Resolution analysis of shallow marine seismic data acquired using an airgun and an 8-channel streamer cable

We conducted a high-resolution seismic survey off Yeosu, Korea, using a 30in3 small airgun as a seismic source and an 8-channel streamer cable with a 5m group interval as a receiver, to find out the proper acquisition and processing parameters at the study area where shallow sedimentary layers were well deposited. The data were digitally recorded with a shot interval of 2s and a sample interval of 0.1ms using an in-house PC-based acquisition and processing system. The quality of the subsurface image depends on the acquisition parameters such as the sample interval, common midpoint (CMP) interval and CMP fold. To understand the effects of these parameters, we resampled the field data with various sample intervals, CMP intervals and CMP folds and processed the data. The analysis results show that thin layers of 70–80cm thickness at a depth of 30–45m from the sea bottom can be imaged with good resolution and continuity using acquisition parameters with a sample interval of less than 0.2ms, a CMP interval of shorter than 2.5m and a CMP fold of greater than 4. The data quality of the shallow marine seismic survey is greatly enhanced through multichannel data processing flows such as spiking deconvolution, frequency filtering and careful static correction. Our results demonstrate that very high-resolution seismic reflection images can be made from 8-channel data recoded with high sample rates and processed with appropriate parameters.