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Wang H.,China University of Petroleum - East China | Sun Z.,Laboratory for Integration of Geology and Geophysics | Xiao Y.,Tarim Oilfield Company
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

Differential effective medium (DEM) model is a recognized effective media model to predict P- and S-wave velocities of rocks with complex pore shapes. But it simulates very high frequency saturated rock behavior and is only appropriate under ultrasonic laboratory condition, which limits its applicability for reservoir prediction due to the effect of velocity dispersion. To solve the problem, a full-frequency velocity prediction model is proposed by coupling DEM model with a dispersion theoretical model (microstructure model) by establishing the transform relationships between the parameters of the two models. Two sets of experimental measurement data are used to validate the rationality of the full-frequency model. Finally, the model is applied to seismic reservoir prediction. The predicted velocities at ultrasonic-, sonic-, and seismic-frequency bands are respectively used for AVO analysis and prestack inversion. The analysis results show that seismic-frequency band velocities have the best reservoir prediction capability. Consequently, a heuristic thought about the rationality of appying logging velocity to well-to-seismic calibration is presented.


Zhang Y.,China University of Petroleum - East China | Sun Z.,Laboratory for Integration of Geology and Geophysics | Fan C.,Northeast Petroleum University | Bai H.,Laboratory for Integration of Geology and Geophysics
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

Seismic data used for pre-stack inversion should be of high quality, so that true and plentiful information about lithology and property can be extracted for reservoir characterization and prediction. Seismic data of Xingma area, Liaohe Oil field, China is used in the study to emphasis the importance of conditioning processes. Three conditioning processes are applied including multiple removal, random noise attenuation, and gather flattening. As the offset increases, the raw amplitudes of target area change from weak to strong, then to weak. But after data conditioning, the amplitudes change from weak to strong. This kind of AVO is coincident with synthetics. A comparison of wavelets extracted from angle stacks found the amplitude and phase spectra of conditioned data to be much more stabilized in 0-42Hz. Furthermore, the seismic/synthetic inversion residuals of target area show at least 20% drop in amplitude. Finally, the reservoir distribution area predicted by raw data is substantially greater than that of conditioned result.


Wang D.,China University of Petroleum - Beijing | Sun Z.,Laboratory for Integration of Geology and Geophysics | Zhou X.,China National Petroleum Corporation | Wang J.,Laboratory for Integration of Geology and Geophysics | And 2 more authors.
75th European Association of Geoscientists and Engineers Conference and Exhibition 2013 Incorporating SPE EUROPEC 2013: Changing Frontiers | Year: 2013

For fractured reservoirs, the routinely used imaging methods are usually isotropic or azimuth-sectored migration, which will result in distorted migration events and amplitude because they fail to handle azimuthal anisotropy problem. In order to obtain focused subsurface imaging and accurate azimuthal AVO, full-azimuth anisotropic imaging which incorporates azimuthal anisotropy into migration algorithm is a better choice. Even so, most azimuthal anisotropic imaging only concerns source-receiver azimuth and offset on the surface, which may not properly represent the wavefield propagating in complex structures area. In this case, anisotropic imaging in subsurface scattering-azimuth and incident-angle domain is more superior. In this paper, firstly full-azimuth isotropic imaging is conducted to analyze azimuthal velocity variation and calculate anisotropic parameters. Then they are used to perform full-azimuth anisotropic imaging. Through the application to data of fractured physical model, it proves that, compared with isotropic and azimuth-sectored migration, full-azimuth anisotropic imaging generates higher-quality CRP gathers, which results in accurate fracture inversion. What's more, compared with anisotropic imaging in source-receiver azimuth and offset domain, anisotropic imaging in subsurface scattering-azimuth and incident-angle domain is more suitable for amplitude-preserved CRP gathering in complex structures area. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.


Wu S.,Laboratory for Integration of Geology and Geophysics | Sun Z.,Laboratory for Integration of Geology and Geophysics | Wang Z.,China National Petroleum Corporation
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

The resolution of the seismic signal can be remarkably enhanced by nonstationary deconvolution because it considers the attenuation of the source signature travelling in the strata. But traditional nonstationary deconvolution extracts wavelet by smoothing the Gabor spectrum dependant of supposing the reflectivity is white. In practice, the reflectivity is nonwhite. This paper deduced the relationship of the wavelet and reflectivity series with the seismic signal in the logarithmic time-frequency spectrum whether reflectivity is white or not. And this relationship is used to obtain the wavelet from the seismic signal in the logarithmic time-frequency spectrum in the nonstationary deconvolution. After testing on the model data and practical data, the method has been proved that it can obtain the wavelet from seismic signal better than the traditional nonstationary deconvolution. Then the new method is applied to the 3-dimension seismic data and obtained more information about the reservoir predictions.


Sun S.Z.,Laboratory for Integration of Geology and Geophysics | Xiao X.,Laboratory for Integration of Geology and Geophysics | Wang Z.,China National Petroleum Corporation
73rd European Association of Geoscientists and Engineers Conference and Exhibition 2011: Unconventional Resources and the Role of Technology. Incorporating SPE EUROPEC 2011 | Year: 2011

Fracture is both the storage space and migration channel of hydrocarbon fluids. The detection of fracture is of great importance to reservoir prediction. Performing the inversion calculation based on anisotropy of fractured media could predict the fracture characteristics effectively. Conventional method of P-wave fracture inversion requires wide azimuth data to overcome the negative effect by noise. However, massive amount of existing data with limited azimuth and the expense of wide azimuth acquisition might restrict application of P-wave pre-stack fracture detection technique. In this paper, we propose an algorithm with noise suppression to accomplish prestack azimuthal AVO inversion using data with limited azimuthal distribution. The results turn out to be reliable. Additionally, based on the method, the effect of acquisition layout and data quality (S/N) is tested. Tests indicate that with the same fold, the higher the signal to noise ratio the better the inversion result. With the same signal to noise ratio, the larger the offset angle from the survey line to natural fracture direction the better the fracture parameter inverted.

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