Numerical analysis of the stress shadowing effects in multistage hydrofracturing
Multistage fracturing is a commonly-used method to improve gas production in tight hydrocar-bon reservoirs.Stress shadowing effect among multi-fractures is crucial in effectively connecting the pre-existing natural fracture of reservoir and forming a complex fracture network that facilitates gas flow.Challenges remain in accurately characterizing the fracture structure and propogation patterns of naturally fractured reservoirs.In this study,we adopt an adaptive finite-discrete element method to simu-late the multistage fracturing of a naturally fractured reservoir by improving the mesh auto-refinement and identification of multiple fracture propagation.The numerical model covers interactions among hy-draulic fractures,pre-existing fractures,and microscale pores,while integrates the nonlinear Carter leak-off criterion to describe fluid leak-off and hydromechanical coupling effects during multistage fractu-ring.We introduce the proppant transport equation for idealised parallel plate flow in fractures,and Darcy's law is adopted to analyse the seepage flow in the fracture network and determine gas recover-y.We then compare the fracture network and consequent fluid flow induced by the hydrofracturing of unfractured and naturally fractured models to assess the influence of pre-existing fractures on multistage fracturing behaviour and gas production.This study provides a new approach to determine and optimize fracturing cluster spacing in tight gas reservoirs.
adaptive finite-discrete element methodstress shadowing effecthydromechanical couplingleak-off of fracturing fluid
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