2:55 PM - 3:15 PM
[NS-06] Relationship between source performance and near-surface structure: An onshore Japan case study
Near-surface conditions have an influence on source performance, which represents the magnitude of energy propagated/measured in active seismic surveys. However, it is mostly difficult to accurately understand the relation between source performance and near-surface structures in the regions where complex surface with topography and near–surface conditions are present, while the optimization for source locations in such regions has large impacts on the quality of acquired seismic data even at deep layers. In this study, we analyzed source performance and near-surface structures by using a crooked 2D seismic vibroseis dataset acquired in the densely populated region, with complex topography, near-surface structures and various noises, onshore Japan.
Two types of methods for evaluating source performance were exploited in this research. One is a method proposed by a prior study, which uses middle-offset data to calculate source performance from the stack with absolute amplitude. Although it estimates the degree of signal penetration to the depth for each shot, the results seem to be contaminated by high-level noises recorded in the field. Therefore, we additionally presented another method which utilizes the first arrival amplitude in near-offset data to compensate the drawback of the first method and then compare their results.
Since the first arrivals within the near offsets are clearly observed in the data, near-surface models of P-wave velocity are analyzed by 3D first arrival seismic tomography, which takes the effects of crooked line geometry and topography into account, and also public borehole datasets.
The comparison between the calculated source performance distributions and near-surface models shows that the regions with relatively high P-wave velocity, and the stiff lithology is correlated with the parts with relatively high source performance. Hence, this indicates that the above approach based on the two methods is capable of detecting the locations with potentially high-source performance even in onshore field with complex topography, near-surface structures and strong noises.
Two types of methods for evaluating source performance were exploited in this research. One is a method proposed by a prior study, which uses middle-offset data to calculate source performance from the stack with absolute amplitude. Although it estimates the degree of signal penetration to the depth for each shot, the results seem to be contaminated by high-level noises recorded in the field. Therefore, we additionally presented another method which utilizes the first arrival amplitude in near-offset data to compensate the drawback of the first method and then compare their results.
Since the first arrivals within the near offsets are clearly observed in the data, near-surface models of P-wave velocity are analyzed by 3D first arrival seismic tomography, which takes the effects of crooked line geometry and topography into account, and also public borehole datasets.
The comparison between the calculated source performance distributions and near-surface models shows that the regions with relatively high P-wave velocity, and the stiff lithology is correlated with the parts with relatively high source performance. Hence, this indicates that the above approach based on the two methods is capable of detecting the locations with potentially high-source performance even in onshore field with complex topography, near-surface structures and strong noises.
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