小波边缘分析建模波阻抗反演方法在煤层解释中的应用

Application of Wavelet Marginal Analytical Modeling Wave Impedance Inversion in Coal Seam Interpretation

受限于地震波主波长的1/4,常规地震处理难以分辨较薄煤层。基于模型的波阻抗反演虽然克服了厚、薄煤层计算问题,但因难以得到准确的高频部分,很多情况下反演结果的精度和分辨率往往不能满足地质预测的要求。小波边缘分析建模波阻抗反演方法是从地震数据中提取地震特征参数,用于建模并参与迭代反演。该方法即可以弥补反演过程中高频成分的误差,减少对钻井数据的依赖程度,得到较为合理的初始模型,又可提高反演的精度和分辨率,使反演结果更好的反映实际地下地质情况。利用该方法,对大井—将军庙及新疆红沙泉2个勘探区的侏罗系中统西山窑组含煤地层进行波阻抗反演,反演结果与钻井资料进行比较,其中大井—将军庙0802及0809号孔单煤层厚度误差分别为3%、8%,新疆红沙泉多煤层厚度及煤层之间的夹层厚度预测结果除B6煤层误差较大外,其它误差均小于7%,可见该反演方法的计算结果比较准确。

Thin coal seams are difficult to identify through conventional seismic data processing because of restricted by 1/4 dominant wavelength. Inversion based on model wave impedance although has overcome thick and thin coal seams estimation, while exact high frequency part is hard to get and caused in accuracy and resolution of inversion results frequently dissatisfying geological prediction requirements. The wavelet marginal analytical modeling wave impedance inversion is pickup characteristic parameters from seismic data used in modeling and participated in iterative inversion. The method can make reparation high frequent component errors in inversion and reduce rate of dependency on drilling data and get rather reasonable initial model, as well as to raise accuracy and resolution of inversion make the result reflecting actual underground geological situation even better. By the use of the method have carried out wave impedance inversion of Xishanyao Formation coal-bearing strata in Dajing-Jiangjunmiao and Xinjiang Hongshaquan two exploration areas. Comparing with drilling data, single coal seam thickness errors in Dajing-Jiangjunmiao Nos.0802 and 0809 boreholes are 3% and 8% respectively, errors of predicted results of muhiple coal seam thicknesses and parting thicknesses between them in Xinjiang Hongshaquan are all less than 7% except B6 coal seam, so the results are rather correct.