Fluid Infiltration vs Hydraulic Fracturing in Weakly Cemented Reservoirs

ABSTRACT: This study explores the transition from fluid infiltration to hydraulic fracturing in weakly cemented sandstones, which is critical for various geo-energy applications. Fluid flow experiments were conducted on artificially generated specimens with controlled mechanical and hydraulic properties. The experiments demonstrated that the mean applied stress and flow rate are the most influential factors affecting this transition, followed by material strength, viscosity, and permeability. Further, the use of Support Vector Machine regression analysis validated these findings, achieving R-squared values between 0.72 and 0.94 in predicting peak pressures. The study highlights the complex interactions between stress conditions, fluid properties, and rock strength in weakly cemented reservoirs. The results are relevant for optimizing hydraulic fracturing, groundwater applications, reservoir management, and wellbore strengthening, and provide a foundation for understanding fluid flow behavior in highly porous media. 1. INTRODUCTION Fluid flow injection in reservoirs is relevant to many applications in the geo-energy field, with the most well-known being hydraulic fracturing, which is used to stimulate productivity in tight reservoirs or to control sand production in weak formations. In water flooding for enhanced hydrocarbon recovery, reservoir fracturing must be avoided to achieve a uniform sweep of the reservoir (Yan et al., 2022; Nguyen, 2021). Another related application is wellbore strengthening, which helps prevent mud losses during drilling, especially in offshore deep-water environments. In weakly cemented reservoirs, the conditions for achieving fracturing vs fluid infiltration are unknown, as hydraulic fracturing is not governed by the classical theory of linear elastic fracture mechanics and the fluid diffusion may dominate in the parameter space which is defined by the in-situ stresses, rock strength, and the injection parameters of flow rates and viscosity (Konstantinou, 2021; Zhai, 2006; Khodaverdian, 2010; Omori et al., 2013; Huang et al., 2012). Understanding these complex mechanisms which govern the coupled processes requires knowledge of both geomechanics and hydraulics.