Method and system for simulating air gun hypocenter wavelets for offshore seismic prospecting

Abstract

The invention provides a method and a system for simulating air gun hypocenter wavelets for offshore seismic prospecting. The method includes measuring basic parameters of seawater and air gun devices; calculating a throttle constant of a gun body, an initial temperature of a gun chamber of an air gun, an initial molar mass of a gas in the gun chamber, an initial molar mass of the gas in a bubble, a molar mass of the gas in the balanced bubble, initial still water pressure, an initial radius of the bubble, an initial volume of the gas in the bubble and a bubble balancing radius; determining a function of a temperature time history of the bubble in the vibration process of the bubble, a function of a molar mass time history of the gas in the bubble and a function of a volume time history of the gas in the bubble; simulating a time history seawater viscosity; simulating a pressure wave produced by the bubble in consideration of the seawater viscosity and a ghost reflection pressure field; using the pressure wave produced by the bubble to simulate a ghost reflection pressure wave of the pressure wave; and overlying the pressure wave produced by the bubble and the ghost reflection pressure wave to synthesize the air gun wavelets. By means of the method and the system, the consistency of simulation wavelets and actual measurement wavelets is enhanced.

Description

technical field [0001] The invention relates to the field of seismic data acquisition in oil and gas geophysical exploration, in particular to an air gun seismic source wavelet simulation method and system for marine seismic exploration. Background technique [0002] Offshore seismic exploration is an exploration method that uses artificial seismic technology to detect underground structures. It excites seismic waves near the sea surface in a certain way, and generates vibration signals called seismic wavelets. Seismic wavelets propagate downward from the source, and after encountering a geological interface, transmission and reflection occur at the interface, and the transmitted seismic wavelets The wave continues to propagate downward, while the reflected wavelet propagates upward at the interface location. Seismic wavelets from interfaces at different depths arrive at the seawater surface at different times, and receive reflected waves from geological interfaces at diffe...

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Problems solved by technology

[0006] However, there are two basic defects in the above model. First, the above model assumes that the fluid viscosity is a constant, ignoring the influence of the temperature and pressure changes of the bubbles on the fluid viscosity during the vibration process.

Furthermore, although the above model also considers the influence of ghost reflection on the far-field wavelet, it simply superimposes the ghost reflection on the bubble vibration, ignoring the influence of the pressure field generated by the ghost reflection on the bubble vibration

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