Patent ID: 8157537

Claim:
A method of compensating for offset and amplitude drift in position or load sensor data from a sucker rod pump, the method comprising the steps of: (a) providing position sensor data proportional to an inclination of a walking beam of said pump and load sensor data proportional to a well load during operation of said pump; (b) calculating a position horizon value from a midpoint of consecutive minimum and maximum position or load values; (c) measuring a time interval between a positive horizon crossing and a negative horizon crossing; (d) calculating a peak time from a midpoint of said time interval; (e) updating the horizon and peak time values by repeating steps (b) to (d) for every cycle; (f) for each pump cycle recording a minimum load, maximum load, start-up load and start-down load; and (g) calculating a new reference load boundary for a subsequent pump cycle by adding to the minimum load a predetermined fraction of a difference between the start-down load and the minimum load; whereby compensation for offset and amplitude drift in the position and load sensor data is achieved.