US2708567A - Pellet impact bore hole enlarger - Google Patents

Description

May 17, 1955 A. B. HILDEBRANDT PELLET IMPACT BoRE HOLE ENLARGER Filed May 15, 1955 Qlexnnder ED. Hildebrandt ave r1 t or 615D). Cbbownez PELLET IMPACT @GRE HLE ENLARGER Alexander B. Hildebrandt, Tulsa, Okla., assigner to Esso Research and Engineering Company, a corporation of Delaware Application May 13, 1953, Serial No. 354,805

7 Claims. (Cl. Z55- 61) The present invention relates to a method and apparatus for enlarging the lower end of a bore hole. More particularly, the invention concerns apparatus for utilizing the pellet impact principle for increasing the diameter at the bottom of a bore hole.

It is often desirable to increase the productivity of an oil well by enlarging or under-teaming the bore hole in the region of the producing formation so as to increase the area from which production takes place. Conventionally such under-reaming is done by drilling apparatus of a rather complicated nature. The present invention enables such enlargement to be elfected with relatively simple apparatus.

The basic principles of the pellet impact technique for the drilling of bore holes involve the use of a stream of uid pumped from the surface of the earth through a 5 tubular member to a jet nozzle assembly adjacent the bottom of the bore hole. The jet nozzle assembly is adapted to direct a high velocity jet of fluid against the formation being drilled and is provided with means for entraining in the jetted iluid a multitude of pellets which are accelerated to high velocity in the jet stream and thereby acquire considerable kinetic energy so that when the pellets impinge against the formation the resulting percussive and fracturing forces exert a drilling action. Preferably the pellets that are employed are smooth, nonabrasive and essentially spherical and are of substantial size, preferably in the size range of about l/s to about l in diameter. lt is preferred that hard, tough metallic alloys be employed as the pellet material. The basic principles of the technique of drilling by pellet impact are set forth in copending application Ser. No. 268,873, iiled by Philip S. Williams, on January 29, 1952, and entitled Pellet Impact Drilling Method and Apparatus.

The present invention is directed to the use of the pellet impact technique for the enlargement of a bore hole adjacent the bottom thereof. A fluid jet issuing from a primary nozzle is directed into a secondary nozzle wherein pellets are entrained in the iluid jet and the jetted lluid and pellets are discharged from the lower end of the secondary nozzle which is angled or bent in such a manner that the pellets impinge on the side of the bore hole and thereby enlarge the same. A tail pipe on the nozzle assembly creates a narrow annulus in the bore hole through which the returning uid and pellets are directed to enter the tail pipe for recycling upwardly to the entrance of the secondary nozzle. A slotted deflector adjacent the entrance to the secondary nozzle directs the pellets to the primary jet entering the secondary nozzle while permitting returning fluid to pass upwardly in the bore hole annulus.

A fuller understanding of the nature of this invention may be obtained by reference to the accompanying drawing in which:

Fig. 1 is an elevational view in section illustrating the upper portion of one form of apparatus suitable for the practice of this invention, in position in a bore hole, showing the primary nozzle, means for directing pellets into the lCC jet entering the secondary nozzle and means for directing the returning stream of fluid up through the bore hole annulus, and

Figure 1A is a lower continuation of Figure 1 and illustrates the manner in which the pellets leaving the secondary nozzle are directed outward to effect a desired bore hole enlargement and the manner in which the pellets fall to the bottom of the bore hole to be recycled for entry into the secondary nozzle.

Referring now to particular details of the apparatus as depicted in Figures 1 and 1A, the drilling apparatus is supported in the bore hole 1 by means of a tubular support 2 which may be a conventional drill string. Attached to the lower end of the drill string or support 2 is an elongated tubular member 3 having a lower portion of smaller internal diameter 9. Arranged within the upper portion of tubular member 3 is a primary nozzle 4. Positioned below primary nozzle 4 is an open secondary nozzle 14 the lower portion of which, designated as l5, curves outwardly and terminates exterior of tubular member 3.

The lower end of tubular member section 9 flares outwardly to provide a shoulder portion 10. A sleeve l2 lits siidably about the shoulder portion 10 and has an upper portion 13 of restricted diameter so as to slidably engage section 9 of the tubular member 3. Thus sleeve 12 can slide vertically on portion 9 but is limited in its downward travel by engagement of the restricted portion 13 with the shoulder 10.

A packer member S supported on sleeve 19 surrounds tubular member 3. It is not necessary that packer member S furnish a fluid tight seal in the bore hole annulus but merely that it be of suicient size so as to essentially prevent fluid ow past the packer in the bore hole annulus. Thus a packer size may be selected that is approximately that of the bore hole diameter and no provision is necessary for expanding the packer against the bore hole wall to provide an absolute seal. Preferably sleeve 19 is fixed against vertical travel along tubular member 3 but is adapted to rotate freely with respect to member 3 so that packer member 8 will oler no resistance to rotation of member 3 and thus also preventing undue Wear on the packer member. This can be accomplished for example by means of annular rings 2l) tted into appropriate grooves in member 3. Packer member 8 is preferably constructed of somewhat resilient material.

Fitted within tubular member 3 adjacent the lower termination of primary nozzle 4 is a perforated or slotted baille or guide member 1S that is adapted to permit fluid to pass through it into the chamber 11 that is defined by nozzle 4 and the interior of tubular member 3. The slots in member 18 are of such size that the pellets employed in the drilling operation will not pass therethrough. Thus these pellets will be directed into the top of secondary nozzle 14. Fluid that enters chamber 11 will pass out into the bore hole annulus above packer 8 through slots 7, fluid communication between chamber 11 and the interior of the drill pipe being blocked olf by the enlarged throat 6 of the primary nozzle. It is preferred that guide member or dellector 18 be curved in the manner shown to aid in directing pellets into the nozzle 14.

To conduct the desired bore hole enlarging operation a plurality of pellets are placed at the bottom of the bore hole and then the apparatus described is lowered into the bore hole. Fluid is then pumped down the drill pipe through nozzle 4. As it leaves this nozzle the fluid is converted into a high velocity jet stream which then enters secondary nozzle lil from whence it is directed laterally against the wall of the bore hole. Packing member 8 prevents the ejected fluid from passing directly up the borehole annulus so that instead the fluid must flow down through the annulus between sleeve l2 and the bore hole and then up through the tail pipe comprising sleeve 12 and extension member 9. The velocity of the stream flowing upward through the tail pipe will be suciently great to carry pellets with it up to the baille member 18 which by its construction will direct the pellets into the entrance of the secondary nozzle 14. Entry of the pellets into the secondary nozzle is also facilitated by the aspirating effect created by passage of the uid jet from the primary nozzle into the secondary nozzle. A portion of the upowing stream of lluid will also enter the secondary nozzle and the balance will pass up through passageway 11 and out through ports 7 into the bore hole annulus to constitute the returning stream of uid owing up up the bore hole. rl`he pellets that enter the secondary nozzle 14 will be admixed with the high velocity jet of tluid and will attain substantially the same velocity as the tluid stream so that they will be directed with great force laterally against the bore hole wall to drill an enlarged portion designated as 16. It will be observed that the secondary nozzle has a somewhat greater diameter than the primary nozzle in order to accommodate the jet of fluid in combination with the volume occupied by the entrained pellets.

lt can be seen by virtue of the arrangement of sliding sleeve 12 that some vertical adjustment of the position of nozzle 14 is possible while the bottom of sleeve 12 at all times rests on the bottom of the bore hole, thus enabling the drilling of an enlarged hole similar to the shape illustrated. By rotating the drill pipe the jetted stream of pellets can be directed in every direction about the bore hole.

The bottom of sleeve 12 is provided with slots 17 so as to allow sleeve 12 to rest on the bottom of the bore hole and at the same time provide access of returning fluid and pellets to the interior of sleeve 12.

It is obvious that the drilling apparatus of this invention could be used for enlarging a portion of a bore hole some distance from the bottom by providing a suitable plug in the bore hole adjacent the area to be enlarged, the plug then serving in lieu of the bore hole bottom as a support for sleeve 12.

The scope of this invention is to be limited only by the following claims.

What is claimed is:

l. A drilling apparatus for enlarging the bottom of a borehole comprising an elongated tubular member adapted for placement in the bore hole, a nozzle assembly supported by the tubular member and including a nozzle element adapted to direct a high velocity stream of fluid and entrained pellets laterally against the wall of the bore hole, means eiecting recycling of pellets from the bottom t of the bore hole into said nozzle assembly, packing means essentially blocking fluid ow in the borehole annulus between a region above said nozzle element and the region adjacent said nozzle element, and conduit means for conducting a portion of the return stream of fluid from a region adjacent the entry of recycled pellets into said nozzle assembly to a region in the bore hole annulus above said packing means.

2. Apparatus as defined by claim l including a perforated baflle member at the lower end of said conduit means adapted to permit uid flow therein while prevent ing the entry of pellets therein.

3. A drilling apparatus for enlarging the bottom of a bore hole in the earth comprising an elongated tubular member adapted to be placed in a borehole, a first downwardly directed nozzle member supported by said tubular member and having its upper opening in fluid communication with said tubular member, a second nozzle element supported by said tubular member below said rst nozzle element with its upper opening generally aligned with and spaced a fixed distance from the outlet of said tirst nozzle element, the lower end of said second nozzle element being directed outwardly in a lateral direction, a second tubular member extending below said second nozzle and terminating at its upper end adjacent and in lluid communication with the upper opening of said second nozzle element, a fluid conduit member arranged in general parallel relation to said primary nozzle with its lower end in uid communciation with said second tubular member and its upper end in fluid communication with the borehole annulus, a perforated baflle separating said second tubular member and said conduit member and a packing element surrounding said first nozzle element and said conduit member to essentially prevent duid tlow past said packing element in the bore hole annulus adjacent thereto. f

4. Drilling apparatus as defined by claim 3 including a sleeve member arranged in telescopic sliding relation with said second tubular member and extending downwardly therefrom whereby to provide a pellet return channel of variable length.

5. A drilling apparatus for enlarging the bottom of a borehole in the earth comprising an enlarged tubular member adapted to be placed in a bore hole, a rst downwardly directed jet nozzle element positioned within said tubular member with its upper end in open communication with the bore of said tubular member, means blocking tluid communication between said bore above said nozzle element and the chamber defined by said nozzle element and said tubular member, a perforated battle member closing the lower end of said chamber, a second nozzle element positioned within said tubular member with its upper open end in general alignment with said rst nozzle element and spaced therefrom a suicient distance to provide an entrance for pellets of appreciable size, the lower end of said second nozzle element being directed outwardly in a lateraldirection and terminating exterior of said tubular member in a region above the lower termination of said tubular member, and an annular packing member supported on said tubular member in a region intermediate the ends of said chamber, said packing member being of size to essentially prevent lluid fiow past said packing element in the borehole annulus adjacent thereto, and said tubular element having at least one port in its outer wall com# municating with said chamber at a point above said packing element.

6. Apparatus as defined by claim 5 wherein said packing element is rotatably mounted on said tubular member.

7. Apparatus as defined by claim 5 including a sleeve member arranged in telescopic sliding relation with said tubular member and depending therefrom whereby to provide a pellet return channel of variable length.

References Cited inthe tile of this patent UNITED STATES PATENTS 1,547,461 Steele July 28, 1925 2,018,285 Schweitzer et al. Oct. 22, 1935 2,072,627 Zublin Mar. 2, 1937 2,233,260 Hawthorne Feb. 25, 1941

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