How hydraulic fractures interact with natural fractures: A review and new observations

Hydraulic fracturing is one of the most effective conventional reservoir-stimulation techniques currently utilized in the petroleum industry. Hydraulic fracture (HF) – Natural fracture (NF) interactions during the hydrofracturing process are complex in space and time. Although in the past five decades, several numerical, analytical and experimental studies have explored and characterized the interactions between natural fractures and hydraulic fractures, there remains differing opinions on the fundamental behaviors of hydraulic fractures when and where they interact with natural fractures. Here, we present a comprehensive review of the propositions and limitations of these studies in order to emphasize the need for further studies on NF-HF interactions and highlight the important fundamental questions that are yet to be answered. Our review focuses on previous experimental, analytical and numerical studies that investigated the impact of geomechanical and geometrical properties, and operational parameters on the result of NF-HF intersections during fracture initiation and propagation. We envisage that advancement in our understanding of NF-HF interactions will help in optimizing the fracture-stimulation processes during hydrofracturing operations.