Controlling transient pressure conditions in a wellbore

Abstract

A method and apparatus for use in a wellbore includes running a tool string to an interval of the wellbore, and activating a first component in the tool string to create a transient underbalance pressure condition in the wellbore interval. Additionally, a second component in the tool string is activated to create a transient overbalance pressure condition in the wellbore interval, or vice versa.

1 . An apparatus comprising: 
 a propellant having a plurality of cavities; and    explosive devices mounted in the cavities.    
     
     
         2 . The apparatus of  claim 1 , wherein the explosive devices comprise shaped charges mounted in the cavities.  
     
     
         3 . The apparatus of  claim 1 , further comprising a detonating cord ballistically connected to the explosive devices, 
 wherein activation of the detonating cord causes detonation of the explosive devices and initiation of the propellant.    
     
     
         4 . An apparatus comprising: 
 a strip;    explosive devices mounted on the strip; and    propellant inserts positioned between the explosive devices.    
     
     
         5 . The apparatus of  claim 4 , wherein the explosive devices comprise shaped charges.  
     
     
         6 . The apparatus of  claim 4 , further comprising a detonating cord ballistically connected to the explosive devices and the propellant inserts.  
     
     
         7 . The apparatus of  claim 4 , wherein the explosive devices are arranged in a spiral pattern.  
     
     
         8 . A tool string comprising: 
 a first component activatable to create a transient underbalance pressure condition in a wellbore interval proximal the tool string; and    a second component activatable to create a transient overbalance pressure condition in the wellbore interval.    
     
     
         9 . The tool string of  claim 8 , wherein the first component comprises a carrier containing explosive devices, 
 wherein activation of the explosive devices causes openings to be created in the carrier to enable the communication of wellbore pressure into a low-pressure chamber of the carrier to create the transient underbalance pressure condition in the wellbore.    
     
     
         10 . The tool string of  claim 8 , wherein the second component includes a propellant that is initiated to generate high-pressure gas in the wellbore interval to create the transient overbalance pressure condition.  
     
     
         11 . The tool string of  claim 10 , wherein the propellant includes cavities, and the second component comprises explosive devices mounted in the cavities.  
     
     
         12 . The tool string of  claim 11 , wherein the explosive devices comprise shaped charges.  
     
     
         13 . The tool string of  claim 13 , wherein the second component includes a carrier having a plurality of explosive devices, and the propellant is included in the carrier.  
     
     
         14 . The tool string of  claim 8 , wherein the second component includes a propellant and a pressure chamber to receive high-pressure gas generated by initiation of the propellant.  
     
     
         15 . The tool string of  claim 8 , wherein the second component further comprises a rupture element adapted to rupture the rupture element by the pressure in the pressure chamber.  
     
     
         16 . The tool string of  claim 15 , wherein the second component further comprises a vent sub having one or more openings to release high-pressure gas from the pressure chamber.  
     
     
         17 . An apparatus comprising: 
 a propellant;    a pressure chamber, the pressure chamber to receive high-pressure gas released by initiation of the propellant; and    a rupture element to be ruptured by pressure greater than a predetermined level in the pressure chamber.    
     
     
         18 . The apparatus of  claim 17 , further comprising a vent sub to vent high pressure in the pressure chamber in response to rupture of the rupture element.