US2903239A - Eccentric spud bit - Google Patents

Description

I p 1959 c. M. STANDRIDGE 2,903,239

- ECCENTRIC SPUD BIT Filed Sept. 6, 1956 C Mad/e if, Sfflof/ oy e INVENTOR.

A TTORA/[YS United States Patent ECCENTRIC SPUD BIT Claudie Mack Standridge, Houston, Tex., assignor to Houston Oil Field Material Company, Inc., Houston, Tex., a corporation of Delaware Application September 6, 1956, Serial No. 608,373

8 Claims. (Cl. 255-1.6)

This invention relates to an improved eccentric spud bit and more particularly to such a bit utilizing a fluid jet as an aid to spudding in at a side of a well bore. The initiating of a hole by a bit is known in the trade as spudding in.

In the drilling of oil and gas wells it frequently be comes necessary or desirable to leave the original well bore and drill at an angle to this well bore for sidetracking operations or directional drilling. When this occurs the bit must be deflected from its normal path to make a cut through a side of the well bore. If the cut is to be made through the side of the well bore at the bottom of the well it is oftentimes possible to deflect the bit, such as an eccentric spud bit, through the side of the Well bore by forcing downwardly on the drill string connected to the bit thereby slightly bending the drill string above the bit because the bit is resting on the bottom. Such action tends to deflect the bit to an angle from the original direction of the well bore and cause it to cut at an angle to the well bore.

However, it is diificut to cut through a side of the well above the bottom of the well without the use of. a mechanical aid in the well to deflect the drill but such as the use of a whipstock. For example, an eccentric spud bit works satisfactorily at the bottom of a well for deflection but is not satisfactory for cuts through the well bore wall above the bottom of the hole without some mechanical assistance to deflecting the bit such as the use of a whipstock.

It is a general purpose of the present invention to provide an improved eccentric spud bit which may be used to cut through a wall of the well bore above the bottom of the well bore for directional drilling or sidetracking operations without the use of mechanical devices in the well to deflect the drill stem such as whipstocks and the like.

It is another object of the present invention to provide an improved eccentric spud bit which when used for sidetracking or directional drilling above the bottom of a well bore causes the blade of the eccentric bit to strike the same portion of the wall of the well bore upon each downward movement of the bit when the bit is moved upwardly and downwardly to spud in.

A still further object of the present invention is to provide an improved eccentric spud bit having a passageway in fluid connection with a jet port on the trailing surface of the eccentric blade so that fluid leaving the jet port forces the eccentric blade of the bit against a side of a well bore and which bit includes means for sealing the jet port against the passage of fluid once the bit has been spudded in and permits a circulation over the leading surface of the bit during further drilling op erations.

And still a further object of the present invention is to provide such an improved eccentric spud bit in which the circulation port which causes drilling fluid to circulate over the leading surface of the eccentric blade is releasably plugged while fluid from the jet port forces the blade against the side of the well bore and thereafter the plug may be expelled by fluid pressure from the drill string by sealing oil the jet port.

Other objects and advantages will be more apparent from the following description of a preferred example of the invention, given for the purpose of disclosure, and taken in conjunction with the accompanying drawing, Where like character references refer to like parts throughout the several views, and where Fig. 1 is a sectional elevation of the improved eccentric spud bit of the present invention illustrating the initial spudding in of the bit at a side of a well bore,

Fig. 2 is similar to Fig. 1 and illustrates the improved bit after the spudding in and with circulation at the leading surface of the blade, and

Fig. 3 is a view along the line 33 of Fig. 1.

Referring now to the drawings, and particularly to Figs. 1 and 2, the improved eccentric spud bit, indicated generally by the numeral 10, includes an elongate generally tubular body 12 adapted to be fitted into a well bore 13, an eccentric cutting blade 14 at the lower end of such body 12 and means at the upper end of body 12 for securing the bit 10 to a string of conventional drill pipe 16 having a fluid passage 33 therein. This means for securing the body 12 to the drill string 16 may take any conventional form such as the internally threaded box 18 adapted to internally receive the pin member 19 at the lower end of the drill string 16. The body 12, the box member 18, and the eccentric blade 14 are all normally formed from a single casting.

As illustrated in the drawings, the eccentric blade 14 is directed at an angle from the axis of the body 12 and has a leading surface 20 and a trailing surface 22 opposite the leading surface 20 and terminates at the toe 24 which extends outwardly from the body 12. Formed on the bit 10 at the upper end of the trailing surface 22 is the convex exterior surface 26 on which are a plurality of generally vertical guide ribs 28 (see Fig. 3) for a purpose which will be made clear later.

At the upper end of the leading surface 20 is the tapered plate 30 at the lower end of which is a circulation port 32 in fluid communication with the fluid passageway 33 in the drill pipe 16. This circulation port 32 combined with the plate 30 serves to provide circulation for the leading surface 20 to wash cuttings aside and prevent balling of earth around the blade 14.

The foregoing structure is conventional in an eccentric spud bit and needs no further explanation or description.

Drilled in the bit 10 is the inverted Y-shaped fluid passageway 34 including in the body 12 the trunk 35 in fluid communication at its upper end with the fluid passageway 33 in the drill string 16 and having a first downwardly directed branch 36 in the blade 14 and a second downwardly directed branch 37 in communication with the circulation port 32. Located in the trailing surface 22 of the blade 14 is a jet port 38 which is in fluid communication with the first branch 36 and thereby in fluid communication with the fluid passage 33 in the drill pipe 16. This jet port 38 is drilled in the eccentric blade 14 at an angle to the axis of body 12 so that the reaction of drilling fluid coming out of this jet port 38 into the well bore 13 forces the leading edge 20 and toe 24 of the eccentric blade 14 against a side 40 of the well bore 13 as best illustrated in Fig. 1. This jet port 38 is preferably located on the bit 10 as close to the toe 24 as is practical in the drilling of the first downwardly directed branch 36 as this jet port 38 may be used to aid in wash-' ing the blade 14 on the initial rotations of the bit 10 after spudding in has been accomplished as will be made clear later.

Apprr )xirnatethe point ofjuncture 42 of first branch .36 v

and secondbranch 37 the first'branch36 is againcounterbored to makeit thesame diameter .as the trunk 35 of the fluid passageway .34.

Referring now to the second branch 37, there is provided in the circulation port 32 the .expellable plug .as- .sembly- 47 whichincludes thegland .48 threadedlysecured in .cireulation port -32 and the expellable plug 49 .releasably held within the bore 50 .extending the length of the ,filand 48, While this expellable plug 49 may be of various material, preferably it is .cast from molten lead poured into the gland 48 before the gland 48 is insertedlin .the circulation .port 32. Provided at the upper end of the bore 50 of the gland 48 as this gland is viewed in Figure 1 there is provided the annular space 52 vwhich is filled with molten lead at the time of the forming of the expellable plug 49 .and which holds the expellable plug 49 Within the gland 48 until sufficient fluidpressure is placed on the upper end of the expellable plug 49..to shearthe lead filling the annular ring 52 and forcethisexpellablevplug 49 out .the gland 48. By varying .the size of theannular space 52 theamount of fluid pressure needed to expel the plug 49 can be varied. Other types of expellableplugs may .be usedand if desired the gland 48 may be entirely omitted and an expellable plug of shearable material may be inserted directlyinto-the circulation port 32. However, the particular .expellable plug assembly .47 illustrated is preferred.

j At the point of juncture 42 of .the first and second branches 36 and 37 respectively, the second branch 37 islessin diameter than the ball 54 so that when the ball '54 is dropped down drill string 16 it will sealingly seat on theball seat 44 and will not lodge in the second'branch 37. Obviously, any other desired meansv may be used in connection with the second branch 37 which willprevent the ball from seatingin the second branch 37 'but will .not prevent the passage of fluid, for example, the means illustrated in United States ,PatentNo. 2 ,l9l,'702, gr anted February 27, 1940 on the application of O. P. Yowll for a Bypass Fitting,.although other means may be used. I In operation the plug assembly 47 including the expellable plug 49is threaded into circulation port 3.2. .The biti12 is then secured to the'lower end of the drill string 16 and lowered .into the well bore 13 until itvreaches the desired place for cutting through a .side 40 of the we1llbore13, During this'lowering the ball 54.is not in use and circulation from trunk 35 passes out ,the jet port 38 as the circulation port 32 is closedby the plug assembly 47. During this lowering of the bit the pressure :of .the drilling fluid is kept sufiiciently lowso that'the toe 24 of eccentric blade '14 is not forced against a side of the well bore 13.

Upon reaching the desired elevation for sidetracking .or directional drilling to begin, the bit 10 is oriented by any conventional methodused in the art so-that the toe 24 points in the direction desired. Once oriented, the fluid pressure inithe drill string '16 is increased so that the action of the fluid leaving the jet port 38 forces the toe '24 against the side 40. Downward movement of the bit 10 by the drill string 16 then causes the toe'2'4 to cut into-the side 40 causing resistance to downward movement of the bit 10 which deflects the 'bit '10 from the axis of the Well bore 13 as is illustrated in 'Fig. 1. This causes theconvex surface '26 opposite the leading bore 13 forcing the toe 24 in the same direction as it is urged by fluid from the jet port 38 thus also aiding in spudding in. To insure that the bit 10 is thoroughly spudded in before rotation begins it may be necessary to raise the bit 10 slightly and then lower it to jam it through the wall 40. In this raising and lowering operation the guide ribs 28 cut iinthe wall on the opposite side from the leading .edgeiflhelping ,to keep the bit 10 properly oriented as to direction. "Further, the convex surface '26 tends to :ride:in the same place in the .well bore opposite the side-40, which action combined with the action of fluid from jet port 38, deflects the toe 24'into the cut it-originally made.

After the bit 10 is spudded in it may then be rotated for a few turnsthroughthe .action ofdrill pipe 16 with fluid from the jet port 38 washing around the blade 14 to carry away cuttings. As shown in Figures 1 and 2 this jet port 38 is directed at less than right angles to the axis of body 12 andpreferably'atapproximately 45 thereto and as has been'heretofore stated is alsolocated close'to toe 24'so the'fluid'from'this jet port 38 is directed' toward the cutting area oftoe 24 andhelps in removing the cuttings in addition to.forcing the blade 14 in the direction desired on originally spudding in. While the jet port 38 may :be directed at right angles to the axis of body '12,this reduces the circulation around the toe 24 'when circulation is through jet port38 and also in such construction there would be more danger of the circulationthrough'the bit 10 while it was being lowered causing accidental hanging ofthe toe .24 me side of the wellbore.

After the bit 10 has been spudded in and, if desired, after a few turns have'been made the ball 54 is dropped down the fliud passageway'33 ,in 'the drillpipe '16 and seats on the ball seat 44in sealing engagement therewith thereby preventing any'fiuid from reaching the jet port 38. 'The 'counterbored'portion of 46 immediately above the ball seat 44 being of approximately the same diameter-as ball'54prevents turbulence of the drilling fluid 'f-rornreaching the ball 54'and unseating it. Because of thepressuresinvolved "a temporary unseating of the ball-54 can cut away the ball seat 44 and prevent a sealing engagement'fromtorrning between the ba1l.5.4 and the ball seat 44.

As soon as the ball 54ghas'seated the 'fluid pressure intheflnid passageway 34 then expels the expellable phig 49 from circulation port 32 permitting drilling fluid under pressure to pass along the-leading surface 20 of blade -14'so"that cuttings are removed in a more efficient manner than by fluid leaving the bit 10 at the trailing-surface of the'blade 1'4. Thereafter drilling continues in-thenorrnal manner of an eccentric spud bitand the bit 10 may be removed from thewell bore when desired in the same manner as a conventional eccentric spud bit.

-It is to benote'd that in cutting through the side "46 no whipstock; or other external mechanical aid in the well-bore 13 was'neeessary-to make the cut.

If it-should be desiredto make the cut in the Wellbore at the bottom of the well bore, the same bit 10,may be used and in the same manner sothe same'bit 10 performs the sidetracking or directional drilling operation whether at the bottom of a wellbore 13 or up from the bottom.

The present invention is, therefore, wellsuited to carry out zthe objects and attain-the advantages mentioned as well as others inherent therein. Changes in details and rearrangements of-parts will suggest themselves to those skilled ill-the art and accordingly'it is desired to be limited only by'the-spirit-o'f the invention as defined by the scope of the appended claims.

What is claimed is: l. In an eccentric spud bitincludin-g an elongate-body adaptedto fit into a well-bore, aneccentric cutting blade at the lower end of the-body including a leading surface surface 20 to bear against the opposite side of-the' well extending-outwardlyfromthe body and a trailing surface opposite the leading surface, and first fluid passageway in the body establishing fluid communication at the upper end of the body with a string of drill pipe, the improvement comprising a second fluid passageway in the bit in fluid communication with the first passageway, a jet port in the trailing surface in fluid communication with the second passageway and directed at an angle to the axis of the body, a ball seat in the second passageway above the jet port adapted to sealingly receive a ball dropped down the drill string, a third fluid passageway in the bit in fluid communication with the first passageway above the ball seat, said third passageway being of lesser diameter at its point of communication with the first passageway than the ball, a circulating port approximate the leading surface in fluid communication with the third passageway, and an expellable plug in the circulating port whereby drilling fluid passing downwardly through the first and second fluid passageways and leaving the jet port forces the leading edge of the cutting blade against a wall of the well bore until the ball is seated whereupon the expellable plug is forced out by fluid pressure.

2. The improvement of claim 1 in which the second fluid passageway is reduced in diameter from that of the first fluid passageway above the ball seat.

3. The improvement of claim 1 in which the jet port directs fluid at approximately 45 to the axis of the body.

4. The improvement of claim 1 in which the expellable plug comprises lead.

5. In an eccentric spud bit including an elongate body adapted to fit in a well bore, an eccentric cutting blade at the lower end of the body including a leading surface extending outwardly from the body and a trailing surface opposite the leading surface, and a first fluid passageway in the body establishing fluid communication at the upper end of the body with a string of drill pipe, the improvement comprising a convex surface on the exterior of the bit at the upper end of the trailing surface, a second fluid passageway in the bit in fluid communication with the first passageway, a jet port through the trailing surface in fluid communication with the second passageway and directed at an angle to the axis of the body, a ball seat in the second passageway above the jet port adapted to sealingly receive a ball dropped down the drill string, a third fluid passageway in the bit in communication with the first passageway above the ball seat, said third passageway being of lesser diameter at its point of communication with the first passageway than the ball, a circulating port approximate the leading surface in fluid communication with the third passageway, and an expellable plug in the circulating port whereby drilling fluid passing downwardly through the first and second fluid passageways and leaving the jet port forces the leading edge of the cutting blade against a wall of the well bore until the ball is seated whereupon the expellable plug is forced out by fluid pressure.

6. The improvement of claim 5 including at least one generally vertical guide rib on the convex surface.

7. An eccentric spud bit comprising, an elongate body adapted to fit in a well bore, an eccentric cutting blade at the lower end of the body including a leading surface extending outwardly from the body and a trailing surface opposite the leading surface, an inverted generally Y-shaped fluid passageway in the bit establishing fluid communication at its upper end with a drill string and having first and second downwardly directed branches, a jet port in the trailing surface in fluid communication with the first branch directed at an angle to the axis of the body, a ball seat in the first branch above the jet port adapted to sealingly receive a ball dropped down the drill string, means associated with the second branch preventing the ball from sealing the second branch, a circulation port proximate the leading surface in fluid communication with the second branch, and an expellable plug in the circulation port whereby drilling fluid passing down wardly through the fluid passageway and through the jet port forces the leading edge of the cutting blade against a side of the well bore until the ball is seated whereupon the drilling fluid forces out the expellable plug.

8. An eccentric spud bit comprising, an elongate body adapted to fit in a Well bore, an eccentric cutting blade at the lower end of the body including a leading surface extending outwardly from the body and a trailing surface opposite the leading surface, a fluid passageway in the bit establishing fluid communication at its upper end with a drill string and having first and second downwardly directed portions, a jet port in the trailing surface in fluid communication with the first portion directed at an angle to the axis of the body, a ball seat in the first portion above the jet port adapted to sealingly receive a ball, means associated with the second portion preventing the ball from sealing the second portion, a circulation port proximate the leading surface in fluid communication with the second portion, and an expellable plug in the circulation port whereby drilling fluid passing downwardly through the fluid passageway and out the jet port forces the leading edge of the cutting blade against a side wall of the well bore until the ball is seated whereupon the drilling fluid forces out the expellable plug.

References Cited in the file of this patent UNITED STATES PATENTS

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