Ways to solve production problems of gas wells in West Siberia’s mature fields
A considerable number of West Siberia’s gas fields have reached the maturity stage characterized by pressure depletion, ever-increasing watercut, and severe sand production. The paper focuses on comprehensive analysis of reservoir and operational challenges including liquid loading, damage of near-bottomhole zone, aging and abrasive wear of equipment. Factors contributing to these processes and ways to address the issues are discussed. The paper presents methods to calculate minimum necessary gas production rates in watered and non-watered wells, as well as a procedure to evaluate the erosion rate. The paper also discusses methods to control water breakthrough. They include hydrochemical and electrochemical methods, in that number, use of a mineralization detector in the wellhead equipment to signal beginning of water breakthrough to production wells. The generally used sand detectors have a high measurement error, so to improve the erosion control, the sand detection system can be backed up by erosion signaling indicators, which are activated as soon as their control elements installed in the gas flow are destructed. Common technologies to improve production of marginal gas wells including free-piston pumping, concentric tubing, gas-lift, surfactant flooding are discussed, and case studies are presented. Results of well tests allowed a comparative analysis of available technologies and selection of the most effective methods to improve the performance of maturing gas assets. The industry efforts must be aimed at search of advanced technologies to control water production. This problem is particularly acute in low-thickness gas reservoirs, and the authors offer some possible ways to address this issue.