Study And Application Of Prediction Model Of Adsorption Capacity Of Coal Under The Influence Of Pressure-temperature-water Content

Natural gas is a kind of clean energy,which plays a very important role in the consumption structure of all countries in the world.With the increasing depletion of conventional natural gas,unconventional natural gas,as a huge potential energy source,has become the focus of everyone's research.Coalbed methane,as a resource rich in unconventional natural gas,develops rapidly and has relatively mature technology,which has become a key research field.The main component of coalbed methane is methane,and the main storage mode is adsorption gas.Therefore,the study of methane adsorption in coalbed methane is of great significance for the study of unconventional gas reservoir resources.However,due to the control of pressure(P),temperature(T)and water content(M)and other variable factors,the quantitative evaluation of CBM adsorption is a challenge.In this paper,through the study of the adsorption model put forward by the predecessors on these three factors,it is found that the models put forward by the predecessors have certain limitations,and can not predict the adsorption capacity of coalbed methane reasonably and accurately.The commonly used Langmuir isotherm model does not consider the influence of temperature and water,so it is not enough to quantitatively evaluate the gas adsorption capacity under different p-t-m conditions.On the basis of Langmuir adsorption model proposed by predecessors.Based on the P-M and P-T models,this paper presents a P-T-M index model,which is suitable for the correlation of temperature,pressure and water content of different coal rank in different areas.In the P-M model,the adsorption capacity and water content show exponential correlation,while in the P-T model,the adsorption capacity and water content show exponential correlation.In the P-T-M model,the adsorption capacity has exponential correlation with temperature and water content.The above three models are verified by the experimental data of different temperature,pressure and water content of different coal rank in different areas.The results show that the above three models can fit the gas adsorption data under different conditions accurately and conveniently.In addition,based on the measured data under some specific P-T-M conditions,the model can be used to estimate the adsorption capacity of methane under other conditions not covered by the experimental data.In a word,P-T-M gas adsorption models provide a benchmark for the evaluation of gas adsorption capacity under different conditions.Through the improved adsorption model,the adsorption capacity of coalbed methane can be predicted more reasonably and accurately,which is of great significance for the prediction of unconventional natural gas resources.