Study on gas-water two-phase seepage laws and water production mechanisms in high-temperature, high-pressure tight gas reservoirs

To address the unclear gas-water seepage laws and inaccurate water production predictions in high-temperature, highpressure tight gas reservoirs, this study conducted unsteady-state displacement experiments at 150 °C/50 MPa, revealing changes in gas-water relative permeability characteristics: bound water saturation decreased by 48%, residual gas saturation reduced by 20%, and relative permeability curves exhibited concave-downward shapes. A gas-water relative permeability conversion model incorporating temperature-pressure effects was established to correct deviations in traditional models. A water-cut rate equation was derived based on a parallel capillary tube model, identifying a critical gas saturation threshold (50%) and the dominant role of pore-throat structures. Field application in Well A demonstrated a prediction error of