Dispersed source array concept under severe operational restrictions in an urban environment onshore Japan

Abstract Seismic data acquisition onshore Japan presents numerous challenges. Particularly, various restrictions are inevitably imposed on field operations to ensure the safety of local communities, making a seismic survey both time-consuming and expensive. Recognizing the need for improved acquisition efficiency under these conditions, we explored the implementation of the dispersed source array (DSA) concept. This innovative technique employs multiple source units, each dedicated to a specific frequency range, thereby reducing the amount of source effort required at each vibrator point. To evaluate the effectiveness of the DSA method, we acquired two distinct data sets. The first data set used a single fleet, referred to as the conventional survey. In this case, a conventional sweep response, covering from low to high frequencies, was applied to each vibrator point. The second data set was acquired with the DSA method, referred to as the DSA survey, which involved low-frequency (LF) and high-frequency (HF) sweeps. The DSA survey also incorporated simultaneous source acquisition, meaning that the source wavefields from both LF and HF sweeps were stored in a single record. Due to the distinct frequency contents of the two sweeps in the DSA survey, it was possible to extract two narrowband shot gathers without requiring additional seismic processing effort.The processing of these two sets of narrowband data included data reconstruction to generate broadband data at the early stage of data processing. Upon completing the depth imaging, comparisons were made between the conventional survey and the DSA survey. The results demonstrated comparable outcomes between the two surveys. Furthermore, daily operational statistics highlighted a significant increase in productivity provided by the DSA method, achieving a threefold improvement in acquisition efficiency in our case. As a consequence, the application of the DSA concept to seismic data acquisition in urban areas onshore Japan led to a substantial enhancement in operation efficiency while delivering the required data quality.