Gas Well Performance Analysis for Different Velocity Strings’ Diameter at Certain Surfactant Concentration: A Simulation Approach

Abstract

Liquid loading in gas wells is a critical challenge that limits gas production and can lead to well abandonment if not effectively mitigated. Analyzing the performance of a gas well under different liquid loading mitigation methods is necessary to achieve optimal gas production. Mitigation techniques such as surfactant injection and velocity strings have shown varying degrees of success but are rarely studied in combination. This study aims to evaluate the combined effectiveness of surfactant injection and varying velocity string diameters in mitigating liquid loading to optimize gas production rates. A numerical simulation approach was employed using the PROSPER simulator. Four wellbore models were developed: a base model without mitigation, a model with surfactant injection, a model with velocity strings, and a combination model utilizing both techniques. Sensitivity analysis was performed for varying surfactant concentrations and velocity string diameters to determine optimal deliquification conditions. The results reveal that the gas production rate increased with surfactant concentration up to the critical micelle concentration (CMC). The highest production rate was achieved at a surfactant concentration of 0.4 mass percent, which was determined to be the optimal concentration for liquid unloading. A velocity string diameter of 0.2 inches yielded the highest gas production rate. However, velocity strings alone were insufficient to fully deliquify the well and achieve optimal production. The combination of surfactant injection and velocity strings proved to be a more effective approach to deliquification compared to individual methods. These findings provide valuable insights for enhancing gas well performance under liquid-loaded conditions.