US2296939A

US2296939A - Well bit protector

Info

Publication number: US2296939A
Application number: US391848A
Authority: US
Inventors: Thomas E Mcmahan
Original assignee: Individual
Current assignee: Individual
Priority date: 1941-05-05
Filing date: 1941-05-05
Publication date: 1942-09-29
Anticipated expiration: 1959-09-29

Description

E T'. E. MGMAHAN WELL BIT PROTECTOR Sept. 29, 1942.

Filed` May 5, 1941 Patented Sept. 29, 1942 UNITED STATES y PATENT `OFFICE WELL BIT PROTECTOR Thomas E. McMQalian, Long Beach, Calif.

Application May 5, 1941, Serial No. 391,848

11 Claims.

This invention relates to well drilling tools and has particular reference to protectors for the bits employed in the rotary method of well drilling.I A-general object of the invention is to provide a practical, eiectivie and inexpensive protector 1'or well bits.

In the drilling of deep wells with the rotary method it is a common practice to employ roller rock bits. These bits embody toothed roller cutters supported at the lower end of the bitbody to independently rotate through contact with the earth formation as the bit is rotated and fed downwardly. It is essential that the cutters be free to rotate and the speed of operation or efficiency of the bit is greatly .impaired if the teeth of the cutters become clogged with mud and cuttings. In running a bit down through the Well to its operative position the exposed roller cutters accumulate mud and ball up and the mud 'gathers in the valleys between the cutter teeth. The mud or solid matter is scraped from the wall of the well bore as the bit descends and is picked up or accumulated from the column of mud laden iluid standing in the Well. In many cases the bit is balled up by the time it reaches the bottom of the well bore and is thus made uneflicient before it goes intooperation. v

An important object of this invention is to provide a protector for a well bit which prevents the bit from accumulating mud, cuttings and other solid matter as it is run into the well.

Another object of this invention is to provide a well bit protector which is effective in preventing the cutting parts of the bit from accumulating mud from the well fluid and in presive to manufacture and that is readily shipped and transported.

Another object of the invention is to provide a bit protector of the character mentioned that is easily and quickly applied to the bit when the same is to be run into the well.

A further object of this invention is'to provide a bit protector that is quickly drilled up,

venting the cutting parts from gouging, scraping or cutting mud vand earth formation from the wall of the well as the bit is being run into t'he well. The protector of the present invention not only shields the cutters against the mud v permits the free passage of uidbetween the cutters and body legs and into or through the well string so that it does not interfere with the free lowering of the bit through the well.

Another object of this invention is to provide a well bit protector of the character referred to that is extremely simple and inexpenwhen 'the drilling operations are begun, to be reduced to small fragments that are readily carried to the ground surface with the circulation iiuid.

The various objects and features of my invention will be fully understood from the following detailed description of typical preferred forms and applications of my invention, throughout which description reference is made to the accompanying drawing, in which:

Fig. 1 is a side elevation of a typical roller rock bit equipped with one form of protector of the invention. Fig. 2 is a plan view of the protector shown in Fig. 1 in a flat or stretched out condition with broken lines illustrating the positions of the bit cutters. Fig. 3 is a view similar to Fig. 2 showing another form of protector of the invention arranged on the bit, and Fig. 4 is a fragmentary elevation stretch-out view of the under side of the protector shownin Fig. 3.

The protectors of the present invention may be designed for use on the various forms and types of well drilling tools. In the following detailed description I will describe typical embodiments of the invention as employed on conventional roller rock bits. It is to be understood that the invention is not to be construed as vlimited or restricted to the specicforms or. ap-

plications of the inventionl herein described.

The typical roller rock bit illustrated in thel vlower ends of the legs I3 to cut the well bore to gauge. 'I'he bit further includes cross cutters or inner cutters I6 rotatable about a general horizontal axis and supported between the legs I4 which are spaced about 90 from the legs I3. The cutters I5 and|6 have the usual teeth I'I for acting on the earth formation at the bottom of the well bore and the body I has the usual circulation passage I8 and discharge ports.

'I'he protector of the invention illustrated in Figs, 1 and 2 may be said to comprise, generally, a exible body 2|! to be engaged against the lower side of the bit, tabs or straps 2| on the body 20 adapted to be trained upwardly over the exposed toothed sliie parts of the outer cutters I5, and means-22 for cooperating with the straps 2| to secure the protector to the bit. g

The protector body I0 is designed to engage upwardly against and shield the exposed or projectinglower parts of the cutters I and I6 and in practice may be designed to cover substantially the entire lower side of the bit. In accordance with the invention the body is formed of a flexible, pliable and readily shaped material to be easily draped or trained over the bit and to generally conform to the cutters I5 and I6. The invention contemplates the formation of the protector body 20 of various materials and contemplates the construction of the body of any inexpensive readily obtained and produced material that possesses the required flexibility and that may be readily drilled up by the bit. The protector body 20 may be formed of fabric, rubber, rubber composition, synthetic rubber, ilexlble plastic, or the like, or combinations of such materials. I may prefer to form the body 20 of undercured rubber with or without fabric as such material has the desired characteristics of flexibility, strength and low specific gravity and is readily broken up or ground up into small fragments by the bit. The material of which the body 20 is formed preferably has a specific gravity comparable to or less than the specific gravity of the well fluid so that its particles or fragments will be readily carried from the well by the well fluid when the bit is put into operation.

The protector body 20 is preferably, though not necessarily, in sheet form and may be a relatively thin member having upper and lower surfaces occupying parallel planes. 'I'he shape of the sheet-like body `20, of course, depends upon the type of bit on which it is to be used. In the case illustrated the body III has two diametrically opposite edge portions or edges 23 curved outwardly to substantially conform to the outer active edges of the cutters I5 when the protector is trained over the bit. As illustrated in Fig. l of the drawing these edges 23 lie within the cutting range or circumference of the cutter I5 and occur at-the outermost active edge parts of the cutter teeth I1 so that the body serves to prevent the teeth from engaging the wall of the well and from accumulating mud as the bit is run down the well. The other edge portions of the body 20 may be formed to merge with the straps 2|, as illustrated.

In accordance with the invention the body 20 of the `protector is porous, perforated or ported to permit th-e flow of fluid through the passage I8 when the tool is run into the well. Those portions of the body 2|) which lie under the channels or spaces occurring between the spaced adjacent legs I3 and I4 are porous, perforated or ported to provide for the required flow of fluid to and from the passage I8. In the simple pre.- ferred construction illustrated the protector body 20 has spaced ports 25 of substantial capacity located to communicate with the spaces or channels occurring between the adjacent legs I3 and Il. The ports 25 are proportioned and arranged to allow the free iiow of fluid upwardly vpast the bit and through the passage I8 when the bit is being run down through the well.

'I'he straps 2| are employed to retain the. protector in position on the bit and serve to shield or protect the exposed toothed portions of the bit cutters that are above the 'plane occupied by the bodyY 20. The number and location of the straps 2| may vary with protectors intended for use on different styles and types of bits. In the particular application of the invention illustrated there are four straps 2| extending from the body 20. In the embodiment of the invention being described the straps 2| are integral with the body 20 being continuous extensions of vthe body. With this construction the complete protector may be readily cut from a sheet of the selected material or stock. As above described, the margins or edges of the body 20 may merge with the edges of the straps 2|. With this formation the inner or lower portions of the straps 2| are of increased width, as best shown in Fig. 2. The major upper portions of the straps -2| may have straight generally parallel edges. The straps 2| are of sufficient length to extend upwardly to the shank or drill collar I2 of the bit.

In accordance with the invention the straps 2| are located to extend upwardly around or over the toothed portions of the cutters I5 which are exposed at the sides of the bit and the lower portions of the str-aps 2| are of suiiicient width to fully and eectively shield these portions'of the cutters and to close or cover the slots or spaces between the legs I3 and I4. 'I'his is clearly illustrated in Fig. 1 of the drawing where it will be seen that the straps 2| engage upwardly around the cutters I 5 to fully cover their toothed parts andextend across orcover the gaps between the cutters I5 and the legs I 4. Further, it will be observed that the portions of the body 20 at the bases of the straps 2| also curve upwardly at the lower end of the bit to better protect the cutters I5.

The means for attaching the protector to the well -bit may be varied greatly Without departing from the broader aspects of the invention. In the simple case illustrated the means 22 comprises a length of cord, wire 26, or the like, wrapped or trained about the upper portion of the bit or the drill collar I2 thereof and engazed with the straps 2|. I have shown slots 21 formed in the upper parts of the straps 2| and have shown the wire 26 threaded through the slots to have dependable engagement with'the straps. The ends of the wire 26 are tied or twisted together as at 28.

It is believed that it will be apparent how the protector in Figs. 1 and 2 of the drawing may be easily and quickly secured in its operative position on the bit. The body 20 is merely engaged against the under side of the bit with its edges 23 in the correct relation to the cutters I 5 whereupon the straps 2| are trained upwardly over the cutters I 5 to bring their upper parts to the shank or drill collar I2. The wire 26 is then trained about the shank or drill collar I2 and tied or twisted together at 28. It is preferred to secure the protector so that the body 2U and the straps 2| are tightly drawn on the bit to closely hug and conform to its cutters I5 and I 6 and other parts. The protector may be applied to the bit immediately before running the bit into the well. When the bit is lowered through the well the body 20 and the straps 2| cover and shield the when the bit is operated to drill up the protector.

otherwise exposed toothed portions of the cutters -I and I5 and the gaps betweenV the legs I3 and I4 so that they cannot accumulate mud. The body 20 and straps 2| also serve to prevent the cutters from scraping, gouging or cutting into the side wall of the well bore and thus prevent the cutters from being clogged with the mud layer or earth formation from the well wall. The ports 25 permit the free upward ilcw of fluid into the passage I l so that the protector does not obstruct the lower end of the drilling string. When' theV bit reaches the bottom of the well it is put into operation in the usual way. The toothed cutters I5 and I5 quickly drill up the protector, the protector being cut or reduced to small fragments. These fragments are carried away by the circulation iiuid and do.

not interfere with the drilling operation. The cutters I5 and I6 reach the lower end of the well in a clean condition to operate at their greatest efficiency.

The form of the invention illustrated in Figs. 3 and 4 of the drawing may be said to lcomprise, generally, a body 20, straps 2|l on the body and means 22B for securing the protector to the bit.

In the structure illustrated in Figs. 3 and 4 the body 2i)8L and the straps 2|* are separately formed members. 'I'he -body 2li'l may be a generally dat plate or disc-like part formed of a readily drillable material. The body 20* may be constructed of rubber, rubber composition, synthetic rubber, fabric or a combination of such materials or may be constructed of Bakelite, plastic, or the like. It may be preferred to construct the body 20 of laminated material whose laminations are readily separated and broken up when the bit is put into operation. It is preferred to construct the body 2li8L of a material having a specific gravity comparable to or less than that of the well fluid. The body 20 may possess substantial nexibility to conform to the cutters I5 and I6 or may be fairly rigid. In the drawing the body 20 is shown flat when engaged against the bit, it being understood that the body may be suiiiciently ilexible to be bent upwardly around the cutters I5 and I6 when the protector is operatively secured to the bit. The protector body 2lil is shaped and proportioned to fully cover the under sides of the cutters I5 and I6. In the particular case illustrated the body 20 has curved edges 30 formed and positioned to lie fiush with or to conform to the outermost active edges of the cutters IB.

As shown in Fig. 3 of the drawing these edges 3i)v occur at the lower ends of the cutters I5 and follow the outermost cutting edges of the cutters but do not project beyond the cutters. The body 2|)a may' have straight edges 3| at the outer ends of the inner cutters I6. The protector body 20 is porous, perforated or ported to provide for a controlled or directed circulation of iluid through the protector. I have shown four spaced ports 32 formed in the body 20 and located to register with the Igaps or passages between the legs I3 and I4 of the bit.

It may be desired to roughen, corrugate or tooth the protector body 2lia to assure the ready kdrilling up of the protector by the bitand' to prevent the protector from spinning in the well when the bit is put into operation. In the construction illustrated there are corrugations or ridges 33 formed on the upper side of the body 2U,a and positioned for engagement by the teeth of the cutters I5 and I6. 'I'he corrugations or ridges 33 prevent the cutters from slipping or skidding over the surface of the protector body The under side of the body 20* may likewise be ridged to have non-rotatable cooperation with the earth formation to the bottom of the well. In the case illustrated, however, the under side of the body 20* is provided with a central diametric ridge or blade 3l. 'I'he engagement of the blade Il with the earth formation effectively prevents the protector from sliding or skidding when the bit is operated to drill up the protector.

The straps 2|* serve the same function as the above described straps 2I beingoperable to protect or shield the otherwise exposed parts of the cutters I5, to close the otherwise open sides of the spaces between the bit legs I3 and I4, and to assist in securing the protector on the bit. The inner or lower ends of the straps 2|* are suitably fixed to the edge portions of the body 20. The straps 2la may be riveted, pinned, cemented, vulcanized or stitched to the body 20, depending upon the nature of the materials of which the body and straps are constructed. The straps 2 I I may be formed of any selected flexible material that is drillable and that will readily flush from the well. For example, the straps 2|a may be formed of fabric, rubber, rubber composition,` or combinations of such materials. The lower portion of the straps 2 I may be thickened as at to better shield the toothed parts of the cutters I5 which extend laterally beyond the legs I3. The straps 2ln are sumciently long to engage upwardly around the cutters I5 and the upper portion of the bit body III to have their upper ends at the bit shank or drill collar I2.

The means 22 may be the same as the means 22 described above and may consist of a flexible element, such as a cord or wire 36, wrapped about the bit shank and passed through slots 31 in the straps 2|. The ends of the wire 36 are tied or twisted together to dependably secure the protector on the bit.

The use and operation of the protector illustrated in Figs. 3 and 4 are the same as in the previously described form of the invention. The protector is applied to the bit before running the same into the well and is positioned so that its body 20ai and straps 2l fully shield the exposed parts of the cutters I5 and I 5. The straps 2| further serve to seal or close the spaces between the legs I3 and I4. When `the tool is lowered through the well the protector prevents the ex-` posed toothed parts of the cutter from gathering or accumulating mud and effectively prevents the teeth of the cutters from gouging lor scraping the wall of the well. the bottom of the well it is put into operation. The protector is quickly drilled up or reduced to small fragments which are carried away by the circulation fluid. The ridges 33 and the blade 34 assure the quick drilling up of the body 20a.

The present invention provides well bit Vprotectors that are very inexpensive to manufacture and that are easily and quickly applied to the bits. The protectors are formed to be readily shipped and transported without danger of breakage and may be employed on practically all forms of well bits.

Having described typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art or fall within the scope of the following claims.

When the bit has ,reachedA Having 'described my invention, I claim:

1. `Aprotector for a well bit having toothed cutters, the protector comprising a ilexible drillable body for covering the cutters, and means for securing the body to the bit.

2. A protector for a Well bit having toothed cutters with exposed parts, the protector comprising a flexible drillable body for covering the under sides of said parts, and means for securing the body to the bit.

3. A protector for a. well bit having toothed cutters with exposed parts, the protector comprising a drillable body for shielding the under sides of said parts, and straps extending upwardly from the body and trained over the sides cof said parts to shield the same.

4. A protector for a well bit having toothed' cutters with exposed parts, the protector com' prising a drillable body for shielding the under sides of said parts, flexible straps on the body adapted to be trained over the sides of said parts to shield the same, and means cooperating with straps for securing the protector to the bit.

5. A protector for a well bit having roller cutters at its lower end, the protector comprising a flexible body to be engaged under the bit cover and shield the lower parts of the cutters, and

flexible parts extending upwardly from the body to be trained over the side parts of the cutters to shield the same.

6. A protector for a well bit having roller cutters at its lower end, the protector comprising a ilexible body to be4 engaged under the bit cover and shield the lower parts of the cutters. and

flexible strap-like parts integral with the body and adapted to be trained upwardly over the side parts of the cutters to shield the same and to close the spaces between the cutters.

'7. A protector for a well bit having roller cutters at its lower end, the protector comprising a ilexible body to be engaged under the bit cover and shield the lower parts of the cutters, the body having a iiuid port, exible strap-like parts on the body adapted to be trained upwardly over the side parts of the cutters to shield the same, and means engaged with the strap-like parts for securing the protector to the bit.

8. 'A protector for a well bit having spaced cutters on its lower end. the protector comprising a sheet-like body of ilexible drillable material shaped to conform generally to the contour of the lower end of the bit and its cutters and adapted to be arranged against the lower side of the bit to shield the cutters, the body having at least one port for communicating with the space between the cutters.

, 9. A protector for a well bit having spaced cutters on its lower end, the protector comprising a sheet-like body of iiexible drillable material shaped toconform generally to the contour of the lower end of the bit and its cutter and to lie entirelywithin the cutting gauge of the cutters, and straps integral with the body to be trained upwardly over the sides of certain of the cutters to shield the same.

10. A protector for a well bit having roller cutters on its lower end, the protector comprising a drillable body adapted to be engaged against the lower side oi the bit and having its margin shaped to conform generally to the contour of 'the periphery of the blt and its cutters, a part on the under side of the body for engaging the bottom of the well to hold the body against turning, and means for securing the protector to the bit comprising exible straps on the body to be trained upwardly over the side portions of the cutters, and securing means for engaging with the straps.

11. A protector for a well bit having roller cutters on its lower end, the protector comprising a drillable body adapted to be engaged against the lower side of the bit and having its margin shaped to conform generally to the contour of the periphery of the bit and its cutters, the body having at least one port'for passing iiuid through the bit, a part on the under side of the body for engaging the bottom of the well to hold the body against turning, and means for securing the protector to the bit comprising ilexible straps on the body to be trained upwardly over the side portions of the cutters, and securing means for engaging with the straps.

THOMAS E. MCMAHAN.