Application of tectonic coal prediction by AVO attributes under tuning effect

AVO attributes of different coal body structure under the influence of tuning effect was analyzed and distribution of tectonic coal in Ordos region was predicted in this paper. The AVO curve for the roof and floor of the 3 models (primary coal, tectonic coal-1 and tectonic coal-2) were firstly analyzed. Because the wide-angle reflection of coal floor happened earlier, the roof of the coal is more suitable for the AVO analysis. AVO attribute analysis for the roof and floor of the three kinds shows that with the increase of the damage degree, the absolute value of intercept and gradient will be higher. Taking 5 m, 7 m, 10 m, 12 m and 15 m coal seam models to forward, it was found that although the AVO attributes were still influenced by coal body structure, tuning effect exists. The AVO attribute change rule was also consistent with the situation without tuning effect, namely tectonic coal has higher intercept and gradient absolute value, so it can be used to predict the distribution of the tectonic coal. Applying the theory to the detection of tectonic coal for seam 8 in the east margin of Ordos region, the prediction results match with the situation revealed by wells. Therefore, according to theory and practice it proved that the detection of tectonic coal by AVO attributes is feasible.