Vertical seismic profiling data acquisition from Well CSDP-2 in the Central uplift of South Yellow Sea

The Well CSDP-2, located in the west of central uplift of the South Yellow Sea basin, is the first drilling hole performed to detect the Mesozoic-Paleozoic marine sedimentary deposits under the Indosinian surface on the central uplift of the South Yellow Sea basin as a part of the Continental Shelf Drilling Program, which is aimed at better understanding the Pre-Cenozoic bedrocks and their occurrence on the central uplift. In order to get highly precise formation velocity of the well and seismic wave field characteristics with high signal-to-noise ratio and to establish accurate corresponding relation between the seismic horizon and the drilling formation, VSP (Vertical Seismic Profile) well logging was carried out. To solve the problem of strong reflection interface on the top of the marine strata, we designed a large volume air-gun array composed of 4 1500in3 Bolt air-guns. Using the method of three component digital geophone equal spacing observation, the seismic wave field signal spreading into the well was recorded. The preliminary processing results show that the high signal-to-noise seismic wave field signal was received and the PP and PS direct wave and reflected wave signals were clear and characteristic.