Operational control of wellsite pumping unit with continuous position sensing

Abstract

A well pumping system can include an actuator that reciprocably displaces a rod string, a continuous position sensor that continuously detects a position of a member of the actuator, and a control system that modifies reciprocal displacement of the rod string by the actuator, in response to an output of the continuous position sensor. A well pumping method can include reciprocably displacing a rod string, continuously detecting a velocity profile with a continuous position sensor, and modifying the velocity profile while the rod string reciprocably displaces, in response to an output of the continuous position sensor.

What is claimed is: 
     
         1 . A well pumping system, comprising:
 an actuator that reciprocably displaces a rod string;   a continuous position sensor that continuously detects a position of a member of the actuator; and   a control system that modifies reciprocal displacement of the rod string by the actuator, in response to an output of the continuous position sensor.   
     
     
         2 . The well pumping system of  claim 1 , wherein the control system modifies the reciprocal displacement of the rod string, without displacement of the continuous position sensor relative to the actuator. 
     
     
         3 . The well pumping system of  claim 1 , wherein the control system modifies a stroke extent of the actuator member, in response to the output of the continuous position sensor. 
     
     
         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 continuous position sensor. 
     
     
         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 continuous position sensor. 
     
     
         6 . The well pumping system of  claim 1 , wherein the control system maintains a preselected velocity profile of the actuator member, in response to the output of the continuous position sensor. 
     
     
         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 continuous position sensor. 
     
     
         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 continuous position sensor. 
     
     
         9 . A well pumping method, comprising:
 reciprocably displacing a rod string;   continuously detecting a velocity profile with a continuous position sensor; and   modifying the velocity profile while the rod string reciprocably displaces, in response to an output of the continuous position sensor.   
     
     
         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 detected by the continuous position sensor. 
     
     
         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 detecting a position of a member of the actuator with a continuous position sensor; and   modifying reciprocating displacement of the rod string by the actuator, in response to an output of the continuous position sensor.   
     
     
         19 . The well pumping method of  claim 18 , wherein the modifying is performed without displacing the continuous position sensor relative to the actuator. 
     
     
         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 actuator member as detected by the continuous position sensor. 
     
     
         21 . The well pumping method of  claim 20 , wherein the varying comprises varying a duration of the energy input, in response to the output of the continuous position sensor. 
     
     
         22 . The well pumping method of  claim 20 , wherein the varying comprises varying a level of the energy input, in response to the output of the continuous position sensor. 
     
     
         23 . The well pumping method of  claim 18 , wherein the modifying comprises varying a stroke extent of the actuator member, in response to the output of the continuous position sensor. 
     
     
         24 . The well pumping method of  claim 23 , wherein the varying comprises displacing the stroke extent until either:
 a) the stroke extent as detected by the continuous position sensor is positioned at a preselected stroke extent, or   b) the stroke extent has displaced a preselected distance as detected by the continuous position sensor.   
     
     
         25 . The well pumping method of  claim 18 , wherein the modifying comprises modifying a stroke extent of the rod string at surface, in response to the output of the continuous position sensor. 
     
     
         26 . The well pumping method of  claim 18 , wherein the modifying comprises modifying a stroke extent of the rod string proximate a downhole pump, in response to the output of the continuous position sensor. 
     
     
         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 the actuator member, in response to the output of the continuous position sensor. 
     
     
         29 . The well pumping method of  claim 18 , wherein the modifying comprises maintaining a preselected velocity profile of the rod string at surface, in response to the output of the continuous position sensor. 
     
     
         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, in response to the output of the continuous position sensor. 
     
     
         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, in response to the output of the continuous position sensor.