FLOW RESPONSIVE TIME DELAY PUMP MOTOR CUT-OFF LOGIC

摘要

An automatically controlled fluid flow responsive method for achieving de-energization of an electric motor operatively connected with a downhole pump being connected to a production tubing string of a well when flow from the downhole pump becomes abnormally low. A selective electronic cut-off signal is programmed, representing a selected minimum acceptable rate of discharge flow from the downhole pump. A flow transducer provides an electronic flow related signal to the control circuitry, representing actual pump discharge flow. The control circuitry is also programmed with a selected electronically controlled time delay period which is initiated when the flow related signal becomes less than the selective cut-off signal. When the flow related signal remains less than the cut-off signal for the duration of the time delay period the control circuitry interrupts the electrical power supply to the pump motor. The time delay motor cut-off control logic is provided with an adjustable "set flow" logic and an adjustable "cut-off delay" logic which establish parameters of allowable minimum pump discharge flow and the time period that the pump will be allowed to operate below a preset minimum allowable flow rate. A flow transducer is provided to monitor the pump discharge and continuously provides flow related signals which are received by the control logic. When the preset "minimum flow" and "time period" settings are met the control logic will provide a control signal to deenergize the electrical power circuit of the pump motor, thus shutting down the pump or to shift the pump to a lower operating speed. The pump motor cut-off logic incorporates a startup delay which maintains the pump cut-off logic in a deactivated state for a period of time which is selected to permit the well production system to reach its operational characteristics.