Annular Pressure Reduction System for Horizontal Directional Drilling

Abstract

Working an underground arcuate path around at least a portion of an obstacle with a casing extending into the underground arcuate path, connecting a rotating control device to the casing; and a Venturi device connected to the rotating control device.

1 . A method for working an underground arcuate path around an obstacle, comprising the steps of:
 lowering an annular pressure within a space encircling a drill pipe; wherein said step of lowering the annular pressure within the space encircling the drill pipe is performed by sucking a volume of drilling fluid out of the space encircling the drill pipe.   
     
     
         2 . The method for working the underground arcuate path around the obstacle according to  claim 1 , further comprising the steps of:
 extending a casing into at least a lead portion of the underground arcuate path wherein the underground arcuate path is surrounded by a volume of earth and adjoining the casing into the earth of the underground arcuate path;   placing a Venturi device proximate an opening to the underground arcuate path;   working the underground arcuate path;   pumping the volume of drilling fluid into the underground arcuate path for transferring the volume of drilling fluid from the underground arcuate path to a surface;   wherein said steps of lowering the annular pressure within the space encircling the drill pipe by sucking the volume of drilling fluid out of the space encircling the drill pipe comprises pumping a volume of fluid through said Venturi device; and   recovering the volume of drilling fluid at the surface.   
     
     
         3 . The method for working the underground arcuate path around the obstacle according to  claim 2 , further comprising the step(s) of:
 closing the casing;   together with closing the casing, sealing to the drill pipe whilst optionally turning and axially moving the drill pipe; and   together with closing the casing, controlling the annular pressure within the space encircling the drill pipe.   
     
     
         4 . The method for working the underground arcuate path around the obstacle according to  claim 3 , further comprising the step(s) of:
 wherein said steps of lowering the annular pressure within the space encircling the drill pipe by sucking the volume of drilling fluid out of the space encircling the drill pipe, closing the casing, sealing to the drill pipe whilst optionally turning and axially moving the drill pipe, and controlling the annular pressure within the space encircling the drill pipe, comprises connecting a rotating control device to the casing and to said Venturi device.   
     
     
         5 . The method for working the underground arcuate path around the obstacle according to  claim 4 , further comprising the step(s) of forming an entry pit at the surface proximate the casing and said rotating control device. 
     
     
         6 . The method for working the underground arcuate path around the obstacle according to  claim 5 , wherein the rotating control device is a rotating blowout preventer. 
     
     
         7 . The method for working the underground arcuate path around the obstacle according to  claim 6 , further comprising the step of cleaning the volume of drilling fluid after the step of recovering the volume of drilling fluid at the surface.