考虑挤喷效应的流体因子弹性阻抗直接反演方法及应用——以渤海湾某裂缝发育储层为例

The method and application of elastic impedance inversion for fluid factor with the consideration of squirt flow—taking a fractured reservoir in Bohai Bay as an example

流体因子是识别孔隙流体和确定油气藏空间展布的重要依据。随着地球物理勘探向复杂化、精细化方向发展,储层解释面临的挑战也急剧增大。微观孔隙介质理论指出,地下岩石中发育大量力学性质不均一的孔隙和裂缝,当地震波传播时,赋存在较软的裂缝中的流体受挤压作用会喷射到相邻的硬孔隙中,产生挤喷现象,对流体流动和岩石受力产生一定的影响。常规Russell流体因子建立Biot理论的基础上,对孔隙流体流动的表征不够充分,可能带来一定的油气解释误差。因此,近年来发展出一种考虑挤喷效应的流体因子,提高了薄层流体识别的可靠性。本研究验证了考虑挤喷效应的K_(fs)流体因子反射方程的AVO特性,并根据弹性阻抗反演思路,提出了K_(fs)流体因子弹性阻抗直接反演方法,提高了K_(fs)流体因子预测的稳定性,为叠前地震流体识别提供了新思路。

Fluid factor is essential for identifying pore fluid and determining the spatial distribution of oil and gas reservoirs.With the development of geophysical exploration in the direction of complexity and refinement,the challenge of reservoir interpretation is increasing rapidly.The microporous medium theory points out that a large number of pores and fractures with uneven mechanical properties are developed in underground rocks.When seismic waves propagate,the fluid in soft fractures will be squeezed into adjacent hard pores,resulting in the extrusion and spray phenomenon,which influences fluid flow and rock force.Based on Biot's theory established by the Russell fluid factor,the characterization of pore fluid flow is insufficient,which may lead to specific hydrocarbon interpretation errors.Therefore,in recent years,a fluid factor has been developed to take into account the extrusion effect,which improves the reliability of thin-layer fluid identification.In this study,the AVO characteristics of the fluid factor K fs reflection equation considering the effect of squeezing and spraying were verified,and the direct inversion method of fluid factor K fs elastic impedance was proposed according to the inversion idea of elastic impedance,which improved the stability of fluid factor K fs prediction and provided a new idea for the identification of pre-stack seismic fluid.