基于AVO反演技术的煤层含气量预测

为预测煤层气含气量,结合山西寺河煤矿实际资料,在分析不同含气量AVO异常特征的基础上,通过反演得到AVO属性,建立多地震属性与含气量之间的相关关系,从而获得煤层含气量分布。对于含气量不同的钻井,高含气量的煤层一般能形成较强的AVO异常,低含气量的煤层AVO异常很小。基于截距和梯度属性,可获得纵波阻抗、横波阻抗、极化参数、密度和伪泊松比等地震属性。地震属性与煤层含气量之间具有相关性,其中截距、纵波速度、纵波阻抗、横波阻抗、极化参数、密度、伪泊松比等属性与含气量具有较大相关性。研究表明,井孔处煤层含气量预测结果与实测瓦斯含量预测误差低,吻合性好,表明基于AVO反演技术预测煤层含气量是一种可行的方法。

Coal-bed gas content prediction based on AVO inversion

In order to predict gas content，using actual data of Sihe Coal Mine in Shanxi Province，based on the analysis of different gas content AVO anomalies，the authors obtained AVO attributes by inversion，established the relationship between multiple seismic attributes and gas content，and thereby obtain coal seam gas content distribution.Observing the boreholes with different gas content，it show that the coal seams with high gas content generally form a strong AVO anomaly while the AVO anomaly of low gas content coal seams is normally small.Based on the intercept and gradient properties，the seismic attributes can be obtained such as P wave impedance，S wave impedance，polarization parameters，density and pseudo-Poisson’s ratio.There is a correlation between seismic attributes and coal seam gas content with the greater correlation seismic attributesare intercept，P wave velocity，P-wave impedance，S wave impedance，polarization parameters，densityand Poisson’s ratio.The study show that the prediction error between predicted gas content and measured gas content at the coal seam of borehole is low，and the consistent is good，which indicates that the AVO inversion technique based on the prediction of coal-bed gas content is a valid approach.