GB1410218A - Method and apparatus for minitoring well pumping units - Google Patents

Abstract

1410218 Monitoring pumping electrically MOBIL OIL CORP 29 Nov 1972 ] 28 Dec 1971] 55135/72 Heading G1N Apparatus for monitoring the operation of a pumping unit having a reciprocating sucker string rod, and operating to pump up fluid from a well, comprises a transducer generating a signal representative of the load on the rod string, means for differentiating said signal, and means responsive to said differentiated signal to provide a warning signal. The transducer 40 which may be disposed in the rod string or on an associated walking beam produces a signal which is amplified at 45 giving a signal a. This signal is applied to three sections 42a, 42b, 42c. In section 42a the load signal is differentiated at 46. High peaks on the differentiated signal b indicate "fluid pounding" where pumping is faster than the seepage rate. An amplitude discriminator 47 produces a pulse each time a differentiated signal peak exceeds a pre-set value 54. These pulses have a width dependent on the amount by which the value 54 is exceeded. The pulses are fed to an integrator 48 whose output doperates a trip unit 50 at a specified value 55, to apply a control signal to a "pump off" relay in a control unit 44. If fluid pounding ceases before the trip level is reached the integrator will begin to discharge and the output will return to its former level. The output a may be clipped before differentiation to avoid false operation of the warning arrangement. Section 42b provides normal maximum load determination. The load signal a is fed to an amplitude discriminator 56 set at a value slightly below the normal maximum amplitude of the signal, thus producing one pulse per cycle of operation. The output is fed to a timing circuit comprising an integrator 58 followed by a trip unit 60, which responds if a pulse signal fails to arrive indicating a low load signal. The output of the trip 60 is applied to a malfunction relay 62 in the control unit 44. Section 42(c) comprises two amplitude discriminators 65, 66, which respond to very high and very low load amplitudes respectively. Load signals outside these amplitudes generate signals to the relay 62. In the unit 44, actuation of relay 52 due to fluid pounding activates a shut-down relay 68, energizes an alarm circuit 70, shuts down a running-time totalizer 72, and activates a shut-down timer 74 which runs for a time for fluid to accumulate before it times out and actuates a relay 76 to reset relay 52. The malfunction relay 62 actuates the shut-down relay 68, and an alarm 80, and may be manually reset by trip 62. Actuation of trip 50 in section 42a disables section 42b by means of relay 84. A circuit arrangement for Fig. 2 is disclosed (Fig. 5 not shown). Alternatively computer analysis and control is envisaged.