Assembling a perforating gun string within a casing string

Abstract

Methods are disclosed for assembling a perforating gun string in a wellbore. One method includes assembling a first perforating gun assembly into a lubricator, connecting the lubricator to a blowout preventer coupled to a wellhead, lowering the first perforating gun assembly on a conveyance into the blowout preventer, engaging the first perforating gun assembly with sealing rams of the blowout preventer, detaching the conveyance from the first perforating gun assembly and removing the conveyance from the blowout preventer, disconnecting the lubricator from the blowout preventer, assembling a second perforating gun assembly into the lubricator, re-connecting the lubricator to the blowout preventer, lowering the second perforating gun assembly into the blowout preventer and attaching the second perforating gun assembly to the first perforating gun assembly, and repeating the process to form a perforating gun string.

1 . A method comprising:
 (a) assembling a first perforating gun assembly into a lubricator, the first perforating gun assembly including at least one perforating gun cluster, at least one extended delay assembly, and a first subassembly;   (b) connecting the lubricator with the first perforating gun assembly disposed therein to a blowout preventer coupled to a wellhead;   (c) lowering the first perforating gun assembly on a conveyance into at least a portion of the blowout preventer;   (d) engaging the first subassembly with sealing rams included in the blowout preventer;   (e) detaching the conveyance from the first perforating gun assembly and removing the conveyance from the blowout preventer;   (f) disconnecting the lubricator from the blowout preventer;   (g) assembling a second perforating gun assembly into the lubricator, the second perforating gun assembly including at least one perforating gun cluster, at least one extended delay assembly, and a second subassembly;   (h) connecting the lubricator with the second perforating gun assembly disposed therein to the blowout preventer;   (i) lowering the second perforating gun assembly into the blowout preventer and attaching the second perforating gun assembly to the first perforating gun assembly, thereby forming a portion of a perforating gun string;   (j) disengaging the sealing rams from the first subassembly;   (k) lowering the portion of the perforating gun string through at least a portion of the blowout preventer;   (l) engaging the second subassembly with the sealing rams of the blowout preventer; and   (m) detaching the conveyance from the portion of the perforating gun string.   
     
     
         2 . The method of  claim 1  further comprising:
 (n) repeating steps (f)-(m) as desired until a final perforating gun assembly is attached to the portion of the perforating gun string, thereby forming the perforating gun string, wherein at least one of the first and final perforating gun assemblies includes a firing head, and wherein the final perforating gun assembly optionally comprises a corresponding subassembly; 
 (o) disengaging the sealing rams from a subassembly of a penultimate perforating gun assembly; 
 (p) conveying the perforating gun string to a desired location within a wellbore extending from the wellhead and penetrating a subterranean formation; and 
 (q) actuating the firing head. 
 
     
     
         3 . The method of  claim 1 , wherein the conveyance extends into the lubricator and assembling the first perforating gun assembly into the lubricator comprises:
 (1) attaching a first portion of the first perforating gun assembly to the conveyance;   (2) conveying the first portion of the first perforating gun assembly into a portion of the lubricator;   (3) attaching a second portion of the first perforating gun assembly to the first portion of the first perforating gun assembly; and   repeating steps (2) and (3) to assemble additional portions of the first perforating gun assembly until the first perforating gun assembly is assembled and contained within the lubricator.   
     
     
         4 . The method of  claim 1 , wherein the subassemblies are at least one of an isolation subassembly and a detonation transfer subassembly. 
     
     
         5 . The method of  claim 1 , wherein assembling the first perforating gun assembly into the lubricator comprises coupling the first subassembly to a plurality extended delay assemblies and a plurality of perforating gun clusters, where the pluralities of extended delay assemblies and perforating gun clusters alternate along a length of the first perforating gun assembly and extend from the first subassembly. 
     
     
         6 . The method of  claim 5 , further comprising arranging a bull plug at a distal end of the first perforating gun assembly. 
     
     
         7 . The method of  claim 1 , wherein the conveyance is at least one of a coiled tubing, an ecoil tubing, a wireline, a threaded pipe, and any hybrid thereof. 
     
     
         8 . The method of  claim 1 , wherein the wellbore includes a casing string secured therein and the wellbore is under pressure. 
     
     
         9 . The method of  claim 1 , wherein at least a portion of the wellbore is a deviated wellbore. 
     
     
         10 . The method of  claim 1 , wherein the first perforating gun assembly is a penultimate perforating gun assembly and the second perforating gun assembly is the a perforating gun assembly. 
     
     
         11 . A method comprising:
 (a) actuating a firing head of a perforating gun string disposed within a casing string of a wellbore penetrating a subterranean formation, the perforating gun string comprising a plurality of perforating gun assemblies;   (b) drawing the perforating gun string into a blowout preventer with a conveyance such that a first perforating gun assembly passes sealing rams of the blowout preventer;   (c) engaging the sealing rams with a subassembly of a second perforating gun assembly;   (d) detaching the first perforating gun assembly from the second perforating gun assembly;   (e) drawing the first perforating gun assembly from the blowout preventer into a lubricator on the conveyance;   (f) disconnecting the lubricator from the blowout preventer;   (g) removing the first perforating gun assembly from the lubricator;   (h) detaching the conveyance from the first perforating gun assembly;   (i) attaching the lubricator to the blowout preventer;   (j) attaching the conveyance to the subassembly of the second perforating gun assembly;   (k) disengaging the sealing rams of the blowout preventer from the subassembly of the second perforating gun assemblies; and   (l) repeating steps (b)-(k) as desired until the plurality of perforating gun assemblies has been removed.   
     
     
         12 . The method of  claim 11 , wherein the wellbore is under pressure. 
     
     
         13 . The method of  claim 11 , wherein steps (g) and (h) comprise:
 (1) detaching a first portion of the first perforating gun assembly from the first perforating gun assembly;   (2) conveying a remaining portion of the first perforating gun assembly through a portion of the lubricator;   (3) detaching a second portion of the first perforating gun assembly from the remaining portion of the first perforating gun assembly; and   repeating steps (2) and (3) for additional portions of the first perforating gun assembly until the first perforating gun assembly is fully disassembled.   
     
     
         14 . The method of  claim 11 , wherein the first perforating gun assembly comprises, in order, a first subassembly, and corresponding alternating pluralities of extended delay assemblies and perforating gun clusters. 
     
     
         15 . The method of  claim 11 , wherein the conveyance is at least one of a coiled tubing, an ecoil tubing, a wireline, a threaded pipe, and any hybrid thereof. 
     
     
         16 . The method of  claim 11 , wherein at least a portion of the wellbore is a deviated wellbore. 
     
     
         17 . A method comprising:
 (a) loading a first perforating gun assembly into a lubricator, wherein the first perforating gun assembly comprises, in order, a first subassembly and in alternating order a first plurality of extended delay assemblies and perforating gun clusters;   (b) attaching the first perforating gun assembly to a coiled tubing;   (c) connecting the lubricator with the first perforating gun assembly disposed therein to a blowout preventer coupled to a wellhead that is fluidly connected to a casing string disposed within a wellbore;   (d) pressure testing the lubricator;   (e) opening blind rams of the blowout preventer disposed between sealing rams of the blowout preventer and the lubricator;   (f) conveying the first perforating gun assembly past the blind rams;   (g) engaging the sealing rams on the first subassembly;   (h) detaching the first perforating gun assembly from the coiled tubing;   (i) retracting the coiled tubing into the lubricator;   (j) closing the blind rams;   (k) depressurizing the lubricator;   (l) disconnecting the lubricator from the blowout preventer;   (m) loading a second perforating gun assembly into the lubricator, wherein the second perforating gun assembly comprises, in order, a second subassembly and in alternating order a second plurality of extended delay assemblies and perforating gun clusters;   (n) attaching the second perforating gun assembly to the coiled tubing;   (o) connecting the lubricator with the second perforating gun assembly disposed therein to the blowout preventer;   (p) pressure testing the lubricator;   (q) opening the blind rams of the blowout preventer;   (r) attaching the second perforating gun assembly to the first perforating gun assembly, and thereby forming a portion of a perforating gun string;   (s) disengaging the sealing rams from the first subassembly;   (t) lowering the portion of the perforating gun string within the blowout preventer;   (u) engaging the sealing rams on the second subassembly; and   (v) detaching the portion of the perforating gun string from the coiled tubing.   
     
     
         18 . The method of  claim 17 , wherein the conveyance extends through at least a portion of the lubricator, and wherein steps (a) and (b) comprise:
 (w) repeating steps of (i)-(v) as desired until a final perforating gun assembly is attached to a penultimate perforating gun assembly, and thereby forming the perforating gun string, wherein at least one of the first and final perforating gun assemblies comprise a firing head, and wherein the final perforating gun assembly optionally comprises a corresponding subassembly;   (x) disengaging the sealing rams from a subassembly of the penultimate perforating gun assembly;   (y) conveying the perforating gun string with the coiled tubing to a desired location within the wellbore; and   (z) actuating the firing head.   
     
     
         19 . The method of  claim 17 , wherein the conveyance extends through at least a portion of the lubricator, and wherein steps (a) and (b) comprise:
 (1) attaching a first portion of the first perforating gun assembly to the conveyance;   (2) conveying the first portion of the first perforating gun assembly through a portion of the lubricator;   (3) attaching a second portion of the first perforating gun assembly to the first portion of the first perforating gun assembly; and   repeating steps (2) and (3) for additional portions of the first perforating gun assembly until the first perforating gun assembly is assembled and contained within the lubricator.   
     
     
         20 . The method of  claim 17 , wherein the subassemblies are at least one of an isolation subassembly and a detonation transfer subassembly. 
     
     
         21 . The method of  claim 17 , wherein at least a portion of the wellbore is a deviated wellbore. 
     
     
         22 . The method of  claim 17 , wherein the first perforating gun assembly is the penultimate perforating gun assembly and the second perforating gun assembly is the final perforating gun assembly.