Ground drive apparatus for progressive cavity pumps

Abstract

A ground drive apparatus for a progressive cavity pump in which a rotor of the pump is connected to a rod string and in which the rod string is connected to the polished rod. The ground drive apparatus has a motor with a hollow shaft, an upper sealing structure positioned above the motor and extending around the polished rod, and a well sealing structure positioned below the motor so as to the selectively in sealing and clamping relationship with the polished rod. The hollow shaft has an inner diameter greater than an outer diameter of the rotor and the rod string. The upper sealing structure includes a stationary sealing cap, a rotary sealing bushing extending around the stationary sealing cap, and a sealing ring interposed between the stationary sealing cap and the rotary sealing bushing. The well sealing structure has a housing with a piston slidably mounted in the housing.

I claim: 
     
         1 . A ground drive apparatus for a progressive cavity pump in which a polished rod is connected to a rod string, the rod string is connected to a pump rotor, the ground drive apparatus comprising:
 a motor having a hollow shaft, said hollow shaft having an inner diameter greater than an outer diameter of the pump rotor and an outer diameter of the rod string, said motor suitable for coupling to the polished rod so as to cause a rotation of said rod string;   an upper sealing structure positioned above said motor suitable for extending around the polished rod; and   a well sealing structure positioned below said motor so as to be selectively in clamping and sealing relationship with the polished rod.   
     
     
         2 . The ground drive apparatus of  claim 1 , said upper sealing structure being in sealing relation with said hollow shaft. 
     
     
         3 . The ground drive apparatus of  claim 1 , said upper sealing structure comprising:
 a stationary sealing cap threadedly engaged with said hollow shaft;   a rotary sealing bushing extending around said stationary sealing cap; and   a first sealing ring interposed between said stationary sealing cap and said rotary sealing bushing.   
     
     
         4 . The ground drive apparatus of  claim 3 , further comprising:
 a second sealing ring interposed between a lower end of said rotary sealing bushing and said hollow shaft.   
     
     
         5 . The ground drive apparatus of  claim 3 , said first sealing ring comprising a plurality of sealing rings positioned in spaced relation to each other and extending around said stationary sealing cap. 
     
     
         6 . The ground drive apparatus of  claim 4 , said lower end of said rotary sealing ring extending downwardly below a lower end of said stationary sealing cap. 
     
     
         7 . The ground drive apparatus of  claim 3 , said first sealing ring having a V-shaped cross-section. 
     
     
         8 . The ground drive apparatus of  claim 3 , said rotary sealing bushing cooperative with said motor so as to rotate in relation to the rotation of the polished rod by said motor. 
     
     
         9 . The ground drive apparatus of  claim 1 , further comprising:
 a rod clamp suitable for connection to the polished rod and to said motor so as to cause the polished rod to be rotated by said motor and to hold an axial load the rod string.   
     
     
         10 . The ground drive apparatus of  claim 1 , said well sealing structure comprising:
 a housing suitable for positioning around the polished rod; and   a piston slidably mounted in said housing, said piston slidable in a radial direction toward or away from the polished rod, said piston having teeth formed thereon or affixed thereto at an end facing the polished rod.   
     
     
         11 . The ground drive apparatus of  claim 10 , further comprising:
 a sealing element affixed to said end of said piston, said sealing element extending so as to be in sealing relation with the polished rod when said piston is moved such that said teeth are engaged with the polished rod.   
     
     
         12 . The ground drive apparatus of  claim 10 , further comprising:
 a tightening screw engaged with said piston and extending outwardly therefrom, said tightening screw suitable actuatable as to move said piston toward or away from the polished rod.   
     
     
         13 . The ground drive apparatus of  claim 12 , further comprising:
 a nut received by said frame, said tightening screw threadedly received by said nut.   
     
     
         14 . The ground drive apparatus of  claim 10 , said end of said piston suitable for extending around an outer diameter of the polished rod. 
     
     
         15 . A ground drive apparatus for a progressive cavity pump in which the pump has a rotor thereon, the rotor being connected to a rod string, the rod string having a polished rod connected thereto, the ground drive apparatus comprising:
 a motor having a shaft, said motor suitable for connection to the polished rod so as to cause a rotation of the rod string;   an upper sealing structure positioned above said motor and positioned so as to to be extendable around the polished rod, said upper sealing structure comprising:
 a stationary sealing cap; 
 a rotary sealing bushing extending around said stationary sealing cap; and 
 a first sealing ring interposed between said stationary sealing cap and said rotary sealing bushing; and 
   a well sealing structure positioned below said motor so as to be selectively in sealing and clamping relation with the polished rod.   
     
     
         16 . The ground drive apparatus of  claim 15 , further comprising:
 a second sealing ring interposed between the lower end of said rotary sealing bushing and said hollow shaft, said lower end of said rotary sealing ring extending downwardly below a lower end of said stationary sealing cap.   
     
     
         17 . The ground drive apparatus of  claim 15 , said shaft being a hollow shaft, said hollow shaft having an inner diameter greater than an outer diameter of said rotor and an outer diameter of the rod string. 
     
     
         18 . A ground drive apparatus for a progressive cavity pump in which the pump has a rotor thereon, the rotor being connected to a rod string, the rod string having a polished rod connected thereto, the ground drive apparatus comprising:
 a motor having a shaft, said motor suitable for connection to the polished rod so as to cause rotation of the rod string;   an upper sealing structure positioned above said motor and suitable for extending around the polished rod; and   a well sealing structure positioned below said motor so as to be selectively in sealing and clamping relationship with the polished rod, said well sealing structure comprising:
 a housing suitable for positioning around the polished rod; and 
 a piston translatably mounted in said housing, said piston suitable for translation in a radial direction toward or away from the polished rod, said piston having teeth formed thereon or affixed thereto at an end, said teeth surface for engaging the polished rod. 
   
     
     
         19 . The well sealing structure of  claim 18 , further comprising:
 a sealing element affixed to said end of said piston, said sealing element extending so as to be in sealing relation with the polished rod when said piston is moved such that said teeth are engaged with the polished rod.   
     
     
         20 . The ground drive apparatus of  claim 18 , said shaft being hollow, said shaft having an inner diameter greater than an outer diameter of the rotor and an outer diameter of the rod string.