Study of natural thermogaslift operating conditions in the wellbore

This paper presents methodological approaches to study the influence of temperature and gas content on pressure variations within a well, with the goal of identifying the depth at which oil degassing occurs. The study also examines the accuracy of accounting for variable inflow under non-steady filtration conditions during well testing.The goal is to develop a decision-making model for evaluating pressure changes along the wellbore relative to either wellhead or bottomhole drawdown.Additionally, the model aims to estimate the role of natural thermogaslift in facilitating flow during natural well production and to accurately determine the volume of fluid withdrawn from the wellbore or accumulated within it over time under non-steady flow conditions.We identified the lag time of gas liberation from the reservoir fluid. We identified the lag time of gas liberation from the reservoir fluid. Based on field data, this gas release delay in Bashkirian fields ranges from 4 to 15 minutes. In contrast, similar studies are generally not done in Western Siberia, and this affects the accuracy of reservoir and production modelling. When the wellhead pressure drops below the oil saturation pressure, dissolved gas starts to separate and transitions into the free gas phase from a specific depth upward along the wellbore. The volume of free gas increases continuously as it moves toward the wellhead, reaching its maximum at the surface. At the same time, since the mass flow rate remains constant regardless of gas release, temperature changes occur further along the wellbore due to gas throttling, adiabatic expansion, and the absorption of latent heat of vaporization as gas evolves from the gas-liquid mixture in thermal exchange with the surrounding reservoir.