Abstract: A method and apparatus for controlling the speed of a progressing cavity liquid well pump by driving the pump with a variable speed drive device while measuring the amount of liquid production from the pump. The speed of the pump is varied in speed steps, either upwardly or downwardly, by the variable speed drive device while measuring liquid production, to maintain a linear relationship between liquid production and pump speed.

Abstract: A method of calibrating a well pumpoff controller by calibrating the controller for determining the average load during a pumping stroke, measuring the actual load and averaging the measured maximum and minimum load during each operational stroke, comparing the average measured load with the calibrated average load and providing an offset to the load measurement to correct the measured load towards the calibrated load.

Abstract: In a liquid well pumping system which is provided with a downtime between pumpoff cycles, the method of determining the maximum downtime includes running a plurality of tests to determine the relationship between runtime and downtime and determining when the relationship becomes non-linear for at least two consecutive tests. The downtime is selected adjacent the last linear relationship between runtime and downtime for providing a downtime which allows adequate fluid buildup in the well, but not so long a period as to loose well production.

Abstract: A method of maintaining a substantially constant amount of filling of a liquid well pump actuated by a polished rod which is reciprocated by a prime mover. The load and position of the polished rod is periodically measured to determine the amount of filling of the pump. The change in the amount of filling of the pump of one pumping cycle relative to a previous pumping cycle is compared and the speed of actuation of the pump is varied as a function of the change in the amount of filling of the pump to maintain a substantially constant amount of filling of the pump. The pump is continuously actuated but the speed is varied for preventing the well from being pumped dry.

Abstract: Optimizing the production of well fluids from a well by controlling the injection gas flow rate. Determining the time delay for various gas flow rates to produce a constant liquid flow rate and determining the relationship between the injection gas flow rate and the amount of liquids produced and calculating the required injection gas flow rate to produce a selected amount of liquids. Thereafter the gas flow rate is adjusted considering the determined time delays to reach the required injection gas flow rate without injecting more gas than is needed.

Abstract: A gas gun for producing pressure pulses for measuring the liquid level in a well. A body is adapted to be connected to a well and includes first and second chambers which are interconnected by a passageway. Pressure pulses flowing between the chambers creates a pressure pulse for transmittal to a well which is measured by a microphone measuring pressure variations. A piston actuated valve opens and closes the passageway between the first and second chambers. A firing valve transmits the higher pressure in one of the chambers to the back of the piston for closing the valve, and after one of the chambers is pressurized, exhausts the pressure from the back of the pressurized piston for opening the valve and creating a pressure pulse between the chambers. A spring biases the piston actuated valve to the closed position.

Abstract: A method and apparatus for accepting analog voltage signals from a reciprocating liquid well pump and digitizing the signals and storing the signals for playback at a later time. A receiving circuit accepts two analog signals, one of which is proportional to the load in the polished rod, the other of which is proportional to the displacement of the polished rod. Simultaneously the two analog signals are digitized by means of an analog to digital converter and the digital data is stored on a digital memory integrated circuit. The digital memory may be replayed through a digital to analog converter into an x-y plotter. Digital latches and counters detect the start and end of a pumping cycle to insure that one full cycle of the reciprocating pump is stored in the digital memory. Timing circuitry strobes the load and displacement data into the digital memory in equal time increments to allow time related methematics to be performed by a computer.

Abstract: A control circuit for turning off the electrical power to the drive motor, which reciprocates a polished rod of a pump, when the pump has exhausted the supply of liquid in the well. Simultaneously measuring the polished rod load and rod position and turning off the power when the load is greater than or equal to a preset load and the position is equal to a preset position on the downstroke of the well. A first comparator measures the polished rod load relative to a preset load, and a second comparator measures the polished rod position relative to a preset point so that the power is shut off when the load is greater than or equal to the preset load and the position is equal to the preset point on the downstroke. A set of digital latches act to insure that the load is greater than the preset load for two consecutive strokes before the power is shut off.

Abstract: A hydraulic pumping unit for vertically actuating a downhole pump including first and second hydraulic piston and cylinder assemblies. The first assembly is connected to the downhole pump and the second assembly is connected to a counterweight. A hydraulic line is connected between the first and second assemblies so that the counterweight counterbalances the downhole pumping equipment. A hydraulic pump is connected to the first and second assemblies through switching means for alternately supplying hydraulic fluid to and from the first and second assemblies. A check valve is provided between the hydraulic pump and the hydraulic line for replenishing the assemblies with fluid. A safety valve is connected between the first assembly and the hydraulic line for preventing the first assembly dropping in the event of a hydraulic line failure. A return valve in parallel with an orifice closes in the event the hydraulic pump stops for preventing free fall of the first assembly.

Abstract: A polished rod load transducer for connection to the polished rod for measuring the load in a sucker rod well pumping system in which the transducer body has at least three symmetrical sections pivotally connected together with a clamping means connected to the body for clamping the body about a polished rod. A strain gauge is mounted on each of the sections and the strain gauges are equally spaced about the body when the body is clamped on a polished rod. An electrical circuit is connected to all of the strain gauges for measuring the total output from all of the strain gauges whereby an accurate measurement of the axial strain in the polished rod can be obtained in spite of the fact that the polished rod may be subjected to bending or be under or oversized. Preferably, the strain gauges are connected in series in one leg of a Wheatstone bridge circuit.

Abstract: A control circuit for turning off the power to the pump drive motor when the pump has exhausted the supply of liquid in the well. Means for sensing the instantaneous current to the pump motor and a circuit measuring the average current drawn by the pump drive motor, and turning off the power when the average current decreases below a preset level. An RC circuit having a time constant greater than the time required for the pump to complete one full pumping cycle for measuring the average current to the motor, and a comparator controlling switching means to shut off the power when the average current to the motor decreases to a predetermined amount. A reference voltage supplied to the comparator from an amplifier connected to the electrical power in which the output of the amplifier varies inversely to variations of the voltage of the electrical power thereby preventing fluctuations in the supply voltage from adversely affecting the control circuit.

Abstract: A light source for illuminating film transparencies is in the form of a cathode-ray tube provided with electronic circuitry which causes the beam of the tube to trace a raster on the screen. The circuitry is such that the area of the raster and its position on the screen can be selectively controlled by the observer for illuminating predetermined portions of the screen. The observer can thus illuminate only that portion of the film transparency of particular interest to him, and can select the intensity of illumination by controlling the electron beam intensity. The raster is developed by sweeping the beam in the horizontal and vertical directions at different speeds using a sweep wave form that is of a symmetrical triangular shape thus eliminating the necessity for blanking the beam as the raster is developed.

Abstract: A malfunction detector circuit for use in conjunction with a pump-off control circuit which is periodically actuated by a timer and which monitors the current drawn by the drive motor of a liquid well pump. The malfunction circuit monitors the operation of the timer, pump-off control circuit, and drive motor of the well pump for detecting any abnormalities in operation and provides a signal if a malfunction occurs. The malfunction circuit is actuated by the pump-off circuit timer unless the pump-off circuit gains control of the driver motor and interlocks the malfunction output. A counter is provided to count a predetermined number of sequential failures before a malfunction is indicated. In addition, an excessive current measuring circuit detects malfunctions such as parted rods, split tubings, stuck valves and other abnormal situations.