a extends from the trailing face 40 of each blade 16 toward its leading face 23, but not completely across the entire thickness of the blade, leaving a weakened section or bridging portion 41 between

adjacent sections

17, 17 or 18, 18 to which the hardfacing material portion 24a is welded, brazed, or otherwise suitably attached. The weakened section 41, which, for example, may be of the order of an eighth of an inch in thickness, will have insufficient strength to prevent a lower segment lfrom breaking off after it has been substantially completely cut through by the action of the liner D, or other conduit string. However, after it does break oif, there will be hardfacing material 24a adhering to the weakened section 41, which can act upon the upper end F of the tubular'- conduit string and assist in cutting it away as the result of rotation of the apparatus A by the string of drill pipe B and the imposition of suicient drilling weight thereon. The weakened section 41 provides a backing for the hardfacing material 24a and assures that such hardfacing material will depend below the main body of the blade segment or section above and adjacent to the one broken away, being available and effective for action upon the conduit string D. Thus, a portion 41 of the longitudinally extending blade across its gap, slot or groove 19a is available for action upon the conduit string, in order that all of the blades 16 are always acting upon the conduit string, even when the upper end of the latter is disposed in the region of the slot or groove 19a of a blade. Moreover, the upper section of a blade is immediately in a sharp condition for prompt milling action on the upper end F of the conduit string disposed in the well bore C.

In the form of invention disclosed in FIG. 5, the slots or grooves 19e in each longitudinally aligned set of blades 16a all lie in the same transverse position, or in circumferential alignment, rather than being staggered as disclosed in FIG. 1. The hardfacing material 24a on the leading faces 23 of each blade set still extends across the slots, grooves or gaps 19C. Upon the Wearing away or breaking offl of a lower segment, such hardfacing material 24a will still extend below the lower end ofthe next adjacent upper segment 17a and is capable of immediate action upon the inner or other conduit string D.

The embodiment of invention shown in FIG. 6 is essentially the same as illustrated in FIG. 4, in that the slots 4or grooves 19d do not 'extend completely through each blade set 16 to separate it into aligned segments 17a. Instead, each slot or groove 19d extends from the trailing face 40 substantially to its leading face 23 leaving a lrelatively thin weakened section 41 integrating the segments of the body. The hardfacing material 24, however, is disposed on the leading faces of all of the segments 17a and also on the leading face of the interconnecting weakened portions 41. In FIG. 6, the slots or grooves 19d in the sets of blades are not staggered with respect to one another, as illustrated in FIG. 4, but lie in the same transverse positions. In all respects, however, the milling apparatus of FIG. 6 operates in the saine manner as the milling apparatus illustrated in FIG. 4.

I claim:

1. In apparatus for milling away a tubular conduit disposed in a well bore: a tubular body adapted to be secured to a drill string and having a fluid passage therein; longitudinally aligned cutter blade segments separated from each other by a slot of substantial axial extent and carried by and extending generally radially outwardly of said body for operation upon an upwardly facing end portion of the tubular conduit; a bridging portion integral with said blade segments and extending across said slot at the leading faces of said segments; said bridging portion being substantially thinner than said blade segments to provide a weakened section between adjacent segments adapted to break and disconnect the outer portion of a lower segment from the upper segment after said lower segment has ben substantially completely cut through by the tubular conduit; and hardfacing material on the leading faces of said segments and on the leading face of said bridging portion.

2. In apparatus for milling away a tubular conduit disposed in a well bore: a tubular body adapted to be secured to a drill string and having a fluid passage therein; sets of circumferentially spaced cutter blades carried by and extending generally radially outwardly of said body for operation upon an upwardly facing end portion of the tubular conduit; each set comprising longitudinally aligned blade segments separated from one another by a slot of substantial axial extent; a bridging portion integral with said segments in each set and extending across said slot of each set at the leading faces of said segments; each of said bridging portions being substantially thinner than said blade segments to provide a weakened section between adjacent segments adapted to break and disconnect the outer portion of a lower segment from the upper segment after said lower segment has been substantially completely cut through by the tubular conduit; and hardfacing material on the leading faces of said segments and on the leading face of each of said bridging portions.

3. In apparatus for milling away a tubular conduit disposed in a well bore: a tubular body adapted to be secured to a drill string and having a iluid passage therein; sets of circumferentially spaced cutter blades carried by and extending generally radially outwardly of said body for operation upon an upwardly facing end portion of the tubular conduit; each set comprising longitudinally aligned blade segments separated from one another by a slot of substantial longitudinal extent to provide a wide gap therebetween; and hardfacing material on the leading faces of said cutter blades and extending substantially across said slots; the slots separating the blade segments of one set being longitudinally offset with respect to the slots separating the blade segments of an adjacent set.

4. ln apparatus for milling away a tubular conduit disposed in a well bore: a tubular body adapted to be secured to a drill string and having a fluid passage therein; sets of circumferentially spaced cutter blades carried by and extending generally radially outwardly of said body for operation upon an upwardly facing end portion of the tubular conduit; each set comprising longitudinally aligned blade segments separated from one another by a slot of substantial axial extent; a bridging portion integral with said segments in each set and extending across said slot of each set at the leading faces of said segments; each of said bridging portions being substantially thinner than said blade segments to provide a weakened section between adjacent segments adapted to break and disconnect the outer portion of a lower segment from the upper segment after said lower segment has been substantially completely cut through by the tubular conduit; and hardfacing material on the leading faces of said segments and on the leading face of each of said bridging portions, the slot separating the blade segments of one set being longitudinally oifset with respect to the slot separating the blade segments of an adjacent set.

5. In apparatus for milling away a tubular conduit disposed in a well bore: a tubular body adapted to be secured to a drill string and having a fluid passage therein; sets of circumferentially spaced cutter blades carried by and extending generally radially outwardly of said body for operation upon an upwardly facing end portion of the tubular conduit; each set comprising longitudinally aligned blade segments separated from one another by a slot of substantial axial extent; a bridging portion integral with said segments in each set and extending across said slot of each set at the leading faces of said segments; each of said bridging portions being substantially thinner than said blade segments to provide a weakened section between adjacent segments adapated to break and disconnect the outer portion of a lower segment from the upper segment after said lower segment has been substantially completely cut through by the tubular conduit; and hardfacing material on the leading faces of said segments and on the leading face of each of said birdging portions, the slot separating the blade segments of one set being circumferentially aligned with the slot separating the blade segments of an adjacent set.

References Cited in the tile of this patent UNITED STATES PATENTS 2,830,795 Center Apr. 15, 1958 2,846,193 Chadderon Aug. 5, 1958 2,855,994 Kammerer Oct. 14, 1958 2,999,541 Kinzbach Sept. 12, 1961

Claims

3. IN APPARATUS FOR MILLING AWAY A TUBULAR CONDUIT DISPOSED IN A WELL BORE: A TUBULAR BODY ADAPTED TO BE SECURED TO A DRILL STRING AND HAVING A FLUID PASSAGE THEREIN; SETS OF CIRCUMFERENTIALLY SPACED CUTTER BLADES CARRIED BY AND EXTENDING GENERALLY RADIALLY OUTWARDLY OF SAID BODY FOR OPERATION UPON AN UPWARDLY FACING END PORTION OF THE TUBULAR CONDUIT; EACH SET COMPRISING LONGITUDINALLY ALIGNED BLADE SEGMENTS SEPARATED FROM ONE ANOTHER BY A SLOT OF SUBSTANTIAL LONGITUDINAL EXTENT TO PROVIDE A WIDE GAP THEREBETWEEN; AND HARDFACING MATERIAL ON THE LEADING FACES OF SAID CUTTER BLADES AND EXTENDING SUBSTANTIALLY ACROSS SAID SLOTS; THE SLOTS SEPARATING THE BLADE SEGMENTS OF ONE SET BEING LONGITUDINALLY OFFSET WITH RESPECT TO THE SLOTS SEPARATING THE BLADE SEGMENTS OF AN ADJACENT SET.