Gas Lift Mandrel Spacing & Valve Sizing Calculator
Determine side pocket mandrel installation depths, surface unloading valve closing pressures ($P_{vc}$), and point-of-injection design.
Well Geometry & Pressures
Mandrel Depths & Unloading Sequence
Recommended Tools & Equipment
Tested hardware and components for high reliability
Continuous Gas Lift Unloading Dynamics
When an oil well is shut in for workover, the casing-tubing annulus is filled with dense static completion/kill brine ($0.45 - 0.50\text{ psi/ft}$). Because surface compressor pressure is insufficient to inject gas directly at the deep reservoir depth in one single step, a series of spring- or nitrogen-charged unloading gas lift valves are spaced along the tubing string in side-pocket mandrels.
Sequential Valve "U-Tubing" Cascade
High-pressure injection gas first blows brine through the top Valve 1 into the tubing. As the fluid level drops below Valve 2, gas enters Valve 2, lightening the tubing fluid column. The increased tubing velocity and lower pressure drop cause Valve 1 to snap shut automatically ($P_{vc}$ closing threshold). This cascading hand-off continues downward until gas injection locks permanently into the bottom operating orifice.