基于常规炮检距地震数据预测黄陵矿区煤层气富集区

常规AVO技术预测煤层气,一般需要炮检距大于1.5倍煤层埋深。通过对黄陵矿区常规地震数据进行AVO异常分析,发现黄陵矿区具备明显煤层气AVO异常,而且在最大偏移距为煤层埋度1.11倍、入折射平均角为29°左右时,该区二号煤层顶板反射界面反射系数对入折射平均角的梯度达到最大值(0.1680)。由此认为叠前地震资料的最大偏移距只要接近、等于或略大于目的层深度,就足以反映振幅随偏移距的变化特征,即足以满足该区煤层气AVO反演对地震资料偏移距的要求。通过对常规地震资料的精细处理,对该区煤层富集区进行预测。黄陵矿区AVO异常解释主要基于垂直反演剖面和顺层反演切片,以此圈出约1.6km2、呈近南北向条带状分布的煤层气(瓦斯)富集区。截至2013年底,在生产巷道掘进过程中,已发现14处瓦斯涌出点与预测结果一致。

Huangling CBM Enrichment Area Prediction through Conventional Offset Seismic Data

Using conventional AVO to predict CBM usually needs the offset larger than 1.5 coal seam buried depth. To use conven- tional seismic data in the Huangling study area carried out AVO anomaly analysis, the area has obvious CBM AVO anomaly, under the maximum offset 1.11 coal seam buried depth, average incident refraction angle about 290, while the gradient of coal No.2 roof reflecting interface reflectance to average incident refraction angle up to the peak value （0.1680）. Therefore, only the maximum offset of prestack seismic data close to, equal to or slightly larger than target depth will be enough to reflect characteristics of amplitude vary with offset, enough to satisfy requirements of CBM AVO inversion on seismic data offset. Through conventional seismic data precise processing, carry out prediction of coal seam enrichment in the area. The AVO anomaly interpretation is mainly based on vertical inversion section and bedding inversion slice, on this account cycled out about 1.6km2 near NS banded CBM （gas） enrichment zone. Up to the end of 2013, during the roadway excavation process found out 14 gas outflow points accord with prediction.