The Research On Extacting Multiple Coverage Gather Of Converted Wave

Multi-wave multi-component seismic exploration is a promising exploration methods in the lithology, hidden oil and gas, the use of multi-wave multi-component kinematics and dynamics characteristics, can be well portray reservoir distribution characteristics between the shear wave velocity ratio and amplitude ratio.Multi-wave multi-component seismic exploration can provide a wealth of subsurface information, detection and lithology inversion in oil and gas play a huge role, but how to use and extract the information converted waves is very difficult, especially in data processing, it's difficult to treat much larger than the conventional P-wave seismic exploration. Common conversion point gather the extraction and superposition is one of the important steps, and one of the key factors of how to extract and superpose properly is the location of conversion points.From the development status of conversion point calculation, the calculation of transition point can falls into exact solution and approximate solution. Summarizes three iterative algorithm, through the three iterative algorithm comparison can be seen, with the offset increases, the error also increased, showing positive relationship between the two; when the offset is set, with the increase in the number of iterations, the error decreases, inverse relationship between the two. Based on previous studies, single-layer, multi-level uniform medium, developed a search method to compute the best angle conversion point position. Through the establishment of the theoretical model calculations, and on the premise of shot points and detection points are determined, the conversion point can be calculated more accurate. Search method calculating the best angle accuracy can be achieved by encrypting the grid, but the computation increases. When the conversion point is determined, through data simulation analyse the effect of common conversion point gathering detection point distribution by depth of the reflecting interface, shear wave velocity ratio.Because the difference between vertical and horizontal velocity, in a multi-wave multi-component data acquisition process, not only to meet the requirements of converted-wave exploration, but also take into account the joint exploration of the requirements of S-wave, so the design of observing systems is very important. The traditional observation system for the longitudinal wave, due to the symmetry of wave propagation path, multiple coverage common reflection point gather easily extracted, but wave is converted by the reflector depth, shear wave velocity ratio of the common conversion point gather detection analysis of the impact point distribution, accurate extraction of the common conversion point multiple coverage is very difficult to gather. This paper presents an observation system for the converted waves, conversion point regularly spaced distribution in the reflector, shot point regularly spaced and detection point irregularly spaced distribution. Model the parameters of a given observation system to extract common conversion point trace gather. But it is difficult for this observation system to extract the P-wave common reflection point trace gather.