The Research On Prediction Of Coalbed Methane Enrichment Area Based On Double-porosity Model

Coal bed methane(gas)is an im portant clean energy,and it is also an important factor in the safety production of coal m ine.it has an im portant significance to study th e prediction of coal bed m ethane enrichment area.As a geophysical m ethod used widely in oil and gas exploration,coal field geological exploration,the application of seism ic exploration has been paid more and more attention in the prediction of coal bed m ethane.Coal reservoir is typical Double Porosity medium model,and it is composed of the coal and rock solid skeleton and the fluid filled in the pores and fractures.On the basis of Biot theory,researching on Wave Equation of Dual Porosity m edium model,the result shows that there are one fast com pressional waves(P1),two slow compressional waves(p2,p3)and one shear wave(S).P2 is created by the interaction between solid skeleton and the fluid filled in the p ores,and decreases fast in low frequency range.with the frequency increasing,the decrease becomes more and more weak,and P2 can be observed in high frequency.P3 is created by the interaction between solid skeleton and the fluid filled in the fractures,and it decreases heavily in all seismic frequency range so that it cannot be observed.Through esta blishing different porosities and value of coal bed m ethane geological model for forward m odeling of seismic waves,observing seismic wave response characteristics in the fractur e with different porosity,study on seismic wave propagation law.The research shows that Porosities an d value of coal bed m ethane can lead to the decreas e of velocity,time delay and am plitude increasing.Using seismic attribute technology study the seismic attributes related with coal bed m ethane by extracting a mplitude,frequency,phase attributes and spectral decomposition.The research shows that the am plitude of reflect waves keep increasing and m ain frequency decreasing in the hight value of coal bed m ethane.The goals to predict coal bed m ethane can be ach ieved by ex tracting curvature attributes for predicting fractures,which have received well ef fect compared with the known data.Therefore,the prediction way for coal bed m ethane,based on the Double Porosity th eory,is relatively feasibility by extracting the pore-fracture system attributes...