Inverse Q Filtering For VSP

VSP-vertical seismic profiling exploration technology can provide accurate speed parameters, horizon calibration, the structure around the borehole, lithology and the scope of reservoir distribution. It can provide a reliable basis for structure interpretation, reservoir prediction and oil reservoir description of the surface seismic reflection data. But the propagation of seismic wave in the earth causes attenuation, which will reduce the S/N ratio and resolution of VSP data.The most popular method to compensate the attenuation is inverse Q filtering. Therefore, there are many researches on the methods of inverse Q filtering both at home and abroad. In this paper, the inverse Q filtering methods are distributed into three classes: the inverse Q filtering methods with series expansion compensating approximately high frequency, the inverse Q filtering methods based on wavefield continuation and other inverse Q filtering methods. All kinds of inverse Q filtering methods are reviewed. The efficiency and stability of inverse Q filtering methods are analyzed. And some problems about inverse Q filtering methods needed to settle are proposed. At present, many existing methods for inverse Q filtering are focused on dealing with surface seismic data. Therefore, VSP is different from the surface seismic data in travel time. It results in the different attenuation between VSP and surface seismic data.A stable inverse Q filtering method for VSP data is proposed in this paper. The method compensates the downgoing wave and the upgoing wave respectively after wavefield separation. It is proved to have good effects from testing with model data and real VSP data.