The Application Research Of Walkaway VSP Technique In Daqing Oil Field

Walkaway VSP is one of VSP (Vertical Seismic Profile) technique. And it is a 2D VSP technique developed from Offset VSP, which shoots along varying offset and receives in well. This technique is not mature yet, so it is still in the stage of researching inland and abroad. Especially the migration imaging technology in data processing, the VSPCDP stack imaging is based on the assumption of Horizontal layered media and the migration imaging of Kirchhoff integration is heavily dependent on simple velocity model.Both of them are not able to meet the needs of the actual complex medium.The basic principles of walkaway VSP technique,the method of the geometry designing, data acquisition, data processing, and resulting data interpretation and application were discussed detailedly in this paper based on the comprehensive study on Walkaway VSP technique.The researching work was mainly focused on the method of data processing to Walkaway VSP data during the study.To specific geometry,the study about static correction method has been conducted.At the same time,the study of the method about synthetic of 3 components was conducted.The localization of the synthetic method of 3 components in Cartesian coordinate system for Walkaway VSP method was pointed out.A rotation of Non-Cartesian coordinate system following the propagation direction and the polarization direction of seismic wave should be applied in the future. The wave field separation methods have been studied and successfully isolated pure and simple up-going wave field. Meanwhile, reflection wave imaging method has been studied.The wave equation illumination imaging method based on wave field extrapolation was enhanced. This method converted conventional aperture into VSP illumination range.And the imaging bias caused by the accuracy of velocity is eliminated.The innovations of the paper: (1) The geometry design method of Walkaway VSP technology.Through the design of the geometry with multi-row shooting and lifting the geophones in well, solved the problem of deficiencies of geophone levels and expanded the paragraph of observation in wells. (2) The wave field separation technique. Through separating wave field and removing noises in the different gathers, received a more pure up-going wave field and laid a good foundation for following imaging. (3) The reflection wave imaging technology. The wave equation imaging method based on wave field extrapolation was enhanced.With the illumination range in wells of VSP instead of conventional wave equation migration aperture, the reflection wave was migrated better.(4)Trough the integrated study of Walkaway VSP technology,a integrated Walkaway VSP technique realized flow was formed and guidable meaning to other aera was obtained.The method mentioned above was applied to well GuShen-2 in Songliao Basin. Field data acquisition and processing were carried out, the good result has been obtained for both of the testing lines. It verified the rationality of this method.The study of the paper implies that there will be a good prospect for the application and extension of Walkaway VSP technique in Songliao Basin.