Rate transient of the multiply fractured horizontal well in the shale gas reservoir based on the embedded discrete fracture model and topology

The complex fracture network may be formed by coupling natural fractures (NFs) and hydraulic fractures (HFs) in the shale gas reservoir. In this work, by introducing the topology theory, two types of topological nodes, three types of topological connections, and four types of fracture topologies on the complex fracture network are proposed and, accordingly, the numerical model of the multiply fractured horizontal well (MFHW) is further established based on embedded discrete fracture model and topology analysis. The production analysis shows that large Langmuir volume and pressure contribute to higher production of the gas well under the assumption that the content of free gas in the shale matrix is fixed while the stress sensitivity is unconducive to enhancing the gas well's production due to the decrease in the permeability in the shale matrix and fractures. Meanwhile, it is more efficient to increase the number of topological nodes between HFs and NFs (X1 nodes) than to increase the number of topological nodes among NFs (X2 nodes) to enhance the production of the horizontal well. Moreover, the horizontal well with tree topology is more likely to obtain higher production compared with other fracture topologies during the middle-late flow period. In addition, field pressure analysis suggests that the number of X1 nodes and the condition of the bottom-hole pressure can determine the pressure drop around the horizontal well while the shape of the pressure-disturbed zone of the MFHW is mainly determined by the number of X2 nodes and the fracture topological type.