Study On Seepage Law Of Coalbed Methane Under The Synergistic Action Of Microwave And Steam

As a kind of clean energy,the development and utilization of coalbed methane has gradually become the key research direction of energy strategies in various countries.China is rich in coalbed methane reserves,but the reservoir characteristics of low permeability,low pressure and low saturation hinder its industrial exploitation.Thermal mining coalbed methane technology has attracted wide attention as a new coalbed methane mining technology.Steam injection mining technology,as a kind of thermal recovery technology,has been gradually used in actual coalbed methane mining because of its high thermal potential energy,high heat transfer efficiency and good early production effect.However,due to the large energy consumption of steam in the process of transmission and the easy water lock effect in the coal reservoir,the productivity can not achieve the desired effect,so it is an urgent problem to find the optimization scheme of steam injection.In response to the shortcomings of steam injection technology,microwave radiation can complement steam injection technology due to its selective heating,rapid heating,and uniform heating of the medium,filling the gaps in steam thermal recovery technology and increasing its application prospects.In this paper,based on the steam injection technology,the triaxial loading experimental equipment under the synergistic action of microwave and steam developed by the team is used to explore the changes of temperature and permeability of coal samples under the condition of adding microwave radiation before and after steam injection.The experimental results show that during the heating process,the maximum temperature of the coal sample pretreated by microwave radiation within the specified steam injection time is lower than that of the single steam injection coal sample,and the difference increases gradually with the decrease of the effective stress.In the process of natural cooling,the coal samples treated by steam injection show different degrees of constant temperature stage at the initial stage of cooling.For the coal samples pretreated by microwave radiation,the constant temperature stage lasts longer and the constant temperature effect is better.From the point of view of permeability,the permeability of coal samples at the same temperature shows the results of microwave-steam mode < single steam heat injection < steam-steam mode < microwave-steam-microwave mode.With the increase of microwave radiation time,the permeability of coal samples increased greatly under different cooperative modes,among which the permeability of coal samples increased significantly under microwave-steam-microwave mode,Up to 37% more than other collaborative methods.Starting with temperature,effective stress and heat injection time,based on the calculation formula of coal sample permeability under the effect of temperature,the time of steam heat injection as the hub,and the permeability difference under different synergy modes as the consideration factors,the dynamic process of coal and rock permeability under the microwave steam microwave synergy mode is constructed,and the accuracy of the equation is verified with experimental data validation,revealing the mechanism of synergistic thermal mining to increase permeabilityBased on the steam thermal recovery technology,this paper probes into the temperature and permeability changes of coal samples under different cooperative modes when microwave radiation is added to this technology.Considering the effect of constant temperature and permeability growth of coal samples,a reasonable cooperative mode,microwave-steam-microwave synergistic mode,is proposed,and the dynamic model of coal permeability is constructed.Research results are helpful to optimize the existing steam thermal mining technology.The purpose of this paper is to provide theoretical reference and reasonable prediction for actual mining.