Symmetry orientation can be extracted from azimuthal AVO by remembering that fracture-direction mapping as well as horizontalearth-stress mapping are the objectives of azimuthal AVO analysis. f attenuation arises from intercrack flows, i.e., between parallel fractures that are aligned flow conduits, then attenuation anisotropy may be related to the anisotropy of horizontal permeability Lynn, n the seismic frequency range, attenuation anisotropy has been observed and modeled in walkaround vertical seismic profilings Horne and MacBeth, 997 Maultzsch et al., 2003a and surface seismic reflection data Garrota, 989 Lynn and Beckham, 998 Clark et al., 200. Studies by Crampin 98, Hudson 98, Thomsen 995, and Chapman 2003 show that the more attenuated azimuth is perpendicular to the aligned cracks.
Since we analyze variations of Q-factor versus offset and azimuth, we call this method QVOA analysis Chichinina et al., 2005 by analogy with azimuthal AVO. Here, we study azimuthally varying attenuation and its potential application to fracture characterization. Seismic properties such as azimuthally varying NMO velocity or amplitude variation with angle offset AVOA gradient can be used to determine fracture orientation and other parameters. Specifically, we assume Hudson s first-order effective-medium model Hudson, 98 Hudson et al., 996. The simplest model of such a medium is a dissipative transversely isotropic medium with a horizontal symmetry axis HT. f these rocks are saturated with a fluid e.g., oil, brine, or gas, then fluid flow between or within fractures aligned cracks and also from fractures to pores in the host rock may lead to azimuthally varying attenuation. NTRODUCTON A preferential orientation of fracture networks makes fractured rocks azimuthally anisotropic. To illustrate the QVOA method in synthetic data, we use Hudson s first-order effective-medium model of a dissipative fractured reservoir with fluid flow between aligned cracks and random pores as a possible mechanism for P-wave attenuation. This result is independent of the attenuation mechanism.
This complicates the QVO gradient inversion for the fracture parameters. The attenuation anisotropy magnitude strongly depends on the host rock s V S /V P parameter, whereas the dependence on fracture parameters is weak. The attenuation parameter Q and Thomsen-style anisotropy parameter V are found to be interdependent. We relate the Q-anisotropy parameter Q to fractured-medium parameters and invert the QVO gradient to estimate Q. QVO gradient inversion not only indicates fracture orientation but also characterizes Q-anisotropy. We introduce two new seismic attributes: Q versus offset QVO gradient and intercept. The technique for QVOA analysis is similar to azimuthal AVO analysis. The QVOA formula is similar to Rüger s approximation for PP-wave reflection coefficients, the theoretical basis for amplitude variation with angle offset AVOA analysis. 0.90/ QVOA analysis: P-wave attenuation anisotropy for fracture characterization Tatiana Chichinina, Vladimir Sabinin, and Gerardo Ronquillo-Jarillo ABSTRACT This paper investigates Q-anisotropy for characterizing fractured reservoirs specifically, the variation of the seismic quality factor Q versus offset and azimuth QVOA.We derive an analytical expression for P-wave attenuation in a transversely isotropic medium with horizontal symmetry axis HT and provide a method QVOA for estimating fracture direction from azimuthally varying Q in PP-wave reflection data. Get more details about paying for Colorado School of Mines.1 GEOPHYSCS, VOL. This is significantly lower than the national default rate of 10.1%, which is a good sign that you'll be able to pay back your student loans. The student loan default rate at Mines is 1.7%. That adds up to $36,660 over four years for those students. At Mines, approximately 42% of students took out student loans averaging $9,165 a year. For more information on the sticker price of Mines, see our tuition and fees and room and board pages.Īlmost 66% of college students who graduated with the class of 2018 took out student loans, but that percentage varies from school to school. The net price is calculated by adding tuition, room, board and other costs and subtracting financial aid.Note that the net price is typically less than the published for a school. See the table below for the net price for different income groups.
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