Casing conveyed well perforating apparatus and method

• US 20050121195A1
• Filed: 07/29/2004
• Published: 06/09/2005
• Est. Priority Date: 01/09/2003
• Status: Active Grant

• Current Assignee: Allen Lindfors, Aron Ekelund, Christopher Burres, Edward Paul Cernocky, Eugene Murphy, Matthew Robert George Bell
• Original Assignee: Allen Lindfors, Aron Ekelund, Christopher Burres, Edward Paul Cernocky, Eugene Murphy, Matthew Robert George Bell
• Inventors: Bell, Matthew Robert George, Burres, Christopher, Lindfors, Allen, Ekelund, Aron, Murphy, Eugene, Cernocky, Edward Paul
• Granted Patent: US 7,284,489 B2
• Time in Patent Office: Days
• US Class Current: 166/297
• CPC Class Codes: E21B 43/116 Gun or shaped-charge perforators
• CPC Class Codes: E21B 43/117 Shaped-charge perforators E21B43/118 takes precedence
• CPC Class Codes: E21B 43/1185 Ignition systems
• CPC Class Codes: E21B 43/119 Details, e.g. for locating perforating place or direction

Abstract

Disclosed is a device and method for externally perforating a well-bore casing. The perforating apparatus is attached to the outside of the casing itself and is conveyed along with the casing when it is inserted into the well bore. The perforation is accomplished using two groups of charges which are contained in protective pressure chambers which are arranged radially around the outside of the wellbore casing. The pressure chambers form longitudinally extending ribs which conveniently serve to center the casing within the well bore. One group of charges is aimed inward in order to perforate the casing. A second group is aimed outward in order to perforate the formation. In an alternative embodiment, only one group of bi-directional charges is provided.

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29. An apparatus for perforating a subterranean earth formation through a wellbore lined with casing comprising a plurality of chambers, each chamber containing a gun assembly therein, each gun assembly containing at least one explosive charge, said plurality of chambers disposed about the periphery of said casing such that said casing is substantially centered when introduced into and maintained in said wellbore.

30. The apparatus of claim 29, wherein said plurality of chambers are held within a carrier having a top and a bottom, said carrier defining at least one canal which begins at the bottom of said carrier and terminates at the top of said carrier, said canal forming a protective space in which a transmission medium may be deployed without being vulnerable to damage when said explosive charges are detonated.

31. The apparatus of claim 29, wherein each of said plurality of chambers forms a longitudinal rib on said casing.

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35. A method of perforating a subterranean earth formation through a wellbore lined with casing, comprising the steps of:

providing a plurality of gun assemblies;

disposing each of said gun assemblies in separate sealed chambers;

attaching each of said chambers on the exterior of the casing to form a number of longitudinal fins; and

using the longitudinal fins to substantially center the casing within the wellbore when the casing is run down into the wellbore.

36. The method of claim 35, further comprising the step of firing the gun assemblies in each of the chambers using a firing head common to all of the gun assemblies.

37. The method of claim 35, further comprising the step of providing a plurality of charges on at least one of said gun assemblies, said plurality of charges comprising a first charge directed outward to perforate the formation and a second charge directed inward to perforate the casing.

38. The method of claim 37, further comprising the steps of:

providing a sufficient explosive in said first charge to penetrate the formation; and

providing a sufficient explosive in said second charge to perforate the casing closest to the second charge without perforating any other area of the casing.

39. The method of claim 37, further comprising the step of fluidly isolating said first charge and said second charge by including them in a protective chamber, said chamber being formed by a hollow cylinder secured to said casing and capping the ends of said cylinder.

40. The method of claim 39, further comprising the step of ballistically linking said first charge and said second charge using a detonating cord.

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