An Application of Crooked Wide Line Acquisition Technique in Complex Mountainous Region

摘要

Seismic exploration in complex mountains remains a tough challenge. In this paper, an example of seismic exploration in complex terrains in Central Asia is discussed. The seismic lines cross over mountains, rivers, loess and valleys in the work area. High elevation difference, changeable surface lithologies and great variations of transverse velocity and thickness in the low-velocity layer contribute to the difficulty of seismic exploration. The broad distribution of inhomogeneous bodies in the near-surface induces serious secondary disturbances. Besides, the target layers in the area are as deep as 5-6 seconds with developed faults, broken formation and complex seismic wave fields. Last but not least, the wide distribution of high-risk red zones brings a tough problem to field acquisition. In order to solve the above problems effectively and efficiently, a crooked wide-line geometry was employed in the work area. The results show that the approach has increased the fold of target layers, suppressed the side waves and near surface secondary disturbances. The design of crooked lines and its flexible lateral offset have enhanced the efficiency significantly while reducing the operation risks. In this paper, a quantitative analysis is made on the side wave suppression, the effects of offset and the stack response of inflexions of crooked lines to discuss the rational of the acquisition scheme.