The Application Research On Tomography Velocity Modeling Of Low Range Structure

The YM 46-YM 35 wells area is rich in oil and gas resources.The petroleum reservoir has been found in palaeogene,cretaceous,silurian and Cambrian – Ordovician system.The breakthrough made in cretaceous Brazil group of YM 46 well particularly shows a wide potential of oil and gas exploration and scrolling development in the area.The change of structure in both shallow and deep area is vast,and the horizontal and vertical variation of seismic velocity is also complex.It becomes difficult to guarantee precision of velocity field,which would result in the unidentification of low range structure and even reverse of structure,and finally influence the trap evaluation and implementation.The precision of velocity field is the key factor to identify low range structure.The tomography method is adopted to construct the velocity model,in which the diving wave tomography is used to calculate near-surface velocity model,and grid tomography technology is used to calculate velocity field within the work area.Finally,combining the result of PSTM with PSDM's to analyze the accuracy of velocity field and the recognition effect of low range structure.The research on low range structure in interval of interest can not only provide a high precision of velocity field,but provide experience and method for low range structure imaging on other intervals of Yingmai region.