Abstract:
A perforation gun which provides a means to create perforations required for the hydraulic fracturing of rock formations for the production of natural gas, oil, and other oil well fluids and further comprises a gun body assembly having an inserted carrier tube to nest shaped charge canisters with built in primers, conical liner, and explosive material. The charges are positioned in various angular patterns along various phase angles to create specifically directed perforation tunnels which puncture scalloped areas of the aforementioned gun body and subsequently penetrate through the wellbore, well casing, well cement, and into the rock formations for the release and removal of natural gas, oil, and other oil well fluids after hydraulic fracturing.

Description:
RELATED APPLICATIONS 
     There are currently no applications co-pending with the present application. 
     FIELD OF THE INVENTION 
     The presently disclosed subject matter is directed to hydraulic fracturing of rock formations for the production of natural gas, oil, and other well fluids. More particularly this invention relates to well perforation guns that use shaped charges to create directed hydraulic fracturing perforation tunnels. 
     BACKGROUND OF THE INVENTION 
     One (1) of the largest and more important industries in the world is energy production. A simple basic fact is that the world in general and America in particular needs energy. 
     There are many different types of energy: coal, hydro, solar, nuclear, wind and fossil fuels (non-coal fossil fuels). Coal has a reputation for being dirty and shares with nuclear a reputation as being a source of dangerous pollution. Hydro power has been almost fully developed in the United States. Wind and solar power while attractive are unproven as reliable large scale sources of power. However, fossil fuels are well known and widely used sources of power, particularly for vehicle and heating fuels. 
     Fossil fuels have been widely used for well over a hundred years. The main problems with fossil fuels include price, which is a function of availability. Recovering fossil fuels is become increasingly more difficult as new fields are seldom encountered. However, newer recovery methods have increased the amount of fossil fuels that can be obtained from known fields. 
     The newer recovery methods include hydraulic fracturing. Hydraulic fracturing is based on creating and propagating fractures in a geological formation by first using explosive shaped charges to create perforation tunnels and subsequently pumping liquids and propant material through the perforation tunnels into the geological formation. Hydraulic fractures enable gas and petroleum contained in the source rocks to migrate into a well where the fossil fuel can be recovered using well-known techniques. 
     Hydraulic fracturing is not without its problems and technical challenges. Creating effective perforation tunnels is not in itself trivial. Producing controlled explosions within a well bore to create effective perforation tunnels is even more difficult. First the explosion must be at the proper well depth. This typically requires drilling a well to the proper depth followed by the insertion of one (1) or more perforation guns containing explosive charges. Then, for maximum effect the perforation tunnels must be directed towards a desired direction. Since that location might be up, sideways, down, or at a particular angle the explosive charges should be both shaped to form a tight, effective perforation tunnel and directed towards the proper orientation. At well depth both of these desired attributes are difficult to accomplish. 
     Therefore, a new perforation gun that produces tight, controlled, and effective perforation tunnels in the desired direction would be beneficial. Even more beneficial would be a new perforation gun capable of producing controlled and enhanced perforation tunnels. 
     SUMMARY OF THE INVENTION 
     The principles of the present invention provide for a new explosive perforation gun that produces tight, controlled, and effective perforation tunnels in the desired direction. The perforation gun is capable of producing controlled and enhanced effect perforation tunnels. 
     A perforation gun that is in accord with the present invention includes an outer gun body assembly having a straight steel pipe casing with internal female threads at each end, a plurality of external recessed areas, and an orientation slot extending inward from one (1) end of the steel pipe. The perforation gun further includes a carrier tube assembly having a linear charge tube, a first collar having an external alignment pin that is dimensioned to slide into the orientation slot and which is located at one (1) end of the charge tube, a second collar at the opposite end of the charge tube, a plurality of shaped charge saddle slots through the charge tube, and a plurality of shaped charge body apertures through the charge tube, wherein the plurality of shaped charge saddle slots and the plurality of shaped charge body apertures form a plurality of shape charge holders, and wherein the charge tube is a length of straight steel pipe that is slightly shorter than said outer gun body assembly. The perforation gun further includes a plurality of shaped charges, each having a shaped charge saddle, each having a charge base, and each of which is located in an associated shape charge holder of the plurality of shape charge holders. The carrier tube assembly is inserted into the outer gun body assembly such that the alignment pin slides into the orientation slot to control the orientation of the plurality of shape charges with respect to the external recessed areas. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The advantages and features of the present invention will become better understood with reference to the following more detailed description and claims taken in conjunction with the accompanying drawings in which like elements are identified with like symbols and in which: 
         FIG. 1  is an exploded perspective view of a perforation gun  10  having angled shaped charges according to a preferred embodiment of the present invention; 
         FIG. 2   a  is a side cut-away view of the perforation gun  10  shown in  FIG. 1 ; 
         FIG. 2   b  is a section view of the perforation gun  10  taken along section line I-I of  FIG. 2   a;    
         FIG. 3  is a perspective view of a carrier tube assembly  30  of the perforation gun  10  shown in  FIG. 1 ; 
         FIG. 4  is a side cut-away view of the perforation gun  10  shown in  FIGS. 1 and 3  in use; 
         FIG. 5  is an exemplary perforation tunnel vector diagram for the perforation gun  10  shown in  FIGS. 1 ,  3 , and  4  according to a preferred fan-shot embodiment  80 ; 
         FIG. 6   a  is an exemplary perforation tunnel vector diagram for the perforation gun  10  using a down-shot embodiment  83 ; 
         FIG. 6   b  is an exemplary perforation tunnel vector diagram of a limited-entry embodiment  85  of the invention; and, 
         FIG. 6   c  is an exemplary fracture perforation tunnel vector diagram of a combined-limited-entry-fan-shot embodiment  90  of the invention. 
     
    
    
     DESCRIPTIVE KEY 
     
         
         
           
               10  perforation gun 
               20  outer gun body assembly 
               21  steel pipe casing 
               22  female threaded region 
               23  male threaded coupling 
               24  orientation slot 
               25  recessed area 
               26  male threaded region 
               30  carrier tube assembly 
               32  charge tube 
               33   a  first collar 
               33   b  second collar 
               34  set screw 
               35  orientation/alignment pin 
               37  carrier interior space 
               40  perforation tunnel vector angle 
               42  shaped charge saddle slot 
               43  shaped charge body aperture 
               44  clip feature 
               60  perforation tunnel vector 
               80  fan-shot embodiment 
               82   a  first fan perforation tunnel vector 
               82   b  second fan perforation tunnel vector 
               82   c  third fan perforation tunnel vector 
               82   d  fourth fan perforation tunnel vector 
               82   e  fifth fan perforation tunnel vector 
               83  down-shot embodiment 
               84  down-shot perforation tunnel vector 
               85  limited-entry embodiment 
               86   a  first limited-entry perforation tunnel vector 
               86   b  second limited-entry perforation tunnel vector 
               86   c  third limited-entry perforation tunnel vector 
               86   d  fourth limited-entry perforation tunnel vector 
               86   e  fifth limited-entry perforation tunnel vector 
               90  combined limited-entry-fan-shot embodiment 
               92   a  first combined perforation tunnel vector 
               92   b  second combined perforation tunnel vector 
               92   c  third combined perforation tunnel vector 
               92   d  fourth combined perforation tunnel vector 
               92   e  fifth combined perforation tunnel vector 
               120  shaped charge canister 
               125  shaped charge saddle 
               130  charge base 
               200  well casing 
               300  geological formation 
           
         
       
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The best mode for carrying out the invention is presented in terms of its preferred embodiment, herein depicted within  FIGS. 1 through 6   c , and a person skilled in the art will appreciate that many other embodiments of the invention are possible without deviating from the basic concept of the invention, and that any such work around will also fall under scope of this invention. It is envisioned that other styles and configurations of the present invention can be easily incorporated into the teachings of the present invention, and only one particular configuration shall be shown and described for purposes of clarity and disclosure and not by way of limitation of scope. 
     The terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. 
     Referring to  FIGS. 1 ,  2   a , and  2   b , the principles of the present invention provide for a perforation gun  10  that uses angled shaped charges  120  to explosively perforate geological formations  300 . The perforation gun  10  is first placed inside a well casing  200  (see  FIG. 4 ), the shaped charges  120  are directed to the desired direction, and then the shaped charges  120  are exploded to create fracture patterns that assist extraction of natural gas, oil, and other oil well fluids. 
     The perforation gun  10  comprises an outer gun body assembly  20  that receives and accurately positions a carrier tube assembly  30 . The outer gun body assembly  20  and the carrier tube assembly  30  are aligned and machined so as to position a plurality of internal shaped charges  120  which create interactive angled perforation tunnel vectors into geological formation  300  (see  FIGS. 4 through 6   c ) upon detonation. Those vectors aid hydraulic fracturing of the geological formation  300  and the release and capture of natural gas, oil, and other oil well fluids. 
     Each outer gun body assembly  20  includes a variable length of a specially machined straight steel pipe casing  21  that has internal female threaded regions  22  machined at each end, and a plurality of external machined recessed areas  25 . The female threaded regions  22  enable any number of outer gun body assemblies  20  to be attached together in an “end-to-end” manner using interconnecting male threaded couplings  23  (see  FIG. 4 ). The recessed areas  25  of the outer gun body assembly  20 , which are preferably circular, oval, or rectangular shaped to a depth of approximately one-half (½) of the thickness of the steel pipe casing  21  are arranged to align with corresponding shaped charges  120  that are positioned within the carrier tube assembly  30 . Upon detonation, the recessed areas  25  provide weak sections of steel pipe casing  21  that are readily punctured by the perforation jets produced by the exploding shaped charges  120 . 
     The outer gun body assembly  20  includes an orientation slot  24  along an inside surface at one (1) end of the steel pipe casing  21 . The orientation slot  24  accurately orientates the carrier tube assembly  30  within the outer gun body assembly  20 . The orientation slot  24  works in conjunction with a corresponding orientation/alignment pin  35  of the carrier tube assembly  30 . The orientation/alignment pin  35  is a cylindrically-shaped feature having a diameter sized to provide a sliding fit in the orientation slot  24 . 
     During loading of the carrier tube assembly  30  into the outer gun body assembly  20  the orientation/alignment pin  35  is positioned at a trailing end of the carrier tube assembly  30  during insertion. To completely insert the carrier tube assembly  30  into the outer gun body assembly  20  the orientation/alignment pin  35  slides into the orientation slot  24  to properly establish the correct theta (rotational) position of the carrier tube assembly  30  within the outer gun body assembly  20 . Complete insertion happens when the orientation/alignment pin  35  abuts the inward end of the orientation slot  24 . This longitudinally and rotationally positions the carrier tube assembly  30  within the outer gun body assembly  20  which is then held in place with a recessed snap ring. 
     Referring now primarily to  FIGS. 2   a  and  3 , the carrier tube assembly  30  includes a linear charge tube  32 , a first collar  33   a , a second collar  33   b , a plurality of shaped charge saddle slots  42 , and a plurality of shaped charge body apertures  43 . The charge tube  32  is a length of specially prepared straight steel pipe slightly shorter than the outer gun body assembly  20  into which it is installed. The charge tube  32  enables attachments to the collars  33   a ,  33   b  via respective threaded set screws  34  (only one shown in  FIG. 2   a ). The first collar  33   a  includes the aforementioned integral orientation/alignment pin  35  which protrudes perpendicularly to engage the corresponding orientation slot portion  24  as previously described. 
     The shaped charge saddle slots  42  comprise circular, rectangular, or oval-shaped features that are machined through the charge tube  32  to allow insertion of a shaped charge saddle  125  of a shaped charge  120  placed inside the carrier tube assembly  30 . Each shaped charge saddle slot  42  has a corresponding shaped charge body aperture  43  that is machined through an opposing surface of the charge tube  32 . Each shaped charge body aperture  43  comprises a circular or cylindrical-shaped machined feature having a diameter dimensioned to receive a charge base  130  of a shaped charge  120 . 
     Referring now primarily to  FIG. 2   b , the system  10  uses a plurality of commercially-available shaped charges  120  such as those available from OWEN OIL TOOLS™, TITAN SPECIALTIES, LTD™, and others. Each shaped charge  120  has a cylindrical shaped charge base  130  having a single protruding conical-shaped end that forms the shaped charge saddle  125 . Each shaped charge  120  also has a contained explosive, a conical metal liner, a shaped charge body, and built in primers. The direction of a shape charge  120  can be variably directed via the joint angular and positional characteristics of a shaped charge saddle slot  42  and a shaped charge body aperture  43  that directs an explosion toward a recessed area  25 . Selective pairings of shaped charge saddle slots  42  and shaped charge body apertures  43  can angle a shaped charge  120  toward an end of the carrier tube assembly  30  along a plane which is parallel to and horizontally extending along the center of the carrier tube assembly  30  (see  FIGS. 5 through 6   c ). 
     Referring now primarily to  FIG. 2   a , located along the perimeter of each shaped charge body aperture  43  is at least one (1) machined clip feature  44  which comprises a malleable, finger-shaped appendage that can be bent and positioned using a hand tool against the charge base portion  130  of a shaped charge canister  120  to secure the shaped charge canister  120  in position. 
     Referring again to  FIG. 3 , the carrier tube assembly  30  can be incrementally positioned such that the shaped charge saddle slots  42  and shaped charge body apertures  43  align the shaped charge canisters  120  at selective phase angles along a spiral or straight pattern from one (1) end of the carrier tube assembly  30  to the other. It is understood that various phase angles such as one-hundred-eighty (180°) degrees, ninety (90°) degrees, sixty (60°) degrees, and the like may be used based upon a user&#39;s preference to produce a desired geological perforation formation  300  and hydraulic fracturing effect. 
     Referring now to  FIG. 4 , which is a side cut-away view of the system  10  in use, the system  10  includes the outer gun body assembly  20  with threaded couplings  22  at each end. Male couplings  23  provide male threaded regions  26  that mate with female threaded region  22 . This enables any number of desired outer gun body assemblies  20 , each containing a carrier tube assembly  30  to be coupled together to create a selective length system  10 . 
     Upon detonation, the angular positioning of the shaped charges  120  with respect to corresponding shaped charge saddle slots  42  and shaped charge apertures  43  produce directed perforation tunnel vectors  60  that penetrate the well casing structure  200 , any surrounding well casing cement, and the surrounding geological formation  300 . The outer gun body assemblies  20  and the carrier tube assemblies  30  may be specifically machined with the aforementioned features  42 ,  43  to enable positioning of the shaped charges  120  at various phase angles and angular orientations to create desired geological formation perforations and subsequent fracturing. 
     Possible perforation tunnel vectors  60  are illustrated in  FIGS. 5 through 6   c .  FIG. 5  shows a preferred fan-shot pattern  80 . The carrier tube assembly  30  is configured with shaped charge  120  oriented and arranged at a selected phase angle to form a fan-shot pattern  80  upon detonation. The fan shot pattern  80  is produced by arranging groups of shaped charges  120  at phase angles that progressively increase along the length of the carrier tube assembly  30 . The shaped charges  120  produce monotonically decreasing (measured in an X-Y plane with 0° toward the right) perforation tunnel vectors  60  comprising first fan perforation tunnel vectors  82   a  (such as 135°) near the left hand side of the carrier tube assembly  30 , smaller angled second fan perforation tunnel vectors  82   b  (such as 120°) further way from the left hand side, substantially perpendicular third fan perforation tunnel vectors  82   c  at the middle of the carrier tube assembly  30 , smaller angled fourth fan perforation tunnel vectors  82   d  (such as 60°) past the middle of the carrier tube assembly  30 , and still smaller angled fifth fan perforation tunnel vectors  82   e  (such as 45°) near the right hand side of the carrier tube assembly  30 . The actual number and angle of the shaped charge canisters  120  and resulting fan perforation tunnel vectors  82   a ,  82   b ,  82   c ,  82   d ,  82   e , may be selectively varied to produce a desired fracturing effect. 
       FIG. 6   a  shows another set of preferred perforation tunnel vectors  60  arranged to produce a down-shot pattern  83 . The down-shot pattern  83  is produced by arranging groups of shaped charges  120  at fixed angles, such as 135° along the length of the carrier tube assembly  30 . The down-shot pattern  83  is directed downward. However, by inverting the carrier tube assembly  30  an up-shot pattern that is directed upward can be produced. The actual angle of the shaped charge  120  and resulting down-shot pattern  83  (or up-shot pattern) can be varied to produce a desired geological formation  300  perforation tunnels and subsequent hydraulic fracturing effect. 
       FIG. 6   b  shows another set of preferred perforation tunnel vectors  60  arranged in a limited-entry pattern  85 . The limited-entry pattern  85  is produced by arranging groups of shaped charges  120  to produce perforation tunnel vectors  60  having angles that monotonically vary from the nearest end of the carrier tube assembly  30  toward 90° at the middle of the carrier tube assembly  30 . For example, first limited-entry perforation tunnel vectors  86   a  near the left hand side of the carrier tube assembly  30  at an angle of 45°, second limited-entry perforation tunnel vectors  86   b  further toward the middle of the carrier tube assembly  30  at an angle of 60°, third limited-entry perforation tunnel vectors  86   c  at the middle of the carrier tube assembly  30  that are perpendicular to the carrier tube assembly  30 , fourth limited-entry perforation tunnel vectors  86   d  located to the right of the middle of the carrier tube assembly  30  having an angle of 120°, and fifth limited-entry perforation tunnel vectors  86   e  nearest the right hand side of the carrier tube assembly  30  at an angle of 135°. 
     The limited-entry pattern  85  shown in  FIG. 6   b  produces limited-entry perforation tunnels  86   a ,  86   b ,  86   c ,  86   d ,  86   e  that collectively concentrate the explosive forces from the shaped charges  120  to produce a desired geological formation  300  perforation tunnel and subsequent hydraulic fracturing effect. Again, it should be noted that the angles can be selectively varied to produce a desired perforation tunnel geometry and subsequently hydraulic fracturing effect. 
       FIG. 6   c  shows another set of preferred perforation tunnel vectors  60 , but this time arranged in a limited-entry-fan-shot embodiment  90 . The limited-entry-fan-shot embodiment  90  is produced by arranging groups of shaped charges  120  to produce perforation tunnel vectors  60  having angles that spread out in a wide angle across the carrier tube assembly  30  from each end to the middle, with the middle perforation tunnel vectors  60  being perpendicular to the carrier tube assembly  30 . The shaped charges  120  are arranged along selected phase angles to produce the combined limited-entry-fan-shot embodiment  90 . 
     The combined limited-entry-fan-shot embodiment  90  is envisioned as producing a plurality of first combined perforation tunnel vectors  90   a  (say at 135°) near the left hand side, second combined perforation tunnel vectors  90   b  (say at 45°) left of the center of the carrier tube assembly  30 , third combined perforation tunnel vectors  90   c  at the center of the carrier tube assembly  30  and at 90°, fourth combined perforation tunnel vectors  90   d  right of the center of the carrier tube assembly  30  (say at 135°), and fifth combined perforation tunnel vectors  90   e  near the right hand side of the carrier tube assembly  30  (say at 45°). Such an arrangement of combined limited-entry perforation tunnel vectors  90   a ,  90   b ,  90   c ,  90   d ,  90   e  diffuse the perforation jets from the system  10  at some locations while concentrating them at the middle of the carrier tube assembly  30  so as to produce a desired geological formation  300  perforation geometry and subsequently hydraulic fracturing effect. The combined limited-entry-fan-shot perforation tunnel vectors  90   a ,  90   b ,  90   c ,  90   d ,  90   e  are described as emanating at suggested angles; however, the actual number and angles of the shaped charges  120  and resulting perforation tunnel vectors  90   a ,  90   b ,  90   c ,  90   d ,  90   e  may be selectively varied to produce a desired fracturing effect. 
     It is envisioned that other styles and configurations of the present invention can be easily incorporated into the teachings of the present invention; only one (1) particular configuration is shown and described for purposes of clarity and disclosure and not by way of limitation of scope. 
     The preferred embodiment of the present invention can be utilized by technicians skilled in the art after having received appropriate instructions in the configuring and assembly of the system  10 . After initial purchase or acquisition of the system  10 , it would be installed as indicated in  FIGS. 1 through 4 . 
     The method of using the system  10  may be achieved by performing the following steps: procuring a number of matched outer gun body assemblies  20  and carrier tube assemblies  30  having desired overall lengths, phase angles, and being machined with properly aligned recessed areas  25 , shaped charge saddle slots  42 , and shaped charge body apertures  43  so as to produce a desired geological formation perforation effect with subsequent hydraulic fracturing upon detonation; inserting an initial carrier tube assembly  30  into a matching outer gun body assembly  20  until obtaining full engagement of the orientation/alignment pin  35  within the corresponding orientation slot  24  and securing in place with a snap ring; inserting the system  10  within a horizontal well casing structure in a conventional manner; detonating the system  10  remotely in a normal manner to produce perforation tunnel vectors  60  being projected into surrounding geological formation(s) at desired angles and directions, thereby producing a desired geological formation  300  perforation effect with subsequent fracturing effect using the present invention  10 . 
     The method of utilizing additional units of the system  10  may be achieved by performing the following steps: inserting any additional carrier tube assemblies  30 , as desired, into respective outer gun body assemblies  20 ; arranging the outer gun body assemblies  20  in a desired sequential order in a linear manner; joining adjacent outer gun body assemblies  20  by threading the male threaded regions  26  of the connecting couplings  23  to the female threaded regions  22  of the adjacent outer gun body assemblies  20 ; and, performing detonation, perforation, and subsequent hydraulic fracturing as described above. 
     It is further understood that during preparation and assembly of the system  10 , as described above, any number or sequence of patterns from the system  10  can be produced; including the fan shot pattern  80 , the down-shot pattern  83 , the limited-entry pattern  85 , and the alternate combined limited-entry-fan-shot pattern  90 . The various patterns can also be mixed to produce a desired geological formation  300  perforation jet geometry and subsequent hydraulic fracturing effect. 
     The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention and method of use to the precise forms disclosed. Obviously many modifications and variations are possible in light of the above teaching. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application, and to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions or substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but is intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.