叠前AVO反演在储层含油气性预测中的应用

Oil-bearing reservoir prediction with prestack AVO inversion

与叠后波阻抗反演相比,叠前AVO三参数反演能得到更多的参数,例如纵横波阻抗、纵横波速度等,进而为储层预测提供更可靠的支撑。本文阐述了基于纵波反射系数的Fatti近似公式进行叠前AVO反演的原理,给出了利用叠前AVO反演进行储层含油气性预测的基本思路和关键技术,包括敏感属性分析、角度子波提取、初始模型建立等。松南盆地实例表明,叠前AVO反演比叠后反演能获得更丰富的信息,有利于储层含油气性预测。

Prestack AVO three-term inversion can provide more information than poststack acoustic impedance inversion, such as P-wave and S-wave impedance, and P-wave and S-wave velocity. So it becomes a powerful tool for reservoir prediction. But in practice, some more sophisticated works need to be done for successful prestack AVO three-term inversion. In this paper, we use prestack AVO three-term inversion based on Fatti formula to predict oil-bearing reservation. A comprehensive strategy and some key steps are revealed, including sensitive attributes analysis, angle-depended wavelet extraction, initial model building, and so on. The inversion results are then combined with petrophysical crossplots obtained from well logs to derive more relevant reservoir properties like porosity, Poisson's ratio, water saturation, and sand percentage, which in turn are calibrated with available logs to validate the confidence in the prediction. Our experience and applications show that the proposed idea and strategy provide good help for successful reservoir prediction with the AVO three-term inversion. © 2016, Editorial Department OIL GEOPHYSICAL PROSPECTING. All right reserved.