Pumping with screw pumps is one of the most widely used artificial lift methods. However, a common issue is that the pump may not be fully filled, leading to reduced efficiency and lower production. This happens when the pump's capacity exceeds the well's production rate or when gas interference prevents proper fluid intake. To improve performance, it's essential to eliminate gas interference and manage the pump's operating time so that its displacement matches the liquid inflow into the wellbore. Here are some best practices for maintaining high productivity in screw pump operations:
First, use sonic logging to determine the liquid level and the depth of the pump’s suction inlet. If the liquid level is above the pump intake, the well isn't being produced at maximum capacity. If gas is causing issues, the liquid level should be at or near the pump inlet. Monitoring this helps optimize production.
Second, measure the pump’s fill-up percentage using a dynamometer. Combined with data acquisition systems, this can provide motor power readings and visual diagrams. These tools help identify if the pump is operating efficiently, whether the fluid column is above the suction depth, or if gas is interfering with the pumping process.
Third, assess low energy efficiency wells by calculating the total system efficiency. This involves checking the input power, bottomhole pressure, and production data. A typical beam pump system should have around 50% efficiency. If it's lower, consider improving volumetric efficiency through better gas management, using an evacuation controller, or replacing oversized motors.
Fourth, implement underground gas separation to prevent gas from entering the pump. Gas interference can be detected using acoustic measurements and dynamometers. Ideally, place the pump below the fluid entry point. If not possible, install a gas separator above the pump. These separators typically include a perforated section, an outer cylinder, and a dip tube to separate gas from liquid before it reaches the pump.
Fifth, control the pump’s displacement by adjusting parameters like stroke length, stroke frequency, and daily operating time. Since replacing the pump can be costly, operators often adjust surface equipment, such as changing the beam configuration or motor pulleys. Controlling run time using timers or automatic controllers can also help match the pump’s output to the well’s production capacity.
By conducting 45-minute assessments using sonic, dynamometer, and other diagnostic tools, operators can evaluate well performance, downhole dynamics, and mechanical loads. This allows them to maximize production while reducing operational costs. With careful monitoring and adjustment, screw pump systems can operate efficiently and sustainably over time.
Jiangsu Manrui New Materials Co., Ltd , https://www.manruiwire.com