On the uphole seismogram of desert,some high-velocity layers near the water table have a sudden decrease of frequency.In
the previous shooting depth design,we usually ignored the low-frequency phenomenon in high-velocity layers,which might
inadvertently choose the low-frequency layer as shot depth and led to a sudden change for the quality of single-shot
data.Therefore,we improved the shooting depth design technique by increasing uphole observation points at far gathers and
introduced how to improve the interpretation accuracy of uphole data in terms of the first-break characteristics from far
gathers.Then,the features of low-frequency layers and their identification criteria were analyzed in order to obtain its thickness
and distribution.After achieving accurate depth of water table,shooting depth was designed via the alternation of the
thickness for the low-frequency layers.By using the above technique in shooting depth design,the impact of low-frequency
layers can avoided.As a result,the application on actual data is good.
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