Application Of Seismic Prediction Of Shale Gas Reservoir

Shale gas is located in the dark muddy-shale,high carbonaceous muddy-shale,and interlayer siltstone,silty mudstone,muddy siltstone,and even fine sandstone,it is a kind of gas which is mainly adsorbed and free,it is the result of the nearby accumulation of natural gas generation in the source rock formation.Methane is the main component of shale gas,it is a clean and efficient energy resource.It is very difficult for increase production conditions of oil and gas in China,exploration and development of shale gas resource is particularly important,therefore,it is of great significance to study the prediction of shale gas reservoir.Firstly,this paper introduce the principle of seismic exploration of shale gas reservoir and the methods used in this study;secondly,the seismic geologic model of saturated gas with different porosity is established,on the premise of determining the density and the propagation velocity of seismic wave,the elastic wave equation is used to simulate seismic wave propagation,the wave field snapshot and time section are shown that the reflected wave have obvious time delay and the time delay gradient decrease gradually with the increase of porosity,the section of instantaneous amplitude is shown that the amplitude of the reflected wave of the top of the shale gas formation is weakened and the bottom of the shale gas formation is enhanced with the increase of porosity;the instantaneous attribute information of the seismic horizon of the shale gas formation in the time section are extracted and analyzed by using the seismic attribute technique to study and optimize the sensitive attribute information of shale gas reservoir,characteristics of shale gas reservoir is the low frequency energy enhancement region of instantaneous amplitude increase and instantaneous frequency decrease;the principles of four spectral decomposition algorithms are analyzed and studied,the frequency-division section and frequency gather are obtained by spectral decomposition of the seismic horizon of the shale gas formation in the time section,it is found that,by S transform,the resolution of the frequency-division section is the highest and the frequency gather has the strongest ability to identify the high frequency,the range of shale gas reservoir is confirmed based on frequency-division section and frequency gather of S transform.Therefore,it is feasible to predict of shale gas reservoir by using seismic attributes.