Fracture-direction estimation by QVOA analysis: Validation by physical modeling

We study anisotropy of P-wave attenuation that is Q-anisotropy, and develop an approach named QVOA (seismic quality factor Q versus offset and azimuth) to estimate the fracture-strike direction identified by the azimuth φ0. We derive QVOA formula Q-1 (θ, φ) for the P-wave attenuation Q-1 as a function of the polar angle and azimuth φ, and test Q-1(θ,φ) using physical modeling data. Our testing consists of fitting a function Q-1 (θ, φ) to the data from the physical modeling, using the method of least squares. The QVOA-formula gives the most accurate estimation of the direction φ0 of the HTI-symmetry axis in comparison with other approximation formula. The values of velocity and attenuation are, in some sense, reciprocals of each other: the attenuation is greatest in the direction of the HTI-symmetry axis φ0=0°, where the velocity is least, and vice versa at the orthogonal direction φ=90°, which is the fracture-strike direction. That is, the azimuth of the minimal attenuation φ=90° coincides with the direction of the fracture strike (φ=90°), where the velocity is maximal. Presentation Date: Tuesday, September 17, 2019 Session Start Time: 8:30 AM Presentation Time: 9:20 AM Location: 217D Presentation Type: Oral