Expandable perforating gun string and method

Abstract

A perforating gun string is configured to perforate a casing of a well, and the perforating gun string includes a latch mechanism configured to engage with the casing, one or more perforating guns connected with a cable to the latch mechanism, and a global cable that releasably holds together the latch mechanism and the one or more individual perforating guns. The perforating gun string may also comprise a spreading mechanism configured to move away from the latch mechanism and to spread the one or more individual perforating guns away from the latch mechanism.

What is claimed is: 
     
         1 . A perforating gun string configured to perforate a casing of a well, comprising:
 a latch mechanism configured to engage the casing;   a perforating gun comprising a shaped charge;   a connection cable having a first length L and configured to connect the perforating gun to the latch mechanism; and   a global cable having a second length less than L and configured to releasably maintain the relative position of the latch mechanism and the perforating gun.   
     
     
         2 . The perforating gun string of  claim 1 , further comprising a spreading mechanism configured to move away from the latch mechanism and to spread the perforating gun away from the latch mechanism. 
     
     
         3 . The perforating gun string of  claim 1 , wherein the latch mechanism is configured to engage a feature of the casing. 
     
     
         4 . The perforating gun string of  claim 2 , wherein the spreading mechanism comprises a torpedo. 
     
     
         5 . The perforating gun string of  claim 2 , wherein the spreading mechanism comprises a tractor. 
     
     
         6 . The perforating gun string of  claim 1 , further comprising a plurality of perforating guns, each connected to another one of the plurality of perforating guns by its own connection cable. 
     
     
         7 . The perforating gun string of  claim 6 , wherein each of the connection cables has a length greater than the second length of the global cable. 
     
     
         8 . The perforating gun string of  claim 2 , further comprising electronics configured to:
 send a first command to release the global cable,   send a second command to actuate the spreading mechanism, and   send a third command to detonate the shaped charge.   
     
     
         9 . The perforating gun string of  claim 1 , wherein the latch mechanism comprises an inflatable element. 
     
     
         10 . A method for perforating a casing of a well, comprising:
 inserting into the well a perforating gun string comprising:   a latch mechanism configured to engage the casing;   a perforating gun comprising one or more shaped charges;   a connection cable having a first length L and configured to connect the perforating gun to the latch mechanism; and   a global cable having a second length less than L and configured to releasably maintain the relative position of the latch mechanism and the perforating gun; and   engaging the latch mechanism with the casing;   releasing the global cable; and   detonating the one or more shaped charges.   
     
     
         11 . The method of  claim 10 , further comprising the steps of:
 attaching the perforating gun to a spreading mechanism configured to move away from the latch mechanism and to spread the perforating gun away from the latch mechanism; and   activating the spreading mechanism.   
     
     
         12 . The method of  claim 10 , wherein the latch mechanism is further configured to engage a feature of the casing. 
     
     
         13 . The method of  claim 11 , wherein the spreading mechanism comprises a torpedo. 
     
     
         14 . The method of  claim 11 , wherein the spreading mechanism comprises a tractor. 
     
     
         15 . The method of  claim 10 , wherein the perforating gun string comprises a plurality of perforating guns, each connected to another one of the plurality of perforating guns by its own connection cable. 
     
     
         16 . The method of  claim 15 , wherein each of the connection cables has a length greater than the second length of the global cable. 
     
     
         17 . The method of  claim 11 , further comprising the steps of:
 sending a first command to release the global cable; and   sending a second command to actuate the spreading mechanism.   
     
     
         18 . The method of  claim 10 , wherein the latch mechanism comprises an inflatable element.