Method and Apparatus for Launching Objects in Dual Gradient Systems

Abstract

An apparatus for launching objects, such as during casing cementing operations, in wells having dual gradient fluid systems or certain downhole internal diameter restrictions. A launching assembly is located below a dual gradient valve or other restriction. In one embodiment, control lines extend from the earth's surface to the launching assembly and control actuation of the launching assembly. In an alternative embodiment, a receptacle assembly is positioned above a dual gradient valve or other restriction, with control lines extending from the receptacle assembly to the launching assembly. A dart or other triggering object is launched from the earth's surface to the receptacle assembly in order to control actuation of the launching assembly.

What is claimed: 
     
         1 . An apparatus for launching an object within a wellbore having a dual gradient fluid system and equipped with a dual gradient valve comprising:
 a) an automated launching assembly disposed below said dual gradient valve; and   b) at least one control line extending from said launching assembly to a triggering assembly situated above said dual gradient valve.   
     
     
         2 . The apparatus of  claim 1 , wherein said triggering assembly is situated on a drilling rig. 
     
     
         3 . The apparatus of  claim 2 , wherein said triggering assembly further comprises:
 a) a hydraulic power source; and   b) a hydraulic swivel assembly having an input and an output, wherein said input is in fluid communication with said power source and said output is in fluid communication with said at least one control line.   
     
     
         4 . The apparatus of  claim 1 , wherein said triggering assembly comprises a receptacle assembly disposed within said wellbore above said dual gradient valve, having a central through bore and at least one sliding sleeve adapted to receive a triggering object. 
     
     
         5 . The apparatus of  claim 4 , wherein said sliding sleeve defines a first position and a second position, said central through bore is isolated from fluid communication with said at least one control line in said first position, and said central through bore and said at least one control line are in fluid communication in said second position. 
     
     
         6 . The apparatus of  claim 1 , wherein said automated launching assembly further comprises:
 a) at least one cage assembly for receiving a launch-able object;   b) a hinged door disposed under said launch-able object; and   c) at least one actuator for selectively opening said hinged door.   
     
     
         7 . The apparatus of  claim 6 , wherein said at least one actuator comprises a motorized pin puller. 
     
     
         8 . A method for launching an object within a wellbore having a dual gradient fluid system and equipped with a dual gradient valve comprising:
 a) loading at least one launch-able object within a launching assembly;   b) installing said launching assembly below said dual gradient valve; and   c) triggering launch of said launch-able object from above said dual gradient valve.   
     
     
         9 . The method of  claim 8 , wherein said launching assembly further comprises:
 a) at least one cage assembly for receiving a launch-able object;   b) a hinged door disposed under said launch-able object; and   c) at least one actuator for selectively opening said hinged door.   
     
     
         10 . The method of  claim 9 , wherein said at least one actuator comprises a motorized pin puller. 
     
     
         11 . The method of  claim 8 , further comprising the step of installing at least one control line from said launching assembly to a drilling rig. 
     
     
         12 . The method of  claim 11 , further comprising the step of supplying hydraulic pressure through said at least one control line to actuate said launching assembly. 
     
     
         13 . The method of  claim 12 , wherein said hydraulic pressure is supplied from a hydraulic power unit situated at said drilling rig. 
     
     
         14 . The method of  claim 8 , further comprising installing at least one control line from said launching assembly to a receptacle assembly disposed within said wellbore above said dual gradient valve. 
     
     
         15 . The method of  claim 14 , wherein said receptacle assembly comprises a central through bore and at least one sliding sleeve. 
     
     
         16 . The method of  claim 15 , wherein said sliding sleeve defines a first position and a second position, said central through bore is isolated from fluid communication with said at least one control line in said first position, and said central through bore and said at least one control line are in fluid communication in said second position. 
     
     
         17 . The method of  claim 16 , wherein said step of triggering launch of said launch-able object from above said dual gradient valve further comprises shifting said sliding sleeve from said first position to said second position. 
     
     
         18 . The method of  claim 17 , wherein said step of shifting said sliding sleeve from said first position to said second position further comprises:
 a) launching a trigger object from a drilling rig;   b) seating said trigger object in said receptacle assembly; and   c) applying fluid pressure to said central through-bore of said receptacle assembly.