US 2727727 A
Description (OCR text may contain errors)
Dec. 20, 1955 P. s. WILLIAMS 2,727,727
COMBINATION PELLET IMPACT DRILLING AND ROTARY SHOT DRILLING Filed Jan. 29, 1952 2 Sheets-Sheetl DlIzEdTlo OF TATaou DmEdTloM OF ROTATIQN 'y Dec. 20, 1955 P. s. WILLIAMS COMBINATION PELLET IMPACT DRILLING AND ROTARY SHOT DRILLING 2 Sheets-SheetZ Filed Jan. 29, 1952 @macxnom OF ZOTATION D/EECTION of EoTAT/o/V Z l.) O O In' philip ZLYZL'QHQS flverzbor United States Patent O COMBINATION PELLET IMPACT DRILLING AND ROTARY SHOT DRILLING Philip S. Williams, Tulsa, Okla., assignor to Esso Research and Engineering Company, a corporation of Delaware Application January 29, 1952, Serial No. 268,874
5 Claims. (Cl. Z55- 61) This invention concerns a novel method and apparatus for the drilling of bore holes in the earth and in particular for the drilling of petroleum wells. The invention concerns a method and apparatus for securing effective drilling action by employing a multitude of hard, dense, spherical pellets in a dual function. In one phase of the drilling operation these pellets are ejected in the form of a high velocity jet of pellets effective to fracture the formation encountered thereby. In a second phase of the drilling operation these pellets are carried upwardly along the wall of a bore hole adjacent the impact zone so as to be ground against the wall by rotary movement of a drilling head. Rapid and effective drilling is possible by employing the pellets referred to in order to provide both the impact and shot drilling action identified.
It has been determined that effective drilling can be attained by entraining pellets of a suitable character in a high velocity fluid jet. Entrained in the fluid jet the pellets can be given high kinetic energy so that on impact with an earth formation the pellets will fracture and in part wear away the formation encountered. This drilling action is particularly adapted for cutting away the central area of a bore hole in the direct path of the fluid jet or jets employed to propel the pellets. The present invention couples with this drillingaction a method and apparatus for employing the pellets after impact to grind away the outer portions of the bore hole. This is achieved by positioning the nozzle or nozzles employed to provide the necessary fluid jets in a drilling head which is substantially the size of the bore hole desired. Consequently pellets carried upwardly from the zone of impact with the formation will be rolled between this drill head and the wall of the bore hole so as to exert a shot drilling action.
The pellets to be employed must be particularly chosen in order to secure the benefits of this invention. It has been found necessary to employ pellets of substantial size in order to obtain effective impact drilling action. This requirement is in all probability related to the kinetic energy of the pellets which is a function of the size and density of the pellets. Consequently the pellets must be chosen so as to have a diameter of at least about 1/6 of an inch and preferably larger than 1A of an inch. Nozzle limitations, as will be appreciated, impose an upper limit on the size ofthe pellets whichmay be employed so that in general it is desired to employ pellets having a diameter of about Mi t0 3%; of an inch in diameter. As will be appreciated these pellets must have a high density in order to separate from the fluid employed. Pellets of this character, for example, may consist of iron, steel or other ferrous alloys. For the purposes of this invention, it is required that the pellets be substantially spherical in configuration. Since the desired, action of the pellets depends upon both impactrand a shot drilling action achieved by rolling the pellets forcefuly against the wall of the bore hole, it is necessary that the pellets have a smooth surface.` The drilling action relied upon is not dependent on the abrasive qualities of the pellets and in fact if the pellets were to be abrasive in nature the apparatus employed would be seriously limited in useful life.
Any desired type of fluid may be employed to propel the pellets against the formation to be drilled and to cause recirculation of the pellets. In general the fluid will be chosen so as to provide the proper hydrostatic pressure in the bore hole and so as to have the proper hole conditioning properties. Thus conventional drilling muds may be employed although considerable flexibility exists as to nature of the fluid to be employed. Thus, for example, it is practical in some applications to employ air or other gases as the drilling fluid.
A number of embodiments of the invention are illustrated in the attached drawings. In these drawings:
Figure 1 shows `one form of the invention in crosssection elevational detail in which a plurality of fluid jets or alternatively an annular jet nozzle is employed in combination with a drilling head having vertically arranged flutes on the external surface;
Figure 2 is a cross-sectional view of Figure l taken along the line II-II of Figure l particularly showing the arrangement of the flutes and the annulus providing the necessary fluid jet channel;
Figure 3 illustrates a different arrangement of the invention in which at least one fluid jet channel is directed toward a wall of the bore hole at a point above the bottom of the bottom hole. At least one pellet circulation channel is similarly directed against the wall of the bore hole in verticalvalignment with a fluid jet channel;
Figure 4 shows the cross-sectional arrangement of the apparatus of Figure 3 taken along the line IV-IV of Figure 3 showing the flutes provided therein; v
Figure 5 is a cross-section, elevational view of an embodiment of the invention utilizing a single axial jet nozzle;
Figure 6 is a cross-sectional view of the apparatus of Figure 5 along the line VI-VI; and
Figure 7 is a cross-sectional view corresponding to Figure 2 and representing a modification of the apparatus of Figure l. p
Referring first to Figure l, the numeral 1 designates a tubular support portion of the drill which is connected to and constitutes an extension of a drill string or tubing on which the drill is supported. The lower end of tubing l is received within the upwardly opening central bore of an elongated drill head member 9, the upper portion of the bore being sufllciently large to define with the tubular support 1 an open annular receptacle 6. Tubing 1 is mounted in fluid interconnection with an annular space 2 terminating in constricted manner at the bottom of the drill to provide an annular nozzle opening 3. A seal or plug 4 is centrally positioned above the annulus 2 so that fluid tubular member 1 is forced into the annulus 2 to be j ejected as a fluid jet through the nozzle 3. A central channel 5 is thus provided in the apparatus beneath the central seal 4. One or more connecting conduits'7 extend from the receptacle 6 to the central channel 5. The lower portion of the drill head is constructed to have the inwardly curved or tapering bullet-like shape illustrated. Referring to Figure 2 it is to be seen that a number of flutes 8 are provided around the periphery of 'the drill head. These flutes are formed as cutaway portions of the periphery of the drill head in such a" manner that each tapers outwardly so that it has anl essentially wedge-shaped horizontal cross-section between the drill head and the bore hole.
ln operating the drill of Figure l and Figure 2, a stream of drilling mud or other fluid is pumped through. 1 from the surface of theearth. As; indicated, this drilling mud is ejected through the annupumped downwardly through lar space vZ'andthe nozzle. 3 so as to form a high velocity uid jet which is directed inwardly toward the center of the bore hole. By dropping a multitude of pellets 18 into the bore hole, these pellets will enter the pellet circulation system provided. Thus, under. the inuence of gravity and the aspirating. effecty created: by the nozzle arrangement described, pellets will drop downwardly through. the Cup-.shaped receptacle 6, through: the interconnecting channels 7, to move through the inner channel 5. Afdiacent the lower termination of the drill these pellets will be entrained in the fluid jet from nozzle 3 so as to attain high kinetic energy. These pellets are thus forcefully irnpinged. against the bottom of the bore hole. The cutting pattern obtained by the fracturing force ofthe impinging pellets is ofl the nature shown in Figure l inwhich theprincipal. penetration is attained in the central portion of the bore hole; By virtue of some scattering. of the pellets in the fluid jet, and by solid erosion as the pellets are. carried outwardly and upwardly in the fluid, a less effective drilling action is attainedy along the bottom of the bore hole adjacent the central portion. As the pellets are carried upwardly along. the general path illustrated, they preferentially travel through the openings provided by the utes 8. Howcvenby rotating the drillin the direction illustrated in Figure 2, thepellets will be forced against the formation so as tobe. rolled along, the wall of the bore hole by the tapered utes. The shotdrilling action obtained is operative to drill a bore hole having a diameter of a fixed gauge size. Contact of the drill body against the pellets which` are rolledl against the bore hole also serves to space the jet nozzle from the bottom of the borehole as illustrated.
Pelletsare carried upwardly during the rotational shot drilling action by the high velocity iluid traveling upwardly in the restricted annulus. providedV by the fluted arrangement. Above the drill head a substantially greater'. annulus isprovided between the tubular member 1 and the wall of the bore hole. Consequently the iluid velocity above the drill head is substantially slower. In this area therefore, the dense pellets are permitted to settle from the flow of fluid to drop into the cup-shaped receiver 6 for recirculation as described. The downwardly tapered configuration of the drill head referred to is an important feature of the apparatus. By employing an elongated drill head having a taper along the length of the drill head the life of the apparatus may be greatly extended. This taper permits distribution of the shot drilling action along the entire length of the flutes so. as to minimize undue wear of the drill head.
The apparatus of Figures l and 2 has been described with reference to an annular jet channel 2 and nozzle arrangement 3. It is apparent that if desired, a plurality of conduit passages could be employed to provide the jet action required. In this embodiment of the invention, which is shown in Figure 7, a number of individual jet channels 32 may be positioned so as to encircle the inner channel 5. From 3 to 10 individual jet channels may be employed, for example.
Referring now to Figures 3 and 4 a different embodiment of the invention is illustrated. in which preferentally.y a.. single uid jetis employed. A drill head member 16. provided with a pair of diametrically opposed essentially vertical flutes 12- and 13 is attached to the lowerend: of tubular support member 1. The upper end of the drill headv member is. cut away in cup-shaped fashion. as shown so as to define with the tubular support member an annular receptacle 14. Positioned within drill head member 16 isa channel 10 extending from the tubular member 1 at an angle so as to be directed against the wall of the bore hole. The fluid channel is terminated by a nozzle opening 11 adapted to permit expulsion of a high velocity fluid jet from the opening-z thereof. The nozzle is directed so as to primarily Vjet fluid downwardly with a minor component of outward force. As shown in Figure 4 the jet 11 is arranged within the flute 12 so as to provide fluid access to the space between the ute 12 and the wall of the bore hole. Somewhat above the fluid jet 11 a pellet circulation channel 15 is provided which communicates with annular receptacle 14 and terminates within the tinte 12 in vertical alignment with the nozzle 11. Each of flutes 12 and 13 is formed as a cutaway portion of the drill head soy as to provide a horizontally disposed taper. This creates a wed'ging'configuration between the tintes and the bore hole.
ln the operation of this apparatus, drilling mud pumped through the tubular member 1 is ejected from nozzle 11 so as to pass downwardly through. the uted channel 12. This drilling. mud is carried in the path illustrated in Figure 3' along the rounded termination of the bottom of the drill head and upwardly through the diametrically opposed iiute 13. Pellets of the character identified are forced along the same general circulatory pattern by thev duid. Thus pellets drop from pellet channels 15 under the propelling force of the uid circulation to move downwardly through the channel provided by flute 12 and upwardly through the channel provided by the ute 13. On rotation of this apparatus during the iluid and pellet circulation identified, the pellets will be ground by the tapered flutes 112 and 13 and the lower nose portion of the drill so as to grind the drill hole having the shape illustrated.
Entrainment of pellets inthe fluid jetted through nozzle 11 imparts sufficient kinetic energy to complement this drilling action, particularly below thev nose portion of the drill. Again in the apparatus of Figures 3 and 4, it is desirable to provide ataper along the length of the apparatus so as to distribute the shot drilling action over a major portion of the apparatus. Thus the entire apparatus is taperedv downwardly so that the nose portion thereof is of the smallest diameter.
Referring to Figures 5 and 6, another embodiment of the invention is illustrated, showing one of the many alternative nozzle arrangements which may be employed. 1n this apparatus, the drill string 1 communicates with a primary nozzle 20 adapted to eiect a constricted high velocity jet fluid. Drill head member 2S has a central bore that terminates at its lower end in a secondary nozzle 21. The upper end of the central bore is sufficiently large to receive the lower endv of the tubular support member 1 in a manner that provides an annular receptacle or passageway 26 open at its upper end. Thus the secondary nozzle 2.1 is positioned below and concentric with the primary nozzle. This elongated tubular secondary nozzle serves asian entrainment and acceleration passage for pellets. Web members 22 may be fixed to the support 1 and the drill head 25 to maintain the fixed relation illustrated. As shown in Figure 6, the periphery of the drill head is provided with essentially vertical extending utes 27 in the manner formerly described.
In operation, uid jetted throughy nozzle 20 entrains and accelerates pelletsv in nozzle 21. The jetted pellets cut a percussion drilling pattern of the nature illustrated and ow outwardly and upwardlythrough the: flutes provided. During upward passage, rotation of the drill causes a shot drilling action along the wall of the bore hole. Pellets attaining they top of the drill settle into the hopper-like opening provided for recirculation as described.
Various modifications of the apparatus described may be made within the scope. of this. invention. Thus for example, a wide variety of nozzle arrangements may be employed.
What is claimed is:
l. An apparatus for drilling a bore hole in the earth, comprising in combination: a tubular support member, a massive elongated body member fixedV to the lower termination of said supporty member, the upper end of ber, said body having an opening permitting lluid discharge from said nozzle exterior of said body, and a conduit channel extending through said body member from said annular receptacle to a region communicat# ing with said last named opening whereby pellets mayv pass from said receptacle into contact with a lluid jet from said nozzle, said body element being further char-y acterized by having on its exterior surface a plurality of essentially vertical utes extending from a region adjacent the lower termination of the body member to the top edge thereof, whereby pellets travelling up-v wardly in the bore hole annulus exterior of said body member will bey forced against the bore hole walls to exert a reaming action.
2. Drilling apparatus as defined by claim 1 wherein Said flutes are of essentially wedge-shaped horizontal cross section whereby on rotation of said body member during drilling said pellets will be forced against the bore hole wall by a wedging action.
3. Drilling apparatus as defined by claim 1 wherein the lower end of said body member is curved inwardly to a smaller diameter than the upper portion thereof.
4. Drilling apparatus as defined by claim 1 which the said downwardly directed nozzle and the lower termination of said conduit channel are positioned adjacent the lowermost portion of said body member.
5. The drill dened by claim 1 in which the said body member has a symmetrical configuration about a center axis and tapers downwardly terminating in a rounded nose portion.
References Cited in the file of this patent UNITED STATES PATENTS 649,488 Schrader May 15, 1900 817,296 Besson Apr. 10, 1906 1,343,902 Chapman June 22, 1920 1,420,365 Chapman June 20, 1922 1,502,851 Gale July 29, 1924 1,540,882 Hansen June 9, 1925 1,642,572 Acker Sept. 13, 1927 1,756,503 Baker Apr. 29, 1930 2,072,627 Zublin Mar. 2, 1937 2,233,260 Hawthorne Feb. 25, 1941