Study on flow characteristics of natural gas containing CO2 invading wellbore during drilling

The dissolution of invaded gas in the drilling fluid during results an increase invasion concealment. This is great significance for development acid reservoirs to determine solubility change and multiphase flow law annulus after by natural with high CO 2 content. In this study, control equations gas–liquid are established considering influence solubility. For prediction solubility, interaction parameters CH 4 water Peng–Robinson equation state optimised establish a model. content brine solution measured through phase-equilibrium experiments. indicate that newly model can accurately predict water, error within 5%. Moreover, mixed 15%. analysis example engineering applications reveals leads slow mud-pit increment, concealment strengthens as distance between gas-migration front wellhead increases. Gas has significant impact on monitoring low permeability reservoirs.