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| SA demodulation system based on nonuniform sampling for LWD electromagnetic resistivity logging tool |
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JIANG Ming1, KE Shizhen1, LÜ Shiyao2, LI Chengyuan1, ZHANG Wenhao1
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(1.State Key Laboratory of Petroleum Resources and Prospecting in China University of Petroleum, Beijing 102249, China;2.Xinjiang Oilfield Company Limited, CNPC, Karamay 834000, China)
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| Abstract: |
| Conventional demodulation systems of LWD electromagnetic resistivity logging use widely uniform sampling, and the measurements are usually processed using digital correlation or the digital phase sensitivity detector(DPSD) method. Consequently, the detection results are affected by the quantization error and the spectrum leakage in the sampling process. In this paper, an simulated annealing(SA) demodulation method based on nonuniform sampling is presented and a rapid detection circuit is designed. The detection results of the proposed method are compared with that of the DPSD methods with uniform sampling, and demonstrate that the former method has a strong frequency-selecting capacity, and the correlation with the quantization errors and the measurement errors brought by the spectrum leakage can both be suppressed effectively. This method is more suitable for demodulation systems of the LWD measurements in extreme environment. |
| Key words: nonuniform sampling simulated annealing(SA) quantization errors spectrum leakage LWD electromagnetic resistivity logging tool well logging demodulation |
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