Patent ID: 8684078
Filing Date: 2014-04-01
Classification: E21B,F04D

Abstract:
1. In a well having a pump and a pump motor having a motor speed control, a system for attaining and maintaining a pre-determined fluid level in the well, the system comprising: a second pressure sensor that monitors pump pressure located at the pump depth; a first pressure sensor that monitors casing pressure located at the casing head of the well; a programmable computer connected to the first and second pressure sensors and the motor speed control, where: where the programmable computer computes an error signal proportional to fluid level to control a variable frequency drive motor, where the error signal proportional to fluid level is computed periodically from the difference between the actual fluid level in the well and the target fluid level in the well according to a rate reference curve; and, where the rate reference curve is generated according to an exponential function.