US2873092A - Jet deflection method of deviating a bore hole - Google Patents

Description

Feb. 10, 1959 R. P. DWYER JET DEFLECTION METHOD OF DEVIATING A BORE HOLE Filed Nov. 14, 1957 2 Sheets-Sheet l INVENTOR DWY R .5 VI ..E N R v 0 T T A Feb. 10, 1959 R. P. DWYER 2,873,092

JET DEFLECTION METHOD OF DEVIATING A BORE HOLE Filed Nov. 14, 1957 2 Sheets-Sheet 2 g p, 72% E INVENTOR I7 ROY P. DWVER NEYS TOR

United States PatentO JET DEFLECTION METHOD OF DEVIATING A BORE HOLE Roy P. Dwyer, Venice, La.

Application November 14, 1957, Serial No. 696,383

6 Claims. (Cl. 255-145) requiring the use of whipstocks or other conventional downhole accessories. In accordance with said method, one of the hydraulic nozzles carried by a jet drill bit is oriented with regard to the earths surface, or the well bore, and a greater amount'of fluid is circulated therethrough by restricting, plugging or blanking off flow to the remainingnozzles, so that only said single nozzle oriented off-center with respect to the hole drives the drill bit in a desired direction. Desirably, the .drill bit reciprocated, while at the same time fluid is preferentially supplied under high pressure to said single off-center nozzle to drive the well bore in the same direction as that in which said nozzle is pointed. Where other than multiple-cone drill bits are used with said nozzle,'the borehole is advantageously maintained cylindrical by oscillation of the bit as it rests on the bottom of the borehole by alternate starting and reversing the rotary table to turn the bit through a few degrees of movement.

In directional drilling,it is common practice to use I a hole deflector tool, known as a whipstock set in a borehole drilled 'to a sufliciently large diameter to accept the whipstock body. The Whipstock then guides a normal rotary bit against a side wall of the borehole and causes the bore to be deflected away from the original hole. In such directional drilling, this requires that the borehole be opened from the surface downwardto an earth formation that is sufiiciently consolidated to accept the whipstock which then must be set, using orienting and. directtional survey equipment to assure the driller that the whipstock is properly aligned in thev hole.

In drilling relatively softer formations it is conventional to drill with" rotary equipment that includes a drill string having a jet bit secured to the lower end of the 1 drill string. Jet bits are normally characterized by having .two or three rock bit cones, or cutters, that rotate when the drill string is driven and in addition, have a plurality of hydraulic nozzles positioned so that drilling fluid pumped downwardly through the drill string passes between adjacent rotary bit cones and strikes the bottom near the sides of the borehole. The nozzles are either set to strike the bottom of the borehole at about the same diameter as the outer diameter of the drill bit cones ,or strike slightly to the outer edge of the borehole during drilling.

In such drilling the hydraulic action of the drilling fluid passing through the nozzles at high velocity 'thereto by the drill string and drill collars.

eluding a plurality of drill collars.

2,873,092 Patented Feb. 10, 1959 ice the rock is too' hard for more than slight erosion by the drilling fluid jets. However, at least in theory, it is believed that the jets assist in the removal of chips formed by the drill bit cutters so that the cutting edges are in contact with fresh surfaces at the bottom of the hole at all times. Such jet drill bits have been used in conjunction with whipstocks where it is desired to drill deflected boreholes, such as in directionally drilling under bodies of water, or to change the course of a drilling well, for example, to by-pass junk (pieces of drill string or other undrillable material lost in the hole), sealed 01f in an original borehole by cement plugs or to straighten crooked holes.

It is also common practice to drill pilot holes deflected from the bottom of a full size drill hole using both a flexible drill pipe and flexible connectors. However, such pilot holes are normally guided in the desired direction by complex orienting equipment located in a full-size drill string wherein the pilot bit and pilot drill string are supported.

In accordance with the present invention, a simplified method is provided for performing deflected drilling using the jet drilling technique that does not require whipstocks or other auxiliary deflecting equipment either in starting the well bore or in deflecting the bore after the well has been drilled to any desired depth. In said method, deflection of the jetdrill string is obtained by directing a substantial portion of the drilling fluid through one nozzle of a jet drill bit. In a preferred method of carrying out the invention, said single jet is eccentric to the center of the'drill string and said jet is oriented in the direction and on the same side of the bore that deviation of the borehole is to take. With the single preferred hydraulic nozzle oriented in said desired direction, the Well bore is started by applying sufficient weight to the bit and supplying drilling fluid to said preferred jet nozzle under pressure through the drill string. After suificient penetration has been obtained to permit vertical movement of the drill string therein, the drill bit is reciprocated up and down by increasing and decreasing the weight applied ofthe borehole then proceeds in the direction that the jet is oriented and said directional drilling will proceed at least through the softer portions of the earth. With out full rotation of the drill bit and drill string until after the desired deviation of the borehole is obtained,

the drill string may advantageously be oscillated so that the cutters can maintain the borehole generally cylindrical in form. Such oscillation is particularly useful with a drag-type bit. Desirably, but not necessarily, the jet dr ll'bit is supported on the lower end of a flexible length of drill pipe below a section of normal drill string in- After full, desired de flection is obtained, the drill string is rotated and if de- "sired, the remaining jets in the drill bit unplugged so that conventional jet drilling may proceed.

Further objects and advantages of the present inventron will become apparent from the following detailed description taken in conjunction with the accompanying drawings which form an integral part of the present specification:

In the drawings:

Fig. l is a schematic representation of one arrangeinent of apparatus suitable for carrying out directional drilling with jet drilling apparatus;

FigfZ is a detailed view'of the lower end of drilling apparatus illustrated in Fig. I, particularly showing the flow of drilling fluid directly against the bottom of the borehole through one eccentric nozzle of a conventional jet bit;

1.doesnot actuallydrill the formation, since in general Fig. 3 is avertical sectional view through the lower Deviation end of a drill bit illustrating an alternative arrangement for preferentially blocking drilling fluid flow from all but one of the nozzles in a jet drill bit;

Fig- 4 is a. sectional plan view showing the blocking arrangement in the bits flow passages taken in the direction of arows 44 in Fig. 3;

Fig. 5 is a front elevation view, partially in section, of the flow directing member shown in the embodiment of Figs. 3 and 4.

Referring now to the drawings, and in particular to Fig. 1, there is indicated a. borehole that has been started into the earth. In the present example it is desired to by-pass the lower portion of borehole 10 wherein a fish, such as broken drill string 11, is stuck in the borehole. As indicated schematically, a plug 12 has been set above the top of junk or fish 11 and it is desired to by-pass the lower part of borehole 10 by a defiected borehole, proposed by the well bore outline indicated as 10A, starting from a point directly above plug 12. In accordance with the method of the present invention, the deflected borehole 10A is to be drilled by a jet drill string 13 that includes a series of drill collars 15 and a hydraulic jet drill bit 16 that includes a plurality of jet nozzles 17. As indicated schematically in Fig. l, a jet drill string normally drills Well bore 10 by rotary table 57 turning drill string 13 while drilling fluid is supplied by mud pump 23 to the hydraulic nozzles 17 under high pressure through Kelly bar 19, and swivel 21. Fluid is drawn from sump 25.

As better indicated in Fig. 2, nozzles 17 direct the stream of hydraulic fluid under high pressure directly against the bottom 27 of borehole 10 in such manner that as the cones 29 rotate on the bottom of the well bore, chips are immediately flushed away by the hydraulic stream and rise through the mud column in borehole 10 to return to the sump 25 through well head 33 and return line 35.

In accordance with the present invention, deflected well bore 10A is drilled in the direction indicated by the dotted lines with the apparatus indicated hereinabove, but with the conventional jets 17 modified so that a major portion of the drilling fluid leaves only one of the plurality of jet nozzles 17. The remainder are either blanked off, plugged, or flow restricted so that fluid flowing down the drill string 13 will be ejected from that jet which is oriented in the direction that borehole 10A is to be sidetracked. In practice each nozzle of a conventional jet bit is lined with a hardened insert formed of a wear-resistant material, such as tungsten carbide. These inserts reduce wear by sand and rock particles recirculated with the drilling fluid. The size of said inserts can be varied to take advantage of the capacity of different sizes of mud pumps, such as pump 23. In a preferred manner of carrying out the present invention, one oversized or larger opening insert 171 is pressed into one of the three eccentric nozzle openings 17 and two undersized inserts 172 into the other openings 17. Insert 171 is selected to give maximum jet action with the available mud pump, but the remaining inserts are intended to serve as auxiliary flushing jets to keep cones 29 clean. Additionally, by using flow in all three jets, even though purposefully unequal, normal rotary jet drilling can be resumed without requiring a round trip to unplug the remaining jets or other corrective action to activate the non-directional jets.

Drill string 13 is then lowered into borehole 10 and nozzle 17 oriented by conventional orienting methods, well known in the field of directional drilling, but indicated herein schematically by bar 37 clamped to Kelly bar 19. This bar is normally held in alignment by optical instruments (not shown) using a part of derrick 47 as a base line.

With the single or preferred jet 17 oriented, a predetermined weight is then applied to drill bit 16,'for exby cable 39, threaded through crown block 41 and travelling block 43. Adjustment of said tension is indicated by weight meter 45, located in the deadline and anchored to the floor of derrick 47. Lifting and lowering of drill string 13 is performed by drawworks drum 49 driven by motor 51.

With the single oversized, or unplugged, nozzle 17 directed toward one side of the borehole bottom, the weight thereon is alternately decreased and increased, and desirably bit 16 is raised and lowered in the well bore so that reciprocating, or churning, action occurs as nozzle 171 operates against one side of the bottom and the wall of borehole 10. The lateral erosion of the borehole in this manner is indicated in Fig. 2. Although conventional drill collars (heavy-walled drill pipe) will deflect sufficiently to follow the deviated borehole, drill bit 16 is assisted in following directly after, and in the direction of single nozzle 17, by supporting it upon a short section of regular drill pipe, known as a pup joint, 53. Section 53 is preferably thin-walled so that there is more transverse flexibility in the drill string vdirectly above the bit. To prevent undue, or too rapid,

deflection of borehole 10A away from the direction of original borehole 10, drill string 13 is provided with a stabilizer 55 secured to the outer surface of drill collar 7 15. This stabilizer assists the drill pipe to remain in the center of the borehole 10A and maintains a large radius of curvature while the lower end is deflecting in the desired direction of deviated borehole 10A.

When deflected borehole 10A has achieved the desired angle of deflection, the jet drill apparatus may be returned to normal rotary jet drilling. When restricted circulation has been permitted through the remaining jets, this can be done merely by starting rotation of the rotary table 57 in conventional manner.

There is shown in Figs. 3, 4 and 5 an alternative arrangement for directionally controlling the flow of drilling fluid to a single jet nozzle. As best seen in Fig. 3, flexible plug element 63 forms a flow directing means with bit 16 and drill collar 15. Plug 63 includes a pair of ears 64 adapted to fit into two of the three flow passageways 60 in bit 16. As best seen in Fig. 5, the ears 64 are flexible and normally turn outwardly so that they generally conform to molded passageways 60 and terminate just above nozzle inserts 173. In the present arrangement each of the nozzles 17 have inserts 173 of the same diameter so that upon removal of plug unit 63 from main passageway 61 through pipe collar 15 and bit 16, flow of drilling, fluid will be equal through all three nozzles 17. As further shown in both Figs. 3 and 5, a central passageway 66 is formed in plug member 63 to funnel drilling fluid into a single, unstopped passageway during directional drilling. This flow passageway is best seen in Fig. 4.

Since it is desirable to retrieve the plug member 63 after directional drilling as described hereinabove and the borehole has attained desired deviation, a plug snatcher arrangement 74 is lowered on cable 76 to engage knob 72 on the end of shaft 70. Shaft 70 is connected to plug 63 by bale 68 molded into the plastic or rubber body of flow directing plug 63. As indicated in Fig. 5, when the fingers on snatcher 74 lift plug unit 63, ears 64 are deformed to the position indicated by the dotted lines. Thus, the entire unit can be pulled out of the drill string so that conventional jet drilling can proceed with equal fluid flow through nozzles 17.

Drilling can be performed with only a single jet open, by rotating the drill bit 16 with the remaining one or two other jets plugged, but, of course, it is preferable to remove the plugs in the remaining jet nozzles 17.

Alternative to the arrangements shown in Figs. 3 to 5, individual plugs can be used in the nozzles that are removable.in several different ways. For example, the entire drill bit assembly can be lifted out of the boreample, by releasing a portion of the weight supported 15 hole and the plugs moved manually, or the individual plugs can be made of a 'frangible material that will burst through the nozzles that have been blanked otf upon suflicient increase of mud pressure above a predetermined value, that can be indicated by gauge 59 on the output of mud pump 93. Alternatively, reversed circulation of drilling fluid in the borehole can be used to recover the plugs from within drill string 13.

While the present method has been described as applied to by-passing a previously drilled hole, it will be understood that the present method is particularly adapted to drilling of offshore wells wherein it is desired to position as many producing wells as possible on a single platform by deflecting the wells to cover a large lateral area below'the earths surface. In some operations, it is desirable to be able to begin deflecting the well bore at the underwater bottom. For this purpose, the directional hydraulic jet bit is oriented in the desired direction when the drill string is lowered into contact with bottom. Adequate pressure is then applied to drill bit 16 so that drilling will be started by hydraulic action in the direction of the single oriented nozzle. As soon as the bit has been drilled several feet into bottom by this technique, the bit is alternately raised and lowered while circulation continues.

Preferably a continuing survey of the well orientation is made while directional jetting action continues. This deviation can be surveyed with conventional equipment. In such borehole surveying a record is made either by a continuous indicator or by a socalled one-shot camera method wherein a single photo of the angle and direction of deflection is made at any desired point in the well bore. In such method, the directional recording instrument is recovered at the earths surface without removal of the drill string.

In using the foregoing system, I have found it possible to deflect a borehole through 24 of angle from true vertical in a borehole only 2035 feet deep. In said well bore, the angle of deflection was found to be 2 /4" in the first 17 feet of penetration and 8 A at a depth of 47 feet after deflecting. Additional deflection could have been obtained by the above-described method, but in the particular well being drilled, it was desired to maintain the deflection not greater than about 24 at the 2000 foot depth.

It will be apparent that the present method is not confined to any particular form of bit since jet bits, and jet drilling methods are commonly known that use either two or three cones and have a comparable number of jet nozzles, each directed against the bottom of the well bore, intermediate the cutting surfaces of the bit cones. Additionally, drag bits having jet nozzles can be used in the method described. Further, the degree of flexibility of the drill string can be varied considerably depending upon the direction and amount of deviation desired in a completed'well bore by insertion or omission of a flexible length of pipe below the drill collars.

Various other modifications in the apparatus and in the method of applying the concept of the present invention will become apparent to those skilled in the art from the foregoing description. However, it is intended that all such modifications falling within the scope of the appended claims are to be included therein.

I claim:

l. The method of directionally drilling a well bore into an earth formation by jet drilling method with a drill bit that includes a plurality of rotary cutters and a plurality of fluid-ejecting nozzles adapted to dire-ct drilling fluid against the bottom and Wall of a borehole intermediate said cutters which comprises the steps of restricting drilling fluid flow through all but one of said plurality of nozzles, orienting said drill bit with said one unrestricted nozzle positioned relative to the earth in the direction of desired deviation of the bore-hole, and supplying drilling fluid under pressure through at least said one nozzle to erode said well bottom and wall in the direction of orientation of said unrestricted nozzle, at the same time periodically reciprocating said drill bit into and out of contact with the bottom of the well bore, said reciprocation being performed without rotation of said drill bit.

2. The method in accordance with claim 1 wherein the flow of drilling fluid is restricted to be substantially all through said one oriented nozzle by blocking said flow to the remainder of said nozzles.

3. The method in accordance with claim 1 wherein the flow of drilling fluid is preferentially directed toward the desired direction of deviation by making the flow through said one oriented nozzle substantially greater than that through the other of said nozzles by increasing said flow through said one nozzle and simultaneously restricting flow to the remaining nozzles.

4. The method of directionally drilling a well bore with jet drilling apparatus that comprises a drill string including drill pipe and drill collars, a drill bit secured to the lower end of saidgdrill string, said drill bit including a plurality of cutter members and a plurality of fluid nozzles for directing fluid flow at the bottom of a well bore intermediate said cutter members, means for supplying drilling fluid under pressure therethrough and means for elevating and lowering said drill string to apply a predeterminable weight to said drill bit which comprises the steps of restricting the flow path through said plurality of nozzles so that -a substantial portion of the drilling fluid flow will be through only one of said nozzles, orienting said drill string with said one nozzle in the desired direction for deflection of a borehole from said well bore, lowering said drill bit into contact with said well bore bottom, applying a predeterminable weight to said drill 'bit while pumping drilling fluid under pressure through at least said one nozzle to erode said bottom of said well bore in the direction of orientation of said one nozzle, and maintaining a predetermined rate of circulation of said drilling fluid through said one nozzle while at the same time reciprocating said drill string substantially without rotation thereof.

5. The method of directionally drilling a well bore with jet drilling apparatus that comprises a drill string including drill pipe, drill collars, and a drill bit secured to the lower end of said drill string, said drill bit including a plurality of cutter members, a plurality of fluid nozzles for directing fluid flow at the bottom of a well bore intermediate said cutter members, means for circulaitng drilling fluid through said drill string and means for elevating and lowering said drill string to apply a predeterminable weight to said drill 'bit which comprises the steps of positioning a relatively flexible section of drill pipe intermediate the lower end of said drill collars in said drill string and said drill bit, restricting the flow path through said plurality of nozzles so that a substantial portion of the drilling fluid will flow through only one of said nozzles, orienting said drill string with said one nozzle in the desireddirection for deflection of a borehole from said well bore, lowering said drill bit into contact with said Well bore bottom, applying a predetermina'ble weight to saiddrill bit, pumping said drilling fluid under pressure through at least said one nozzle to erode said well bore bottom in the direction of orientation of said one nozzle, and maintaining a predetermined rate of circulation through said one nozzle while at the same time reciprocating said drill string without rotation thereof to successively increase the weight on said hit up to a predetermined value and decrease it therefrom.

6. In the method of drilling a well bore with jet drilling apparatus that comprises a drill string including drill pipe, drill collars, and a drill bit secured to the lower end of said drill string, said drill bit including a plurality of cutter members, a plurality of fluid nozzles for directing fluid flow at the bottom of a well bore intermediate said cutter members, means for circulating drilling fluid through said drill string and means for elevating and lowering said drill string to apply a predeterminable weight to said drill bit, the method of directionally dcviating said well here which comprises the steps of positioning a relatively flexible section of drill pipe intermediate the lower end of said drill collars in said drill string and said drill bit, restricting the flow path through said plurality of nozzles so that a substantial portion of the drilling lluid will flow through only one of said nozzles, orienting said drill string with said one nozzle on the side of the well bore for the desired direction of deviation of said Well bore, lowering said drill bit into contact with said well bore bottom, applying a predeterminable weight to said drill bit, pumping said drilling fluid under pressure through at least said one nozzle to erode said well bore bottom in the direction of orientation of said one nozzle, maintaining a predetermined rate of circulation through said one nozzle while reciprocating said. drill string without rotation thereof and while successively increasing the weight on said hit up to a predetermined value and decreasing it therefrom, and then rotating said drill string to advance the drilling of said well 'bore after the desired deviation of the well bore has been obtained without withdrawing said drill string and bit from the Well bore.

References Cited in the file of this patent UNITED STATES PATENTS 1,878,292 Pivoto Sept. 20, 1932 2,167,194 Anderson July 25, 1939 2,324,102 Miller et al July 13, 1943 2,679,382 Schmidt May 25, 1954

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