The west part of Biyang sag is in the basin margin with variable depth of target, featuring shallow in the north and steep dips due to existence of major faults in the south.

• 泌阳凹陷西部带处在盆地构造的边缘,目的层深度变化较快,北部目的层较浅,南部存在边界大断裂,地层倾角较大。