The construction of gas storage is an important work in the natural gas industry.Aquifer gas storage is an important type of gas storage,but the research on this type of gas storage is still insufficient in China.In this paper,a self-built physical simulation model is used to simulate the construction and operation process of aquifer gas storage.The research results are of guiding significance to the reconstruction of aquifer gas storage.On the basis of the related research at home and abroad,this paper independently designed the low pressure visualization model and the high pressure large-scale physical model.The effects of displacement velocity,injection and production cycles,formation dip Angle and other factors on the characteristics and distribution of gas and water flow during the construction and operation of aquifer gas storage were studied qualitatively by using the low-pressure visualization model.Based on the high-pressure large-scale physical model,the influence mechanism of reservoir physical property(permeability),injection and production cycles,formation dip Angle,reservoir construction and operation mode on key indexes such as pressure,reservoir capacity and injection and production capacity during the construction and operation of aquifer gas storage is quantitatively studied,and the following main results are obtained:The main results are as follows:(1)Visualization model experiments show that in the process of reservoir construction,there will be flow phenomena such as tongue entry,finger entry,channeling,flow around,and stranded area.Displacement speed,injection and production cycles,and formation dip Angle will all affect the gas and water distribution.When the displacement velocity gradually increases from 1 m L·min-1 to 2 m L·min-1,the phenomenon of interchannel-flow in the model becomes more obvious.For the same model,with the increase of injection and mining rounds,the location of the retention area in the model is basically unchanged,but the area of the retention area decreases gradually.In the process of formation dip Angle increasing from 15°to 60°,the gas and water distribution in the model is gradually affected by gravity differentiation.(2)In the simulation process of high pressure reservoir construction,with the increase of permeability,the gas migration channels in the model increase,the gas storage space increases,and the reservoir capacity increases accordingly.The reservoir capacity of the model with the permeability of 115×10-3μm2 and 994×10-3μm2 are 65 m L and250 m L,respectively,under the model pressure.Under the influence of gravity differentiation,the pore volume swept by gas in the model increases,leading to the increase of the reservoir capacity of the model.In the process of the same model with the formation dip Angle from 0°to 45°,the reservoir capacity of the model increases by 8.071 L under standard condition.(3)With the increase of injection and production rounds,the saturation of bound water and residual gas increases,the movable area in the two-phase zone decreases,and the seepage resistance of gas and water increases.As a result,the average pressure of each injection and production cycle increases,the working gas volume decreases by 5.655 L,and the average gas injection pressure increases by 2.8 MPa.With the increase of the dip Angle,the effect of gravity differentiation becomes significant,and the sweep range of gas in the model becomes larger,which leads to an upward trend of the working gas volume of the model.Under the condition of 0°and 45°dip Angle,the working gas volume of the fourth round is 10.422 L and 20.669 L,respectively.When 20%formation water is discharged,the pressure in the model is reduced by 0.88 MPa. |