Study on the effect of gas-liquid ratio and crude oil viscosity on the gas separation efficiency of composite gas anchor

Abstract In the latter stages of production for fire-drive oil wells, decreasing wellbore pressure results in substantial gas production. This study examines the gas separation performance of a composite gas anchor through experimental and simulation approaches to mitigate the effects of gas entering the pump. The experimental findings indicate that the gas separation efficiency stabilizes at a gas-liquid ratio of 800 m 3 /m 3 , showing minimal variation with further increases. Additionally, examining the efficiency across varying crude oil viscosities reveals a peak efficiency at a viscosity of 20 mPa·s. Beyond this viscosity, efficiency initially increases but subsequently declines. Simulations corroborated these results, highlighting that the gas-liquid two-phase flow dynamics promote effective separation. Increased crude oil viscosity lowers the flow rate and accentuates the viscosity disparity between gas and liquid phases. This disparity predominantly enhances separation efficiency when the viscosity is below 20 mPa·s. However, as viscosity exceeds this threshold, the mixture’s flow rate becomes the dominant factor, decreasing gas separation efficiency. This study identifies the optimal gas-liquid ratio and crude oil viscosity for the composite gas anchor’s operation, offering valuable insights into gas prevention strategies for oil wells with high gas-liquid ratios.