Frequency‐ and angle‐dependent poroelastic seismic analysis for highly attenuating reservoirs

Abstract

We extend the frequency‐ and angle‐dependent poroelastic reflectivity to systematically analyse the characteristic of seismic waveforms for highly attenuating reservoir rocks. It is found that the mesoscopic fluid pressure diffusion can significantly affect the root‐mean‐square amplitude, frequency content, and phase signatures of seismic waveforms. We loosely group the seismic amplitude‐versus‐angle and ‐frequency characteristics into three classes under different geological circumstances: (i) for Class‐I amplitude‐versus‐angle and ‐frequency, which corresponds to well‐compacted reservoirs having Class‐I amplitude‐versus‐offset characteristic, the root‐mean‐square amplitude at near offset is boosted at high frequency, whereas seismic energy at far offset is concentrated at low frequency; (ii) for Class‐II amplitude‐versus‐angle and ‐frequency, which corresponds to moderately compacted reservoirs having Class‐II amplitude‐versus‐offset characteristic, the weak seismic amplitude might exhibit a phase‐reversal trend, hence distorting both the seismic waveform and energy distribution; (iii) for Class‐III amplitude‐versus‐angle and ‐frequency, which corresponds to unconsolidated reservoir having Class‐III amplitude‐versus‐offset characteristic, the mesoscopic fluid flow does not exercise an appreciable effect on the seismic waveforms, but there exists a non‐negligible amplitude decay compared with the elastic seismic responses based on the Zoeppritz equation.

Mobility Effect on Poroelastic Seismic Signatures in Partially Saturated Rocks With Applications in Time‐Lapse Monitoring of a Heavy Oil Reservoir

“…Based on the DPDP theory, by incorporating the dynamic poroelastic responses of mesoscopic flow into the classical Biot theory, Zhao et al () derive the angle‐ and frequency‐dependent poroelastic reflection coefficients at the boundary of heterogeneous porous media. Zhao et al () extend the frequency‐ and angle‐dependent poroelastic reflectivity to systematically analyze the characteristic of seismic waveforms for highly attenuating reservoir rocks due to heterogeneity in rock frame. In this paper, seismic reflectivity at the interface of poroelastic media (Zhao et al, ) is employed to establish the physical link between fluid mobility and seismic characteristics.…”

Stress Relaxing Simulation on Digital Rock: Characterize Attenuation Due To Wave‐Induced Fluid Flow and Scattering

“…Understanding the wave dispersion and attenuation signatures is critical for interpreting multi‐scale heterogeneities from geophysical observations in a broad frequency band (Bailly et al., 2019; Sams et al., 1997; Sarout, 2012), ranging from the earthquake seismology (<10 0 Hz), surface seismic (10 0 –10 2 Hz), sonic logs (10 3 –10 4 Hz), to ultrasonic measurements (10 5 –10 6 Hz). Developing the modeling and simulation tools to quantitatively establish the link between the complex heterogeneity features with both the intrinsic and scattering attenuation characteristics are of considerable interest for many Earth‐science‐related applications (Caspari et al., 2011; Zhao et al., 2017a), including geological storage of CO 2 , geothermal energy exploitation, hydrocarbon reservoir characterization, groundwater and contaminant hydrology, etc. The primary objective of this paper is to develop a new digital rock physics (DRP) modeling technique, stress relaxing simulation (SRS), to simultaneously characterize the attenuation due to wave‐induced fluid flow (WIFF) and scattering in a broad frequency band.…”

Frequency‐Dependent P Wave Anisotropy Due to Wave‐Induced Fluid Flow and Elastic Scattering in a Fluid‐Saturated Porous Medium With Aligned Fractures

“…This wave‐induced fluid flow (WIFF) will give rise to seismic dispersion and attenuation and, hence, the frequency‐dependent seismic anisotropy. This effect has been studied by numerous models, which add pores and fractures into nonporous background or treat fractures as perturbations to porous background (e.g., Ba et al, 2017; Brajanovski et al, 2005; Chapman, 2003; Chapman et al, 2002; Fu et al, 2018, 2020; Galvin & Gurevich, 2009; Guo et al, 2018a, 2018b; Gurevich et al, 2009; Hudson et al, 1996; Jakobsen, 2004; Jakobsen et al, 2003; Zhao et al, 2015, 2017). Apart from WIFF, elastic scattering by fractures with size comparable to seismic wavelength is another important source of frequency‐dependent seismic anisotropy.…”