US 3529684 A
Description (OCR text may contain errors)
Sept. 22, 1970 w. L. HILL HORIZONTAL NOTCHING TOOL Filed May 10, 1968 INVENTOR. WILLIAM L. HILL ATTORNEY United States Patent 3,529,684 HORIZONTAL NOTCHING TOOL William L. Hill, Ponca City, Okla., assignor to Continental Oil Company, Ponca City, Okla., a corporation of Delaware Filed May 10, 1968, Ser. No. 728,142 Int. Cl. E21b 7/18 US. Cl. 175-422 1 Claim ABSTRACT OF THE DISCLOSURE A perforating apparatus rotatably attached to the terminus of a well string and comprising a plurality of jets mounted at an angle so that when the perforating fluid is forced down the well string and out the jets, the perforating apparatus will rotate, cutting a disc-shaped perforation normal to the axis of the well bore.
BACKGROUND OF THE INVENTION In the design and initiation of hydraulic fracture treatments in subterranean formations, it is often necessary to create a horizontally oriented fracture. Rock stresses, tectonic forces, formation depth and lithological factors in a particular-formation affect, to a large extent, the direction that a fracture may take. Therefore, normal perforating techniques, due to the aforementioned factors, may or may not aid in forming a horizontal fracture.
The only known method which will insure a horizontal fracture is to form a 360 horizontal notch in the formation. Various methods are presently being used to perforate the formation in a horizontal plane to form such a notch. The patent to R. W. Brown, et al., No. 3,130,786, discloses a plurality of jets oriented in a horizontal plane. Each jet will, however, erode a single hole into the formation, rather than a 360 notch, so that when the fracturing fluids are applied, it is doubtful that a symmetrical horizontal fracture will result. Other patents, such as the patents to T. E. Quick, No. 3,081,828 and No. 2,720,381, disclose a means for forming a 360 perforation by rotating a jet manually wherein the jet is coupled to the drill pipe and the entire drill pipe is rotated to effect the 360 horizontal perforation. The latter patents, however, would not be satisfactory unless the bore hole is perpendicular, or at least substantially perpendicular. Any offset whatsoever would cause the drill pipe to bind when manually rotated. Further, if the drill string is excessively long, manual rotation would be nearly impossible.
SUMMARY OF THE INVENTION This invention comprises a rotating head journaled on the end of a string of drill pipe. The rotating head has a plurality of jets, mounted at an angle with the radius of the rotating head, so that when perforation fluid is forced down the drill pipe and out the jets, a rotational force is imparted to the head, causing the head to rotate. The abrasive fluid is forced out of the jets at high velocity, forming a 360 notch in the formation.
This invention has several advantages over the devices of the prior art in that the bore hole can have a dog leg and still permit the head to rotate, since the drill string itself does not need to be moved once the head is properly positioned adjacent the formation to be perforated. The perforation tool also includes a ball valve which will permit easy entry and withdrawal of the drill string and will likewise permit cleaning of the head and drill string after the perforation operation is complete.
It is therefore an object of this invention to form a 360 horizontal perforation without necessitating the rotational movement of the drill string holding the perforation tool.
3,529,684 Patented Sept. 22, 1970 It is a further object of this invention to incorporate means for removing and inserting the drill string having the perforation tool attached thereto, without the problem of flotation, or loading, caused by fluid within the pipe.
Other objects and advantages of the invention will be evident from the following detailed description, when read in conjunction with the accompanying drawings which illustrate the invention.
BRIEF DESCRIPTION OF THE FIGURES Referring to the figures in detail:
FIG. 1 is a partial sectional side view of the perforating tool;
FIG. 2 is a top sectional view taken through line 2-2 of FIG. 1; and
FIG. 3 is a cross sectional portion of a bore hole showing perforation tool in operation.
Referring to all of the figures, but in particular to FIGS. 1 and 2, a drill string 10 has attached thereto a perforating head generally referred to as 11. Perforating head 11 essentially consists of a plurality of jets 12, bearings 13, a plurality of seals 14-A and 14-3, and a ball valve 15. Ball valve -15 consists of a seat 16 and a ball 17 which should have a density greater than the material being pumped down the well bore. Jets 12 are removably attached to head 11 by means of threads 20 (see FIG. 2). The opening 21 of jets 12 is likewise in a plane perpendicular to the axis 23 of head 11 and at an angle 24 with the radius 25 of head 11. In the preferred embodiment of this invention, angle 24 is 22. It is obvious, however, that the angle can vary, depending upon the characteristics desired. A more detailed explanation will be given at a later point in the specification.
Head 11 is attached to mounting portion 30 by means of a collar 31 which can be secured to head 11 by a plurality of threads 32. A seat screw 33 anchors the collar 31 in place and prevents accidental rotation during operation of the device. Mounting portion 30 is attached through to drill string 10 by collar 34, using threads 35 to attach collar 34 to the drill string and threads 36 to attach collar 34 to mounting portion 30. Both drill string 10 and mounting portion 30 have an opening 40 used for the passage of perforating fluid. Attached to drill string 10 is a centralizer 41 (see FIG. 3), which is here shown to be the type used to alleviate wear on a drill string; however, other forms of centralizers can be used so long as suflicient clearance is permitted around the centralizer 41 to provide fluid passage either through or around it.
The perforator is operated by lowering the drill string head 11 secured through collar 34 to drill string 10, into the well bore. Normally, ball 17 in ball valve 15 is removed from the drill string during the lowering process. Ball valve 15 will then be free to permit the entry of fluids into the interior 40 of drill string 10. Since the fluids are free to enter the drill string, the air which would normally be trapped therein will be permitted to escape, thereby eliminating flotation problems. Once the jets 12 are positioned adjacent the stratum to be perforated, ball 17 is dropped into opening 40. Since the ball 17 is slightly more dense than the fluid in the well bore, the ball will drop through the fluid to seat 16 of valve 15. The ball can be put into the opening 40 by any well known means (not shown), such as, for example, a pair of valves communicating with opening 40. In this procedure, the ball is inserted between the first and second valves, with the second valve closed (the second valve being adjacent opening 40). The top of first valve is then closed and the second valve opened, permitting the ball to fall through the valve opening and into the drill string opening 40. The above is a standard technique for inserting objects into a drill string and is so well known that it is not shown in the drawing. Perforation of the strata adjacent the head 11 is accomplished by forcing an abrasive slurry down well string through opening 40 into head 11 and out the openings of jets 12. Since jets 12 are at an angle 24 with the radius 25, a torque will be applied to head 11, causing rotation in the direction of the arrow shown in FIG. 2. Head 11 is journaled on mounting por= tion 30 through a plurality of bearings 13; therefore, head 11 is free to rotate about mounting portion 30, causing jet 21 to subscribe a 360 arc. The perforating fluid 50 (see FIG. 3) will be forced out of the jet nozzles and against the strata opposite the jets, causing eroding away of the strata, forming a disc-shaped perforation 51. Stabilizer 41 may be used when necessary to maintain a clearance between the jets 21 and the wall 52 of the well bore. If head 11 were laying too heavily upon well bore 52, rotation of head 11 might be prevented by excessive friction. On substantially perpendicular holes, stabilizer 41 will probably not be needed since the jets would soon erode away any material that would cause the jets 12 to hang up. When the perforation is complete, fluid is reversed in the Well bore, that is, it is pumped down the annulus 53 of the well bore and up valve 15, causing ball 17 to leave seat 16 and travel up the opening 40 in drill pipe 10. The ball can be removed from valve using a procedure reverse to that used for inserting the ball and may be flushed into a fluid tank. Once the ball is removed, the drill string can be removed with ease since the fluids inside the drill string will flow freely out of the opening 15, preventing excessive weight, due to the liquid column form building up during removal of the drill string 10. Reverse flow has a second advantage in that it will tend to clean the perforation fluid from the head 11 and drill string 10, since clear liquid will be pumped up the drill string thereby preventing sand and other sediments from settling out of the perforation fluid.
The preferred embodiment shown in the drawings has only two jet nozzles 12. It is obvious that a single jet nozzle or more than two jet nozzles can be incorporated and stay fully within the teachings of this invention. An angle of 22 was likewise stated as being preferred; however, the angle should be sufficient to cause adequate rotation of head 11 under the pressure and flow conditions during perforation. Therefore, if the pressure within the opening 40 is increased, additional torque will be created by jet 12 and the angle 24 can be reduced conversely if the pressure on opening 40 is reduced. A reducing torque will be developed by jet 12 on head 11; therefore, the angle 24 will need to be increased. The main criterion of angle 24 is that it develops suflicient torque to prevent rotational stoppage of head 11 during the perforation process. Likewise, while the ball valve 15 is highly desirable, for ease of operation, it is fully understood that the perforation tool could be manufactured without the ball valve, particularly where the depth of perforation is fairly shallow. Further, one form of bearings has been shown. It is obvious that other methods of journaling head 11 in mounting portion 30 can be used. Likewise, a simplified version of seals 14A and 14B is shown. More complex or modified seals can be used in order to prevent the high pressure abrasive fluid from damaging bearings 13. These modifications are well within the ability of those skilled in the art and are likewise fully within the scope of this specification and claims.
Changes may be made in the combination and arrangement of elements as heretofore set forth in this specification and shown in the drawings; it being understood that changes may be made in the embodiments disclosed without departing from the spirit and scope of the invention as defined in the following claim:
What is claimed is:
1. A perforating apparatus for a well bore comprising a tubular drill string, a mounting portion on one end of said drill string, a cup-shaped rotating head means having a. longitudinal axis, collar means rotatably mounted over said mounting portion and secured to the open end of said cup-shaped rotating head means, tubular jet means having an axial opening therethrough, means for mounting said tubular jet means through the wall of cup-shaped rotating head means such that the axis of the opening through said jet means lies on a plane perpendicular to the axis of said cup-shaped rotational head means and at an angle to a radius of said cup-shaped rotational means, such that a fluid forced through the opening in said jet means will cause a force to be developed around the axis of said cup-shaped means, causing said cupshaped head means to rotate about said longitudinal axis, a ball valve means located in the bottom of said cupshaped rotational head means, and a centralizing means attached about said drill string in close proximity to said cup-shaped rotational head means.
References Cited UNITED STATES PATENTS 1,715,767 6/1929 Flore 166-223 2,657,753 11/1953 Carpenter 166-223 2,758,653 8/1956 Desbrow 422 3,066,735 12/ 1962 Zingg 175-422 3,130,786 4/1964 Brown et a1. 166223 3,318,395 5/1967 Messmer 166223 JAMES A. LEPPINK, Primary Examiner