AVO Modeling for Coal Seam Prediction

Amplitude versus offset (AVO) technology is an important tool and a leading skill to predict the fluid in reservoir and to identify the lithology. AVO was mainly used to predict the hydrocarbon reservoir. Its application in coal AVO identification technology is just beginning. The key to AVO technology is how to make a reasonable model for interpretation, and then to analyze the actual prestack seismic data. The conventional AVO forward model is based on two-layer model, and it cannot reflect thin interbed reservoirs or inhomogeneous medium. In order to interpret prestack seismic response of interbed coal seams, we construct AVO models by using the full well log data, which we compute the accurate reflection coefficient with different incidence angle, pick up the AVO Intercept and Gradient (I&G) with different frequency, and map the I &G cross-plot. This paper takes Gaojiabu coal field data as an example to make AVO forward models and AVO I&G cross-plots. Based on AVO cross-plots, we established a coal discriminator to distinguish the coal seam, carbonaceous-mud and argillaceous-carbon. Furthermore, we compared the AVO I&G cross-plot made from well log model and two-layer model.