Low-Frequency Sweep Design—A Case Study in Middle East Desert Environments

Abstract

Low-frequency vibroseis acquisition has become a routine operation in land seismic surveys, given the advantages of low-frequency signals in characterizing geological structures and enhancing the imaging of deep exploration targets. The two key points of low-frequency sweep design techniques include controlling the distortion and improving the output energy during the low-frequency stage. However, the vibrators are limited by the maximum flow provided by the hydraulic systems at the low-frequency stage, causing difficulty in satisfying exploration energy requirements. Initially, a theoretical analysis of the low-frequency acquisition performance of vibrators is conducted. A theoretical maximum output force below 10 Hz is obtained by guiding through theoretical formulas and combining actual vibrator parameters. Then, the signal is optimized according to the surface characteristics of the operation area. Finally, detailed application quality control and operational procedures are established. The new low-frequency sweep design method has overcome the maximum flow limitations of the hydraulic system, increased the low-frequency energy, and achieved broadband acquisition. The designed signal has been tested and applied on various types of ground surfaces in the Middle East desert region, yielding good performance. The proposed low-frequency sweep design method holds considerable value for the application of conventional vibroseis in low-frequency acquisition.