Method and system for controlling a mechanical pump to monitor and optimize both reservoir and equipment performance

Self-calibrating apparatus for detecting pump-off of a liquid in a fluid reservoir having a variable fluid level, said apparatus comprising:

• means for measuring a parameter that is variable with a change in the liquid level of the reservoir during pump operation;
• means for generating a first control signal representative of the instantaneous measured value of said parameter;
• first processing means for integrating said first control signal over a first time-base that is long enough to average out pumping transients below a prescribed magnitude to produce a second control signal that is representative of a short-term moving average of said first control signal;
• second processing means for integrating said first control signal over a second time-base that is greater than said first time-base to produce a third baseline reference control signal that is representative of a long-term moving average of said first control signal;
• means for comparing the magnitude of said second control signal with the magnitude of said third control signal to determine when the relative magnitude of said second and third control signals changes to a prescribed ratio that is indicative of either the passage of pumping transients or the depletion of inventoried fluid from said reservoir;
• and
• means for generating a fourth control signal that is indicative of fluid pump-off whenever the relative magnitude of said second and third control signals remains indicative of an undesired pumping condition for a prescribed period of time.

A method for detecting an undesired pumping condition in a fluid reservoir having a variable liquid level, said method comprising the steps of:

• measuring a parameter that is variable with a change in the liquid level of the reservoir during pump operation;
• generating a first control signal representative of the instantaneous value of said measured parameter;
• integrating said first control signal over a first time-base that is long enough to average out pumping transients below a predetermined magnitude to produce a second control signal that is representative of a short-term moving average of said first control signal;
• integrating said first control signal over a second time-base that is greater than said first time-base to produce a third baseline reference control signal that is representative of a long-term moving average of said first control signal;
• comparing the magnitude of said second control signal with the magnitude of said third control signal to determine when the relative magnitude of said second and third control signals changes to a prescribed ratio that is indicative of an undesired pumping condition;
• and
• generating a fourth control signal whenever the relative magnitude of said second and third control signals remain indicative of said undesired pumping condition for a prescribed period of time.