Azimuthally variation of elastic impedances for fracture estimation
| Autor: | Mingshui Song, Yanguang Wang, Xingyao Yin, Chen Zuqing, Jinlei Li, Zhengqian Ma, Zhaoyun Zong, Liu Xiaojing |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Physics
Logarithm Mathematical analysis Inverse transform sampling 02 engineering and technology Density estimation 010502 geochemistry & geophysics Geotechnical Engineering and Engineering Geology 01 natural sciences Standard deviation Physics::Geophysics Azimuth Fuel Technology 020401 chemical engineering Fracture (geology) Reflection (physics) 0204 chemical engineering Nuclear Experiment Fourier series 0105 earth and related environmental sciences |
| Zdroj: | Journal of Petroleum Science and Engineering. 181:106112 |
| ISSN: | 0920-4105 |
| DOI: | 10.1016/j.petrol.2019.05.063 |
| Popis: | Fracture parameters including fracture orientation and fracture density, work as significant information in the fields of the engineering and exploration geophysics. However, it nowadays still remains challenging to concisely and stably estimate those fracture parameters from seismic data due to the limited signal to noise ratio of the azimuthal seismic data. A method based on azimuthally anisotropic elastic impedance (azimuthal AEI) in terms of Fourier series variation with azimuth is proposed to characterize the fracture distribution. Firstly, the azimuthal AEI equation in terms of truncated Fourier series is derived to reduce the number of unknown parameters in the fracture parameters estimation. In addition, KL (Karhunen-Loeve) transformation is used to extract the primary feature of reflection amplitude variation with azimuth and weaken the random noise for azimuthal pre-stack seismic data. And then the azimuthal AEI is estimated from KL transformed azimuthal pre-stack seismic data with the constrained sparse spike inversion method. The fracture orientation without 90° ambiguity can be estimated by an innovative azimuthal AEI equation incorporating the azimuthal AEI equation in terms of Fourier series and the fracture orientation prior information. And the biased estimate for the anisotropic gradient of the azimuthal AEI can be estimated from the second order Fourier coefficient to forecast the fracture density. Besides, we introduce a more convenient way, which is employing the standard deviation of the nature logarithm (SDNL) of the azimuthal AEI in the azimuth domain, than that based on the anisotropic gradient in the fracture density estimation. The synthetic cases demonstrate the rationality and robustness of the innovative primary wave azimuthal AEI equation and the fracture parameters estimation method even with sparse 30° sampling interval in the azimuth. A field data example demonstrates that the proposed method is effective and efficient in the fracture parameters prediction. |
| Databáze: | OpenAIRE |
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