Design and Operational Considerations
Gas well deliquification is critical in extending the economic life of a reservoir. Once liquids begin to accumulate in the wellbore, hydrostatic backpressure builds and gas deliverability declines. Artificial lift is often required to restore flow, and among the available methods, hydraulic jet pumps provide a unique, flexible solution. Unlike mechanical lift systems, jet pumps rely on the energy of injected power fluid and contain no moving parts downhole, making them highly suited for environments where solids, paraffin, or variable gas/liquid ratios are present.
Principles of Jet Pump Deliquification
A hydraulic jet pump operates by injecting high-pressure power fluid from the surface down the tubing to a nozzle set in the pump insert. As the fluid exits the nozzle, velocity increases and static pressure decreases, creating a low-pressure zone at the throat. This draws in accumulated liquids and mixes them with the power fluid. The combined stream is then discharged through the diffuser, where velocity energy is converted back to pressure to lift the mixture to surface.
For gas well deliquification, the system is particularly effective because it tolerates high gas volume fractions, intermittent slugs, and sand-laden fluids that would quickly compromise rod lift or ESP systems.
Design Modifications for Gas Wells
In gas wells, jet pumps are designed with specific modifications:
- Small nozzle diameters are selected to accelerate fluid and create strong suction, allowing effective unloading of light liquid columns.
- Throat sizing is adjusted to accommodate variable inflow conditions and high GVF at intake.
- Power fluid choice may shift between produced water and treated fresh water depending on well conditions, with filtration critical to prevent plugging.
- Concentric Strings of tubing are also commonly used. This allows the jet pump to be placed anywhere in the wellbore as well as leaving a path open for gas to bypass the jet pump and flow up the casing. Typically, integral joint tubing or coil tubing is run inside production tubing.
Operational Considerations
Jet pump deliquification systems can be cycled on and off to match well loading behavior, or they can be run continuously in wells with persistent liquid production. The surface system must provide reliable high-pressure injection, and diaphragm surface pumps are often selected for their tolerance to solids and lack of packing or plunger wear. Chemical treatment through the power fluid circuit allows direct downhole delivery of foaming agents or corrosion inhibitors, improving uptime and reducing secondary interventions.
Performance Across Well Types
Horizontal Wells with Sump Completion
Jet pumps are particularly effective in horizontal gas wells with a sump drilled below the lateral. Liquids accumulate in the sump, and the jet pump positioned there can efficiently remove them without requiring rods or long pump strings through the lateral. The tolerance for deviation makes this configuration highly practical.
Vertical Completions
In vertical gas wells, jet pumps provide straightforward deliquification by unloading liquid columns that build as reservoir pressure declines. They can be cycled intermittently, keeping intervention costs low.
Concentric String Completions
In extremely high GLR wells, typically above 2000 scf/bbl, it may be necessary to run the jet pump in concentric strings to allow the gas to bypass the jet pump intake. This is also the case in completions where either the jet pump needs to be set in a sump, out in the horizontal, or below the perforations.
Slim Hole Completions with Damaged Casing
Where casing restrictions or damage prevent conventional lift installation, jet pumps can be run in slim-hole carriers. The compact design of the nozzle/throat insert allows deployment through restrictions, restoring productivity where ESPs or rod pumps cannot be run.
Reverse Flow Completions
Jet pumps can be configured for reverse flow, where power fluid is injected down the annulus and returns up the tubing. This is particularly useful where tubing restrictions or well design dictate alternate flow paths, giving operators flexibility that mechanical pumps cannot match.
Deviated Wellbores
Rod lift is impractical in highly deviated wellbores due to rod buckling and wear, while ESPs face challenges with cable deployment and high GVF. Jet pumps thrive in these settings, as there is no rod string or motor to install and the downhole assembly is short and compact.
Frac Flowback
During hydraulic fracture cleanup, large volumes of water and sand must be produced quickly. Jet pumps tolerate sand-laden fluids without risk of mechanical seizure, making them an effective temporary lift method for flowback operations. Inserts can be replaced once erosion occurs, without costly workovers.
Reliability and Economics
The key benefit of jet pumps in gas well deliquification lies in their reliability. With no moving parts downhole, wear and failure risks are minimal. The ability to retrieve and resize inserts by circulation avoids expensive workovers. Surface diaphragm pumps, being seal-less and hydraulically balanced, add to system reliability by eliminating packing failures, leakage, and the need for external lubrication.
From an economic standpoint, jet pumps may not be the most efficient lift system in terms of energy consumption per barrel lifted, but they excel in reducing downtime and intervention costs. In gas wells, where production decline is highly sensitive to even short interruptions, uptime is often more valuable than efficiency.
Conclusion
Hydraulic jet pumps are a proven, adaptable tool for gas well deliquification across a broad range of completion types and reservoir conditions. Their design simplicity, tolerance for harsh fluids, and rigless retrievability make them especially effective in horizontal wells, slim-hole or damaged casing completions, frac flowback, and other environments where conventional mechanical lift struggles. When paired with robust surface diaphragm pumps, the system minimizes maintenance, reduces workover frequency, and sustains gas deliverability long after natural energy declines.