Research On Ocean Four-component Seismic Acquisition Technology

Nowadays,four-component seismic exploration is developing from shallow water area with simple terrain to deep water area with complex terrain,from narrow azimuth exploration to wide azimuth exploration,which put forward higher requirements for acquisition technology.At present,the technology of seabed node acquisition has not been deeply studied in China,and it is still in the initial stage.The ocean bottom node system shall be placed on the seafloor for a long time after deployment.It means seismic data cannot be monitored in real time,bringing challenges to quality control.Based on the research results of node acquisition technology in China and abroad and the example of ocean four-component seismic acquisition project,this paper shows the geometry design method,acquisition technology and quality control method of four-component seismic acquisition,and summarizes the progress and achievement in the acquisition practice in order to promote further development of marine four-component seismic acquisition technology.This paper analyzes the operation efficiency and equipment requirements,integrating economic factors into the geometry design stage.It will further improve the design method of the offshore four-component geometry and bring the efficient optimization of the geometry.The mathematical method was used to analyze the influence of seabed slope on the length of rope connecting the nodes,which was combined with the current deployment method to form a more scientific deployment technology against complex terrain.It is conducive to the further promotion and application of efficient acquisition technology by combing and summarizing the dual-source flip-flop mode and two-ship flip-flop mode.A set of comprehensive quality control process is formed for massive seismic data of four components that is applied in actual production.In the condition of poor quality of seismic data from complex topography,the fourquadrant stack method is applied to analyze the energy characteristics of first break and judge the polarity of seismic data.The coupling effect between the geophone and the seabed can be evaluated by comparing the amplitude ratio of the environmental noise and signal recorded by geophone and hydrophone.The resonance frequency can also be used to analyze coupling effect.It further improves the data quality process through the introduction of western coupling analysis.Three-dimensional search method to calculate the position of the bottom node is applied OBN seismic survey.The first break energy is creatively proposed and applied as a criterion to evaluate the calculation,which greatly improves the computing automation.This paper analyzes the impact of operation efficiency and equipment requirement on geometry.The geometry is optimized by integrating economic factors during the stage of geometry design.It analyzes the influence of seabed slope on the length of rope connecting ocean bottom nodes and forms the method of nodes deployment in complex terrain.Based on the distributed and integrated navigation system,the shooting mode is adopted with the combination of one source vessel with dual-source and two source vessels with triple-source,thus achieving efficient acquisition operation.A comprehensive quality control procedure is developed for the large amount of four-component seismic data.One of the key points is to analyze the polarity of seismic data by stacking the first break in four quadrants.The coupling effect between the geophone and the seabed is evaluated by the resonance frequency,and by comparing the amplitude ratio of noise recorded by hydrophone verse the effective signal with the amplitude ratio of noise recorded by geophone verse the effective signal.The paper calculates the actual location of ocean bottom node by the three-dimension search method.It is proposed to evaluate the location of ocean bottom nodes based on the energy of first break that is the stacked data after the near-offset common receiver gather is processed by linear moveout correction.A set of practical ocean four-component acquisition technology is developed for the seismic survey in complex terrain,which has been successfully in some region of the Middle East.The efficient acquisition technology with ocean four-component node has a bright future,so do theoretical research and operation experience.