Seismic Directional Beam-forming With The Cosine Amplitude Distribution

Phased-source system can be used to improve the signal energy, when controlled source is used inseismic exploration. But phased-source system exists some problems such as handling difficult issuesand non-uniformity between the source, the seismic beam-forming based on receiver array can beused to improve signal to noise ratio. The seismic beam-forming based on receiver array is a seismicdata preprocessing method, it can generate high-quality seismic data for subsequent data processing.When we use the conventional beam-forming method, if the noise is strong, we need to increasethe number of single-shot record to improve the quality of data. According to beam-forming theory, thebeam will become narrow, when the beam does not cover the receiver array, the SNR of receiver arraywill not great enough to meet the requirements of seismic data processing.In order to improve the SNR of single shot record, we propose “Seismic Directional Beam-formingwith the Cosine Amplitude Distribution”(SDBCAD), which is also based on beam-forming theory.SDBCAD generates directional seismic records by introducing cosine amplitude distribution inbeam-forming processing. The beam of SDBCAD can be broadened to cover the receiver array.Rational use of SDBCAD can improve the quality of seismic data.Firstly, introduce the directional seismic beam-forming theory. Derivation the direction factor ofseismic beam-forming theory. Analyze the main characteristics of the beam derived factor and studiedthe influence of the main parameters of seismic beam characteristics.Then, this paper introduces the cosine weighted directional beam-forming principles andmethods,deducing the cosine weighted direction factor, analyzing the main characteristics of the beamderived factor and studying the influence of the main parameters of seismic beam characteristics.Theseparameters include the number of sources (single-shot records), shot distance and weightingcoefficient matrix, etc.In addition,this paper provides the cosine weighted parameter selectionmethod and directional beam-forming seismogram synthesis.Secondly, in order to verify the two weighting we applied numerical simulation, and establish ahorizontally layered geological model, using ray tracing method to synthesis multiple single-sourceseismic records,gives the synthesis of single-shot record of single source, uniform weighting methodand cosine weighted method. Comparing with the difference single shot-records, we found uniformweighting method can achieve directional beam, improve seismic data quality, and cosine weightingincreases the effective range of the seismic beam, the target formations with more continuous shaft,quality of seismic records is improved.Finally, this paper analyzes the factors affecting the results of numerical simulation, on this basis,improve cosine weighted beam-forming method parameters design.