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
Fluid factor is essential for identifying pore fluid and determining the spatial distribution of oil and gas reser-voirs.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 Kfs reflection equation considering the effect of squeezing and spraying were verified,and the direct inversion method of fluid factor Kfs elastic impedance was proposed according to the inversion idea of elastic impedance,which improved the stability of fluid factor Kfs prediction and provided a new idea for the identification of pre-stack seismic flu-id.
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