VSP Method And In Formation Absorption Coefficient Of The Application Of The Extraction

VSP (vertical seismic section), is a kind of earthquake observation method. The ground is the source and the detectors will be earthquake are placed with ground, so can receive arrival in underground the interface of the uplink wave, and direct waves along the surface and surface waves. And VSP technology detectors in the well placed in formation internal, not only can receive uplink wave and still can receive downside wave. VSP technology is also a kind of well seismic technology, it directly from the earthquake speed logging, is the improvement of seismic velocity logging methods and development. The earthquake speed is to use the record on logging beginning to wave to determine the speed of the earthquake, VSP technology not only use the record of the early to wave, use the renewal on record to wave to study the actual formation in the medium of seismic wave form and communication system.In the exploration targets to the concealment of the small and medium-sized reservoirs and complex structure, this to the resolution of seismic data put forward higher request. Influence of the resolution of seismic data is an important factor formation attenuation effect, that is, in the process of transmission of seismic signal, the strata due to the effect of attenuation, seismic signals the high frequency component will be absorbed to produce larger formation medium the attenuation, which reduce the resolution of seismic exploration. People have to understand the effects of the attenuation of the resolution of seismic data influence, therefore, in seismic data acquisition process used many compensation technology to abate strata attenuation effect on the influence of the resolution. However, due to the formation of the study of previous attenuation effect mainly concentrated in qualitative analysis, and the study of the mechanism is less, so, take the compensation is simple measures, to improve the resolution of seismic exploration of the effect is not obvious.In this paper, the formation mechanism of attenuation, and researches the strata VSP data use, extracting the absorption coefficient. And computer simulation, and concluded that the absorption coefficient profile. At the same time in the of the traditional points frequency scanning display (bandpass filter signal processing) and time-frequency analysis method to the seismic signal attenuation quantitative analysis on the research, get frequency spectrum attenuation figure.This paper VSP method and application to extract the formation absorption coefficient, some simulation research, and use VSP method to simulate the small structure, the plot of the response characteristics of the piece, and in the light of actual work area, using VSP data obtained to extract absorption coefficient. Specific content as follows:(1) VSP the forward modeling, in view of the thin interbedded, small fault, lens body etc geological problems response model is established, the forward modeling, generating way stacked profile, migration profile, and VSP-CDP stacked profile,3d data volume, and so on.(2) Theory research multi-dimensional VSP data volume converted into a3d VSP data volume is deduced, between coordinates (right Angle coordinate and the polar coordinates) mutual conversion, and through the programming VSP data body all-round convert three-dimensional VSP data volume, and the corresponding simulation results. Discussed the ideal scenario simulation of a3d geological structure VSP data volume, the ideal situation including medium is uniform, formation boundary surface is level and so on, the actual situation is more complicated, but for the exploration of the theoretical method is necessary, at home and abroad for studies of all-round VSP conversion to3d data volume of academics, still not much.(3)It is not the same as the window for seismic data do material quality quantitative analysis, analyze the seismic signal at different depths of different frequency range original material quality change rule, the decay laws, the absorption of seismic wave attenuation is by the media, to the nature of, the same ingredients of wave propagation in different medium, the different attenuation, namely the attenuation is medium itself inherent (formation quality factor Q). Influence formation quality factor Q (or absorption coefficient) and wave amplitude and frequency, saturated fluid properties and saturation, temperature and pressure, stratigraphic lithology, heterogeneity and anisotropic relations.(4)To work area, using VSP method carry stratum take absorption coefficient, the different depth and frequency to the absorption coefficient and the change rule of strata attenuation, including absorption coefficient and quality factor Q value and seismic wave speed, the formation of the relationship between the depth, the absorption coefficient and quality factor Q value and the corresponding relation of seismic wave frequency.Seismic wave in the earth spread medium, medium is ideal because the formation of completely the elastic medium, medium of seismic wave energy absorption is inevitable, and with the absorption coefficient increases the frequency of the signal, the earth medium is a "low pass linear filter", from VSP data comprehensive analysis, through the use of VSP data obtained to extract absorption coefficient, the in-depth study of the seismic signals in the stratum in decay laws, the formation of the high frequency of seismic signal absorption rule, especially the near surface attenuation more serious; The research work area of seismic signal formation depth, with the frequency of the signal attenuation of the basic law, the seismic data acquisition has guiding significance to design. For the ground seismic data processing for attenuation provides the basis for the compensation, so as to improve the purpose of the resolution.