Self-aligning, fluid-driven pumping unit

Abstract

A reciprocating well pumping unit includes a fluid-driven cylinder to drive a reciprocating rod assembly. A valve controls fluid delivery to the cylinder, the valve having a valve spool capable of being positioned in a first position or a second position, the valve in the first position causing fluid flow that allows the lifting rod to extend, the valve in the second position causing fluid flow that allows the lifting rod to retract. A detent assembly provides resistance to movement of the valve spool between the second and first positions. A control rod is coupled to and moves with the lifting rod. A spring is capable of storing energy as the control rod is moved in the first direction and a rod stop engages the spring, the spring engaging the valve spool as energy is stored in the spring to urge the valve spool toward the first position.

What is claimed is: 
     
         1 . A reciprocating well pumping unit comprising:
 a fluid-driven cylinder adapted to be coupled to a reciprocating rod assembly, the cylinder having a lifting rod capable of traveling between an extended position and a retracted position;   a valve capable of controlling fluid delivery to the cylinder, the valve having a valve spool capable of being positioned in a first position or a second position, the valve in the first position causing fluid flow that allows the lifting rod to extend, the valve in the second position causing fluid flow that allows the lifting rod to retract;   a detent assembly providing resistance to movement of the valve spool between the second position and the first position;   a control rod coupled to the lifting rod such that movement of the lifting rod in a first direction results in movement of the control rod in the first direction;   a rod stop coupled to the control rod; and   a spring carried on the control rod and capable of engagement with the rod stop, the spring capable of storing energy as the control rod is moved in the first direction and the rod stop engages the spring, the spring engaging the valve spool as energy is stored in the spring to urge the valve spool toward the first position.   
     
     
         2 . The reciprocating well pumping unit of  claim 1 , wherein when a threshold amount of energy is stored in the spring, the detent assembly permits the movement of the valve spool into the first position. 
     
     
         3 . The reciprocating well pumping unit of  claim 1  further comprising:
 a dampener operably associated with the valve spool or the control rod to control a velocity of the valve spool or the control rod. 
 
     
     
         4 . The reciprocating well pumping unit of  claim 1 , wherein the detent assembly further comprises:
 a detent seat having at least one detent stop;   at least one detent arm supporting a detent bearing and being pivotally movable between an engaged position in which the detent bearing engages the at least one detent stop and a disengaged position in which the detent bearing becomes disengaged from the at least one detent stop;   a detent spring to bias the at least one detent arm toward the engaged position.   
     
     
         5 . The reciprocating well pumping unit of  claim 4 , wherein the at least one detent stop is a recess or a projection disposed on the detent seat. 
     
     
         6 . The reciprocating well pumping unit of  claim 1  further comprising:
 a second rod stop coupled to the control rod; 
 a second spring carried on the control rod and capable of engagement with the second rod stop, the second spring capable of storing energy as the control rod is moved in the second direction and the second rod stop engages the second spring, the second spring engaging the valve spool as energy is stored in the second spring to urge the valve spool toward the second position; 
 wherein the detent assembly provides resistance to movement of the valve spool between the first position and the second position. 
 
     
     
         7 . The reciprocating well pumping unit of  claim 6  further comprising:
 at least one dampener operably associated with the valve spool or the control rod to control a velocity of the valve spool or the control rod. 
 
     
     
         8 . The reciprocating well pumping unit of  claim 6 , wherein the detent assembly further comprises:
 a detent seat having a first detent stop and a second detent stop;   at least one detent arm supporting a detent bearing and being pivotally movable between an engaged position in which the detent bearing engages one of the first and second detent stops and a disengaged position in which the detent bearing becomes disengaged from the one of the first and second detent stops;   a detent spring to bias the at least one detent arm toward the engaged position.   
     
     
         9 . A reciprocating well pumping unit comprising:
 a beam assembly pivotally attached to an anchor member that is fixed relative to a well;   a fluid-driven cylinder having a cylinder housing and a cylinder rod, the cylinder rod capable of extending from or retracting into the cylinder housing; and   a traveling assembly adapted to be coupled to a reciprocating rod assembly extending into the well, the traveling assembly coupled to one of the cylinder rod and the cylinder housing;   wherein the beam assembly is capable of pivoting during operation of the fluid-driven cylinder.   
     
     
         10 . The reciprocating well pumping unit of  claim 9 , wherein an axis of rotation about which the beam assembly is capable of pivoting intersects a longitudinal axis of the reciprocating rod assembly. 
     
     
         11 . The reciprocating well pumping unit of  claim 10 , wherein the beam assembly is capable of lateral movement along the axis of rotation during operation of the fluid-driven cylinder. 
     
     
         12 . The reciprocating well pumping unit of  claim 9 , wherein the anchor member is a wellhead of the well and the pivotal coupling between beam assembly and the wellhead is located at a fluid port of the wellhead. 
     
     
         13 . The reciprocating well pumping unit of  claim 12 , wherein a conduit is fluidly connected to the fluid port to allow fluid communication between the conduit and a wellbore of the well. 
     
     
         14 . The reciprocating well pumping unit of  claim 9 , further comprising a fluid source fluidly connected to the cylinder housing. 
     
     
         15 . The reciprocating well pumping unit of  claim 9 , wherein the beam assembly further comprises:
 a beam; and   a base coupled to the beam.   
     
     
         16 . The reciprocating well pumping unit of  claim 15 , wherein the beam is coupled to another of the cylinder rod and the cylinder housing. 
     
     
         17 . The reciprocating well pumping unit of  claim 15 , wherein the base is coupled to another of the cylinder rod and the cylinder housing. 
     
     
         18 . The reciprocating well pumping unit of  claim 15 , wherein the traveling assembly further comprises:
 a traveling head;   a plurality of rollers rotatingly coupled to the traveling head, the plurality of rollers engaging the beam to allow the traveling head to travel along the beam in a direction substantially parallel to the movement of the reciprocating rod assembly.   
     
     
         19 . The reciprocating well pumping unit of  claim 15 , wherein the beam is an I-beam having a first flange and a second flange joined by a transverse member. 
     
     
         20 . The reciprocating well pumping unit of  claim 19 , wherein the traveling assembly further comprises:
 a traveling head; and   a plurality of rollers rotatingly coupled to the traveling head, the plurality of rollers engaging the beam to allow the traveling head to travel along the beam;   wherein a first and a second of the plurality of rollers are each positioned on an opposing side of the first flange of the beam.   
     
     
         21 . The reciprocating well pumping unit of  claim 9 , wherein the traveling assembly further comprises:
 a rotating member rotatingly coupled to the one of the cylinder rod and the cylinder housing;   a flexible linkage having a first end coupled to the beam assembly and a second end coupled to the reciprocating rod assembly;   wherein the rotating member engages the flexible linkage such that extension or retraction of the cylinder rod moves the rotating member thereby resulting in the lifting or lowering of the reciprocating rod assembly.   
     
     
         22 . The reciprocating well pumping unit of  claim 21 , wherein:
 the rotating member is a sheave or a sprocket; and   the flexible linkage is a cable, a rope, or a chain.   
     
     
         23 . The reciprocating well pumping unit of  claim 9  further comprising:
 a counter weight coupled to the beam assembly to counteract at least a portion of the weight of the beam assembly about the pivotal coupling of the beam assembly. 
 
     
     
         24 . A reciprocating well pumping unit comprising:
 a fluid-driven cylinder having a cylinder housing and a cylinder rod, the cylinder rod capable of extending from or retracting into the cylinder housing, one of the cylinder rod and the cylinder housing being coupled to a reciprocating rod assembly extending into a well, another of the cylinder rod and the cylinder housing being fixed relative to the reciprocating rod assembly;   a heat exchanger having a first fluid pathway fluidly connected to the fluid-driven cylinder, the first fluid pathway receiving a first fluid used to drive the cylinder rod, the heat exchanger having a second fluid pathway to receive a production fluid from the well; and   a temperature determination unit operably associated with either the first or the second fluid pathway downstream of the heat exchanger to determine a temperature of the production fluid following exit of the production fluid from the heat exchanger;   wherein the flow of the first fluid to the fluid-driven cylinder is adjusted in response to the temperature determination.   
     
     
         25 . The reciprocating well pumping unit of  claim 24 , wherein the temperature determination unit further comprises a temperature sensor. 
     
     
         26 . The reciprocating well pumping unit of  claim 24 , wherein the temperature determination unit further comprises a temperature switch. 
     
     
         27 . The reciprocating well pumping unit of  claim 24 , wherein the temperature switch is configured to turn off a pumping circuit, thereby ceasing reciprocation of the reciprocating rod assembly. 
     
     
         28 . The reciprocating well pumping unit of  claim 24 , wherein when the temperature is greater than or equal to a threshold temperature, an operator is notified that pumping operations should be ceased. 
     
     
         29 . The reciprocating well pumping unit of  claim 24 , wherein the one of the cylinder rod and the cylinder housing is coupled to the reciprocating rod assembly by a traveling assembly. 
     
     
         30 . The reciprocating well pumping unit of  claim 24 , wherein the flow adjustment of the first fluid further comprises ceasing delivery of the first fluid to the fluid-driven cylinder.