| 摘要 |
<p>OIL WELL PUMPOFF CONTROL SYSTEM UTILIZING INTEGRATION TIMER. A valve in the production flow line of an oil well closes a reed switch indicative of fluid being pumped through the line. The switch closure activates a first oscillator whose count is compared with a variable frequency oscillator having a frequency of approximately one-half that of the first oscillator. The comparison is made over a given period of time to ascertain the percentage of time the valve has been open and passing fluid. Theoretically, the valve should be open approximately fifty percent of the time because almost that much time is taken on the downstroke of the pumping assembly when no production is occurring. The integrated timer is adjusted to shut down the system when the percentage of time the valve is open drops to the preselected amount, usually equal to or less than around fifty percent. In response to the integration timer producing a signal, a shutdown timer is turned on which restarts the cycle after a preselected amount of time. The length of shutdown time for the pumping unit is preset according to the well fill-in rate. When the system is restarted by the shutdown timer, a pump-up timer is turned on which is adjusted to allow for a desired pump-up time. As the pump-up timer is allowing the system to recycle, the integration timer is reset and the recycling is completed if the requirements of the integration timer are met. Otherwise, the unit is shut down again and the system recycled. A variable electronic scaler is connected to the output of the integration timer which monitors the output signals from this timer.</p> |
