A composite criterion to predict subsequent intersection behavior between a hydraulic fracture and a natural fracture

摘要

Hydraulic fracturing is a highly effective technique applied to enhance the productivity of unconventional reservoirs. The fracture induced by hydraulic fracturing operation may cross, open or get arrested by the pre-existing discontinuities in naturally fractured formations, which greatly influences the efficiency of resource extraction. In order to predict the subsequent behaviors and fully understand the stress stability during the process of a hydraulic fracture approaching a natural fracture, we propose a new composite criterion through coupling the fluid flow and rock elastic deformation. This new criterion can simultaneously predict three intersection behaviors based on the critical stress conditions of slipping, opening and crossing. Besides, the criterion is validated by comparing the predicted results to three independent experiments and published intersection criteria, and good agreement with the experiments as well as sufficient advantages over the previous criteria is observed Finally, the perturbation of different parameters including minimum horizontal stress, fracture toughness and approaching distance is introduced to the composite criterion by analysing the NF stress field and parametric sensitivity which further conforms this criterion's applicability. The results also demonstrate that the variation of the introduced parameters will rezone the intersection scope and then change the geometry of the critical slippage and opening curves, which can promote or inhabit the occurrence of the predicted intersection behaviors to different degrees.