INTERMITTENT GAS LIFT (GAPL) – “WHY NOTHING WORKS?”

This frustrating question from an engineer was uttered to a gas lift vendor. The engineer had tried adjusting gas injection rates, plunger cycle times, plunger types, and afterflow times. His SCADA data showed widely fluctuating field gas line pressures, and wells negatively departing from their historic production decline curves. The vendor commented, “looks like you have been trying the same things repeatedly and getting the same results”. I was then brought into the conversation for input. My ask was what downhole installation existed and was told “the usual upper unloading casing Injection Pressure Operated (IPO) gas lift valves with an orifice valve on bottom”. He said his company had a bad experience with packers and decided to now go packerless on all completions.

The solution I stated was easy for installations still equipped with packers. A “packoff device” is installed within the tubing above the orifice valve containing an IPO valve. The well is then placed on Intermittent Gas Lift (IGL) governed in operation solely by the actions of the surface intermitter and the opening and closing of the IPO valve; not influenced by reservoir pressure surges and wellbore inflow variances now happening on his GAPL wells. If the well had side-pocket mandrels, the orifice valve would simply be replaced with an IPO valve and converted to IGL.

For packerless wells the solution is to pull these wells, install a packer and replace the orifice valve with an IPO valve. The main reason for his fluctuating surface injection line pressure was that a few wells may be blowing around the end of tubing. This causes pressure surges at the wellbore, increased Flowing Bottom Hole Pressures at depth and reduced inflow productivity. These packerless installations also caused pressure sinks within the system, attributing to surface line pressure fluctuations.

Mention was made of the consistent increases above 25% in fluid production when GAPL wells were converted to IGL by replacing the orifice valve with an IPO valve. In many cases, gas injection rates for IGL installations averaged 55% per well less than needed for GAPL wells. He noted the significant economic impact this would have on reducing field compression but thought his management would be hesitant in adopting these changes. He agreed on the increased reservoir drawdown and maximized production resulting in producing his low Bottom Hole Pressure Low Productivity wells.

The low cost of implementing these installation changes (less than $12,000/well) and ease for his company was explained. They already had a surface gas injection system and all that was needed was a properly designed downhole IGL installation based on best gas lift industry practices.

We shook hands and parted with the understanding that old practices die hard.