3D lattice modeling of hydraulic fracture initiation and near-wellbore propagation for different perforation models

Abstract

This work introduces 3D lattice modeling of hydraulic fracturing initiation and near-wellbore propagation for different perforation models, including spiral perforation, oriented perforation and Tristim perforation. For each perforation model, a total of six perforation tunnels are explicitly modeled and the representative intermediate states are chosen to analyze the results. The numerical simulation results show that the perforation tunnels guide the generation of initial microcracks at the roots of the perforation tunnels once the injection starts, however, the subsequent fracture propagation is controlled by the relative locations of perforation tunnels and the stress interference among different perforation tunnels. The spiral perforation gives the highest breakdown pressure while the Tristim perforation gives the lowest. Trans-wellbore fracture surfaces caused by the generation of large amount of microannulus cracks is the main reason of the pressure breakdown. The magnitude of the breakdown pressure is associated with the level of fracture complexity generated before the breakdown. Despite the variation of breakdown pressure for different perforation models, both the initial minimum pressure after the breakdown and the propagation pressure are nearly identical. The study provides a theoretical basis for understanding fracture initiation and near-wellbore tortuosity.