Drilling infill wells is a common way to improve the ultimate recovery of shale gas reservoirs. However, due to preferential planes of weakness and pressure sinks around the older existing producers, there is a high probability for the older wells to be influenced by the hydraulic fracturing of infill wells. Investigating the influence of fracture interference on the well performance of both older and infill wells is significant for progressing fracturing design and economic evaluation.
In this study, a numerical model is developed, including two older wells and an infill well. Fractures in different scales are incorporated in the model by using a hybrid model. Large-scaled hydraulic fractures are handled explicitly, and small-scaled natural fractures are handled using a dual-porosity model. The changing of SRV region and hydraulic fracture networks due to the infill well is considered in the numerical model by using the Embedded Discrete Fracture Modeling (EDFM), which avoids the complication of regenerating the reservoir mesh.
We investigate the impacts of different types of well interference such as interference through the SRV, connecting hydraulic fractures, and both of these combined. The effects on the production performances are significantly different when the well interference types are different. The simulation results show that interference through highly-conductive hydraulic fractures will significantly increase the production of the parent wells after the fracturing of the infill well. In addition, increasing the initial fracture length will have negative effects on the production of the infill well when the wells are connected through fractures, while positive effects are observed when the wells are connected only through the SRV. Further, for cases with high-conductive fracture connections, the fracture conductivity will have a significant influence on the production of the wells when the conductivity is larger than a certain value.
The results and analysis presented in this work provide us with a better understanding of the impact of fracture interference on well performance. And the results also have major implications regarding future completion design and field development planning decisions.