Operational control of wellsite pumping unit with displacement determination

Abstract

A well pumping system can include an actuator that reciprocably displaces a rod string, a flowmeter that measures flow of a fluid between a power source and the actuator, and a control system that modifies reciprocal displacement of the rod string by the actuator, in response to an output of the flowmeter. A well pumping method can include reciprocably displacing a rod string, continuously determining a velocity profile of the rod string, and modifying the velocity profile while the rod string reciprocably displaces, in response to an output of a flowmeter. Another well pumping method can include reciprocably displacing a rod string with an actuator, continuously determining displacement in response to an output of a flowmeter, and modifying reciprocating displacement of the rod string by the actuator, in response to the output of the flowmeter.

What is claimed is: 
     
         1 . A well pumping system, comprising:
 an actuator that reciprocably displaces a rod string;   a flowmeter that measures flow of a fluid between a power source and the actuator; and   a control system that modifies reciprocal displacement of the rod string by the actuator, in response to an output of the flowmeter.   
     
     
         2 . The well pumping system of  claim 1 , further comprising at least one discrete position sensor that detects when a member of the actuator or an upper end of the rod string is at a predetermined position. 
     
     
         3 . The well pumping system of  claim 1 , wherein the control system modifies a stroke extent of a member of the actuator, in response to the output of the flowmeter. 
     
     
         4 . The well pumping system of  claim 1 , wherein the control system modifies a stroke extent of the rod string at surface, in response to the output of the flowmeter. 
     
     
         5 . The well pumping system of  claim 1 , wherein the control system modifies a stroke extent of the rod string proximate a downhole pump, in response to the output of the flowmeter. 
     
     
         6 . The well pumping system of  claim 1 , wherein the control system maintains a preselected velocity profile of a member of the actuator, in response to the output of the flowmeter. 
     
     
         7 . The well pumping system of  claim 1 , wherein the control system maintains a preselected velocity profile of the rod string at surface, in response to the output of the flowmeter. 
     
     
         8 . The well pumping system of  claim 1 , wherein the control system maintains a preselected velocity profile of the rod string proximate a downhole pump, in response to the output of the flowmeter. 
     
     
         9 . A well pumping method, comprising:
 reciprocably displacing a rod string;   continuously determining a velocity profile of the rod string; and   modifying the velocity profile while the rod string reciprocably displaces, in response to an output of a flowmeter.   
     
     
         10 . The well pumping method of  claim 9 , wherein the modifying comprises changing a duration of the velocity profile. 
     
     
         11 . The well pumping method of  claim 10 , wherein the changing is performed while the rod string reciprocably displaces. 
     
     
         12 . The well pumping method of  claim 9 , wherein the modifying comprises changing a position at which an actuator member velocity is zero, the position being determined based on the output of the flowmeter. 
     
     
         13 . The well pumping method of  claim 12 , wherein the changing is performed while the rod string reciprocably displaces. 
     
     
         14 . The well pumping method of  claim 9 , wherein the modifying comprises changing a position at which the rod string velocity is zero at a downhole pump. 
     
     
         15 . The well pumping method of  claim 14 , wherein the changing comprises solving a wave equation in the rod string. 
     
     
         16 . The well pumping method of  claim 9 , wherein the modifying comprises minimizing differences between the detected velocity profile and a preselected velocity profile. 
     
     
         17 . The well pumping method of  claim 9 , wherein the modifying comprises maintaining acceleration of the rod string less than a preselected level. 
     
     
         18 . A well pumping method, comprising:
 reciprocably displacing a rod string with an actuator;   continuously determining displacement in response to an output of a flowmeter; and   modifying reciprocating displacement of the rod string by the actuator, in response to the output of the flowmeter.   
     
     
         19 . The well pumping method of  claim 18 , wherein the determined displacement is calibrated in response to an output of at least one discrete position sensor. 
     
     
         20 . The well pumping method of  claim 18 , wherein the modifying comprises varying a periodic energy input to the actuator relative to the reciprocating displacement of the rod string. 
     
     
         21 . The well pumping method of  claim 20 , wherein the varying comprises varying a duration of the energy input. 
     
     
         22 . The well pumping method of  claim 20 , wherein the varying comprises varying a level of the energy input. 
     
     
         23 . The well pumping method of  claim 18 , wherein the modifying comprises varying a stroke extent. 
     
     
         24 . The well pumping method of  claim 23 , wherein the varying comprises displacing the stroke extent until either:
 a) the stroke extent is positioned at a preselected stroke extent, or   b) the stroke extent has displaced a preselected distance.   
     
     
         25 . The well pumping method of  claim 18 , wherein the modifying comprises modifying a stroke extent of the rod string at surface. 
     
     
         26 . The well pumping method of  claim 18 , wherein the modifying comprises modifying a stroke extent of the rod string proximate a downhole pump. 
     
     
         27 . The well pumping method of  claim 26 , wherein modifying the stroke extent of the rod string proximate the downhole pump comprises solving a wave equation in the rod string. 
     
     
         28 . The well pumping method of  claim 18 , wherein the modifying comprises maintaining a preselected velocity profile of a member of the actuator. 
     
     
         29 . The well pumping method of  claim 18 , wherein the modifying comprises maintaining a preselected velocity profile of the rod string at surface. 
     
     
         30 . The well pumping method of  claim 18 , wherein the modifying comprises maintaining a preselected velocity profile of the rod string proximate a downhole pump. 
     
     
         31 . The well pumping method of  claim 30 , wherein maintaining the preselected velocity profile of the rod string proximate the downhole pump comprises solving a wave equation in the rod string. 
     
     
         32 . The well pumping method of  claim 18 , wherein the modifying comprises maintaining a preselected velocity profile, during the reciprocating displacement of the rod string.