摘要:
与叠后反演相比,叠前弹性阻抗对储层或烃类更为敏感,而扩展弹性阻抗反演是一种利用振幅随偏移距变化来分析、识别岩性和含气性的有效方法技术。笔者论述了扩展弹性阻抗反演方法理论和反演关键技术、步骤,并针对鄂尔多斯盆地北部DND气田盒1、山2段典型致密砂岩气藏的含气预测,提出了一套融合技术思路进行横波估测,该方法将公式法、模型法和神经网络法结合,以便在砂岩段使用模型法估算,在泥岩段以公式法为低频约束,同时结合神经网络法来预测泥岩段横波信息,避免了Xu?White模型由于总孔隙度测量不准确造成的泥岩段预测误差。实际应用表明,该方法能够满足致密砂岩薄储层含气预测,准确地预测了含气砂体的展布情况,预测结果与实钻吻合率高达90%。
Abstract:
Compared with the post?stack inversion,the extended elastic impedance is more sensitive to the reservoir and hydrocarbon.In this paper,the authors discussed the theory,key techniques and steps of the extended elastic impedance inversion.Wetake P1x1 and P1s2 in DND gas field of North of Erdos Basin were taken as the study objects.Based on a detailed analysis of logging data,the authors pro?pose fusion method for estimating data of shear wave.This method combines modeling method,formula method and neural network meth?od.It estimates the sandstone section using modeling method,and mudstone with formula method for low frequency model and,in combi?nation with neural network,predicts the mudstone section of shear wave information,thus avoiding the error of mudstone caused by total porosity measurement inaccurate prediction using Xu?White model. Based on cross pictures analysis,the authors deal with sensitive elas?tic parameters for EEI inversion and effective scale for interpretation of lithology and fluid and,according to deterministic extended elas?tic impedance inversion,determine the variation and range and complete the pre?stack stochastic extended elastic impedance inversion, thus meeting the requirements of thin reservoir prediction.At last,the inversion results are interpreted crossly and the distribution of gas sand is predicted accurately,with the drilling data matching rate reaching over 90%.
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