Search On 3D VSP Multi-Wave Field Separation

The three-dimensional and three-component VSP technology is one of the key methods in developing seismic. As the speciality of the three-dimensional VSP observation system and the characteristics of three-component receivers system itself, there are many new problems in processing the three-dimensional and three-component VSP data,at the same time,it also is an important task of VSP data processing. In this paper, these two problems are in important position. The article based on the analysising conventional VSP processing, integrated the features of the three-dimensional and three-component VSP data and the characteristics of the wave field and studied the three-dimensional and three-component VSP geophone coordinate rotation positioning and wave field separation approach.The paper also analyzed the various factors that impact the wave field separation results, and proposed the improved scheme. Based on the analysising the various methods,the article also has summarized the advantages and disadvantages of various methods and different application conditions. At last, the article used the every method in VSP theoretical models and real three-dimensional three-component VSP data processing and has verified the reliability and validity of the methods. The research of paper was divided into several steps:(1) For the characteristics of the three-component VSP data receiving system, the paper analyzed the orientation around the direction and coordinate relations between the three components and studied the method of three-component coordinate rotation of vertical and inclined wells (including the zero-bias and non-zero partial). At the same time,the paper has discussed how characteristics of the energy impacted the azimuth of thehorizontal component and has get the formula for calculating the azimuth of horizontal component.All above work has layed the foundation for behind the wave field separation.(2)Based on analyzing and summarizing conventional VSP wavefield separation approaches, in combination with 3D VSP characteristics and the apparent velocity of seismic wave propagation and polarization properties,the paper has reserched the methods ofτ-p transformation,Median filter and method ofτ-p transformation with polarization analysis.The paper has also analyzed the various factors that impact the wave field separation results(such as Preferencing,Track pitch and Alias), and proposed the improved scheme and summarized the advantages and disadvantages of various methods and different application conditions.(3) The paper has analoged VSP seismic record with ray tracing method and processed the theoretical model with these methods to verify the their reliability;Then the article has processed the 3D VSP actual data of P6 well of qikou 18-2 Oilfield in rotation orientation and wave field separation and has verified the effectiveness of the methods.