Laboratory for Integration of Geology and Geophysics

United States

Laboratory for Integration of Geology and Geophysics

United States
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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 Co.
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.


Wang K.,Laboratory for Integration of Geology and Geophysics | Sun S.Z.,Laboratory for Integration of Geology and Geophysics | Dong N.,Sinopec
75th European Association of Geoscientists and Engineers Conference and Exhibition 2013 Incorporating SPE EUROPEC 2013: Changing Frontiers | Year: 2013

Economic shale gas production requires hydraulic fracture stimulation and the fracturing effects largely depend on the geo-mechanical brittleness of formation. For this reason, predicting fracture-prone sweet spots is essential for optimizing the development program. The geo-mechanical property of shale can be evaluated by elastic parameters that obtained from three-term AVO inversion. Since pre-stack AVO inversion is an ill-posed problem, the Bayesian framework is employed for its regularization in this paper. Based on normal Bayesian inversion, an edge preserving constraint is introduced on the perturbations of elastic parameters in both vertical and horizontal directions, which could improve the inversion result near geological boundaries and depict the heterogeneity of shale better. The sound anti-noise ability and robustness are fully proved in synthetic data while edge preserving effect is also demonstrated with a 2D model. In practice, this method is also applied on a shale gas play in Sichuan Basin of China and the inverted results show good agreements with well logs. Finally, the brittle sweet spots are discriminated on the basis of elastic property analysis from wells, and an evaluation criterion of gas shale using seismic inverted elastic parameters is established resultantly. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.


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.


Sun X.,Laboratory for Integration of Geology and Geophysics | Sun S.Z.,Laboratory for Integration of Geology and Geophysics | Zhou X.,China National Petroleum Corporation | Meng W.,China National Petroleum Corporation
75th European Association of Geoscientists and Engineers Conference and Exhibition 2013 Incorporating SPE EUROPEC 2013: Changing Frontiers | Year: 2013

The choice of t-f smoothing method is viewed as a significant procedure of Gabor deconvolution. Inspired by homomorphic deconvolution, this paper extends Gabor deconvolution into the log spectra, wherein the explicit linear form of nonstationary convolution model brings great facilities for studying its reverse process. More pertinently, we propose a hyperbolic smoothing method there, in which the linear analysis is iteratively employed to approach the factorization task. Since divisions are transformed to subtractions in log spectra, the usage of the pre-whitening factors in the iteration is avoided, thus reducing human intervention and boosting calculation accuracy. Moreover, a simple piecewise linearization is also introduced to enhance this technique's practical value. And our experiences on reef reservoir and carbonate reservoir show that nonstationary deconvolution based on this new hyperbolic smoothing can acquire higher resolution than ordinary hyperbolic smoothing, thus providing more detailed information and revealing more subtle geological phenomena, which enable better reservoir characterizations and definitions. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.


Sun X.,Laboratory for Integration of Geology and Geophysics | Sun S.Z.,Laboratory for Integration of Geology and Geophysics | Tian J.,China National Petroleum Corporation | Han J.,China National Petroleum Corporation
75th European Association of Geoscientists and Engineers Conference and Exhibition 2013 Incorporating SPE EUROPEC 2013: Changing Frontiers | Year: 2013

In spite of the advantages in handling nonlinear problems, the computation efficiency of KPCA is admittedly slow for large training dataset, which is severely impeding its practical applications. Therefore, this paper attempts to boost the calculation efficiency by introducing a sparse kernel skill, which could greatly streamline the training dataset while effectively preserving its representative information. With this method, the calculation efficiency for seismic denoising is raised nearly by 7 times than the traditional KPCA, while a much higher fitting rate (98.81%) on fluid identification is also achieved as well, even with much fewer training nodes. At present, results with this method is sufficiently rewarding and encouraging enough to motivate further study. Probably, this method would bring profound changes on KPCA's theory and applications in geophysical exploration world. Copyright © (2012) by the European Association of Geoscientists & Engineers All rights reserved.


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.


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.


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 W.,Laboratory for Integration of Geology and Geophysics | Sun Z.,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

This paper introduces the method of generating angle-domain common-image gathers (ADCIGs) by VSP RTM. We modify the equations used to backward propagate receiver wavefield, and then compare the relative amplitude preservation of the ADCIGs. Using a simple model with four horizontal layers, the ADCIGs generated by different types of VSP wavefields (including up-going waves, down-going waves, and direct waves et al.) and the corresponding noise on the angle gathers is analyzed. Finally, this method is also applied to a real VSP data, and the results show that this method is accurate and feasible. The angle gather has a wide range of application, which can offer potential for VSP migration velocity analysis, AVA/AVO analysis and elastic inversion.


Sun S.Z.,Laboratory for Integration of Geology and Geophysics | Li C.J.,Laboratory for Integration of Geology and Geophysics | Wang Z.M.,China National Petroleum Corporation | Zhang L.J.,China National Petroleum Corporation | And 4 more authors.
76th European Association of Geoscientists and Engineers Conference and Exhibition 2014: Experience the Energy - Incorporating SPE EUROPEC 2014 | Year: 2014

Large amount of fractured carbonate reservoirs are developed in Ha7 area, Tarim Basin. At present, azimuth-sectored migration is routinely used to analyze velocity and output azimuthal CRP gathers. But it cannot resolve reliable azimuthal anisotropy in both velocity and amplitude. Different from this conventional method, we employ an amplitude-preserved full-azimuth anisotropic migration algorithm in this paper for better fracture characterization. Based on iterative NMOz analysis, anisotropic parameters required by anisotropic migration are finally established. More importantly, both a kinematic and a dynamic fracture prediction result are obtained and integrated for comprehensive fracture interpretation, in which the former is derived during the NMOz process while the later is obtained by performing AVAz inversion over the amplitude-preserved azimuthal CRP gathers from full-azimuth anisotropic migration. Resultantly, fracture detection results with our method well agree with the FMI data, and the predicted strike reaches 86% compared with 57% from conventional method. All of these results suggest a more accurate and reliable fracture detection method in comparison with traditional method based on azimuth-sectored migration.

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