An all-metal 3-component optical fiber seismometer was proposed and experimentally demonstrated. The theoretical analysis was given based on the electro-mechanical theory. Calibration results showed that the axis sens...An all-metal 3-component optical fiber seismometer was proposed and experimentally demonstrated. The theoretical analysis was given based on the electro-mechanical theory. Calibration results showed that the axis sensitivity was about 41 dB （re： 0dB=1rad/g） with a fluctuation ＋2dB in the frequency bandwidth of 5 Hz - 400 Hz. A transverse sensitivity of about -40 dB was achieved. The fluctuation of the acceleration sensitivity for the three accelerometers in the seismometer was within ±2.5 dB. The minimum phase demodulation detection accuracy of the phase-generated cartier （PGC） was 10-Srad/√Hz, and the minimum detectable acceleration was calculated to be 90 ng/√Hz.展开更多
A 2.5-dimensional method in frequency wave-number domain is developed to investigate the mode waves in a deviated borehole penetrating a transversely isotropic formation. The phase velocity dispersion characteristics ...A 2.5-dimensional method in frequency wave-number domain is developed to investigate the mode waves in a deviated borehole penetrating a transversely isotropic formation. The phase velocity dispersion characteristics of the fast and slow flexural mode waves excited by a dipole source are computed accurately at various deviation angles for both hard and soft formations. The sensitivities of the flexural mode waves to all elastic constants in a transversely isotropic formation are calculated. Numerical results show that, for a soft formation, the fast flexural mode wave is dominated by c66 at high deviation angles and low frequencies, while the slow flexural mode wave is dominated by c44 at the same conditions. Waveforms in time domain are also presented to support the conclusions.展开更多
文摘An all-metal 3-component optical fiber seismometer was proposed and experimentally demonstrated. The theoretical analysis was given based on the electro-mechanical theory. Calibration results showed that the axis sensitivity was about 41 dB （re： 0dB=1rad/g） with a fluctuation ＋2dB in the frequency bandwidth of 5 Hz - 400 Hz. A transverse sensitivity of about -40 dB was achieved. The fluctuation of the acceleration sensitivity for the three accelerometers in the seismometer was within ±2.5 dB. The minimum phase demodulation detection accuracy of the phase-generated cartier （PGC） was 10-Srad/√Hz, and the minimum detectable acceleration was calculated to be 90 ng/√Hz.
基金supported by the National Natural Science Foundation of China(Grant No.11134011)the National R&D Projects for Key Scientific Instruments(Grant No.ZDYZ2012-1-07)the"12th Five-Year Plan"Period for Informatization Project in Supercomputing Key Demonstration,Chinese Academy of Sciences(Grant No.XXH12503-02-02-2(07))
文摘A 2.5-dimensional method in frequency wave-number domain is developed to investigate the mode waves in a deviated borehole penetrating a transversely isotropic formation. The phase velocity dispersion characteristics of the fast and slow flexural mode waves excited by a dipole source are computed accurately at various deviation angles for both hard and soft formations. The sensitivities of the flexural mode waves to all elastic constants in a transversely isotropic formation are calculated. Numerical results show that, for a soft formation, the fast flexural mode wave is dominated by c66 at high deviation angles and low frequencies, while the slow flexural mode wave is dominated by c44 at the same conditions. Waveforms in time domain are also presented to support the conclusions.
