US2987130A - Bit passage plug inserts and bit with plugged passages - Google Patents

Description

June 6, 1961 w. D. MclNTYRE 2,987,130

BIT PASSAGE PLUG INSERTS Ab I D BIT WITH PLUGGED PASSAGES Filed Aug. ,22, 1957 W////a/77 17. M ffl/y/e I INVENTOR. 25

2e- 1 BY $10k ATTORNEY United States 41 2,987,130 BIT PASSAGE PLUG INSERTS AND BIT WITH PLUGGED PASSAGES William D. McIntyre, 1917 Westheimer, Houston, Tex., tissignor of fifty percent to William E. Ford, Houston,

Filed Aug. 22, 1957, Ser. No. 679,620 3 Claims. (Cl. 175-318) This invention relates to bit passage plug inserts, and to bits with plugged passages, and in particular it relates to any conventional type drilling bit for drilling wells by the rotary method when such bits have plugged passages therein to prevent the upward flow of circulating fluid through such passages as the bit is lowered into the well bore, and in detail it also relates to plugs, and to structures thereof, employable to plug such passages against the upward passage of hydrostatic fluid under great pressure through such passages.

It is a primary object of this invention to provide a drilling bit of the conventional class, in combination with plugs installed in the passages above the bit cones, when such passages have abrasion resistant inserts therein, such plugs being of strength to resist upward expulsion by the hydrostatic pressure from below, and being sufiiciently pliant and resiliently contractive to contract from the tapered surface of the insert within which it is installed to pass downwardly responsive to the fluid pressure of the drilling mud or circulation fluid from above.

It is a further object of this invention to provide a plugged drilling bit of this class in which the plugged bit passage inserts receive plugs therein to remain installed as the bit is lowered into the well bore, the plugs being so contractive under the pressure of drilling mud or circulating fluidas to be expelled downwardly from the insert responsive to the pressure of the mud or fluid exerted from above.

It is still another object of this invention to provide a bit of this class equipped with plugs which are easily insertable to remain in place in the bit passage inserts when a bit, having a drill stem connected thereabove, is handled in the well bore.

It is also another object of this invention to provide bit passage plugs of this type which are adapted to lip over the tapered bit passage insert and stay lodged therein when under substantial fluid pressure from above in cases when it is found expedient to carry a certain amount of drilling mud or circulation fluid in the drill string when operating in wells under exceedingly high hydrostatic pressures, thereby obviating collapsing of the drill pipe; such plugs, although withstanding such fluid pressures from above, being capable of being expelled from the bit passages when the drill string is later filled with fluid and pump pressure exerted thereon.

It is another and further object of this invention to provide a method of running a drill string dry into the well bore by plugging the bit passages with plugs which will resist being blown out upwardly by the hydrostatic pressure fluids through which the drill string passes downwardly, and then expelling the plugs by pumping circulating fluid down the drill string to expel the plugs from the bit passages so that drilling may proceed by the rotary method.

' Other and further objects will be apparent when the specification hereinbelow is considered in connection with the drawings in which:

FIG. 1 is a sectional elevation through a conventional bit and through a plug embodying this invention;

' FIG. 2 is an elevation of the plug employed to stop "up the passage through the conventional insert employed in bit passages; and

ice

FIG. 3 is a sectional view taken along lines 33 of FIG. 2. r

In the conventional manner of drilling wells by the rotary method, a conventional type bit similar to the bit shown in FIG. 1 is installed on the lower end of the drill collar forming the lowermost element of the drill stem which is rotated by conventional means at the top of the well to thereby rotate the cutting elements, usually rotating cones, which wear away the formation of the well bore in rotation and responsive to the great weight exerted thereon during rotation by the drill stem thereabove.

In order to lubricate the drilling operation and wash away the cuttings abraded away from the formation by the cutting elements of the bit, it is necessary to circulate a fluid, as a drilling mud, down the well bore to pass out through passages in the bit and to contact the cutting elements, as the rotary cones, and wash away the detritus and/or cuttings from the cones and transport them up the annular space between the drill stem and the well bore to the top of the well to be settled out of the drilling mud which may then be recirculated downwardly.

As the drill stem is lowered into the well bore, as in an example case, after a worn bit has been replaced by a new bit, if the passages through the bit are not plugged the hydrostatic fluid in the well bore will enter the'bit passages and time permitting, the fluid entering through the bit passages into the drill stem will rise therein to the level of the fluid in the well bore around the drill stem. Then, should the drill stem be lifted, if it is lifted more rapidly than the fluid can run back out by gravity through the restricting area of the passages through the bit, at first the weight of substantially all of the fluid which has entered the drill stem will be added to the weight of the load conventionally placed upon the conventional derrick handling the drill stem from the top of the well. Thus this load can be greatly increased and at times increased to a weight above the designed load capacity of the derrick. Of course, if the derrick lifts the load, as lifting proceeds the load will continually diminish as more and more fluid runs out through the restricting area of the bit passages.

It also can occur that this hydrostatic fluid can be of such pressure that it can pass upwardly through the bit passages and up the drill stem and cause damage upon arrival at the top of the well. In fact a combination of the hydrostatic fluids thus entering through the bit passages, and the hydrostatic pressure fluids acting therebelow on the body of the bit base, have been known to seriously resist the downward passage of the drill stem and at times to blow the drill stem upwardly.

In order to avoid the possibility of occurrences such as herein described it has been found advantageous to plug the bit passages prior to lowering the bit on the drill stem on which it is installed, into the well bore, such practice in oil field terminology being described as running the drill stem dry in the well.

Various devices have heretofore been employed for this purpose, such as upwardly seating valves termed backpressure valves, which are provided either in the structure of the bit to close off the upward passage of fluid to the drill stern thereabove, or else such structures have been provided in the drill stem above the bit. The difliculty with such installations is that they later obstruct the downward flow of circulation fluid or drilling mud when drilling is carried out, and thereby increase the tendency to stop up the drill stem or the bit against the free downward circulation of such drilling fluid.

This difliculty is avoided by providing a drilling bit equipped with plugs in the bit passages which may resist the upward action of the hydrostatic pressure in the well as the drill stem is lowered, no matter how great that ammo hydrostatic pressure may be, whereas on the other hand the shape and substance of such plugs, in combination with the shape of the passages, as for instance the inserts in the l ower ends thereof, is such that the plugs may be easily expelled responsive to the downward'action" of drilling mud or circulation fluid in the drill stem from above; after the bit is'in place many on drilling i With plugs of this type it' is not necessary that they may be lost when ejected downwardly, as they will tend to be carried upwardly with the circulatedfluid to the top of the well bore and at least inpart recovered. Referring in detail to the drawings an embodiment of a conventional bit is shown in FIG; land designated by the reference numeral 10. As shown, such a bit is of the pin type, having the upper end 11 thereof externally threaded to be received viu'thin the lower or box end of a conventional drill collar, not shown, constituting the lower element of a drill stem. The body of the bit has a shoulder 12 thereon as it broadens out from the pin 11, and projecting downwardly from the body at equally radially spaced apart angles are provided legs 12 which extend downwardly from the bit body and have diagonally inwardly projecting axles 13 about which the cutting element of cones 14 are mounted, of the shape and configuration shown in FIG. 1. These cones are mounted to rotate on contact with the formation surface to be abraded, and to this end have teeth 15 thereon, and rotation is effected in great degree due to the fact that roller bearings 16 and ball bearings 17 are provided between the axle 13 and the cone 14 to facilitate rotation. As an added feature bushings or rollers 18 may be provided around the lower ends of the axle. As indicated in FIG. 1 a bit as shown would have three such cones 14 equally angularly spaced to extend downwardly from the body 12, the axes of such axles being spaced 120 apart in plan view.

In order that an ample volume of circulating fluid or drilling mud may be distributed without undue restrictio'ns through the bit, a substantially large axial flow port I9 is provided downwardly through the pin 11 and into the body 12 of the bit and from this larger, central flow port, passages 20 extend diagonally from the lower end thereof at angles todirect fluid preferably between the cones which are generally of sizeto be placed in close adjacency, or optionally on the cones, or in compromise partially on the cones and partially between the cones. As the fluid passing through such passages 20 must be at some extensive acceleration it is necessary to provide inserts 21 at the lower ends of such passages 20, as it is necessary to restrict the lower ends, of the passages 20 in order to concentrate or jet the downward flow of drill ing fluid in order to eifect the necessary washing of the cone teeth.

Such inserts are of high abrasion resistant qualities, being preferably of ceramic material as porcelain Usually they are of diameter to be most tightly press-fitted into the passages 20, but to insure that they remain in the passages 20, hold-down rings 22 are provided inthe lower ends of such passages, against which the lower end faces of the inserts 21 may bear. Generally the inserts have a cylindrical bore 23 through the lower endthereof and a countersunk upwardly and outwardly tapered bore 24 thereabove, and in this manner the downwardly passing fluid is concentrated and directed in jet form against and/ or between the cones.

"The plugs 25 of this invention, being designed to be inserted into the inserts from below, have flanges 26 on the lower ends thereof which are of great strength and of high resistance to pressure so that even the greatest pressure cannot shear oi the outer rim of such a flange thereby leaving the inner part of the same diameter as the cylindrical body 27 extending thereabove. If this could happen it is obvious that all of the plug except the rim of the flange could be expelled upwardly by such excessive hydros tatic pressure. The cylindrical body 27 above the flange 26 is of a character to be firmly connected to the (5 ing by the hydrostatic pressures from below,

4 flange 27 and is of outer diameter and of suflicient resilience that it can be easily pressed through the cylindrical bore 23 of the insert 21. Above the cylindrical part 27 the plug 25 consists of a frusto-conical part 28 extending upwardly and outwardly of contour to bear upon the tapered surface 24 of the insert and to thus form a lip within the insert to resist the downward expulsion of the plug. Above the part 23 a second frusto-conical part 29 is provided which is tapered upwardly and inwardly, and thus oppositely to the part 28, and which terminates upwardly in an upper end 30 of a lesser diameter than the diameter of the bore 23, to thus facilitate insertion of the plug 25 in such bore 23.

In order that the plug 25 may be easily inserted and easily expelled from the insert 21, in addition to the innate compressibility of the material thereof, as for instance rubber, it may be necessary that such plug have slots, holes, or vacant spaces provided therein to insure that there is ample space into which the material thereof may be compressed, so, that when inserted upwardly the upper end of the plug may contract to pass through the bore 23. As shown in FIG. 3, radially extending passages 31 are provided in the frusto-conical part 28, and an axially downwardly extending passage 32 is provided through the top of the plug to extend downwardly at least farther than the radial passages 31. In this manner suflicicnt material is removed from the upper end of the plug to insure its facile contraction when inserted into the insert 21. This also insures that it may be easily injected as the top of the plug may contract under pressure exerted downwardly.

In the design of the plug, consideration is given to certain conditions when it is not found expedient to run the drill string "dry the well bore, but in wells such as wells of great depth, and such as wells wherein excessively high hydrostatic fluid pressures are encountered, it is necessary to carry a certain amount of drilling mud or circu lating fluid in the pipe to prevent its being caved in by such pressures and under certain conditions as much as 2000 feet of such: drilling fluid may be carried above the bit. In such cases the lip orpart of the plug which overhangs into the tapered. bore in the jet insert must be of very special construction so that it will remain in place under the pressure of such fluid from above until such time as the bit comes to drilling position in the well and the drill string is then completely filled with drilling fluid and pump pressure exerted to expel the plugs from the well bore. I

This invention is not limited to the exact type of bit disclosed, nor to the exact shape of plug disclosed, nor to a plug having the material removed from the upper part in the exact manner as shown, but any type of plug is considered within the scope of this invention, including as solid plug without parts removed, so long as the plug is of sufficient resiliency and compressibility to contract when inserted upwardly to pass through the insert bore to then expand as a lip on the tapered surface thereabove, also the invention considers any type of plug which will contract responsive to pressure exerted from above so that the head of such plug, will pass downwardly through the insert bore 23 to permit the eviction of the plug from the big body.

Also, in case difl'iculty may be encountered bonding a hardened rubber flange to the pliant and compressible upper parts of the plug, a plug may be provided in WhlCh the rubber flange may-be replaced with a metallic washer, say of lesser inner diameter than the bore 23, and of outer diameter slightly less than the inner diameter of the holddown ring 22. Such a washer may be moulded with the softer parts of thelplug so that the rubber extends on each side of the washer, and then a cupped or dished metal part may beprovided to cover the metal on the underside of the washer from below, such cupped or dished metal part then being connected to thewasher as by welding. Thusa part of amplestrength is provided to resist shearwhereasthe upper part of the plug is pliant and compressible for upward insertion and downward ejection from the bit passages. Another example of this type would be a flanged metal cup with inner diameter less than the cylindrical bore through the insert, in which case the cup could be threaded internally so that the pliant rubber could easily bond therewith in the mould.

Additionally it is pointed out that a plug can serve in which the outer part of the cylindrical member fitted within the cylindrical bore 22 may be metallic, in which case the complete metallic part employed could be a metallic cup having a flange around the base thereof of diameter to fit within the hold-down ring 22. In such case the lowermost or smallest diameter of the frustoconical part 28 could be the same as the outer diameter of the cup. In this case the inner diameter of the cup could be threaded to facilitate the bonding of the pliant material, as rubber, to the cup in moulding.

As a variation of construction, the upper part of a plug need not be of the configuration shown in FIG. 1, but such upper part may include a spring which may contract to be inserted through the bore 23 and which may thereafter expand to fit into the tapered surface 24 of the jet insert 21. In such case the spring employed is of a material and of such size and configuration that it will contract responsive to the exertion of fluid pressure by the pumps from above and responsive to such pump pres sure the spring is contracted to pass back downwardly through the bore 23.

The material of which the plug is made is subject to a number of variations. In addition to rubber, plastic may be one of the materials of which the plug is fabricated, and also it may be fabricated of a light metal, as aluminum. In fact, any number of metallic, ceramic, and plastic materials and the like may be employed as well as a number of woods.

The invention is thus not limited to the exact structures shown in either bit or plug, nor to the exact recited methods of employing plugs to run drill string dry into a well bore, but various bit and plug forms are considered and various methods are included, as such may fall within the broad spirit of the invention and within the broad scope of interpretation claimed and merited for the appended claims.

What is claimed is:

1. A drilling bit of the roller cone type having a downward opening through the center thereof and passages extending downwardly therefrom through the bit above the cones, said bit including an abrasion resistant insert in each passage tapered inwardly and downwardly and ending downwardly in a cylindrical bore and also including a hold-down ring positioned below said insert to hold said insert in the lower end of said passage, and in combination with said bit a plug for each passage comprising successively from top to bottom a frusto-conical part of pliant, contractible material with upper diameter insertable in the cylindrical bore of the insert, an inverted frusto-conical part with upper face connected to the base of said frusto-conical part, said inverted frusto-conical part being of pliant, contractible material and having such upper diameter that said inverted frusto-conical part forms a lip against the tapered surface of said insert, a cylindrical part with upper end connected to the lower face of said inverted frusto-conical part to fit snugly within the cylindrical bore of said insert, and a pressure resistant flange connected to the lower end of said cylindrical part and of diameter to fit within each hold-down ring to bear against the lower face of the insert and of strength to resist the shearing off of the rim thereof outwardly of a center of substantially the diameter of the cylindrical bore so that the plug may not be blown upwardly by the hydrostatic pressures of fluids in well bores, said frustoconical and inverted frusto-conical parts providing opening space therein whereby responsive to the pressure of well bore circulating fluid from above said frusto-conical and inverted frusto-conical parts may be contracted so that said plug may pass downwardly through the cylindrical bore of the insert to be carried downwardly out of the bit by the circulating fluid.

2. A drilling bit having downwardly extending passages therethrough and abrasion resistant inserts held in each passage and tapered inwardly and downwardly and ending downwardly in a cylindrical bore, and in combination with said bit a plug for each passage comprising successively from top to bottom an upper part of pliant contractible material and of dimension to be inserted upwardly through the cylindrical bore of the insert in the passage, an inverted frusto-conical part connected to the lower end of the said upper part of pliant, contractible material of such upper diameter that said part forms a lip against the tapered surface of the insert, a cylindrical part connected to the lower face of said inverted frustoconical part to fit snugly within the cylindrical bore of the insert, and a pressure resistant flange connected to the lower end of said cylindrical part and bearing against the bit surface around the lower end of the cylindrical bore and of strength to resist the shearing oil of the rim thereof outwardly of a center of substantially the diameter of the cylindrical bore so that the plug may not be blown upwardly by the hydrostatic pressures of fluids in well bores, the two uppermost plug parts providing opening space therein whereby responsive to the pressure of the well bore circulating fluid from above said two uppermost plug parts may be contracted to pass downwardly through the cylindrical bore of the insert so that the plug may be carried downwardly and out of the bit by the circulating fluid.

3. A plug for a drilling bit passage including parts connected to adjacent parts successively from top to bottom and compressing a frusto-conical part of pliant, contractible material, an inverted frusto-conical part of a pliant, contractible material with upper face connected to the base of said frusto-conical part, a closed cylindrical part of slightly greater diameter than the upper diameter of said frusto-conical part, and less than the base diameter thereof, and a flange of hardened, pressure resistant material, the two uppermost parts providing opening space therein whereby the plug may be contracted to pass through a bore of substantially the diameter of said cylindrical part.

References Cited in the file of this patent UNITED STATES PATENTS 1,915,249 Jorgensen June 20, 1933 1,918,096 Grebe July 11, 1933 2,546,672 Le Clair Mar. 27, 1951 2,848,130 Jesnig Aug. 19, 1958 FOREIGN PATENTS 296,352 Great Britain Aug. 28, 1928 763,676 Great Britain Dec. 12, 1956

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