Perforation and Loading Parametric Effects on Dynamic Rock Deformation and Damage Behaviors During Initial Fracturing Stages in Tight Reservoirs

Hydraulic fracturing technologies introduce deformation, damage, and fractures into tight oil reservoirs, which facilitates the production of hydrocarbons for the economic development of such fields. In addition to typical plug-and-perf fracturing techniques where the loading is usually increased with time, some field attempts have been made where cyclic and periodically dynamic loadings were used to create damage and failure in the reservoir rocks. This paper presents a numerical analysis of rock deformation and damage behaviors induced by dynamic loadings, specifically focusing on the beginning stage of hydraulic fracturing in tight oil reservoirs. An elasto-viscoplastic model based on finite element methods was utilized to simulate the effects of varying loading and perforation parameters. Three distinct scenarios were modeled: a single perforation, multiple perforations, and a single perforation with greater periodical loading magnitudes. The study characterized the spatial and temporal evolution of plastic strain, displacement, acceleration, and strain rate in rock formations. The analysis revealed that the plastic effects were highly localized around the perforations in all scenarios. The acceleration magnitudes were highly cyclic, while locations away from the perforations experienced an accumulation of acceleration magnitudes. The strain rate and induced plasticity were also highly correlated with the loading magnitude. The findings demonstrate that increasing the perforation number or loading amplitude significantly influences the deformation magnitudes, dynamic response patterns, and plastic strain accumulation. These insights provide a reference for optimizing the perforation and fracturing parameters during the development of tight oil reservoirs.