US 3599734 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
United States Patent  References Cited UNITED STATES PATENTS 84,852 12/1868 Beach 175/272 X 821,816 5/1906 Myrick... 30/107 1,561,523 11/1925 Riedle 175/285 X 1,614,368 l/1927 Kergan 175/202 1,822,216 9/1931 l-lartson.. 175/272 2,372,875 4/1945 Benke 175/78 FOREIGN PATENTS 331,945 7/ 1930 GreatBritain 175/202 Primary ExaminerDavid H. Brown Attorneys-Joseph C. Kotarski, Henry H. l-luth, Jerry B.
Peterson, William J. Miller and David H. Hill ABSTRACT: An apparatus for forming a biconical notch by moving a symmetrical extendable cutter out of a rotating drill casing into the formation. Once the biconical notch is completed, the extending device can be retracted back into the drill casing and the casing removed.
PATENTEU AUG] 71971 lllllllll NATHANDALE FARR/S TIBOR O. EDMOND ATTORNEY NOTCHING TOOL BACKGROUND OF THE INVENTION Description of the Prior Art The normal method for causing a horizontal fracture in a formation is to use either a jet, such as fluid impinging on the wall of a well bore at a high velocity and rotating the jet through 360, or a high-velocity projectile or projectiles. It is normally assumed that the jet will cut a horizontal slice in the formation; however, it has been found that even if the jet does form a horizontal slice, the fracture will not always be horizontal since the forces may not be concentrated properly. It has been discovered, however, that a biconical notch horizontally formed in a formation having a sharp edged periphery will concentrate the forces in a manner to cause a proper horizontal fracture.
SUMMARY OF THE PRESENT INVENTION This invention will form a biconical notch in a formation providing a superior cross-sectional form for horizontal fracture. The invention essentially consists of a tubular housing having an extendible notching tool confined inside the housing. The notching tool consists of two bars joined at one end by a pivot. The other end is attached to a bearing on an extending and retracting mechanism. A sharp cutting end is attached to one of the bars at the common pivot point. The sides of the bars are formed to shape a notch having a conical cross section in the wall of the bore hole.
This invention has several advantages. First, it can be easily inserted into a bore hole since it can be collapsed to the same diameter as the tubular housing. Second, it forms a nearly ideally shaped notch having conical sidewalls and a sharp periphery so that the concentrated stresses will be equally applied in all directions around the notch, causing the fracture resulting from the stresses to propagate in all directions in a horizontal plane. Further, the notch is cut deeply into the formation and symmetrically about a vertical axis to insure that the fracture will propagate in all directions along the horizontal plane.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a cross-sectional view of the housing, with the extending mechanism shown in full view;
FIG. 2 shows a portion of the notching tool in cross-sectional view with the extending mechanism in full view and fully extended;
FIG. 3 shows one method, up hole, for extending and retracting the notching tool; and
FIG. 4 shows a second method for extending and retracting the notching tool.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Referring to all of the drawings, but in particular to FIG. 1, the preferred embodiment of a biconical notching tool is shown having a tubular housing 10 which has a bottom 11 and a longitudinally extended notch 12 cut through the wall of the housing. A rod 13 is mounted axially inside of the tube into a bearing 14 formed in the bottom 11 of housing 10 and secured at the other end by assembly 15. Formed into rod 13 are threads 20 and 21. Threads 20 and 21 must be of opposite hand, for example, if thread 20 is a right-hand thread, then thread 21 must be a left-hand thread. A pair of extending means 22 and 23 are threaded onto rod 13. The outer diameter 22A or 23A must be sufficient to transmit the cutting forces to permit ease of movement of extender means 22 or 23 longitudinally inside tubular housing 10. The clearance should also permit free passage of water so that accumulation of mud and chips can escape between extender means 23 and bottom 11. Bottom 11 is not necessary for the operation of the tool but in this embodiment does furnish a good bearing mount for the rod. It is obvious, of course, that holes can also be formed through the extender means 22 or 23 to permit passage of liquids. The notching tool consists of a pair of arms 25, 26 and a cutting end 30. Arm 25 is attached to extender means 22 at pivot 27 and arm 26 is attached to extender means 23 by a pivot 28. Cutting end 30 is attached to arm 26 and may be made of a hardened steel or edged with tungsten carbide to provide longer life and better cutting action. Arms 25 and 26 are connected to each other by a pivot point 31.
The assembly can be retracted completely within the housing 10 by virtue of the shape of arms 25 and 26. The entire assembly is extended or retracted by means of assembly 15 which consists of a mount 40, a shaft, bearing combination, and hexagonal extension 41. One end of the shaft 41 is threaded to receive rod 13. A nut 42 is tightened against shaft 41 to prevent accidental rotation of the shaft and a pin 43 is passed through the entire combination of shaft and rod to further insure that the system will not loosen during use. A
turning shaft 50 having a hexagonal socket 51 is slipped down housing 10 and coupled over the hexagonal extension of shaft 41. Shaft 50 (see FIG. 3) is then passed through a. seal 52, and a handle 53 is affixed to the end of the shaft 50. Housing 10 also has attached to it a handle 54 for rotation of the housing 10 about bore hole 16. Cleaning of the down hole equipment, that is, removal of mud and chips, is accomplished by having a water source 55 connected through a pipe 56 to a swivel joint 57 having the usual bearings 58 and seal 59. The water passes down the inside of housing 10 to a pair of pipes, for example, 60 and 61. Pipe 61 connects with a jet 62 and pipe 60 has an opening 63 near the bottom 11 of housing 10.
OPERATION To form a biconical notch, the entire housing 10 is lowered into a bore hole to a point where the slot 12 is centrally located over the area to be notched. Once the pipe is in the proper location, an anchor plate 70 is secured to the housing to prevent further downward movement of the housing 10. Other means than anchor plate 70 can be used, for example, hooks can be mounted on pipe flange 57 and the entire apparatus suspended by a cable suspended above the hole. The water 55 is then turned on and the handle 53 rotated in a manner to cause extender means 22 and 23 to move closer together. Since the threads are of opposite hand, rotating rod 10 in one direction will cause extender means to move together and rotation of the rod in the opposite direction will cause the extender means to move away from each other. The handle 53 will be rotated sufficiently to cause cutting end 30 to engage the wall 17 of bore hole 16. Once the point engages the wall, handle 54 is rotated sufficiently to cause housing 10 to move through 360. Continuous pressure of the cutting end 30 against the bore hole will be accomplished by applying co tinuous pressure to handle 53 while handle 54 is being rotate d through 360. Continuous pressure by handle 53 will eventually cause extender means 22 and 23 to urge the cutting end 30 fully into the formation. As it does so, however, the sides of arms 25 and 26 (see FIG. 2) will begin to engage at a point in the wall of the bore hole cutting away this area and forming a biconical slot. During the cutting operation, jets 62 and 63 will be flushing away the cut particles moving them uphole and away from the cutting operation. It is obvious, of course, that additional jets can be used whenever they are needed. Once the notch is fully cut, rotation of handle 54 can be stopped and rotation of handle 53 will commence in the opposite direction, causing rod 20 to rotate in the opposite direction, moving extender means 22 and 23 away from each other. Arms 25 and 26 will retract back into the inside of housing 10. The entire assembly can then be lifted out of the hole and the fracturing procedure commenced. Another method for extending and retracting the arms 25 and 26 can be an electrical motor 82 (see FIG. 4). A pair of wires 83 and 84 are connected serially through a switch 85 and a battery 86. Switch 85 is a reversing switch so that operation of the switch will cause the motor to rotate in one direction and operation of the switch in the opposite direction will cause the motor to rotate in the opposite direction. In operation, switch 85 would be closed until the motor ceased operating, indicating the cutting end 30 was engaging the bore hole wall. Handle 54 would then of course be rotated and the motor periodically operated, maintaining the end 30 continuously in contact with the bore hold wall. Once the slot was cut, the switch would be reversed and the apparatus retracted and lifted from the bore hole in the usual manner. Obviously, a clutch could be employed so that the switch need not be operated in an intermittent manner. It is also obvious that other apparatus can be employed to retract cutting end 30.
The notching tool, as above described, will cut a deep notch symmetrically located about a vertical axis. The tool will also form a notch having a sharp periphery. The symmetrically formed notch will provide equal application of fracturing pressures at every point along the periphery of the notch. The sharp edge periphery will form a high stress location, resulting in a fracture radiating out from the high stress location in every direction. It should also be noted that the walls of the notch meeting the sharp edged periphery have the same angle with respect to the horizontal plane passing through the periphery. A uniform angle will result in the fracturing stresses falling on the horizontal plane and not at some other undesirable direction. In addition to the above, the threaded rod 13 has an extremely desirable effect on the movement of the point 30 into the formation; for example, at the initial point of penetration, the point will be moving fairly rapidly into the formation for each rotation of the rod; however, as point 30 enters its maximum extend into the formation, it will be moving at a fairly slow rate in comparison to the initial rate of movement into the formation. The differential rates of movement of the point 30 per rotation of the rod is desirable since it affords much better control of the notching process. The particular shape of the arms 25 and 26 also provide for an extremely deep, narrow notch, yet the rods will maintain sufficient strength to cut the notch in most formations and will also permit complete retraction of the notching mechanism into the housing. In the preferred embodiment of this invention, point 30 has an angle of approximately 30, or when fully extended, 15 on each side of the horizontal plane. This is illustrated in FIG. 2.
It is of course obvious that this device will work best when used in plastic soils, such as clay mixed with sand. However, the tool should work equally well in harder and consolidated formations by proper design of the cutting edge. One device built in accordance with the teachings of this invention produced a notch approximately six times the tool diameter.
What we claim is:
l. A notching tool for the wall of a bore hole comprising:
a. a tubular housing having an elongated longitudinalslot therethrough;
b. first and second spaced extender means;
c. a threaded rod means one-half of which is threaded in the opposite direction from the remaining half, each set of threads having screwed thereon one of said spaced extender means,
d. means connected to one end of said threaded rod for turning said rod about its axis;
e. first and second symmetrically formed notching members pivotally attached at one end to each other and at the other end to said first and second spaced extender means to uniformly urge said first and second symmetrically formed notching members out of said slot; and
f. notching means attaching at one end to the pivotal end of said first notching member, the remaining end having a sharp periphery with a cutting angle of approximately 30.
2. A device as described in claim I wherein said rotating means comprises an electrical motor.
3. A device as described m claim 1 wherein said rotatmg means comprises an elongated rod coupled to said threaded rod at one end and to handle at the other end, the length of said elongated rod being sufficient to extend out of said bore hole.