The most common mechanical oil recovery method in the world is screw pumping, and its most common operational problem is that the pump cannot be completely filled, resulting in low productivity. The pump is not fully filled because the pump capacity is greater than the well production or the pump suction port. If the separation is not good, part of the pump displacement will be lost due to gas interference. If the interference of the pump air is eliminated and the running time of the pump is controlled, the pump displacement can be matched with the liquid amount flowing into the bottom of the well, which can improve efficiency and reduce cost. The specific practice of maintaining high yields of screw pumping oil is as follows:
1. Acoustic level measurement should be performed to determine the relative depth of the production surface and the pump suction. If the liquid level is higher than the pump suction, the well cannot be mined at maximum production. If the gas interference affects the yield, the liquid level is higher than the pump suction port; if the pumping volume is too large, resulting in low production, the liquid level should be at or near the pump suction port.
2. The power meter measures the percentage of the pump fullness coefficient, and the integrated data acquisition system can simultaneously obtain the motor power and the indicator data. One of the main uses of the dynamometer is to diagnose how the pump is operating and to analyze downhole problems. Applying the production level measurement combined with the dynamometer to see if the well is produced at maximum production, if the liquid column height is higher than the pump suction depth, if the pump is not fully filled, and if the free gas is moving up the casing annulus.
3. Diagnose low energy efficiency wells. The method of diagnosis is to determine the overall efficiency of the pumping system, while determining the total efficiency requires only measuring the power input to the prime mover, determining the downhole production pressure and accurate production test data. Generally, the total efficiency of the beam pumping system should be about 50%. If it is lower than this, its performance should be improved. Techniques to increase overall efficiency include maintaining high volumetric efficiency (pump specifications match wellbore injection, eliminating gas interference, pumping with an evacuation controller or timer) and replacing oversized motors.
4. Separation of underground gas. Ineffective pump operation is often caused by gas interference and can be diagnosed by acoustic level measurement and dynamometer. It is best to place the pump suction port below the fluid inlet section and, if placed above, a gas separator. If the valve seat short section is placed at least 10 ft below the bottom of the fluid entry section, effective gas separation may occur in the annulus, at which point the sleeve acts as a separator outer cylinder. However, well conditions often do not allow the pump to be placed below the fluid entry layer, and a downhole gas separator is contemplated. Conventional gas separators consist of a fluid inlet section (such as a perforation nipple), an outer cylinder (such as a section of tubing with a plug at the bottom), and a liquid-sealing tube at the bottom of the pump.
5. Control pump displacement, which can be controlled by adjusting 4 parameters: plunger size, stroke length, pump stroke, daily running time. Pumps of an unsuitable size are usually not replaced due to the high cost of the equipment. The easiest way to do this is to change the configuration of the ground equipment, such as moving the beam lever to change the stroke length of the ground and pump; the second is to replace the motor pulley to control the pump stroke. The matching of pump volume to well capacity can be achieved by changing the daily running time. The following devices can be used to control the running time: the air pump controller, the interval timer and the percentage timer. The air pump controller stops the pump if it detects that the pump is not fully charged. The timer controls the running time of the pump, which is cheaper and simpler to operate. The duration of the pump stop should be as short as the well pressure at the bottom of the well does not exceed 10% of the reservoir pressure.
The operator can perform the above-mentioned sound wave and dynamometer measurement for 45 minutes for each well to determine the well productivity, downhole pump dynamics, downhole gas separator dynamics, sucker rod and beam pumping unit load, and motor dynamics. Through 45 minutes of analysis, operators can maximize well production and reduce operating costs.
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