Downhole tool piston assembly

Abstract

A piston assembly may comprise a housing with a wall, and at least one chamber formed in the wall. A piston may be disposed within the chamber and at least one passageway may pass through the piston. At least one pin may be disposed within the passageway and attached to the chamber, and the piston may be free to translate relative to the pin.

What is claimed is: 
     
       1. A piston assembly, comprising:
 a housing comprising a wall;   at least one chamber formed in the wall;   a piston disposed within the chamber;   wherein the piston comprises a working surface adjacent the wall, a base surface opposite the working surface, and an intermediate surface joining the working surface and the base surface;   at least one passageway through the piston;   wherein the base surface comprises an opening to the passageway;   at least one pin disposed within the passageway and attached to the chamber; and   wherein the piston is free to translate relative to the pin.   
     
     
       2. The assembly of  claim 1 , wherein the chamber is in fluid communication with a fluid source. 
     
     
       3. The assembly of  claim 1 , wherein the housing is selected from a group consisting of drill bits, calipers, reamers, shock absorbers, jars, clamps, tractors, stabilizers, fishing tools, and combinations thereof. 
     
     
       4. The assembly of  claim 3 , wherein the housing consists of a drill bit and the wall and the chamber are disposed on a gauge surface of the drill bit. 
     
     
       5. The assembly of  claim 1 , wherein the housing comprises a tube and the wall is disposed within the tube. 
     
     
       6. The assembly of  claim 1 , wherein the housing comprises a tube and the wall is disposed on a surface of the tube. 
     
     
       7. The assembly of  claim 1 , wherein the chamber comprises a cross section selected from the group consisting of a circle, oval, polygon, star, rectangle with circular ends, and annulus. 
     
     
       8. The assembly of  claim 1 , wherein the piston comprises a cross sectional shape similar to the chamber. 
     
     
       9. The assembly of  claim 1 , wherein the chamber comprises openings to allow passage of the pin and fluid communication with the chamber. 
     
     
       10. The assembly of  claim 1 , wherein the chamber is lined with a sleeve and the sleeve comprises openings to allow passage of the at least one pin. 
     
     
       11. The assembly of  claim 1 , wherein the passageway intersects at least one of the intermediate surface and base surface. 
     
     
       12. The assembly of claim wherein the working surface comprises wear resistant elements disposed thereon. 
     
     
       13. The assembly of  claim 1 , wherein the base surface is nonplaner and comprises a topography selected from the group consisting of grooves, dimples, flutes, fins, troughs, and protrusions. 
     
     
       14. The assembly of  claim 1 , wherein the pin comprises a cross section selected from the group consisting of a circle, oval, polygon, star, rectangle with circular ends, and annulus. 
     
     
       15. The assembly of  claim 1 , wherein the pin comprises an aperture there through. 
     
     
       16. The assembly of  claim 1 , wherein the pin comprises a sleeve surrounding at least a portion of the pin. 
     
     
       17. The assembly of  claim 1 , wherein the passageway comprises a cross-sectional area greater than a cross-sectional area of the pin. 
     
     
       18. The assembly of  claim 1 , further comprising a seal disposed between the chamber and the piston, the piston and the sleeve, or the chamber and the sleeve. 
     
     
       19. A piston assembly, comprising:
 a housing comprising a wall, the housing having a longitudinal axis;   a first piston disposed within the wall and configured to translate relative to the housing; and   a second piston disposed within the wall and configured to translate relative to the housing, the second piston being offset from the first piston in a direction along the longitudinal axis, and at least a part of the second piston overlapping at least a part of the first piston about the longitudinal axis, wherein the first piston and the second piston are configured to actuate independently.    
     
     
       20. The piston assembly of claim 19, wherein the first piston is retained within the wall of the housing by contact with a shoulder.  
     
     
       21. The piston assembly of claim 19, further comprising a first chamber and a fluid channel in communication with at least the first chamber, the first piston positioned at least partially within the first chamber.  
     
     
       22. The piston assembly of claim 19, wherein the second piston is angularly aligned with the first piston relative to the longitudinal axis.  
     
     
       23. The piston assembly of claim 19, wherein the first piston and second piston are configured to translate relative to the housing at a specific time period.  
     
     
       24. The piston assembly of claim 19, further comprising a pin extending through the first piston and part of the housing, the pin configured to limit rotational and translational movement of the first piston relative to the housing.  
     
     
       25. The piston assembly of claim 19, wherein at least part of the first piston or second piston includes diamond.  
     
     
       26. The piston assembly of claim 25, further comprising at least one cutting element positioned on a working surface of the first piston or the second piston.  
     
     
       27. The piston assembly of claim 19, further comprising a seal positioned between the first piston and the wall of the housing.  
     
     
       28. The piston assembly of claim 19, wherein the housing is selected from a group consisting of drill bits, calipers, reamers, shock absorbers, jars, clamps, tractors, stabilizers, fishing tools, and combinations thereof.  
     
     
       29. The piston assembly of claim 19, wherein the first piston and the second piston are configured to actuate independently and in combination with each other.  
     
     
       30. A method of steering a drilling system, the method comprising:
 positioning a piston assembly adjacent a formation, the piston assembly including a first piston and a second piston, the second piston being offset from the first piston along a longitudinal axis of the piston assembly;   opening a valve to redirect a portion of drilling fluid;   extending the first piston radially using the portion of the drilling fluid applied to a base surface of the first piston;   contacting the formation with the first piston;   extending the second piston radially using the portion of the drilling fluid applied to a base surface of the second piston; and   contacting the formation with the second piston, wherein contacting the formation with the first piston and the second piston pushes the drilling system to move in a desired direction.    
     
     
       31. The method of claim 30, wherein extending the first piston and extending the second piston occur at different times.  
     
     
       32. The method of claim 30, wherein extending the first piston includes applying a fluid pressure to the base surface of the first piston.  
     
     
       33. The method of claim 30, wherein the first piston and the second piston are both extended by a fluid pressure of a single fluid source.  
     
     
       34. The method of claim 30, further comprising:
 measuring a first distance traveled by the first piston while extending the first piston, wherein measuring the first distance includes measuring with a first set of calipers connected to the first piston; and   measuring a second distance traveled by the second piston while extending the second piston, wherein measuring the second distance includes measuring with a second set of calipers connected to the second piston.    
     
     
       35. The method of claim 30, wherein extending the first piston and extending the second piston occur at different times.  
     
     
       36. The method of claim 30, wherein the portion of the drilling fluid is applied to the base surface of the first piston and the portion of the drilling fluid is applied to the base surface of the second piston by activating the valve.  
     
     
       37. The method of claim 30, further comprising connecting a bit to the piston assembly.  
     
     
       38. A downhole tool comprising:
 a body comprising a wall, the body having a longitudinal axis and an outer surface;   a first chamber in the wall and having an opening in the outer surface of the body;   a first piston positioned in the first chamber and configured to translate within the first chamber and relative to the body;   a second chamber in the wall and having an opening in the outer surface of the body;   a second piston positioned in the second chamber and configured to translate relative to the body, the second piston being axially displaced from the first piston along the longitudinal axis, and at least a part of the second piston angularly overlapping at least a part of the first piston about the longitudinal axis; and   a valve configured to redirect a portion of a drilling fluid to contact the first piston and the second piston to cause the first piston and the second piston to actuate.    
     
     
       39. The tool of claim 38, wherein the first piston includes at least one sensor.  
     
     
       40. The tool of claim 39, wherein the at least one sensor includes at least one of a pressure transducer, linear displacement variable transformer, resistivity sensor, or seismic sensor.  
     
     
       41. The piston assembly of claim 38, further comprising a cutting structure.  
     
     
       42. The piston assembly of claim 41, wherein the cutting structure includes a bit.  
     
     
       43. The piston assembly of claim 42, wherein the wall is on a gauge surface of the bit.  
     
     
       44. The piston assembly of claim 41, wherein the cutting structure includes at least one of a bit, a caliper, a reamer, a shock absorber, a jar, a clamp, a tractor, a stabilizer, or a fishing tool.