Study On Seepage Laws Of Gas And Liquid Of Multiple Rounds Injection-production In Gas Storage Of Aquifer

Aquifer gas storage is one of the important forms of underground gas storage,in the operation of gas storage,multiple rounds of gas-water mutual flooding will occur,so it is very important to study the gas-liquid seepage law under multiple rounds of injection and production.In this text,a combination of physical simulation and numerical simulation was used to carry out microphysical simulation of multiple rounds of injection and production,test of gas-water mutual flooding phase permeability curve at atmospheric pressure and numerical simulation of multiple rounds of injection and production,so as to provide theoretical guidance for the construction and operation of aquifer gas storage.The main contents are as follows:（1）Five rock cores with different permeability are selected to conduct online visualization research on four rounds of gas/water interflooding by NMR,to clarify the pore distribution characteristics of cores with different typical physical properties,as well as the seepage law and distribution variation characteristics of gas and water with the increase of interflooding cycles.（2）Five rock cores with different typical characteristics were tested for gas-water interflooding phase permeability curves in four rounds,comparison and analysis different physical parameters of cores under different displacement rounds and characteristics of the seepage rule changes,To determine the the influence of displacement rounds,displacement pressure and permeability to irreducible water saturation,residual gas saturation isotonic point,gas and water relative permeability and pore space utilization.（3）Using the gas-water permeability curve by phase permeability curve test experiment,use numerical simulation to establish plane and vertical conceptual models of heterogeneous aquifer gas storage,conduct four rounds of injection-production simulation,on the gas storage scale,simulation calculation the influence of flow characteristic difference,physical distribution difference and operating parameter difference to capacity,pressure,production ability,two-phase region range and the interface about gas-water,analysis the influence regular about important parameters to gas storage,to provide theoretical guidance of construction and operation for aquifer gas storage.The results show that:（1）Through NMR visualization study,it is found that the singal peak more higher of T₂ spectral curve and the relaxation time more lager,the core permeability and pore radius and connectivity more larger,the gas water distribution more homogeneous.（2）In the test of gas-water interflooding permeability curve,with the increase of interflooding wheels,the relative permeability curve of gas phase moved down,the relative permeability curve of water phase moved up,and the isosmotic point moved to the lower left;At the end of four interflooding cycles,the irreducible water saturation and residual gas saturation increase by about 10%and 20%,the two-phase seepage zone decreases,and the pore space availability decreases.With the increase of the permeability,displacement pressure,the aquifer gas storage injection-production capacity and effective capacity increased,and the permeability is bigger,the influence of permeability of core about 953.87×10^-3μm²,four rounds of gas water flooding after,two phase seepage area are 40.09%,and the storage space is still as high as 84.6%.（3）Research on the dynamic mechanism model of multi-round injection and production shows that the formation pressure and reservoir capacity of the differentiated model are higher than those of the undifferentiated model,and the production capacity of the differentiated model is lower than that of the undifferentiated model.Under the same rotation and displacement process,the range of two-phase zones of the differentiated model is smaller than that of the undifferentiated model.The smaller the difference of physical property distribution is,the more uniform the gas-water distribution is,and the stronger the capacity and production capacity are.Appropriately increasing the gas injection rate,gas recovery rate and shortening the shut-in time can accelerate the gas-water interface migration speed,slow down the trend of formation pressure rise,and increase the production capacity and emergency peak regulation capacity of the gas storage.