A LARGE-SCALE SEISMIC SOURCE, DEEP GUN AND CABLE SINKING AND LONG CABLE PENGTH APPLICATION IN MESOZOIC-PALEOZOIC BASIN IN THE SOUTH HUANGHAI SEA

Because of diversified antetype basins, complicated background of basin formation and later intensive structural reconversion, the quality of seismic data has always been the key problem in hydrocarbon exploration of the Mesozoic-Palaeozoic basins in the South Yellow Sea. This paper aimed to solve this problem by seismic acquirement technology. By analyzing geophysic and geologic conditions, we researched the key problems existed in this area, such as hard shielding interface in shallow layer, weak impendence interface and poor seismic quality in target layer. So relevant target oriented acquiring methods is developed which is characterized by large-scale seismic source, deep gun and cable sinking, and long cable length. The abstract parameters are 6 180 cu.in³ source volume, 10-25 m gun-cable depth and 10 050 m cable length. This new acquiring practice testified that it can increase the low-frequency component of seismic energy that propagated to the Mesozoic-Palaeozoic basin, so the S/N in the target zone has been raised and the entire seismic section quality has been improved greatly.