Microscopic mobilization mechanism of gas and water in deep shale nanopores
Deep shale gas has become one of the most practical fields for natural gas production increase in China.Existing research results have proved that deep shale possesses abundant nanopores,but high temperature,high pressure and water bearing aggravate the complexity of gas and water mobilization in shale reservoirs.The traditional desorption and displacement experiment of shale core scale is costly and time-consuming,and can hardly reveal the microscopic mobilization mechanism of gas and water in nanopores under the conditions of deep reservoirs.Based on the molecular simulation method,this paper proposes a shale gas-water mobilization simulation method considering gas and water mass diffusion and transfer.Then,the mobilization mechanisms of methane and water in the dual-medium nanopores of deep shale under two different modes are simulated.Finally,the adsorbed,dissolved,and free methane are quantified,and the microscopic mobilization mechanisms of pore water and methane in different occurrence states are revealed.And the following research results are obtained.First,illite in shale has a greater affinity for methane than kerogen,and illite is much more hydrophilic than kerogen.Second,under the two mobilization modes,water in the illite is basically immovable while the water clusters on the kerogen surfaces are movable.Third,in the dual-medium nanopores,free methane has the highest mobilization rate,while dissolved methane and adsorbed methane have a lower mobilization rate,so they are the important potential resources for shale gas reserves increase in the late stage.In conclusion,the theoretical research on the microscopic mobilization of gas and water in deep shale nanopores is of great theoretical significance to the recoverable reserves estimation,production capacity evaluation and recovery factor improvement of deep shale gas reservoirs.
Deep strataShale gasNanoporeDesorptionWaterOccurrence stateMobility
万方数据
维普
