Vibroseis source improvements towards broadband land acquisition

Abstract

Zhouhong Wei and Yuanzhou Pan demonstrate how to improve the amplitude through hydraulic and mechanical improvements and explore whether vibrator control electronics effectively supress harmonic distortion at low frequencies. Increased seismic frequency bandwidth towards both low and high frequencies can improve image resolution, reservoir characterization and quantitative seismic interpretation. However, using the vibroseis method to acquire broadband seismic data is very challenging in land data acqusition. At low frequencies, due to mechnical and hydraulic limitations, such as limited reaction mass stroke, the pump flow and harmonics, it is very difficult for a seismic vibrator to produce sufficient ground force at fundamental frequencies. At high frequencies, due to low rigidity of the vibrator baseplate resulting in poor coupling, it is also difficult for the vibrator to efficiently radiate the ground force into deep ground. Often, the high-frequency force energy produced by the hydraulic system is wasted in bending the baseplate. Therefore, the first challenge in broadband vibroseis data acqusition is to improve the vibrator performance so that the vibrator can produce sufficient force with a good S/N ratio in a wide frequency bandwidth.