The Study Of Seismic Response Characteristics Of Fluids

The application of seismic data to fluid identification and hydrocarbon-saturated reservoir detection is one of the highlights in the exploration geophysics. There is a close relationship between the variation of seismic response characteristics and the property of fluid within reservoir, which is thus worth studying. There are many factors affecting the relationship between the fluid and the seismic response characteristics. So far there is not a theory which can fully summarize the relationship between the fluid and the seismic response characteristics. The main research content is fluid seismic response characteristics in this paper. Based on the theory of viscous-diffusive wave equation and numerical simulation, this paper studied the relationship between the fluid and the seismic response characteristics, which provided guidance for fluid identification based on seismic data.The method of numerical simulation applied in this paper is F-K domain one-way wave equation forward modeling and migration. Numerical simulation of one-way wave only considers the upward or downward wave of seismic wave propagation during calculating. The generated record only contains effective wave. So the SNR of record is pretty high and the speed of computing is very fast. It is also easy to study the seismic response characteristics of complex reservoir. By applying one-way wave equation, the numerical simulation of the assumed geological model can be achieved and high SNR pre-stack or post-stack record can be obtained. Generally there is special attenuation characteristic in seismic response of fluid-saturated reservoir. This cannot be accurately described by conventional acoustic wave equation. The viscous-diffusive theory which proposed by Korneev etc. has been introduced in this paper and combined with F-K domain numerical simulation to study fluid seismic response characteristics. The viscous-diffusive equation simultaneously considers the influence of viscosity and diffusive of fluid-saturated reservoir on seismic response characteristics. It can accurately describe the seismic response characteristics of fluid. This paper discusses the fluid seismic response characteristics in the following aspects: ①Firstly, the method of F-K domain numerical simulation and the principle of viscous-diffusive theory have been introduced with their concerning formula derived. Secondly, we ②use numerical simulation methods to analyze the effects of parameters in viscous-diffusive theory(such as viscous coefficient, dispersion coefficient, Q, thickness of reservoir) on seismic response. ③Then the theoretical model of oil-saturated and brine-saturated has been established. The fluid detection and oil-water recognition has been achieved with simulating the seismic response in theoretical model by viscous-diffusive equation, analyzing the seismic response of different fluid and utilizing the spectral differences(domain frequency, bandwidth and correlation coefficient) of reservoir seismic response. ④Finally, compared with other fluid detection methods, the feasibility and reliability of this method are validated in field seismic data. Through the analysis and study above, we draw the following conclusions: ① The attenuation of seismic wave increases versus the increasing of viscous coefficient and the high-frequency component of seismic wave will be more attenuated. The attenuation of seismic wave increases versus the increasing of diffusive coefficient and the attenuation is independent of frequency. The lower value of the quality factor Q is, the more phase shift of seismic wave is. ②The fluid has a strong influence on spectrum characteristics of seismic wave which performs through domain frequency, bandwidth and correlation coefficient. The effect of oil-saturated is stronger than brine-saturated, so the fluid detection and oil-water identification can be achieved by analyzing these characteristics. ③After using this method and other fluid detection methods to analyze the same seismic data, it can be proved that the method in this paper is more efficient.