Well Cleaning Device

Abstract

A tool for cleaning a casing of an oil well may include an elongate housing configured to be lowered into a well casing. A discharge head may be disposed at one end of the housing, the discharge head including a first electrode having a first end surface, a first insulator surrounding the first electrode, a surface of the first insulator substantially flush with the first end surface, and a second electrode having a second end surface separated from the first end surface by a discharge gap. An energy reservoir and a switch may be disposed within the housing, the switch configured to selectively couple the energy reservoir to the first electrode and the second electrode to cause energy stored in the energy reservoir to discharge across the discharge gap.

It is claimed: 
     
         1 . A well cleaning tool, comprising:
 an elongate housing configured to be lowered into a well casing;   a discharge head disposed at one end of the housing, the discharge head comprising:
 a positive electrode having a first end surface, 
 a first insulator surrounding the positive electrode, a surface of the first insulator substantially flush with the first end surface, and 
 a negative electrode having a second end surface separated from the first end surface by a discharge gap; 
   an energy reservoir disposed within the housing; and   a switch disposed within the housing, the switch configured to selectively couple the energy reservoir to the positive electrode and the negative electrode to cause energy stored in the energy reservoir to discharge across the discharge gap.   
     
     
         2 . The well cleaning tool of  claim 1 , further comprising:
 a power converter disposed within the housing, the power converter configured to convert primary electrical power into a DC voltage level to charge the energy reservoir.   
     
     
         3 . The well cleaning tool of  claim 1 , further comprising:
 a first electrode mount configured to couple the first insulator to the housing.   
     
     
         4 . The well cleaning tool of  claim 3 , further comprising:
 a second electrode mount configured to retain the negative electrode, the second electrode mounting including three or more elongate legs to couple the second electrode mount to the first electrode mount.   
     
     
         5 . The well cleaning tool of clean  4 , wherein the second electrode mount is configured to retain the negative electrode in a plurality of positions to provide for adjustment of a width of the discharge gap. 
     
     
         6 . The well cleaning tool of  claim 1 , wherein the positive electrode, the negative electrode and the housing are generally cylindrical in shape and disposed along a common axis. 
     
     
         7 . The well cleaning tool of  claim 6 , further comprising:
 a centralizer adjacent to the discharge head, the centralizer configured to center the discharge head within the well casing.   
     
     
         8 . The well cleaning tool of  claim 6 , wherein the surface of the first insulator is configured to direct a shock wave generated by the discharge generally orthogonal to the common axis. 
     
     
         9 . The well cleaning tool of  claim 8 , wherein the surface of the first insulator is one of a convex curved surface and a conical surface. 
     
     
         10 . The well cleaning tool of  claim 6 , further comprising:
 a second insulator surrounding the negative electrode, a surface of the second insulator substantially flush with the second end surface.   
     
     
         11 . The well cleaning tool of  claim 10 , wherein the surface of the second insulator is configured to direct the shock wave generated by the discharge generally orthogonal to the common axis. 
     
     
         12 . The well cleaning tool of  claim 11 , wherein the surface of the second insulator is one of a convex curved surface and a conical surface. 
     
     
         13 . The well cleaning tool of  claim 1 , wherein the positive electrode and the negative electrode are one of carbon steel, low alloy steel, stainless steel, and corrosion resistant steel.