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.%在沙漠地区的微测井合成记录上,潜水面附近会存在频率突然变低的高速层段.以往由于忽视了这种高速层内的低频现象,在设计激发深度时未能避开潜水面下的低频层,引起单炮资料品质产生突变.为此,提出了增加远道观测点的微测井改进方法,介绍了如何根据远道初至波特征来提高微测井资料解释精度；分析了低频层特征及其识别依据、厚度求取方法与空间展布规律；最后,在求准潜水面埋深的基础上,根据低频层厚度变化进行激发深度设计.采用该方法设计的激发深度能有效避开低频层的影响,在实际生产中取得了良好的应用效果.
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