According to the typical geometry of complex hydraulic fractures of shale

a new method which takes the fracture complexity

the fracture distribution and the attribution of fracture to production into consideration was proposed to describe complex fractures.Moreover

the concept of fracture potential index was put forward

and it can be used as one of the parameters for quantitative evaluation of the complex fractures.The density of fractures with different distances from the stimulation location was estimated with the method for determining the effectiveness of the fracture network.Compared with the fracture network with the characteristics of being dense inside but sparse outside

the fracture network being sparse outside but dense inside is more effective in enhancing production according to the description results.Hydraulic fracturing experiments were conducted and the geometries of hydraulic fractures in the shale were described with the application of the method.Results show that the potential index of fracture network formed under low horizontal geostress difference is greater than that of fractures formed under high horizontal geostress difference.It reflects that the fracture network formed under low horizontal geostress difference has higher potential for enhancing production.The above results indicate that the method established for describing complex fractures can comprehensively reflect the fracture complexity

fracture distribution and attribution to production.It provides a mean for evaluating the effectiveness of complex hydraulic fracture network.