Surfactant Assisted Gas Lift (SAGL) – Large-Scale Lab Testing, Field Pilots and New Use for Frac Hit Recovery

Surfactants were investigated to improve production and reduce gas injection requirements for high water-cut oil wells in the Permian. For liquid-dominated production, surfactants alter multiphase flow structures, so gas is more efficient in lifting liquids, reducing both liquid holdup (HL) and bottomhole pressure (pbh). Improving gas lift (GL) performance using trace amounts of chemicals injected from the surface is very attractive as a low-cost method to inject deeper and faster and reduce gas injection rates. This Surfactant Assisted Gas Lift (SAGL) method is also beneficial for unloading water and restoring oil production in GL wells impacted by adjacent Frac treatments. In this case, providing an alternative to changing lift methods to unload Frac water. This paper documents large-scale lab experiments and field pilot results in Permian. Laboratory tests were conducted to investigate the effectiveness of various commercial surfactants in synthetic high-salinity brines. The Zero Net Liquid Flow (ZNLF) test was shown to be effective in screening surfactants relative to their ability to alter slip, HL, and efficiency in lifting liquids. The tests showed HL could be reduced 2 to 5 times using surfactants, suggesting a significant impact on Pbh could be obtained with this method. The best-performing surfactants identified through the screening tests were then subjected to large-scale, low-pressure flow loop testing to further understand the enhancement mechanisms and surfactant performance over a range of gas and liquid rates. Field tests were conducted in both the Midland and Delaware Basins and showed uplifts in oil rates from 10-38% were possible using the SAGL technique. The highest levels of uplift were achieved when the surfactant lowered the gas lift injection point, and for higher rate annular flow wells versus tubing flow wells already injecting at the lowest valve. The surfactant injection via a capillary string and with the injected gas were investigated. Surfactant concentrations of less than 100 ppm were found to be sufficient in many cases, and products were identified that minimized emulsion and foaming issues in the surface separators. For Frac Hit wells, surfactants dramatically improved water unloading in the 80% range on average, with significant increases in the post-frac oil rates.