Study On Seepage Flow Mechanism In Low Permeability Gas Reservior

The geologic condition of low permeability gas reservoir is complex,it has strong heterogeneity,low porosity,low permeability and low production.The percolation mechanism and percolation characteristic of low permeability gas reservoir are different from conventional gas reservoir.So far, many problems remain to be researched,it needs theoretical working out and technological exploration continuously,then it can offer fundamental foundation for developing this type of gas reservoir reasonably.The containing water in the rock pore of low permeability gas reservoir can precipitous decline the effective permeability of gas phase and affect the gas well productivity of the reservoir. Therefore, understanding the mobility of the containing water and the characteristic of gas-water seeping could provide the theoretical criteria and technical support for developing reasonably working system.By means of using the experimental method of pressurizing air driven water and nuclear magnetic resonance method,we analysed and developed many contends which include the existence of water in the different permeability rock pore , the mobility of water , the flow condition of gas and water ,and the saturation of irreducible water affecting the gas seepage. The findings indicate that the occurrence situation of water in the rock pore is influenced by pore structure and gas drive pressure.The water in the macropore is exsited by movable water and the water in the fine pore is exsited by irreducible water;When the gas drive pressure is low,the water in the macropore will be first driven out,along with the increase of the gas drive pressure,the water in the fine pore will be then driven out;Establish the great driving pressure or produce pressure can sweep out some of the water in the rock pore .Then we can improve the permeability of the gas bearing reservoir, raise the gas supplying capacity of the gas reservoir.A core sample had different filtration method in the different water saturation.In the article,we used experimental method to know that the fluid in the core was affected by different force at the different water saturation.The core was affected by capillary power and slippage effect during the flow event.In the different stage,the core was ffected by different acting force.By means of experimental study,we can find out that the dominant factors that affect the actuating pressure are core permeability, compaction, water saturation and the length of the core.