灰质浊积岩储层地震叠后波阻抗反演方法的适用性分析

Applicability Analysis of Seismic Post-stack Impedance Inversion Method for Calcareous Turbidite Reservoir

济阳坳陷滑塌浊积砂体多含有灰质泥岩,砂体薄且灰质泥岩砂体的波阻抗差异小,导致储层预测难度大,储层反演技术是刻画各类储层的重要手段之一,储层反演方法日益增多,各种反演技术针对于不同地质目标存在适用性。为此,本文通过典型灰质浊积岩储层地震模型建立和波动方程正演模拟,对合成记录分别采用约束稀疏脉冲反演、波形指示反演方法进行叠后波阻抗反演,并且对不同记录主频、不同记录频带、不同记录信噪比、不同井数约束情形下的波阻抗反演结果进行对比分析,明确浊积岩储层反演技术的适用性;并在此基础上,建立浊积岩储层反演策略。结果表明,提高记录主频、频带宽度以及信噪比,储层反演的精度和分辨率增加;随着经过储层井数增多,储层反演精度逐渐提高。

The slump turbidite sand bodies in Jiyang depression mostly contain calcareous mudstone.It is difficult to predict the reservoir when sand bodies are thin and the impedance difference between mudstone and sandstone is small.Reservoir inversion technology is one of the important means to characterize various types of reservoirs.With the rapid development of reservoir inversion methods,various inversion techniques are applicable to different geological targets.The typical calcareous turbidite reservoir model is established in this research and synthetic records are obtained by wave equation modeling in this paper.Two post-stack impedance inversion methods,constrained sparse spike inversion and seismic meme inversion are used for impedance inversion.The inversion results for seismic records with different dominant frequencies,different frequency bands,different signal-to-noise ratios,and for different number of wells constrained are comparatively analyzed.The applicability of reservoir inversion technology for calcareous turbidite is clarified and the inversion strategy for turbidite reservoir is established.It turns out that the accuracy and resolution of reservoir inversion are improved by increasing the main frequency,frequency bandwidth and signal-to-noise ratio.With the increase of the number of wells,the reservoir inversion accuracy is gradually improved.