Improving vibrator structure to eliminate vibration noise

Advances in Structural Engineering

Huang

et al. 2020

The amount of energy transferred to the ground truly represents the performance of the seismic vibrator. So, it is crucial to investigate the transfer of energy in the vibrator-ground system and how parameters affect it. For this purpose, a model of vibrator-ground system considering frequency change is developed based on half-space theory, and methods of calculating energy transfer is innovatively proposed. Results show that the total energy done by the hydraulic force on the vibrator-ground system in the frequency band of 3–200 Hz is 3.156×105 J, and 9.11% of the energy is transferred to the ground. In addition, effects of structural parameters and soil parameters on energy transfer are carried out. It is concluded that lightweight reaction mass can significantly increase the total energy, but heavier reaction mass generates more ground energy. Baseplate with small mass not only helps the vibrator to transmit energy uniformly but also generates more ground energy above 100 Hz. Larger baseplate area can improve the baseplate-ground interaction to transfer more energy to the ground. For the effects of soil on energy transfer, the ground energy in low-frequency band is mainly dominated by soil elastic modulus, and both elastic modulus and density of soil have great effects on energy transferred to ground at high frequencies.

Section: Introductionmentioning

confidence: 99%

Modeling of energy transfer and parameter effects on it of a vibrator-ground system

Advances in Structural Engineering

Huang

et al. 2020

“…Low-frequency content of the output signal is helpful for the inversion of seismic trace data, improving the resolution of seismic data and obtaining structural information of deeper reservoirs, especially the shale gas reservoirs. [2][3][4] Extending the seismic vibrator bandwidth toward low frequency attracts lots of attention.…”

Section: Introductionmentioning

confidence: 99%

Method and application of extending seismic vibrator bandwidth toward low frequency

Advances in Mechanical Engineering

Ding³

et al. 2019

Low-frequency content of the output signal is very helpful in seismic exploration. In this study, method and application are conducted to extend the bandwidth of a seismic vibrator toward low frequency. Factors limiting vibrator’s low-frequency extension are studied, and stroke load capacity and pump-displacement load capacity are proposed and act as vibrator’s low-frequency performance evaluation indexes. Low-frequency performances of five seismic vibrators available in the market are analyzed. Then, multi-objective optimization is used to extend low frequency, and a newly designed seismic vibrator EV56 is developed based on this method. Results show that stroke load capacities of these vibrators are not much different, and all are beyond 5 Hz at 100% level. Moreover, none of the vibrators reaches a frequency lower than 8 Hz at a full pump-displacement load capacity. Through the optimization, the ground force increases by 8.55%, and the standard deviation of the ground force is reduced by 32.99%. Compared to other five vibrators, the EV56 vibrator generates more than twice the output force at 70% drive force level of 3 Hz and improves more than one full-load capacity octave. Field test shows that compared to a conventional seismic vibrator, the EV56 vibrator is more helpful to discover and reflect the underground structure.

“…1 High-quality seismic signals are conducive to improving the vertical resolution of the reservoir and to full-waveform seismic inversion, 2,3 which are very beneficial for improving the deep imaging quality, especially in special areas such as shale gas. 4,5 In order to meet the development of exploration, it is necessary to investigate the dynamic characteristics of the vibrator.…”

Section: Introductionmentioning

confidence: 99%

Modal characteristics and phase response of vibrator under excitation of sweep frequency

Advances in Mechanical Engineering

Huang

et al. 2014

To analyze the dynamic responses of vibrator, a vibrator-ground coupling vibration model considering sweep frequency is proposed based on half-space theory, and modal characteristics and phase response of the structure are investigated. Results show that the sweep frequency has a significant effect on the dynamic responses of the vibrator. The natural frequency of the vibrator changes with sweep frequency, and the resonance may occur at 2.071 Hz and 53.12 Hz. The vibrator has two mode shapes. The first-order mode shape is that the reaction mass and the baseplate move in the same direction and the structure is dominated by the reaction mass. At the second-order resonance, the reaction mass and the baseplate move in opposite directions and the baseplate dominates the system. The phase of the vibrator also changes with the frequency and varies greatly. The phases of reaction mass acceleration, baseplate acceleration and ground force suffer abrupt changes at about 2 Hz and 50 Hz. Especially, the phase of the baseplate acceleration experiences a 180° jumping at about 50 Hz. The abrupt change/jumping frequencies of the phase are basically the same as the natural frequencies, indicating that the resonance has significant effect on the vibrator output.