An Improved Method to Calculate Gas-Lift Valve Set Pressure

Abstract

Summary This study aims to enhance the accuracy of gas-lift valve (GLV) design set pressure calculations by incorporating the effects of silicone thermal expansion, silicone compression, and dome thermal expansion. The proposed method is compared with experimental measurements and current industry methods. The analysis includes an experimental assessment of the impact of internal dome volume changes on the design set pressure, considering various silicone fill levels, pressures, and temperatures. Experimental conditions cover silicone fills of 25%, 50%, and 75%, initial pressures from 975 psig to 1,250 psig, and temperatures from 60°F to 175°F. These conditions cover the conventional operating range in the industry. The results show that silicone expansion is the most dominant factor among silicone compression and chamber thermal expansion. The proposed method significantly improves GLV design set pressure calculations, especially for high-pressure and high-temperature conditions. The study suggests improvements in injection-pressure-operated (IPO) valve design practices to avoid multipoint injection and unloading failures. To the best of the authors’ knowledge, the impact of silicone expansion on GLV set pressure has not been investigated in the open literature. The enhanced method proposed in this research could significantly impact well unloading and production operations for wells equipped with GLVs. In addition, this work suggests an improvement on the American Petroleum Institute (API) recommended practice, especially when dealing with high-pressure, high-temperature wells and when utilizing refurbished GLVs.