Abstract：Offshore 4-C seismology is a new seismic exploration and development technology. Because of different particle vibration mode and transmission mechanism of shear wave and P-wave,the sensibility to existence of the fluid in formation is different. The fluid in formation has more serious impact on transmission velocity,absorption of energy and shield for P-wave than for shear wave,so that there exists a large amount of seriously blurred seismic reflection zone("gas chimney") which is very difficult to determine the structure,accurately calculate the area and the reserve of gas reservoir. There basically no exists the gas chimney on P-SV converted wave section,which is a great help to determine the structural high and feature.The structural exploration results of offshore 4-C seismology are excellent.
