大牛地气田纵向上存在多个产层，层间跨距较大，储层致密，单层产能低，甚至不压裂就无自然产能。运用灰色关联分析原理优化了影响压裂选井的各个因素，在确定权重时采用系统工程层次分析原理， 考虑影响选井选层因素的复杂性和不均衡性，确定出各因素的权重来优选压裂井层，结果更加符合实际情况。应用实例验证了该方法的科学性和适用性。

Daniudi Gasfield is characterized by multi-layers in vertical, large interval between layers, tight reservoir and low deliverability of single layer, even no natural deliverability without fracturing. The grey correlation analysis method is used to optimize the factors which affect the well selection in fracturing. The level analysis principle of system engineering which takes the complexity and malconformation of each factor into consideration is applied to ascertain the weight of each factor. The application result proves the scientificity and applicability of this grey correlation analysis method.