US3439757A

US3439757A - Drilling apparatus

Info

Publication number: US3439757A
Application number: US712561A
Authority: US
Inventors: Wayland D Elenburg
Original assignee: Individual
Current assignee: Individual
Priority date: 1968-03-12
Filing date: 1968-03-12
Publication date: 1969-04-22
Anticipated expiration: 1986-04-22

Description

April 22, 1969 w. D. ELENBURG DRILLING APPARATUS Sheet Filed March 12 1968 N m & F m A m w MARCUS L. BATES April 22, 1969 w, ELENBURG 3,439,757

DRILLING APPARATUS Filed March 12, 1968 Sheet 3 of 2 INVENTOR. WAYLAND D. ELENBURG BY MARCUS L. BATES United States Patent US. Cl. 175-9325 9 Claims ABSTRACT OF THE DISCLDSURE A well drilling apparatus for preventing excessive flow of fluid into a formation while at the same time maintaining the cones of a bit free from the cuttings. This apparatus is comprised of concentrically arranged drilling pipes flow connected to a sub with the sub having a formation cutting bit attached to the lower depending end thereof. The sub and bit include longitudinally extending passageways, with one such passageway centrally extending through the sub and bit and into communication with the tubing located within the drill pipes, and with the remaining passageways being radially arranged to communicate with the annulus of the drill pipes. A cylindrical downwardly depending skirt is rigidly attached to the sub and downwardly depends about the drill bit, thereby enclosing the drill shanks therewithin. A weir in the form of a plate member is attached between adjacent shanks and is spaced apart from and enclosed by the lower terminal end of the skirt thereby providing a passageway for clean drilling fluid which flows from the drill pipe annulus and between the weir and skirt. The passageway forces the clean fluid to flow in close proximity of the drill cones to thereby maintain the cones free of debris in an improved manner. This action also removes large formation cuttings from the vicinity of the drill bit so as to prohibit further reduction in their size, thereby effecting a savings in the expenditure of power which must be used by the cone, as Well as immediately returning large cuttings or chips of the formation to the surface for analysis.

Background of the invention Drilling wells by utilizing concentrically arranged drill pipe wherein the outer drill pipe is threaded at each depending end to permit connections to be effected therebetween in the usual manner, and wherein a concentrically located tubing is positioned within the outer drill pipe in a manner whereby the depending ends sealingly cooperate together to permit rapid connections between the entire assembly to be effected has grown in popularity in the drilling art. The purpose of the concentrically arranged drill pipe is to permit rapid return of large cuttings to the surface of the earth while at the same time maintaining the cones of a tri-cone bit, for example, free of debris; that is, reground cuttings. This combination of elements is especially useful in carrying out a continuous sampling operation wherein the chips produced by the action of the bit are used for obtaining geological information. This operation continuously recovers large pieces of formation to thereby permit continual analysis of the formation since every particle of the drilled formation must pass through the tubing which is located within the drill pipe. Therefore, the likelihood of hold-up of the drilled chips is minimized and at the same time loss of fluid up the annulus formed by the drill pipe and the bore hole is minimized.

The drilling fluid may be either liquid or air. Where the bore hole passes through an aquifer, air is often utilized in the form of an air lift by pumping air down through the annulus while air and water are rapidly returned to the surface through the centrally located tubmg.

3,439,757 Patented Apr. 22, 1969 Summary of the invention The present invention comprehends an improved sub and an improved bit for use in a well drilling apparatus which prevents excessive flow of fluid into a formation while at the same time maintains the cones of a bit free from the cuttings. This apparatus is comprised of concentrically arranged drilling pipes flow connected to a sub with the sub having a formation cutting bit attached to the lower depending end thereof. The sub and bit include longitudinally extending passageways with one of the passageways centrally extending through the sub and bit and into communication with the tubing located within the drill pipes, and with the other passageways radially extending in a manner to communicate with the annulus of the drill pipes. A cylindrical downwardly depending skirt is rigidly attached to the sub and downwardly depends about the drill bit, thereby enclosing the drill shanks therewithin. A weir in the form of a plate member is attached between adjacent shanks and is spaced apart from and enclosed by the lower terminal end of the skirt thereby providing a passageway for the clean drilling fluid which flows from the drill pipe annulus and between the Weir and skirt. The passageway forces the clean fluid to flow in close proximity of the drill cones to thereby maintain the cones free of debris in an improved manner. This action further prevents the bit from balling up in sticky formations, as well as removing large formation cuttings from the vicinity of the drill bit so as to prohibit further reduction in their size. This effects a savings in the expenditure of power which must be used by the cone, as well as immediately returning large cuttings or chips of the formation to the surface for analysis.

Therefore, a primary object of the present invention is the provision of a combination drill bit and sub which includes an improved circulation pattern to thereby enable an improved chip drilling operation to be carried out.

Another object of the present invention is the provision of a sub in combination with a bit and includes a simple modification which is effected upon a conventional bit to thereby enable an improved sub and drill bit combination.

Still another object of the present invention is the provision of an improved sub and bit combination which includes radially arranged passageways which are always in communication with one another when the bit and sub are made-up.

A further object of the present invention is the provision of an improved flow passageway associated with a drill bit and sub for maintaining the cutting teeth of the bit free of debris.

Another object of the present invention is the provision of a drill bit and sub combination which maintains the drill bit free of debris, permits the rapid return of large chips which are loosened from the formation by the cone of the bit, and which reduces the power expenditure required in order to rotate the bit.

The above objects are attained in accordance with the present invention by the provision of a drill bit and sub combination which are fabricated in a manner whereby passageways are always aligned with each other when the bit and sub are made-up, with one passageway being arranged whereby fluid flow is directed across the forma* tion cutting cone in an improved manner.

These and other objects of the present invention will become evident as the remainder of the present disclosure is digested.

Brief description of the drawings FIGURE 1 is a longitudinal cross-sectional view of a drill bit and sub made in accordance with the present invention;

FIGURE 2 is a fragmentary elevational view of the lower depending end of the present invention;

FIGURE 3 is a fragmentary representation illustrating a portion of the combination seen in FIGURE 1, taken substantially along lines 3-3 of FIGURE 1;

FIGURE 4 is a side elevational view of part of the device seen in FIGURE 1, with some parts being broken away for clarity;

FIGURE 5 is similar to FIGURE 4 and sets forth a modification thereof; and

FIGURE 6 is a cross-sectional view taken along lines 6-6 of FIGURE 1.

Description of the preferred embodiments Looking now to the details of the drawings, and particularly to FIGURE 1, there is seen illustrated a tool joint, hereinafter called a sub, which attaches to a drill collar or outer pipe of a dual string by means of threads 12 in a manner known to those skilled in the art. A second set of threads 14 are provided at the lower portion of the sub in order to threadedly receive a tri-cone rock bit, hereinafter called a bit. A downwardly depending skirt, generally indicated by the arrow at numeral 16, is rigidly attached to the sub with the outer periphery of the skirt being coextensive with that of the sub. Abrasive welding at 18 secures the skirt to the sub while at the same time provides a hard surfacing material for wear purposes and for maintaining the gauge of the bore hole. The lower depending marginal edge portion of the skirt is also provided with hard surfacing material as indicated by the numeral 20, with the lowermost edge portion of the skirt being indicated by the numeral 22. A centrally located passageway 26 longitudinally extends through both the bit and sub with the inside peripheral wall 28 being formed by a return tube inner-pipe connector 32 which telescopingly receives the inside surface of the tubing of the before mentioned drill pipe. The connector is rigidly affixed to shoulder seat 30 by any suitable means, or alternatively can be made an integral port of the sub.

Radially spaced apart from the connector are a series of passageways, two of which are seen at 34 and 36, and each of which flow connect to a first annular chamber 38, with the last named chamber being formed between the before mentioned skirt and sub.

Four spaced apart passageways 40 each communicate the first annular chamber with a second annular chamber 44 with the second annular chamber being formed between the skirt and the main body of the bit.

The inside peripheral wall of the lower depending marginal edge portion of the skirt, indicated by numeral 50, is sealingly received by a shoulder, generally indicated by the arrow at numeral 52, which circumferentially extends about the outer periphery of the downwardly depending shank of the bit, thereby leaving an edge portion at 54 against which the skirt and bit mate together in abutting relationship, and leaving the bit shank exposed as indicated by the arrow at numeral 56. Each cone 58 includes teeth 60 thereon with the cone being rotatably attached to the shank in the usual manner. While three cones are illustrated herein, other numbers of cones may be em ployed while still remaining within the scope of the present invention.

A weir or baflle plate, generally indicated by the arrow at numeral 62, is attached along upper edge portion 64 to adjacent shanks with the weir being spaced apart from the inside peripheral wall surface of the skirt to thereby form a passageway 66 therebetween.

Each weir is secured to adjacent depending shanks in a manner whereby three passageways are formed with each passageway being defined by the skirt, weir, and adjacent shanks, assuming the modified bit to be of a tri-cone design.

As seen in FIGURE 2 in conjunction with FIGURE 5, the weir is upwardly sloped at 62' so as to provide ample clearance between the upwardly rotating teeth of the cone and the lowermost edge portion of the weir, while at the same time fluid is forced across the cone teeth in an improved manner. Where deemed desirable, however, the lowermost edge portion can be maintained horizontal with respect to the bit as seen at 62 in FIGURE 5. Sometime it is also advantageous to modify the skirt by providing the lower marginal edge portion thereof with a cut-out as indicated by the arrow at numeral 70.

Operation In operation, the sub and bit are connected together and to a dual drill pipe. The dual drill pipe consists of an outer main drill pipe which rotatably turns the bit and which threadedly cooperates with the threads of the sub as indicated by numeral 12. The drill pipe is screwed to gether with other joints of drill pipe in the usual manner. As the various pipe threads are made-up, the inner pipe, or inner tubing (not shown) telescope together with a suitable ring seal such as an O-ring so as to leave concentrically arranged drill pipes having an inside flow passageway and an annular flow passageway. This arrange ment permits drilling fluid to flow down through the annular or outer passageway, through radially spaced apart

passageways

34 and 36, and into the first annular chamber. The flow then continues through one of the four passageways 40 to where it enters the second annular chamber which in turn is flow connected to one of the three passageways formed between each of the, depending shanks. As the fluid flows down between the passageway formed between the weir and lower depending end of the skirt as seen at 66 in FIGURE 1, the fluid is forced across the weir, where it is forced to flow in intimate contact across the bit teeth as it continues toward the central passageway. Therefore the fluid flow is forced to follow the path described between the shanks which support the cones, to thereby enhance cleaning of the cone as well as immediately placing large chips into suspension before they are re-ground into smaller pieces. Fragments of the formation mix together with the fluid and continue to flow upwardly through the central passageway 26 of the bit and inner return tube connector whereupon the flow then continues up through the centrally located tubing of the drill pipe.

Accordingly, the weir together with the skirt directs the flow of water, air, or a combination thereof, as well as other drilling fluid about the cones of the bit in an improved manner. This action efiiciently and rapidly removes large chips of formation which results in a more efiicient drilling operation as well as providing a more desirable means of rapidly obtaining core samples for geological study. In sticky formations, the bit is less likely to become balled up" for the reason that debris of this nature will become intermingled with the intimate flow of fluid thereabout due to the improved circulation in the cone area which is brought about by the skirt and the weir. This also reduces the tendency of fluid to return up the hole annulus.

It will be noted that the four passageways 40 are arranged with respect to the three passageways formed between the shanks in a manner whereby flow is always effected between the sub and bit, regardless of the resulting relative position of the former with respect to the latter when the bit and sub are made-up or threadedly mated at 14. Furthermore, should the bit design fail to leave a second annular chamber, such as seen at 44, it is considered within the comprehension of this invention to further modify the bit to thereby provide flow communication between passageway 66 and passageways 40.

As noted when comparing FIGURE 1 with FIGURES 4 and 5, the relative position of the lowermost edge portions of the skirt and weir may be arranged wherebythe skirt depends below the weir (FIGURE 5) or where the skirt is located substantially above the weir (FIG- URE 4). Where the drilling operation requires no splitstream'ing, the lowermost edge portion of the skirt is preferably positioned with respect to the weir as illustrated in FIGURE 1 or 5. Depending upon the bit design, this may sometime result in a shoulder design at 52 which does not leave an edge portion at 54 for abutment between the lower edge of the skirt. This requires closer tolerance between the inside diameter of the skirt and the shoulder in order to effect a positive seal therebetween. It is considered within the comprehension of the present invention to reinforce each shank should the shoulder require the removal of excess material from each bit shank.

The hard surfacing 20 helps to stabilize the bit, reduces circulation of water up the hole annulus, and reduces wear on the sub and bit shanks.

The present invention enables a standard rock bit, such as the illustrated tri-cone bit of FIGURE 1, to be utilized as a part of the present novel combination by merely machining a shoulder as seen at 54 of FIGURE 1, for example, in order to sealingly accommodate the downward depending terminal end of the skirt. The three weirs (assuming a tri-cone bit) are easily installed as an integral part of the bit by merely welding the weir between adjacent shanks of the bit in spaced apart relationship with respect to the skirt. A tri-cone =bit requires only three weirs.

When drilling in hard rock formation, it is advantageous to slope the lower terminal end portion of the weir as seen in FIGURES 2 and 4 in order to prevent the upwardly traveling teeth of the cone from carrying a hard chip around with it whereupon it may strike the weir causing damage to the apparatus. When the weir is sloped in a manner as illustrated in FIGURES 2 or 4, and since the drill stem conventionally turns in a direction to cause the teeth of the cone of FIGURE 2 to be moving upwardly with respect to the lower portion of the weir, the area between the lower edge of the weir and the teeth of the cone is increased by sloping the weir in the above described manner. When drilling through formations which do not pose this problem, the bottom edge portion of the weir can be maintained horizontally disposed as illustrated in FIGURE 5.

As further seen in FIGURE 5, it is sometime desirable to provide the marginal edge portion of the lower depending end of the skirt with a semicircular cut-out, as generally illustrated by the arrow at numeral 70. The cutout facilitates flow of fluid back up the annulus of the hole where it lubricates the outer peripheral surface of the drill pipe, sometime referred to as split streaming, where a part of the fluid is deliberately returned up the outside of the drill pipe with the major fluid flow occurring up the inside tubing of the drill string.

Accordingly, it will now be appreciated by those skilled in the art that the novel sub of the present invention can be utilized in conjunction with a multiplicity of different drill bits by merely eflecting the illustrated modifications upon a standard bit. The modification includes the provision of a shoulder which can be formed on the bit in a conventional turning lathe. The weirs may be in the form of the illustrated plate members which are best welded between each adjacent shank which supports the cone of the bit. The sub and bit are preferably fabricated as two separate units, as illustrated in the figures of the draw- The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

I claim:

1. A well drilling apparatus for preventing excessive flow of fluid into a formation by restricting the major flow of drilling fluid to dual passageways of concentrically arranged drilling pipe, comprising, in combination:

a sub and a formation cutting bit, said sub having fastener means for removably securing said bit to the drilling pipe;

means forming a centrally located passageway longitudinally extending through said sub and said bit, means forming radially spaced apart passageways through said sub;

said bit including a main body member, spaced apart cones, and spaced apart shanks with each said cone being connected to said main body by one of said shanks;

means forming a circumferentially extending shoulder about the outer periphery of said main body;

means forming a coextensive downwardly depending.

cylindrical skirt member having an upper end attached to said sub and a lower end slidably received about said shoulder,

a weir attached to adjacent shanks and spaced apart from said skirt to thereby form a flow passageway between said shank and said skirt; whereby:

fluid flow from said radially spaced apart passageways flows between the weir and skirt, into close proximity of the cones, and through the centrally located passageway to thereby remove the formation as it is cut away by the cones.

2. The combination of claim 1 wherein said weir is rigidly attached between adjacent shanks to thereby cause fluid to flow between the weir and skirt, about the lowermost edge portion of the weir, and across the bit cones.

3. The combination of claim 1 wherein said weir is downwardly sloped in the direction of the rotation of the bit to thereby prevent damage to the trailing edge portion of the weir.

4. The combination of claim 1 wherein the lowermost edge portion of said skirt extends in a downward direction to a lower position as compared to said weir.

5. The combination of claim 1 wherein said weir is attached to adjacent shanks in a manner to thereby cause fluid to flow between the weir and skirt, about the lowermost edge portion of the weir, and across the bit cones; and

said weir is downwardly sloped in the direction of the rotation of the bit to thereby prevent damage to the trailing edge portion of the weir.

6. The combination of claim 1 wherein said weir is downwardly sloped in the direction of the rotation of the bit to thereby prevent damage to the trailing edge portion of the weir;

said lowermost edge portion of said skirt extends in a downward direction to a lower position as compared to the weir.

7. The improvement of claim 1 wherein said bit includes three cones, and four said radially spaced apart passageways are provided to thereby assure communication between each passageway formed by the weir, and each said radially spaced apart passageway.

8. he improvement of claim 1 wherein said bit is a conventional tri-cone bit which is modified by fabricating said shoulder thereon, and by welding said weirs in the recited positions.

9. The improvement of claim 1 wherein the lowermost edge portion of said weir is parallel to the lowermost edge portion of said skirt.

References Cited UNITED STATES PATENTS 2,894,727 7/1959 Henderson -321 X 3,151,690 10/1964 Grable 175325 X 3,208,539 9/1965 Henderson 175215 DAVID H. BROWN, Primary Examiner.

US. Cl. X.R.