Time-depth Conversion Velocity Analysis Methods With The Construction Of Field Research And Software Implementation

The average velocity is necessary for the structural mapping and the time-depth conversion. In order to obtain the average velocity field in line with the geological of the work area , to provide a more accurate average velocity for the seismic geological interpretation and other time-depth conversion application, We establish the subsystem of the time-depth conversion under the system of the GEOEAST V2.0. The velocity field subsystem of time-depth conversion makes full use of the data of STK velocity from the seismic processing or the data of RMS velocity, After T-V interpolation along the horizon, calculating interval velocity, smoothing interval velocity and the average velocity along the horizon, constraining correction of the well data and so on, To obtain more accurate average velocity for structural map. Since the complex surface structure in western China, covered by a thick lay of sand, it is impacted by the deceleration of the shallow low-velocity. The structure is buried deeply, amplitude is very small, It is difficult to find the reservoir, the igneous rock is another characteristic of China, as the effect of the igneous rock, It is difficult for us to implement structure.With the development of exploration techniques and a higher level for regional exploration, the exploration area is turned to the mountains and other complex areas, leading to an increase in three-dimensional collection of information. These areas of surface and underground geological conditions is extremely complex, mountains and cliffs, such as geographical distribution, The quality of the earthquake records is poor , It is difficult to get the information of the static correction. There is reversal in the poor quality of velocity spectrum. In the ground, it’s mostly high and steep reflective structure, there is much of multi-thrust fault underground, it is difficult to improve the accuracy of the implementation and construction. It requires us to consider new ways to improve the accuracy of the variable velocity of the time-depth conversion.In this paper, based on the full use of methods and research experiences of our predecessors, we design and study the method of the velocity analysis on Time-depth conversion, it has made rapid development in the research of velocity. Based on the horizon velocity theory, we have formed a three-dimensional method of calculation on interval velocity, in the aspect of the visualization, we have control the quality of the velocity spectrum and the interval velocity. On the way of the complex treatment, we use the sophisticated smoothing、the well constraint and other means, considering the special geological phenomenon to process the sub-blocks data. In the restriction of well data, based on the data of deep-time curve, through the correction of the horizon of the along velocity, to eliminate the velocity errors of the average velocity and the deep of the wells, leading to improve the final accurate of the average velocity, thus greatly to improve the accuracy of the time-depth conversion velocity field structural mapping.