Effects of gas release rate on gas-water migration in shallow gas reservoir

Abstract

Laws for gas-water migration in shallow gas reservoirs were analyzed in path of gas release with the theory of two-phase seepage in unsaturated soil in order to verify the rationality and necessity of the controlling measure for pre-exhausting gas in the process of preventing shallow gas geological engineering disasters.The effects of different release rates of exhaust shafts on the gas-water migration in shallow gas reservoirs were described by using numerical methods.Results show that the gas release rate significantly affects the gas-water migration and distribution in shallow gas reservoirs.The faster the gas release rate,the more significant water-coning effects are.According to the detailed geological investigation data,the appropriate gas release rate should be selected to implement the controlling measure for gas release in practical engineering in order to avoid premature flooded shaft and rapid failure of the exhaust shaft.There are still some residual gas bubbles in sandy soil after the gas release,which should be regarded in process of construction.