Joint inversion in the application of coal seam roof and floor lithologic prediction

In order to improve the accuracy of lithologic prediction for coal seam roof and floor, impedance inversion was firstly conducted to distinguish the coal and limestone because coal has a characteristic of abnormally low value for impedance and limestone has an abnormally high value.For the rest of mixed sand mudstone lithologic body, due to the natural gamma curve is extremely sensitive to sandstone and mudstone, natural gamma pseudo acoustic inversion method was used to obtain the natural gamma data volume so the sand and shale can be identified easily, therefore the accurate forecast of lithologic prediction for coal seam roof and floor is realized.As a result, by combining the methods of impedance inversion and pseudo acoustic inversion, the lithology prediction of coal roof and floor can be effectively predicted.