Method and device for computing porous medium acoustic velocity containing non-Newtonian fluid

Abstract

The embodiment of the invention discloses a method and device for computing porous medium acoustic velocity containing non-Newtonian fluid. The method comprises steps of: establishing a porous medium micro-tube flow model, deriving dissipation energy inside the non-Newtonian fluid, shear stress between fractional order derivative Maxwell fluid and solid, and the average flow velocity of the non-Newtonian fluid according to the flow model, and computing a fluid-solid relative motion energy dissipation factor according to the shear stress and the average flow velocity; establishing a porous medium wave equation containing a non-Newtonian fluid effect on the basis of the fluid-solid relative motion energy dissipation factor; performing plane-wave analysis on the established porous medium wave equation to obtain a dispersion relation containing the non-Newtonian fluid effect and computing longitudinal wave velocity dispersion and attenuation. The method and device for computing porous medium acoustic velocity containing non-Newtonian fluid may relatively accurately predict the dispersion and the attenuation of the acoustic velocity in an unconventional oil and gas reservoir.

Description

technical field [0001] The present application relates to the technical field of seismic rock physics, in particular to a method and device for calculating the acoustic velocity of porous media containing non-Newtonian fluids. Background technique [0002] The geological characteristics of tight oil reservoirs are complex, and hydrocarbon-generating reservoir rocks contain heterogeneous phases such as mineral particles and solid organic matter, with strong heterogeneity and high capillary pressure. This type of rock mainly develops connected micro-nano pore systems, with complex pore structures and poor connectivity, with pore diameters ranging from nanometers to micrometers, low porosity (generally less than 10%), and permeability generally less than 0.1mD. These factors lead to the complex fluid seepage behavior in reservoir pores often not following the constitutive relation of Newtonian fluid, which brings challenges to conventional methods such as seismic wave explorati...

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Problems solved by technology

However, due to the complexity of the molecular structure of oil and gas in the dense pore structure, it is difficult to describe it with the idealized classical non-Newtonian model in textbooks, that is, the constitutive relation The derivative order α of medium strain rate with respect to time may not be a positive integer

[0007] The inventors have found that there are at least the following problems in the prior art: the Viscous Newtonian fluid model is used in the Biot wave equation for porous media, and this assumption cannot satisfy the application of heterogeneous and complex porous media

In addition, the Biot theory introduced into Maxwell's fluid assumes that the pores are filled with an idealized viscoelastic fluid, but the constitutive relationship of the actual fluid is unknown. If this idealized assumption is not satisfied, it cannot be accurately and completely described in tight reservoir rocks. The wave field propagation process

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