Patent Publication Number: US-2007107899-A1

Title: Perforating Gun Fabricated from Composite Metallic Material

Description:
TECHNICAL FIELD  
      The present invention relates generally to enhancements in production of hydrocarbons from subterranean formations, and more particularly to a perforating gun for use downhole in a wellbore.  
     BACKGROUND  
      After a well has been drilled and casing has been cemented in the well, one or more sections of the casing, which are adjacent to formation zones, may be perforated to allow fluid from the formation zones to flow into the well for production to the surface or to allow injection fluids to be applied into the formation zones. In other productions, hydrocarbons are retrieved from an uncased or “openhole” well. Whether in a cased or open hole well, a perforating gun string is lowered into the well to a desired depth and then the gun is fired to create openings in the casing (in cased well operations) and to extend perforations into the surrounding formation. Production fluids in the perforated formation can then flow through the perforations and the casing openings into the wellbore.  
      Typically, perforating guns (which include gun carriers and shaped charges mounted on or in the gun carriers) are lowered through tubing or other pipes to the desired well interval. Shaped charges carried in a perforating gun are often phased to fire in multiple directions around the circumference of the wellbore. When fired, shaped charges create perforating jets that form holes in surrounding casing as well as extend perforations into the surrounding formation.  
      Various types of perforating guns exist. One type of perforating gun includes capsule shaped charges that are mounted on a strip in various patterns. The capsule shaped charges are protected from the harsh wellbore environment by individual containers or capsules. Another type of perforating gun includes non-capsule shaped charges, which are loaded into a sealed carrier for protection. Such perforating guns are sometimes also referred to as hollow carrier guns. The non-capsule shaped charges of such hollow carrier guns may be mounted in a loading tube that is contained inside the carrier, with each shaped charge connected to a detonating cord. When activated, a detonation wave is initiated in the detonating cord to fire the shaped charges. In a hollow-carrier gun, charges shoot through the carrier into the surrounding casing formation.  
      One problem with a carrier gun is the damage done to the gun housing which can create unwanted debris and contaminants in the wellbore. During a perforation operation, the gun housing is subjected damage caused by internal pressure from the explosive gases released by the charges, and by high-velocity impacts from fragments of charge cases. Accordingly, a need exists for a gun housing that is capable of withstanding the damage caused by these extreme pressures and high velocity impacts. The present invention is directed at providing such a system. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The manner in which these objectives and other desirable characteristics can be obtained is explained in the following description and attached drawings in which:  
       FIG. 1  illustrates an embodiment of a perforating system assembly including the components linked on a perforating gun string.  
       FIG. 2  illustrates a profile view of a shaped charge in accordance with the present invention.  
       FIG. 3A  shows a partial view of the perforating system in accordance with the present invention.  
       FIG. 3B  displays a cross-sectional view of the shaped charge in accordance with the present invention.  
       FIG. 4  shows an enlarged view of a component in the perforating system assembly. 
    
    
      However, it should be noted that the appended drawings illustrate typical embodiments of this invention and are not to be considered limiting in scope. The invention may admit to other equally effective embodiments.  
     SUMMARY  
      In general, according to one embodiment of the present invention, a gun system, fabricated from a multi-layer metallic/intermetallic laminate material that is used to perforate a wellbore, is provided.  
     DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION  
      In the specification and appended claims, the terms “connect”, “connection”, “connected”, “in connection with”, and “connecting” are used to mean “in direct connection with” or “in connection with via another element”. The term “set” is used to mean “one element” or “more than one element”. The terms “up” and “down”, “upper” and “lower”, “upwardly” and downwardly”, “upstream” and “downstream”, “above” and “below”, and other like terms indicating relative positions above or below a given point or element are used in this description to more clearly described some embodiments of the invention. However, when applied to equipment and methods for use in wells that are deviated or horizontal, such terms may refer to a left to right, right to left, or other relationship as appropriate.  
      Typically, the steel used to fabricate gun carriers or housings for perforating guns is compounded and processed to balance high strength with high toughness, for collapse and swell resistance and cracking/splitting resistance, respectively.  
      In general, an embodiment of the present invention includes a laminate material used to fabricate the perforating gun components (e.g., gun carrier or housing, loading tube, and so forth) that are susceptible to damage from high internal gas pressures and impact of explosive components during perforation operations. The laminate material comprises interleaved layers of metallic and intermetallic compounds. For example, combinations of metallic and intermetallic compounds include titanium and titanium aluminide, nickel and nickel aluminide, iron and iron aluminide, and iron and iron stanide.  
      In some embodiments, the laminate material may be produced by stacking multiple layers of aluminum and titanium (or other metals), and subsequently subjecting the stack of metals to high pressures and elevated temperatures. In such embodiments, the aluminum reacts with a portion of the titanium to form a hard, strong intermetallic compound. Layers of titanium remain in between the layers of brittle intermetallic compound, providing toughness (crack resistance) to the laminate. The resulting material has advantageous mechanical properties, namely increased strength and penetration resistance. U.S. Pat. No. 6,357,332, which is incorporated herein by reference, describes a process for making metallic-intermetallic composite laminate material for use in lightweight armor applications. The &#39;332 Patent describes the process for making the laminate material from sheets with a tough first metal interleaved with sheets, and a second metal compounded with the first metal. The confined metal layers resist cracking and fracturing of the intermetallic layers. The interleaved sheets react under heat and pressure to react the metals to form a region of an intermetallic compound. The first set of metals may be fabricated are from metal or metal alloys such as titanium, nickel, vanadium, or iron; and the second set of metals may be fabricated from metal or metal alloys such as aluminum and alloys of aluminum.  
      Intermetallic compounds are comprised of two specifically proportioned metals or metal alloys having a defined ratio of one atomic species to another, on specific lattice sites. The bonding is metallic, rather than ionic, but the ordered structure (which can be visualized as two interpenetrating lattices, each containing one atomic species) gives rise to high strength and hardness with limited ductility.  
      In an embodiment of the present invention, a perforating gun (e.g., a carrier, housing, loading tube, or other components) may be fabricated from a metallic-intermetallic laminate material. The material may be formed into a tubular shape of appropriate dimensions. Once a suitable tube is available, application as a perforating gun is a simple matter of direct substitution of the high-strength steel tube conventionally employed.  
      In another embodiment of the present invention, a method is provided to form a metallic-intermetallic laminate tube. Such a tube may be formed by wrapping alternating layers of aluminum and low-carbon steel such as iron (or alternatively, aluminum and titanium) around a mandrel with sufficient turns to build up a tube with an appropriate thickness and with an appropriate number of layers. The aluminum and iron form a series of iron aluminides analogous to a titanium aluminide. This is done by inserting a wrapped tube into a heated tubular die, with an inside diameter equal to the desired outside diameter of the finished laminate tube. Then using suitable end caps, the inside of the laminate tube is pressurized with air, nitrogen, argon, helium, or any suitable gas, to the required pressure, and the die is heated to the proper temperature. The die may be a clamshell shaped furnace that when closed, forms a cylindrical mold and can be opened to remove the finished tube.  
      After allowing time for the aluminum to diffuse into and react with the iron, the laminate is cooled. This is one proposed means of fabricating the laminate material into a tubular shape suitable for use as a perforating gun. Although this particular embodiment was described using layers of aluminum and iron, in other embodiments of the present invention other metals may be used for such layers that including and elements that form ordered intermetallic compounds.  
       FIG. 1  illustrates a perforating “carrier” gun string as used in conventional perforating operations in a wellbore  11 . The perforating gun string  5  may be suspended and run into the wellbore  11  by a wireline  1 , or any other conveyance mechanism (e.g., tubing, slickline, and so forth). The perforating gun string is positioned downhole within a casing  3  to the desired depth via the wireline  1 . In other embodiments, the perforating gun may be deployed in uncased or open hole wells. The perforating gun string  5  may include one or more guns coupled together in series, each holding at least one explosive charge, and connected together by an adapter  9 .  
       FIG. 2  shows an embodiment of a shaped charge  101  that is connected to a detonating cord  109 . The shaped charge  101  includes an outer case  103  that is designed to hold an explosive  105  and liner  111 . The liner  111  and the case  103  encompass an explosive  105  that is contained inside the case. The primer column  107  provides the detonating connection between the detonation cord  109  and the explosive  105 . When activated, a detonation wave is created in the detonating cord  109  and activates the primer column  107 . This causes the explosive  105  to detonate and consequently create a detonation wave through the shaped charge  101 . The liner  111  collapses under the force of the explosive  105  charge.  
       FIGS. 3A and 3B  demonstrates an embodiment of a perforating gun system including an outer cylindrical tube or carrier  201 , and a loading tube  113 . The loading tube mechanically holds the holds the charges and is then inserted into the gun carrier  201 . After the shaped charges are detonated, the energy is transmitted through the loading tube  113 , to the gun carrier  201 . In accordance with the present invention, an embodiment of the gun carrier  201  may be formed from a multi layered metallic-intermetallic laminate  203 A. Moreover, the loading tube  113  may also be formed from a multi-layered metallic and /or inter-metallic laminate  203 B. Embodiments of the present invention include a perforating gun system having a multi-layered laminate gun carrier or loading or both.  
       FIG. 4  illustrates a tubular member  301  formed from a multi-layered laminate material. For example, a perforating gun carrier or loading tube could represent the tubular member  301 . Each layer consists of a metal or metal alloy and an intermetallic compound of that element. The illustrated embodiment includes a tubular formed from five laminated layers, but it is intended that the present invention includes tubes for use in perforating gun systems including two or more laminate layers.  
      Although only a few exemplary embodiments of this invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention.