基于自适应时窗的瞬时子波吸收分析技术

Instantaneous wavelet absorption analysis technique based on adaptive time window

地层吸收特性是识别储层含油气性的有效指标之一。考虑到含油气地层具有低频的地震反射特征,将局部频率算法引入到吸收分析技术中,提出了基于自适应时窗的瞬时子波吸收分析技术(AWEA)。算法实现分为3步:①基于正则化反演算法计算目标储层地震记录的局部频率,进一步计算自适应时窗;②对于每个样点,利用复赛谱技术计算时窗内的瞬时子波频谱;③对频谱高频段和低频段进行非线性反演,计算高、低频吸收因子。采用含气砂体模型测试分析了AWEA算法的抗噪性;通过某气藏实际地震资料的应用试验,对比分析了AWEA技术与常规吸收分析技术在强、中、弱振幅型气层预测中的应用效果和实用性。

Absorption is an effective indicator for hydrocarbon reservoir identification. As hydrocarbon reservoir has the low frequency attribute in seismic records, the local frequency algorithm is introduced to absorption analysis technology, and an instantaneous wavelet absorption analysis method based on adaptive time window（AWEA） is proposed. The implementation of AWEA algorithm includes three steps：using regularization inversion algorithm to calculate the local frequency of seismograms in target reservoir, then computing adaptive time window for each sample point, utilizing cepstrum algorithm to calculate instantaneous wavelet time-frequency spectrum getting high and low frequency absorption factors through nonlinear inversion. A gas-bearing sand body model is established to analysis the anti-noise of AWEA method. Meanwhile, through the comparison of AWEA method with the conventional absorption analysis method two application results of real seismic data of a gas reservoir show the adaptability in strong-, medium- and weak-amplitude gas reservoir prediction.