Abstract:
Gas content is the essential data for coalbed methane (CBM) areas selection and evaluation as well as development deployment.Accurate prediction of gas content and its distribution is even crucial for new exploration areas of CBM.On the comprehensive analysis of seismic data,logging and test data,seismic attributes highly related with the gas content of coalbed methane are verified and preferred.Seismic wave absorption attenuation attributes,eliminating the influence of buried depth,have significantly positive correlation with gas content.Tectonic (positive) curvature shows negative correlation with gas content.Density attribute has significantly negative correlation with gas content.The correlations of hydrocarbon index (P×G) provided by seismic AVO analysis and pseudo Poissons ratio with the enrichment of coalbed methane are fairly good,which can be used to predict gas content.In the way of the seismic multi-attributes analysis,multiple linear regression equations among seismic attributes,geological parametres and gas contents measured from CBM wells are established for Heshun Block in northern Qinshui Basin.The equation is applied to seismic prestack inversion attributes volume in the area,to the exclusion of CBM wells,and gas content of 15th coalseam in Taiyuan group of this area is quantitatively predicted.