Experimental Study On Gas And Liquid Seepage Laws At Nanometer Porous Media

There is a serious imbalance in the supply and demand of oil and gas resources in China.The national consumption of oil and gas resources far exceeds the actual production of China's oil and gas resources.In 2017,China's crude oil output was192×10⁸t,and the apparent consumption of crude oil was 610×10⁸t.In 2017,China's natural gas consumption was 2373×10⁸m³,a year-on-year increase of 15.3%,resulting in a natural dependence of 39%on natural gas in 2017.Conventional oil and gas resources can no longer meet the domestic demand of China,and the development of unconventional low-permeability oil and gas resources can help alleviate this contradiction to some extent.Shale gas and tight oil and gas are important components of unconventional oil and gas.Studying the seepage law and carrying out scale mining are of great significance to alleviate China's oil and gas demand.China's shale gas technology can recover 31.55×10¹²t of resources,accounting for 17%of the world's total recoverable capacity.The geological resources of tight reservoirs in China are 146.6×10⁸t,the recoverable resources are 14.55×10¹²t;the tight gas geological resources are22.88×10¹²t,and the recoverable resources are 11.26×10¹²t.It accounts for one-third of the country's total natural gas production and shows great potential for resource development.This paper mainly studies the gas and liquid seepage laws in nano-micron porous media,mainly through experimental methods.Firstly,when analyzing the gas seepage in shale reservoirs from the nanometer scale,the existence of formation water shows the starting pressure of shale gas development in actual production,and theoretical analysis of this phenomenon,and a calculation hole is obtained.The method of the number of throats in the throat system;then,the influence of the permeability of the tight sandstone reservoirs on the micro-scale under the influence of the formation stress,the influence of the permeability of the tight sandstone reservoirs on the confining pressure and internal pressure,and the comprehensive analysis of the effective stress coefficient The effect of effective stress on the permeability change of the actual tight sandstone development process is obtained,and the permeability decreases with the increase of the effective stress.Finally,a low-permeability carbonate considering the incomplete development of the crack is analyzed from the micrometer scale.The seepage law of salt rock reservoirs introduces the concept of fracture density,which is regarded as a single medium seepage model with fractures,some incompletely developed fractures and low-permeability carbonate reservoirs without fracture development.The law of seepage flow was studied,and the variation characteristics of water content and the law of decreasing production were analyzed through experiments.In the actual development of micro-nano porous media reservoirs,the phenomenon of starting pressure in gas percolation is due to the presence of small water droplets in the nano-scale pore-throat structure,which brings an additional resistance to the gas percolation process,thus hindering the flow of gas;The pore structure in micro-nano porous media generally has strong stress sensitivity,which will cause certain damage to the actual reservoir,and the existence of crack will cause the yield of micro-nano porous media reservoir to decrease more quickly.