Abstract:
A shaped charge for use with a perforating gun having an adapter that can couple the shaped charge with perforating gun systems of more than one size. An interference fit can couple the adapter to the open end of a shaped charge. The adapter includes a base section having an outer diameter exceeding the shaped charge outer diameter. The adapter larger diameter can be coupled to perforating gun systems formed to receive shaped charges whose outer diameters exceed the outer diameter of the shaped charge coupled to the adapter. Thus the adapter can couple a shaped charge to a perforating gun that might otherwise have fittings too large to accommodate the shaped charge.

Description:
BACKGROUND 
       [0001]    1. Field of Invention 
         [0002]    The invention relates generally to the field of oil and gas production. More specifically, the present invention relates to an adapter for a shaped charge used in perforating. Yet more specifically, the present invention relates to an adapter for a perforating shaped charge that couples a shaped charge in a perforating gun or tube configured for a different sized shaped charged. 
         [0003]    2. Description of Prior Art 
         [0004]    Perforating systems are used for the purpose, among others, of making hydraulic communication passages, called perforations, in wellbores drilled through earth formations so that predetermined zones of the earth formations can be hydraulically connected to the wellbore. Perforations are needed because wellbores are typically completed by coaxially inserting a pipe or casing into the wellbore. The casing is retained in the wellbore by pumping cement into the annular space between the wellbore and the casing. The cemented casing is provided in the wellbore for the specific purpose of hydraulically isolating from each other the various earth formations penetrated by the wellbore. 
         [0005]    One typical example of a perforating system  4  is shown in  FIG. 1 . As shown, the perforating system  4  comprises one or more perforating guns  6  strung together to form a perforating gun string  3 , these strings of guns  6  can sometimes surpass a thousand feet of perforating length. Connector subs  18  provide connectivity between each adjacent gun  6  of the string  3 . Many gun systems, especially those comprised of long strings of individual guns, are conveyed via a conveyance means  5 . Examples of conveyances means  5  for deploying or suspending the gun systems within a wellbore include tubing, wireline or slickline. 
         [0006]    Included with the perforating gun  6  are shaped charges  8  that typically include a housing, a liner, and a quantity of high explosive inserted between the liner and the housing. When the high explosive is detonated, quickly expanding explosive gases are formed whose force collapses the liner and ejects it from one end of the charge  8  at very high velocity in a pattern called a “jet”  12 . The jet  12  perforates the casing and the cement and creates a perforation  10  that extends into the surrounding formation  2 . The resulting perforation  10  provides fluid communication between the formation  2  and the inside of the wellbore  1 . 
         [0007]    A side partial sectional view of a portion of a perforating gun  6  is illustrated in  FIG. 2 . The perforating gun  6  includes an elongated cylindrical gun body  14  housing a gun tube  16  therein. A shaped charge  8  is mounted in the gun tube  16  generally orthogonal to the tube axis A X . The gun body  14  includes an optional recess  19  aligned with the shaped charge opening  11  to reduce gun body  14  material in the jet  12  path. A lower opening  15  through a portion of the gun body  16  receives the base  9  or closed end of the shaped charge  8 . A corresponding upper opening  17  receives the shaped charge  8  open end  11  therethrough; the openings ( 15 ,  17 ) are generally aligned with the shaped charge axis A SC . Shaped charge  8  detonation typically occurs by sending a detonation signal through or along the conveyance means  5  from the surface  13 . A firing head  7  receives the signal that responds by igniting a detonation cord  20  that passes through the gun string  3  and connects to each shaped charge  8 . Igniting the detonation cord  20  creates a pressure wave that contacts each shaped charge  8  and activates an initiator  21  that in turn detonates the high explosive in the shaped charge  8 . 
         [0008]    Typically the upper opening  17  in the gun tube  16  is sized to match the shaped charge  8  dimensions. Since shaped charges  8  may be produced in multiple standard sizes, gun tubes  16  having correspondingly sized openings ( 15 ,  17 ) are required for these shaped charges  8 . In some instances, operational delays may occur if a properly dimensioned gun tube  16  is not available to accommodate certain sized shaped charges. 
       SUMMARY OF INVENTION 
       [0009]    The present disclosure concerns a perforating system having an adapter used with shaped charges that allows shaped charges to be used in perforating systems configured for larger shaped charges. In one example the present disclosure includes a perforating system for use in a subterranean wellbore that includes a tubular shaped charge holder, an aperture formed through the tubular, where the aperture dimensions are defined by a first size. Also included is an adapter coupled to the shaped charge holder at the aperture, the adapter dimensions defined by a second size. A shaped charge is coupled in the adapter, the shaped charge having a shaped charge case with a closed end and an open end. The adapter is coupled to the shaped charge proximate to the charge case open end, the shaped charge case dimensions defined by a third size. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]    Some of the features and benefits of the present invention having been stated, others will become apparent as the description proceeds when taken in conjunction with the accompanying drawings, in which: 
           [0011]      FIG. 1  is a partial cutaway side view of a perforating system. 
           [0012]      FIG. 2  illustrates a partial cutaway of a portion of a perforating gun. 
           [0013]      FIG. 3  is a perspective partial sectional view of a shaped charge having an adapter. 
           [0014]      FIG. 4  is an overhead view of the shaped charge and adapter of  FIG. 3 . 
           [0015]      FIG. 5  is a side view of a shaped charge with an adapter in a perforating gun body. 
           [0016]      FIG. 6  is a side view of a shaped charge with an adapter in a perforating gun body including a spacer shim. 
       
    
    
       [0017]    While the invention will be described in connection with the preferred embodiments, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications, and equivalents, as may be included within the spirit and scope of the invention as defined by the appended claims. 
       DETAILED DESCRIPTION OF INVENTION 
       [0018]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be through and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. 
         [0019]    It is to be understood that the invention is not limited to the exact details of construction, operation, exact materials, or embodiments shown and described, as modifications and equivalents will be apparent to one skilled in the art. In the drawings and specification, there have been disclosed illustrative embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. Accordingly, the invention is therefore to be limited only by the scope of the appended claims. 
         [0020]    The present disclosure concerns an adapter used with a shaped charge, where the shaped charged is used in subterranean perforating for oil and gas hydrocarbon production. One example of a shaped charge  30  with an adapter  38  is provided in a perspective partial sectional view in  FIG. 3 . As shown, the shaped charge  30  includes a shaped charge case  32  having a base  37  on one end and upwardly extending walls. The walls terminate in an opening  33  at the end of the case  32  opposite the base  37 . A frusto-conical liner  34  is inserted within the case  32  with its conical end disposed proximate the base  37 . High explosive  36  is disposed between the liner  34  and the inner circumference of the case  32 . 
         [0021]    The adapter  38  is coupled to the charge casing  32  on its outer circumference and proximate the opening  33 . In the embodiment of  FIG. 3 , the adapter  38  includes an annular collar  40  coupled to the charge case  32  by an interference fit. The adapter  38  includes a split section  42  extending axially through the adapter  38  at a location along the adapter  38  circumference. The adapter  38  circumference is thus expandable by increasing the split section  42  length. Forming the adapter  38  from an elastic material, such as steel, enhances interference coupling by internal stresses in the material urging together the adapter ends  43  adjacent the split section  42 . The collar  40  has an elongate cross-section with the elongate length substantially parallel to the shaped charge  30  axis A S . 
         [0022]    An optional tab  44  is affixed to the inner circumference of the collar  40  extending radially inward towards the axis A S  of the shaped charge  30 . The tab  44  may provide a stopping point for the shaped charge  30  upper terminal end and to align the shaped charge  30  within a shaped charge holder. Also formed on the inner circumference of the collar  40  is a raised profile  46  shown extending substantially along the entire inner circumference of the collar  40 . A corresponding groove  35  on the charge case  32  outer circumference registers with the inwardly protruding profile  46 . The profile  46  and groove  35  can be used as a latching means between the adapter  38  and shaped charge  30  as well as a means for aligning the adapter  38  on the shaped charge  30 . 
         [0023]    The adapter  38  of  FIG. 3  also includes a base member  48  extending radially outward from the collar  40 . As will be discussed in more detail below, the base member  48  outer diameter enables coupling between the shaped charge  30  and a shaped charge holder. Radially extending outward from the collar  40  outer surface is an annular disk-like connector ring  50  that terminates on its outer periphery at an annular outer ring  52 . The outer ring  52  has an elongate cross-section, with its elongate length generally perpendicular with the axis A S  of the shaped charge  30 . The connector ring  50  includes apertures  51  formed therethrough at various locations along the connector ring  50  circumference. Optionally, however, the base  48  may include other configurations, such as a single member having a uniform cross-section around the entire circumference. 
         [0024]    An overhead view of the combination shaped charge  30  with adapter  38  is provided in  FIG. 4 . In this embodiment, the terminal ends of the tabs  44  are shown generally aligned with the shaped charge case  32  inner circumference thereby disposed above the entire width of the charge case  32  walls. Alternatively, the tabs  44  may extend over a portion of the charge case  32  wall width. The adapter  38  substantially circumscribes the shaped charge  30  outer circumference. Other embodiments of the adapter  38  exist where the adapter  38  circumscribes about 50% or more of the shaped charge  30  outer circumference. 
         [0025]    A side partial sectional view of a shaped charge  30  with an adapter  38  is illustrated disposed within a perforating system. In this embodiment, the shaped charge  30  is combined with a shaped charge holder that is illustrated as a gun tube  56 . Optionally, the shaped charge holder could include a gun body. The gun tube  56  includes an opening  54  through a portion of its section on which the adapter  38  is coupled. For the purposes of discussion herein, the coupling comprises the adapter  38  outer diameter exceeding the opening  54  diameter thereby allowing the coupling  38  to rest over the shaped charge holder and retain the shaped charge  30  within the shaped charge holder  56 . As is known, shaped charges are available in multiple standard sizes, thus most shaped charge holders include openings or apertures configured to match those standard sizes. Use of the adapter  38  herein enables a shaped charge  30  having a particular size to be utilized within shaped charge holders  56  wherein the corresponding openings  54  may be one or more standard sizes greater than the standard size of the particular shaped charge  30 . Accordingly, a shaped charge having the adapter  38  described herein and equivalents thereof can be installed into more than one gun system or kit, where the gun systems include openings  54  of more than one size. Additionally, use of the adapter  38  also enables a single gun body  58  having the same size openings  54  to have installed individual shaped charges  30  of more than one size. For example, an embodiment exists where a gun body  58  has single size openings  54 , but includes some deep penetrating shaped charges and some gravel pack shaped charges, where the charges smaller than the openings  54  are adapted for installation with the adapter  38 . 
         [0026]    As illustrated in  FIG. 5 , the gun body  58  is disposed above the opening  33  of the shaped charge  30 . Thus, in the example shown, the dimensions of the opening  54  can be defined as having a first size, the dimensions of the adapter  38  can be defined as having a second size, and the dimensions of the shaped charge  30  can be defined as having a third size. The first size sufficiently exceeds the third size, such that the smaller shaped charge  30  passes through the opening  54 . However, because the adapter  38  has dimensions of a second size, wherein the second size exceeds the dimensions of the first size, the adapter  38  is shown coupled onto the shaped charge holder  56 . Additionally, due to the press fit or interference fit of the adapter  38  with the shaped charge  30 , the shaped charge  30  is affixed with the adapter, and also coupled with the shaped charge holder  56  by virtue of its connection with the adapter  38 . 
         [0027]    With reference now to  FIG. 6 , an example of a shim spacer  53  and adapter  38  is illustrated in a side partial sectional view. The shim spacer  53 , as shown in cross section, is an annular member disposed between the base member  48  lower surface and the gun tube  56  outer surface. Installing the shim spacer  53  positions the shaped charge  30  closer to the gun body  58  and can enhance shaped charge performance by adjusting jet  12  formation and extension. Jet  12  formation and extension can be a function of the jet  12  focal point, which is extended into the formation  2  by repositioning the shaped charge  30  as illustrated. Based on the formation encountered, adjusting the jet  12  formation can extend perforations  10  and increase hydrocarbon production from the formation  2 . Those skilled in the art have sufficient capabilities to adjust jet  12  formation by sizing and/or positioning the spacer shim  53 . The spacer shim  53  can be integral with the adapter  38 , or can be a separate component. The shim spacer  53  is not limited to an annular shape, but can have other configurations. Additionally, the shim spacer  53  can also be comprised of two or more elements spaced around the shaped charge  30 . Moreover, the present disclosure includes embodiments where a shim spacer  53  is installed with shaped charges that do not include an adapter, but where the shaped charges with a shim spacer  53  are disposed within the same size shaped charge holder. 
         [0028]    The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. For example, the adapter  38  can also affix shaped charges within carrier strips and other charge holders. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.