Modeling Fracture Mechanics for 3D-Printed Porous Replicas Using Phase-Field Finite Element
Authors: Almetwally A. G. , Wheeler M. F. 
Published: August 2024

ABSTRACT:
This paper investigates fracture mechanics in 3D-printed porous replicas using phase-field modeling. The study focuses on uniaxial confined and point load test mechanical experiments, as well as fracture indentation tests, conducted on 3D-printed replicas as an economical alternative to reservoir core samples. The replicas are created by segmenting solid and pore spaces of a Berea core sample, triangulating, and printing them with gypsum. Stress-strain curves and fracture profiles are generated from the experiments, and phase-field modeling is used to simulate fracture propagation. Comparison with visual fracture configurations confirms the accuracy and reliability of the phase-field approach. The results provide insights into fracture behavior, such as breakdown pressure and fracture friction angle, which can optimize hydraulic fracturing simulations for enhanced recovery. The integration of uniaxial and fracture indentation experiments with phase-field modeling in 3D-printed replicas presents a cost-effective method for studying the mechanical behavior of porous materials. This research enhances geomechanics experimental research and contributes to improved understanding and optimization of fracture propagation in subsurface formations, particularly in the context of hydraulic fracturing in the petroleum industry.

1. INTRODUCTION
Geomechanics experiments play a vital role in the oil and gas industry as they provide essential insights into the in-situ stress state and local failure modes, which are of utmost importance for successful well drilling, hydraulic fracturing, and production optimization practices (Zhang, 2019). These experiments offer a unique opportunity to directly observe and measure the mechanical behavior and failure modes of rock materials under controlled laboratory conditions. Researchers employ various geomechanics tests, including the uniaxial compression strength test (UCS test) and point load test, to characterize the mechanical behavior and failure modes of rock samples (Li et al., 2013). These experiments provide crucial data on stress-strain relationships, fracture profiles, and other key parameters, enhancing the accuracy of geomechanical predictions, and informing decision-making processes. Accurately predicting failure modes in rock materials poses significant challenges due to the complex combination of geometric and compositional uncertainties. The spatial variability of geomechanical properties within unconventional reservoirs further complicates the understanding of rock behavior (Almetwally et al., 2021b). These challenges necessitate comprehensive geomechanics experimental research to gain a deeper understanding of rock behavior and improve the accuracy of predictions. The destructive nature of geomechanical experiments also limits their application to a limited number of samples, making it challenging to extend the findings to other rock formations (Kong. et al., 2017). Additionally, analytical and numerical modeling approaches encounter limitations when capturing the intricacies of geomechanical behavior, especially in repetitive laboratory-scale experiments (Almetwally et al., 2020b).