Axial Oscillation Device

Abstract

A downhole pressure pulsing apparatus comprising: an upper sub that comprises a tube having a hollow interior through which fluid can flow; a middle sub that comprises a tube having a hollow interior through which fluid can flow; a lower sub that comprises a tube having a hollow interior through which fluid can flow; wherein said upper sub is connected to said middle sub by a connection such that the hollow interior of said upper sub 1 is in fluid communication with said middle sub's hollow interior; wherein said middle sub is connected to said lower sub by a connection such that the hollow interior of said middle sub is in fluid communication with said lower sub's hollow interior; an impeller assembly, wherein said impeller assembly comprises an impeller that is rotatably mounted inside said middle sub's hollow interior; a stator, wherein said stator is housed inside said upper sub's hollow interior and wherein said stator directs fluid flow into said impeller; a cam assembly mounted within said lower sub's hollow interior; a restrictor assembly that varies total flow area in order to generate pressure pulses, wherein said restrictor assembly is mounted within said lower sub's hollow interior; and wherein said cam assembly converts rotational motion created by said impeller assembly to reciprocating axial motion within said restrictor assembly.

1 . A downhole pressure pulsing apparatus, comprising:
 an upper sub that comprises a tube having a hollow interior through which fluid can flow;   a middle sub that comprises a tube having a hollow interior through which fluid can flow;   a lower sub that comprises a tube having a hollow interior through which fluid can flow;   wherein said upper sub is connected to said middle sub by a connection such that the hollow interior of said upper sub is in fluid communication with said middle sub's hollow interior;   wherein said middle sub is connected to said lower sub by a connection such that the hollow interior of said middle sub is in fluid communication with said lower sub's hollow interior;   an impeller assembly, wherein said impeller assembly comprises an impeller that is rotatably mounted inside said middle sub's hollow interior;   a stator, wherein said stator is housed inside said upper sub's hollow interior and wherein said stator directs fluid flow into said impeller;   a cam assembly mounted within said lower sub's hollow interior;   a flow restrictor assembly that varies total flow area in order to generate pressure pulses, wherein said flow restrictor assembly is mounted within said lower sub's hollow interior; and wherein said cam assembly converts rotational motion created by said impeller assembly to reciprocating axial motion within said restrictor assembly.   
     
     
         2 . A downhole pressure pulsing apparatus according to  claim 1 , wherein said axial impeller assembly comprises:
 an impeller housing having a hollow interior;   an impeller rotatably mounted within said impeller housing wherein fluid flow causes impeller rotation;   a lower threaded connection to connect said impeller assembly to said cam assembly.   
     
     
         3 . A downhole pressure pulsing apparatus according to  claim 2 , wherein said axial impeller's rotational speed is directly proportional to the rate of fluid flow directed by said stator into said impeller. 
     
     
         4 . A downhole pressure pulsing apparatus according to  claim 1 , wherein said cam assembly comprises:
 a cam housing having a hollow interior;   a barrel cam having at least one cam profile, wherein said barrel cam is mounted inside said cam housing's hollow interior;   at least one cam follower;   at least one barrel cam retainer is mounted within said lower sub's hollow interior;   top inner diameter threads to connect said impeller assembly to said cam housing;   lower inner diameter thread to connect the rocket holder.   
     
     
         5 . A downhole pressure pulsing apparatus according to  claim 4 , wherein said at least one cam follower engages said at least one cam profile to convert said impeller's rotational motion to said barrel cam's axial reciprocation;
 and wherein said barrel cam retainer restrains said barrel cam from rotational motion.   
     
     
         6 . A downhole pressure pulsing apparatus according to  claim 1 , wherein said flow restrictor assembly comprises:
 a rocket holder;   a rocket; and   a venturi;   wherein said rocket is constrained by said rocket holder to the desired range of axial motion; and   wherein said rocket can reciprocate axially into and out of said venturi.   
     
     
         7 . A downhole pressure pulsing apparatus according to  claim 1 , wherein said impeller rotates said cam assembly; and wherein said cam assembly engages said flow restrictor assembly to generate axial motion within said flow restrictor assembly to vary total flow area. 
     
     
         8 . A downhole pressure pulsing apparatus according to  claim 1 , further comprising a pressure actuated device that reacts to pressure pulses generated by said flow restrictor assembly in order to oscillate axially. 
     
     
         9 . A downhole pressure pulsing apparatus according to  claim 7 , further comprising a housing for location in a drill string, said housing defining a through bore to permit fluid passage through said pressure pulsing apparatus and a shock tool mounted on said drill string;
 wherein said pressure pulsing apparatus generates axial reciprocation in said drill string in a well bore:   wherein said drill string comprises a drill bit, drilling motor, or rotary drilling system, a measurement while drilling tool, and drill pipe; and   wherein said flow restrictor assembly generates pressure pulses within said drill string and said shock tool converts pressure pulses into axial oscillation.   
     
     
         10 . A downhole pressure pulsing apparatus according to  claim 6 , further comprising a hydromechanical indexing apparatus that switches pulsation on and off as fluid flow starts and stops by moving said venturi axially move away from said rocket;
 wherein said hydro-mechanical indexing apparatus is mounted within said lower sub's hollow interior and comprises a base plate, a housing for a base plate, an indexing barrel having a top and a bottom and an indexing profile, at least one indexing pin that engages said indexing profile, a wash pipe, a shear pin mechanism having a bottom, and a spring;   wherein said indexing barrel is attached to said venturi and said indexing barrel and said venturi can move axially within said lower sub's hollow interior;   wherein said indexing profile comprises an engagement position and a disengagement position;   wherein said base plate is connected to the top of said indexing barrel;   wherein said spring pushes said indexing barrel upward and fluid flow pushes said indexing barrel downward when fluid flow is sufficient to overcome said spring;   wherein said indexing barrel's upward and downward movement causes said indexing pin to move within said indexing profile between said indexing profile's engagement position and said indexing profile's disengagement position;   wherein said shear pin mechanism is connected to said indexing barrel's bottom;   wherein a shear pin is inserted into said indexing barrel and said shear pin mechanism;   wherein said wash pipe is connected to said shear pin mechanism's bottom and is positioned inside said lower sub's hollow interior to form an annulus between said wash pipe's outer diameter and said lower sub's inner diameter; and   wherein said spring is located in said annulus between said wash pipe's outer diameter and said lower sub's inner diameter.   
     
     
         11 . A downhole pressure pulsing apparatus according to  claim 10 , in a drilling operation, where the axial oscillation of a drill string using said downhole pressure pulsing apparatus, facilitates the weight transfer to a bit due to lower friction between said drill string and a formation. 
     
     
         12 . A downhole pressure pulsing apparatus according to  claim 10 , where said downhole pressure pulsing apparatus can be used to reduce the possibility of a drill string getting stuck in a well bore or freeing a stuck object in a well bore. 
     
     
         13 . A downhole pressure pulsing apparatus according to  claim 10 , where said apparatus facilitates running tubular into a well bore.