Mastering Jet Pump Pressure: A Comprehensive Guide

Jet pump pressure is a critical parameter in the operation of jet pumps, which are artificial lift techniques used extensively in the oil and gas industry. Understanding the factors that influence jet pump pressure and how to accurately measure and analyze it is essential for optimizing the performance and efficiency of these systems.

Understanding Jet Pump Pressure

Jet pump pressure is determined by several key factors:

1. Power Fluid Pressure: The pressure of the power fluid, typically a high-pressure liquid or gas, is the primary driver of the jet pump system. This pressure is responsible for creating the necessary flow and pressure differential to lift the wellbore fluid.

2. Pressure Drop across the Nozzle: As the power fluid passes through the nozzle, it undergoes a significant pressure drop, which creates the suction force that draws in the wellbore fluid. The size and design of the nozzle play a crucial role in determining the pressure drop.

3. Wellbore Pressure: The pressure in the wellbore, which can vary depending on the depth, fluid composition, and other factors, also influences the overall jet pump pressure. This pressure must be overcome to lift the fluid to the surface.

Measuring Jet Pump Pressure

Accurately measuring jet pump pressure is essential for optimizing the system’s performance. There are several methods used to estimate the Pump Intake Pressure (PIP), a critical parameter in jet pump systems:

1. Acoustic Fluid Level: This method uses acoustic waves to determine the fluid level in the wellbore, which can then be used to estimate the PIP.

2. Pump Dynamometer: By analyzing the pump card (a plot of the load on the pump rod versus the position of the pump), the PIP can be approximated during the upstroke.

3. Valve Check Measurements: This approach involves measuring the pressure drop across the pump’s intake and discharge valves, which can provide an estimate of the PIP.

It’s important to note that each of these methods has its own strengths and limitations, and the PIP values computed may differ. The PIP computed using the max and min loads from the pump card may yield too low PIP, while PIP computed using loads from the valve test usually are too high. The PIP computed from dynamometer measurements is generally a good approximation of the pressure at the pump intake and the pressure in the annulus at the depth of the pump, provided that additional pressure losses are not present.

Determining Flow Rate in a Well Pump System

To determine the flow rate of a well pump system with a pressure tank, the following steps can be taken:

1. Allow the well pump to build up to full pressure by running water in the home or from a hose bib or faucet until the well pump kicks in or the pressure switch points click.
2. Close the faucet and ensure no water is being used in the home. The well pump will build up pressure for a few minutes, and then the pressure switch will shut off the well pump.
3. Open a hose bib (also referred to as a ‘spigot’ or ‘faucet’) anywhere near or after the pressure tank.
4. Run the water into a 5-gallon bucket, noting how many gallons you collect. If the bucket fills up, dump out the water and keep measuring and filling.
5. Measure the number of gallons drawn down from the pressure tank until the well pump turns on.
6. When you hear the pump turn on, immediately close the hose bib.
7. Time the period in seconds it takes for the well pump to build back up to pressure, that is, between the cut-in and cut-off of the pressure switch.
8. The formula for determining the flow rate is gallons drawn down (that were measured above), divided by the seconds required for recovery, then multiplied by 60: (Gallons / Seconds) x 60 = Gallons per Minute (GPM) flow rate.

Troubleshooting Jet Pump Pressure Issues

If you encounter issues with jet pump pressure, such as a jet pump that won’t build pressure, there are a few common causes to consider:

1. Nozzle Blockage: Debris or scale buildup in the nozzle can restrict the flow of the power fluid, reducing the pressure drop and the suction force.
2. Worn or Damaged Components: Over time, the jet pump’s components, such as the nozzle, diffuser, or impeller, can wear down or become damaged, affecting the system’s performance.
3. Incorrect Sizing: If the jet pump is not properly sized for the specific well conditions, it may not be able to generate the necessary pressure to lift the fluid effectively.
4. Power Fluid Issues: Problems with the power fluid, such as low pressure, flow rate, or temperature, can impact the jet pump’s ability to create the required pressure differential.

To address these issues, it’s essential to regularly inspect and maintain the jet pump system, ensure proper sizing and installation, and monitor the power fluid parameters.

Conclusion

Jet pump pressure is a critical parameter that must be thoroughly understood and accurately measured to optimize the performance and efficiency of jet pump systems in the oil and gas industry. By mastering the factors that influence jet pump pressure, the methods for measuring it, and the troubleshooting techniques, you can ensure your jet pump operations run smoothly and effectively.

References

1. Podio, A. L., McCoy, J. N., & Rowlan, O. L. (2009). Pump Intake Pressure: Comparison of Values Computed from Acoustic Fluid Level, Pump Dynamometer and Valve Check Measurements. SWPSC.
2. Defining Jet Pumps | SLB. (2016). SLB Resource Library.
3. How to Determine Your Well Pump Flow Rate on Wells with Pressure Tanks. (n.d.). Clean Water Store.
4. deep-well jet pump that will not build pressure – DoItYourself.com. (n.d.). DoItYourself.com.
5. How can a New Jet Pump Cause Pressure Switch Problems? – terrylove.com. (n.d.). Terry Love Plumbing & Remodel DIY & Professional Forum.