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Results
ABSTRACT Heavy oils are viscous fluid having three phases: fluid, quasi-solid and glass solid depended on temperature. We have measured ultrasonic velocities on 10 heavy oil samples at different phases. Measured data suggest that heavy oil properties are similar to the light oil properties if temperatures are higher than the point. With temperature decreases below the point, heavy oil transfers from liquid phase to a quasi-solid phase with drastic increase of viscosity, S-wave velocity appears measurable and P-wave velocity deviated up from the light oil trend. P- and S-wave velocities of heavy oils show a systematic relation to API gravity, temperature, pressure, GOR, and appear dispersive as heavy oil in the quasi-solid state.
- Geophysics > Seismic Surveying > Seismic Processing (0.75)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.32)
ABSTRACT Bayesian AVO inversion method is the developed prestack inversion technique for inverting seismic elastic parameters (p-wave velocity, s-wave velocity and density). The method is included AVO processing and analysis, well-log editing and calibration, and prestack seismic inversion. This analysis draws rock physics and Bayesian AVO inversion to discuss the fluid discriminator based on Bayesian inversion scheme. The fluid discriminator is calculated by Gassmann's equation. The uncertainty is analyzed in the inversion procedure for elastic parameters and modulus. The rock physics relationship and gain function are also used to calculate the fluid modulus. This method is applied to seismic data from the Gulf of Mexico. The result is inverted at the target horizons for the small 3D cubes around two wells. The fluid discriminator inverted from prestack seismic data is sensitive to the pore fluid content.
- North America > United States (0.36)
- North America > Mexico (0.34)
ABSTRACT In this work, we explore the feasibility of estimating velocity dispersion based on velocity analysis of pre-stack seismic data. We tested the methodology on a set of synthetic CMP gathers with different central frequencies. Pre-stack synthetic seismic data was generated from model that consists of 509 homogeneous and isotropic layers and includes a periodically layered zone. The results show that the velocity variation due to multiple scattering ranges from 4% to 28%. Most of the values are higher than 10%, which is a realistic uncertainty in velocity analysis.
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (1.00)
ABSTRACT Seismic attenuation measurements from surface seismic data using spectral ratios are particularly sensitive to inaccurate spectral estimation. Spectral ratios of Fourier spectral estimates are subject to inaccuracies due to windowing effects, noise, and spectral nulls caused by interfering reflectors. We have found that spectral ratios obtained using continuous wavelet transforms as compared to Fourier ratios are more accurate, less subject to windowing problems, and more robust in the presence of noise.
ABSTRACT Analysis of laboratory measurements of 301 core samples found in the literature for different lithologies, clay content, porosities and pressures was employed to constrain the C constant that accounts for the frame properties of the rock in the AVO inversion method proposed by Batzle et al. (2001). The results showed that C varies for sandstones between 2 and 2.9 and for carbonates between 2.5 and 3.5. If clay content increases C decreases, and if cementation (carbonates) and porosity increases C increases. We applied this method to a small 3D seismic volume corresponding to the King Kong field in Gulf of Mexico in order to estimate the fluid properties of the reservoir (gas sandstones) and the water bearing sandstones. Specifically we used this method to estimate the fluid term, which is composed by density of the rock and the fluid bulk modulus (?K). The results successfully discriminate two pay sands intervals from the background; however absolute values of fluid bulk modulus are not comparable to the results yield by well-log data available of the prospect. Probable causes are tuning effect and calibration of seismic amplitudes with well-log data.
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Exploration, development, structural geology (1.00)
- Reservoir Description and Dynamics > Formation Evaluation & Management > Open hole/cased hole log analysis (1.00)