Method determining controllable vibration source best low-frequency scanning signal

Abstract

The invention discloses a method determining a controllable vibration source best low-frequency scanning signal. Equal-frequency scanning signals are adopted, vibration source output force is increased gradually to carry out excitation, the least square method is used for carrying out matching on measured vibration source low-frequency sampling point actual output maximum output force, a controllable vibration source low-frequency output curve is determined according to a fitting heavy punch maximum displacement curve and the focus of a system flow curve, a low-frequency section scanning time length is calculated, the frequency, amplitude and phase of each sampling point of the low-frequency section are calculated, a scanning signal is generated to carry out practical testing on the vibration source, and the best low-frequency scanning signal is obtained until a vibration result does not exceed heavy hammer displacement limitation or the flow limitation. According to the method determining the controllable vibration source best low-frequency scanning signal, the low-frequency components of the controllable vibration source scanning signal are significantly enhanced, the method determining the controllable vibration source best low-frequency scanning signal is suitable for an existing controllable vibration source, can exert the maximum potential of the low frequency of the controllable vibration source, the low frequency signal is small in signal distortion, the output frequency spectrum of the controllable vibration source is smooth and white-noised, and the controllable vibration source can be protected well.

Description

technical field [0001] The invention belongs to the scanning signal design technology of a land vibrator in seismic exploration, and is a method for determining the best low-frequency scanning signal of a vibrator. Background technique [0002] In the oil and gas industry, geophysical exploration techniques are commonly used to find and evaluate underground oil and gas reserves. Earthquakes are artificially excited to generate a seismic wave that travels underground. Usually, at least part of the seismic signal is reflected by an underground seismic reflector (for example, the interface between layers of different acoustic impedance). These reflections are picked up by seismometers placed near the surface, in the water, or in wells of defined depth, while seismic instruments are used at the surface to record the propagation of seismic waves through subsurface formations. Through data processing, analysis and interpretation, study the characteristics of underground geologica...

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Problems solved by technology

[0029] Although the existing public methods have achieved certain results in the design and application of low-frequency signals, they have not comprehensively considered the hammer stroke of the vibrator and the flow limitation of the vibrator (such as the flow rate of the pump, the effect of the accumulator, etc.); Considering that the same parameters are inconsistent in the performance of the source output on different control systems, the best scanning signal cannot be obtained for seismic acquisition, so that the low-frequency exploration performance of common models of sources cannot achieve better results

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