Abstract: Geometry design plays an important part in seismic exploration. Optimum geometry can not only improve the quality of datum but also reduce the cost of acquisition. Through the forward modeling, with the increase of offset we found the phenomenon that the events would cross or even merge, and the stratigraphic sequence would become confused. According to the characteristics of a single vertical cable and multiple vertical cables, we designed the corresponding geometries, and then evaluated and optimized the designed geometries. The conclusions are drawn as follows:First, to increase shot point density is better than to increase shot area to improve bin fold; when a shot line interval is equal to a shot point interval, the distribution uniformity of a bin fold in each bin is the best. Second, when the target layer is inclined, the illumination area shows the shape of trapezoid, and part of the area can't be illuminated. The illumination loss can be compensated through increasing the number of shot line along the structural trend, and increasing the length of shot line along the downdip direction at the same time. Third, when the target layer is anticline or syncline, to increase the scope of illumination by increasing the radius of the maximum ring is small, although the marine vertical cable is moved every where. The best way is to deploy multiple marine vertical cable in a ring. Fourth, when a shot area is equal to a receiver area, to improve bin fold of the center area by increasing both of them doesn't work. However, it works thoroughly when the shot area is bigger than the receiver area.

Key words: vertical cable, geometry, bin fold, illumination analysis, forward modeling, natural gas hydrate, three dimensional marine seismic exploration