Well service pump system and methods

Abstract

A well service pump system supplies high pressure working fluid to a well. The pump system is a linear design which incorporates a diesel engine, a hydraulic drive gear box, open loop hydraulic Pumps, hydraulic ram cylinders, controls for the hydraulic system hydraulic cylinders, working fluid end cylinders and a coupling to connect the hydraulic cylinders and the working fluid ends. The engine powers the hydraulic system which, in turn, provides hydraulic fluid to operate the hydraulic ram cylinders. Each of the polished rods of the hydraulic ram cylinders is connected axially to a plunger rod end of a working fluid end cylinder. There is no crankshaft or automatic transmission required. The linear design allows for a longer plunger stroke length while still allowing highway transport on a truck or skid.

1 - 28 . (canceled) 
     
     
         29 . A well service pump for delivering fracturing fluid at high pressure to a well, the pump comprising:
 a working fluid end cylinder having an end cylinder housing, a plunger rod configured to reciprocate in the end cylinder housing;   a hydraulic ram cylinder having a ram cylinder housing, a ram piston configured to reciprocate in the ram cylinder housing, and a piston rod coupled to the ram piston and configured to be coupled to the plunger rod of the working fluid end cylinder such that piston of the hydraulic ram cylinder can be actuated to move the plunger rod of the working fluid end cylinder:
 in a first direction to expel working fluid from the end cylinder housing during a forward stroke of the plunger rod, and 
 in a second direction to draw working fluid into the end cylinder housing during a return stroke of the plunger rod; 
   where the end cylinder housing of the working fluid end cylinder has a cylindrical inner wall defining an end cylinder inner diameter, and the plunger rod has an outer surface that is spaced apart from the cylindrical inner wall such that the working fluid end cylinder can pump abrasive fluids without the plunger rod and the end cylinder inner wall simultaneously contacting individual particles in the working fluid.   
     
     
         30 . The well service pump of claim  1 , where each working fluid pump assembly further comprises:
 a coupling member configured to couple to the plunger rod of the working fluid end cylinder and to the piston rod of the hydraulic ram cylinder.   
     
     
         31 . The well service pump of  claim 29 , where the piston rod is configured to be coupled in an axially aligned relation to the plunger rod. 
     
     
         32 . (canceled) 
     
     
         33 . The well service pump of  claim 29 , where the outer diameter of the plunger rod is between 70 percent and 98 percent of the inner diameter of the cylindrical inner wall. 
     
     
         34 . The well service pump of  claim 33 , where the outer diameter of the plunger rod is between 85 percent and 95 percent of the inner diameter of the cylinder inner wall. 
     
     
         35 . The well service pump of  claim 29 , where the plunger rod has a length that exceeds 12 inches. 
     
     
         36 . The well service pump of  claim 29 , where the length of the plunger rod exceeds 40 inches. 
     
     
         37 . The well service pump of  claim 29 , where the length of the plunger rod is between 50 inches and 60 inches. 
     
     
         38 . The well service pump of  claim 29 , where the ram cylinder housing includes a first port on a first side of the ram piston and second port on a second side of the ram piston. 
     
     
         39 . The well service pump of  claim 38 , further comprising:
 an inlet check valve coupled to the end cylinder housing and configured to permit working fluid to be drawn into the end cylinder housing but prevent working fluid from exiting the end cylinder housing through the inlet check valve; and   an outlet check valve coupled to the end cylinder housing and configured to permit working fluid to exit the end cylinder housing while preventing working fluid from being drawn into the end cylinder housing.   
     
     
         40 . The well service pump system of  claim 39 , where the outlet check valve and inlet check valve are each disposed at least partially in the end cylinder housing. 
     
     
         41 . The well service pump of  claim 29 , further comprising a position sensor coupled to at least one of the hydraulic ram cylinder and the working fluid end cylinder. 
     
     
         42 . The well system pump of  claim 29 , further comprising a position indicator coupled to at least one of the piston, piston rod, and plunger rod. 
     
     
         43 . A method comprising:
 delivering fluid to a well with a well service pump system of  claim 29 .