claim: 1. The method of producing a bore having curved and straight portions which comprises rotating and advancing a drllling bit while resitlently and continuously urging the bit against one side wall of the bore to cause the bit to advance along a curved path to form the curved portion of the bore, and rotating and advancing the bit while resiliently urging the bit radially outward from the axis of the bore and progressively changing the outward radial direction in which the bit is resiliently urged to cause the bit to form the straight portion of the bore. 2. The method of drilhng from an existing weli bore a deviating v@ell bore having an initiai curved portion and a continuing straight portion comprising flexing to reduce the curvature and thus setting up stresses in an elongated normauy curved resiffent drill guide, disposing said guide in the existing well bore and restraining the same:flexed to a curvature substantially less than its norinal unstressed curvature by contact .With the walls of the existing well -bore, utilwng the' energy expended against a side wall of the existing well bore during the return of said drill guide to its normal unstressed curved conflguration for pressing a drill bit on one end of 'said guide into a side wall of the existing well bore, rotating and advancing the bit while holding the drill guide against rotation to drill the curved portion of the deviating bore, and thereaft;6r and without removal of the drill guide from the curved deviating bore Initiating rotation of said guide and simultaneously rotating and advancing the drih bit wmle rotating said drill guide to drill a stralgh@ continuation of said deviating curved bore. JOHN A. ZUBLIN.

Patented Mar. 14, 19" 29344@277 UNITED STATES PATENT OFFICE 2,314,277 METHOD OF DRMUNG ]LATERAL BORES John A. ZubUn, Los Angeles, Calff. Application January 27,19420 Serial No. 428,409 2 Clahns. (Cl. 255--l.6) This invention relates to the drilling of an- into the well after the curved side hole has been gular holes which originate and terminate within the oil sand and which emanate with sharp deviations from the vertical well bore penetrating this sand. 3 In my prior application, "Method and means to drill deviating holes," Serial No. 423,227, filed December 16, 1941, I have described a method and means to drill lateral bores, said bores being curved or stmight, consisting of the provislon of 10 a flexible resilient guide having a curvature substantially equal to the desired curvature of thi bore. Said flexible resilient guide is held stationary in the curved bore being produced while the bit Is rotated either by a turbine or by a flexible 15 hollow shaft. Tb drill a straight extension of a curved bore so produced, a normally straight resilient drill guide Is Inserted in the curved bore and the bit on the end thereof rotated -by any means desired causing It to drill a substantiaily 20 straight bore. The above patent application fully describes this process, particularly the drilhng of the curved bore, the subsequent withdrawal of the normally curved flexible resihent guide, and the insertion thereafter of the norrnally straight flexible resillent guide. The insertion of the straight drill guide into the laterally curved bore cannot, however, be accomplished without additional means to force the norinally stri@ight drill guide Into 30 this o@urved side hole, for the reason that due to gravity the normally straight drib guide hangs freely within the vertical well bore with no energy whatsoever to force it into the waH of the bore in the direction and at the place where the 3.5 curved side hole leaves the vertical bore. Previously, I have contemplated using conventional deflecting means, such as whipstocks and the like, to be set In the well bore where the deflectIng bore starts. In many cases, however, this 40 procedure is complicated, expensive and difficult to apply, particularly when lateral bores are required extending in different directions from one and the same weil bore. I have therefore made the lrivention herein explained which comprises 45 methods of entering curved side holes without the use of such tools, In order to simplify the method of driuing straight holes out of curved side holes. The resilieney and flexibility of drill guides 50 made of helically slotted Pipe of proper steel as described in my application Serial No. 423,225, Med December 16,, 1941, entitled "Mexible resilient drill Pipe,!'Is very great. A normally slightly curved drill guide of @these characteristics Is run 05 drilled' The resiliency and curvaturi@ of the guide aresufficient to drive the bit @towards one side of the well bore so that, when the bit reaches the depth at which the,side hole starts, the bit will, upon proper orientation of the drill pipe from the surface,,readily fall into the mouth of the side hole, whence it can be Iowered to the end of the curved side hole where the straight hole is to be started. If now the bit and this slightly curved resilient drill guide are rotated, then the bit will start to make hole. Different bits have different cutting motions. Some of @ them will drill more forwardly in the direction of the axis of the well bore, while others have cutting edges on the side, enabling them to penetrate forwardiy and sidewlse at the same time. Any drilling bit will follow the way of least resistance, and the rotating slightly curved resilient drill pipe will have a natural tendency to rotate the bit around an enlarged circle, due to,the side pressure which the normally curved resilient pipe exerts on the bit in a straight hole. The resiliency of the guide, the type of the bit, the number of revoliitions of bit and guide, and the characteristics of the fbr#iation can be related in such a manner as to predetermine the desired size of oversize hole which the bit is supposed to drill. The straightness of the hole is not affected by the normal curvature of the resilient flexible drill guide because its curvature In one direction is offset by its curvature in the opposite direction after one-half of a turn of the guide itself. AlthGugh It is contemplated to use for 'the drilling of the straight hole a flexible resilient drill pipe of normally less curvature than the drill guide used to drill the originally curved hole, it is possible to use the curved drill guide utilized for drilling the curved hole without rotation for drilling the straight hole by rotating this curved drill guide. It is therefore to be understood that the elongated n6rmally curved guide is flexible and resilient enough to be rotated not only in a straight. hole but also in the curved hole which has been previously drilled. With the above in mind, it is the primary object of the present invention to provide an improved method to cause a bit with an eionE,,ated resilient guide to enter an existing curved side hole in a well bore without the help of deflecting tools set in the weli bore. 'It Is another object of the present invention

2 2,8",277 to provide an Improved method and mems for drilling a suiftht extension from a ahwply curved lateral bore. It is a further object of the present invention to provide a method for cutting a stra*ht bore with the same equipment which previmWY lias been used to drill a curved lateral bore. It Is a further object of the prewnt Invention to provide a method and means of Producing a lateral stmight bore which Is of greater diameter than the bit. It is a further object of the present invention to permit customary rotauve speeds in the drillIng of straight lateral bores which enables the use of customary dduing tooll It is a further object of the present Invention to provide a novel method for ur)Aerreaming well bore& Other objects and advantages will become apparent as the description proceeda. Tuming now to the dmwing: Plgure 1 Is a diagrammatic ' view of one form of the present invention shown in a well, with the bit about to enter a lateral bore; ngure 2 is a view similar to Mgure 1 illustrating the production of a stralght, enlarged extension of a curved side bore; Mgure 3 is a section of the lower. end of a modified form of a device such as shown in Figure 1; and, Plgure 4 is a section simflar to Mgure 3 of a further modified form of the device shown In Flgure 1. Referring fimt to Pigure 1, the method by which a bit and guide are caused to enter a lateral bore has been shown. The well I 0 has a lateral bore I f into which It is desired to have a bit and a flexible resflient guide enter for further drilling. The flexible guide is Indicated at 12 and is',secured to either the drill pipe or another length of fle3dble pipe 13 by means of the coupling 14. 7be lowermost end of this flexible gidde 12 carries a bit 15 which may be rotated by a turbine, a ftexible shaft, or by rotation of the guide 12. It can be appreciated that, if the guide were straight, the bit 16 would not enter the side bore II as the entire apparatus Is lowered Into the well 18, because gra;vity would normally cause the bit to pass the mouth of the side bore I I and continue to the bottom of the well. For this reason, the resilient guide 12, instead of being normally straight, is provided with a curvature in its length. This curvature need not be as great as that which was necessary to Produce the bore II. It need be, for example, only sufficient to cause the guide 12 to take the configuration shown in dotted hnes In Mgure 1 except when restrained by the walls of the well 10. If the flexible guide is properly oriented iL the well bore by any suitable known method, it can be seen that lowering the bit and guide will cause the bit to tmvel along the outside surface I 6 of the lateral bore until the bit has entered the mouth of the bore I 1. After such entry the bit can be forced to the end of the lateral bore and drilling may proceed. As the guide 12 is normally curved, rotation of the bit 15 while the guide 12 remains stationary would result in the production of a curved bore as described in my application entitled "Method and means to drill deviating holes" mentioned above* If It is desired to drill a straight bore, it becomes necessary to utflize some method of operation which will ciluse the bit on this curved guide to make such a straight bore. In Mgm 2 the guide 12 ha3 been shown in the curved bore I I and, as shown in this figure, the bore has been continued from the point 20 with a substantiauy straight axis. This is accomplished by simply rotating the guide 12 as drilung proceeds. As shown in Plgure 2, the first effect of drilung with a rotating guide is to cause theproduction of a tapered bore 2 1, which eventually merges into a cylindrical bore 22. The reason 10 for the straightness of the bores 21 and 22 is tho fact that rotation of the drill guide neutralizes the effect of the curvature thereof. The reason for the enlargement of a bore so that It is of a greater diameter than the diameter of 15 the bit is the side pressure exerted on the bit by the tuming guide 12. Continued driuing will therefore produce a straight enlarged bore. 7be above described drill guide 12 has a curvature in its length sufficient to cause it to enter 20 the side bore I 1. It is possible, instead of utirzing a special curved guide, to utflize the curved guide which was used to produce the original curved portion 19 of the lateral bore I 1. In fact, it is possible to drill the curved portion I 9 of 25 the bore i 1, and then by changing the operative technique to cause a continuation of this bore in a straight line. In order to accomplish this result it is necessary that, while the portion 19 Is being drilled the guide 12 be held against rat&- 30 tion while the bit is rotated to cut the formation. This rotation of the bit while the gwde remain& stationary can be accomplished by the use of a turbine as described in7my above mentioned copending application. It may also be accom35 plished by some such means as Is shown in Figure 3. In Flgure 3 a resflient guide 30 consisting essentially of a helicary slotted resilient pipe Is provided with a rotating head 31, which carries a bit 32 by means of the conventional pin 49 and,b6x connection. This head 31 is held In place on the lower end of the resilient guide 30 by means of balls 33 running in races on the interior of the guide 30 and on the exterior of the head 31. Rotation of the head 31 and the bit 32 45 without rotation of the guide 30 is accomplished by rotating an interior flexible tubular shaft 34, which is secured to the head 31 by any suitable means. This interior shaft 34 may be conveniently used to convey the drilling fluid to the 50 bit through to interior bore 35. It can be appreciated that the curved portion of a side bore can be produced by simply arowing the e'xterior guide 30 to remain stationary while the shaft 34 is rotated. To produce a straight bore the shaft r,5 34 and the guide 30 may be rotated as a unit or at different speeds as desired. The guide 30 may be most conveniently secured to the drill pipe extending to the surface while the flexible shaft 34 Is secured to a smaller diameter pipe 60 passing through the bore of the drill pipe, this s-aller pipe also extending to the surface and being capable of connection to the rotating machinery there situated. However" the inner shaft may be rotated by any other means desired. 65 In the event that it Is desired to use a curved resilient gaide solely for the production of a straight bore, the construction showed In Mgure 4 may be used. In Uiis form of construction the bit 48 is attached to a coupling 4 1, which is in 10 turn threaded into the resment guide 42. On As lnteriot this guide 42 carries a flexible hose 43, which Is used to convey the drihing fluid to the bit. This hose Is connected to a nipple 44 which Is RW threaded into the guide 42 and 76 serves to tmnsmlt the fluid to the bit through

2,344,277 3 a passage 45 extendingthrough the coupllng 41. Of course it Is to be understood that the cgupling, guide and hose uwmbly can also be used when the bit is intended to be rotated by a turbine inserted between the guide and a bit, as de- 5 scribed In my copending appucation, "Method and means to driu deviating holes," mentioned above. With the above constructions and prlnciples In niind, variations In opemtive technique readily 10 suggest themselves. Perhaps the simplest method in drilling a straight hole is to secure the bit to the lower end of a resibent drUI guide and rotate the guide and bit as a unit. However, the bit may be rotated Independently of the guide 15 as by means of a flexible hose or shaft driven from the surface or by means of a turbine at the lower end of the guide. If It is desired to drill a curved hole, the bit must be rotated while the normally curved resilient guide remains sta2,,) tionary, in which case, a turbine or some such expedient as that shown in Mgure 3 must be employed. If the device In Flgure 3 Is utfflzed, the same equipment can be used for the curved and straight portions of a lateral bore by simply stopping rotation of the guide to produce curved bores and causing the guide to rotate to produce straight bore& Normally curved resilient guides, of the construction shown in either Flgure 3 or Flgure 4 can be used to produce enlarged bores, Z;o even to theextent of underreaming a weU bore. The tapering and cylindrical portions shown In Flgure 2 would then exist in the portion of the well bore acted upon by a rotating normally curved guide having a bit on its lower end wbich 35 rotates either at the same or at different speeds from the speed of the rotating guide. I