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Multi-Azimuth, Simultaneous Pre-stack Inversion 3-D Fault Visualization with Fracture Swarms Multi Azimuth PSTM High Resolution Coherence Petrophysical Analysis, Shear-log modeling Porosity Cross-plotting Multi Attribute Visualization

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Simultaneous inversion for Fractures, Shales and Porosity By Bob Parney Ph.D.,

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Inversion We can use Inversion to calculate Elastic Coefficients: Young's Modulus, Poisson's Ratio … In shales we can locate Brittle/Frac-able rock by cross- plotting Young’s Modulus and Poisson’s Ratio. We can go a step further and map Elastic coefficients by azimuth.

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Inversion Reflection amplitude is controlled by Vp, Vs, (density), incident angle Top of Layer 2: Difference between layer 1 and layer 2 Bottom of Layer 2: Difference between layer 2 and layer 3 Offset Inversion does the “accounting” to find Vp, Vs, within reservoir

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Post-stack inversion works by making a connection between impedance contrast, the wavelet, and the final seismic section P-impedanceChanges in P-impWaveletStack

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Pre-stack inversion: Using gathers or angle stacks we invert For multiple offsets instead of just the stack P-wave ImpedanceS-wave Impedance Gather/Angle Stack

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Examples of Simultaneous Inversion: 1.P-impedance/ Sonic Velocity for Lithology 2.Poissons ratio for Porosity and Vshale 3.Youngs Modulus: Identify frac zones 4.Interval Velocity for Pore-pressure 5.Azimuthal Inversion: Natural fractures and frac zones by azimuth. Outputs: (1) P-impedance (velocity*density) (2) S-impedance (3) Density (less reliable) Can be used for:

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Example (1): Standard processing vs. High Frequency (Xfreq) and P-impedance from inversion

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Example (2): Wire Line P-impedance vs. Poisson’s Ratio, Colored by Effective porosity P-impedance Poisson's Ratio

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Wireline: Rockies Cross plot Effective Porosity Log P-impedance Poisson's Ratio

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SEISMIC: Crossplot of P-impedance vs. Poissons ratio same zones as effective porosity on wireline P-impedance Poisson's Ratio

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Inline Close up of Porosity

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Example (3) Shales: Elastic Moduli can be calculated from Inversion results Poissons ratio = F (Vp/Vs) = F (Pimp/Simp) Youngs Modulus E · = 2 · (1+ ) · Simp 2 (1) Either Cross plot E · (density) vs Poisson, or (2) take from the inversion and divide to get E

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Cross-plot of Young's Modulus (E) vs. Poisson's Ratio ( ) to Determine “Brittle” Rock for Induced Fracturing in Shale High E and low = Brittle Rock Young's Modulus Poisson's Ratio

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Inline of E · and Young's Modulus · Poisson's RatioStack

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Cross-plot of Ymodrho to Poir Young's Modulus · Poisson's RatioStack

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Inversion We can use Inversion to calculate Elastic Coefficients: Young's Modulus, Poisson's Ratio … In shales we can locate Brittle/Frac-able rock by cross- plotting Young’s Modulus and Poisson’s Ratio. We can go a step further and map Elastic coefficients by azimuth.

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Example (4) Fractured Reservoir Analysis from Seismic Migrate by sector to reduce uncertainty in source of Anisotropy Simultaneous Inversion by Sector Stack then Coherence by Sector Now have all elastic moduli by azimuth

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P waves and S waves slow down across fractures Neither P or S waves “see” fractures Parallel. P wave (velocity) anisotropy and S wave (AVO) anisotropy can be described as ellipse. Map view of single set of vertical fractures

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Vertical Fractures, or matrix anisotropy Azimuthal changes in velocity and amplitude Dipping reflector Fault displacement, Heterogeneity

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Pre-stack Migration by Azimuth for correct azimuthal amplitudes and velocities Sort Gathers by Azimuth Prior to Migration N

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Fracture Workflow Sector by Azimuth PSTM Coherence (Stack) Pre-stack Inversion (Angle Stack)

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Fit Ellipses To Sectored Inversions (1) Orientation of Maximum P and S Anisotropy (2) Magnitude (Max-Min) of Maximum P and S Anisotropy (3) Magnitude and Orientation of Anisotropy in all other Inversion Products: Poisson's Ratio, Young's Modulus, Lambda Rho, Mu Rho... ++=

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Magnitude of Poisson's Ratio Anisotropy (Max-Min) over Coherence on all azimuth stack. Poisson's Ratio and Coherency

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Magnitude of P-Impedance Anisotropy (Max-Min) over Coherence on all azimuth stack. P-impedance and Coherency

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Magnitude of Shear Anisotropy vs. Full Coherence

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Magnitude of Shear Anisotropy vs. S1 Coherence

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Magnitude of Shear Anisotropy vs. S2 Coherence

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Magnitude of Shear Anisotropy vs. S3 Coherence

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Magnitude of Shear Anisotropy

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Sector 3 Azimuth High Res. Eigen

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Summary of Simultaneous Inversion: 1.P-impedance/ Sonic Velocity for Lithology 2.Poisson's ratio for Porosity and Vshale 3.Young's Modulus: Identify frac zones 4.Interval Velocity for Pore-pressure 5.Azimuthal Inversion: Natural fractures and frac zones by azimuth. Outputs: (1) P-impedance (velocity*density) (2) S-impedance (3) Density (less reliable) Can be used for:

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