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Duan W.-X.,China University of Petroleum - Beijing | Duan W.-X.,Earth Explorer and Information Technology Laboratory | Qiao W.-X.,China University of Petroleum - Beijing | Qiao W.-X.,Earth Explorer and Information Technology Laboratory | And 3 more authors.
Applied Geophysics | Year: 2014

Ultrasonic cement bond logging is a widely used method for evaluating cementing quality. Conventional ultrasonic cement bond logging uses vertical incidence and cannot accurately evaluate lightweight cement bonding. Oblique incidence is a new technology for evaluating cement quality with improved accuracy for lightweight cements. In this study, we simulated models of acoustic impedance of cement and cementing quality using ultrasonic oblique incidence, and we obtained the relation between cementing quality, acoustic impedance of cement, and the acoustic attenuation coefficient of the A0-mode and S0-mode Lamb waves. Then, we simulated models of different cement thickness and we obtained the relation between cement thickness and the time difference of the arrival between the A0 and A0′ modes. © 2014, Editorial Office of Applied Geophysics and Springer-Verlag Berlin Heidelberg. Source


Cai M.,China University of Petroleum - Beijing | Cai M.,Earth Explorer and Information Technology Laboratory | Qiao W.-X.,China University of Petroleum - Beijing | Qiao W.-X.,Earth Explorer and Information Technology Laboratory | And 8 more authors.
Dianzi Yu Xinxi Xuebao/Journal of Electronics and Information Technology | Year: 2014

Data compression is an effective measure to save the costs of data transmission and storage. A new and effective bit-recombination mark coding method that can be used to lossless data compression is proposed for the integer data sequence which has a small mean squared value. In the new method, the bit-recombination process is firstly applied to the integer data sequence to increase the occurrence probabilities of some data; then, the correct coding format is adaptively selected to encode the data stream according to the occurrence probability distribution characteristics of local data. Integer data sequences that have small mean squared values are applied to test the proposed method with several other lossless compression methods, and the compression effects are compared and analyzed. Test results show that, the integer data sequences can be compressed and decompressed losslessly by the proposed method. Moreover, the compression effect of the proposed method is superior to that of the classical arithmetic coding method, the LZW method, the universal WinRAR software, and the professional audio data compression software FLAC. The experimental results demonstrate the proposed method has a good application prospect. Source


Liu P.,China University of Petroleum - Beijing | Liu P.,Earth Explorer and Information Technology Laboratory | Qiao W.,China University of Petroleum - Beijing | Qiao W.,Earth Explorer and Information Technology Laboratory | And 8 more authors.
Proceedings of the 2013 6th International Congress on Image and Signal Processing, CISP 2013 | Year: 2013

An algorithm of extracting formation permeability from array waveform data is specially designed for multipole array acoustic logging tool (MPAL). Purely transmitted Stoneley waves are obtained after digital filtering and waveform truncation. The corresponding amplitude curves of Stoneley waves are acquired by carrying out a Fast Fourier Transformation (FFT). Weighted spectral semblance method is used to calculate the slowness dispersion curve of Stoneley waves, and attenuation dispersion curves are obtained by using the least square fitting method. Matrix equation based on the boundary conditions at the borehole wall is applied to calculate slowness dispersion curves of Stoneley waves of equivalent elastic formation. At the end, the simplified Biot-Rosenbaum model is used to inverse formation permeability. This method is attached to log evaluation and application desktop (LEAD) of CNPC to process the logging data of oilfields. Processing results demonstrate that this method is able to calculate formation permeability fast and effectively, and the permeability obtained this way has good consistency with that of the nuclear magnetic resonance (NMR) method. © 2013 IEEE. Source

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