This work investigates the fracture resistance method for wellbore strengthening through modeling hydraulic fracture propagation and plugging using finite element analysis. Results reveal that plugging behavior and stress redistribution differ significantly between impermeable and permeable formations, with diffusion playing a critical role. The study highlights the limitations of elasticity-based simulators and emphasizes the importance of coupled poroelastic effects in predicting fracture reinitiation.
Location
Online
Date
8 December 2020
Time
4:00 PM
Bio / Abstract
In drilling engineering, the fracture resistance method is applied for wellbore strengthening. Particles, commonly known as Loss of Circulation Material (LCM), are added to the drilling fluid and directed into unwanted hydraulic fractures to act as a plug. A key question is the effectiveness of the plug and its impact on stress redistribution. Understanding whether a new fracture may form at the plug location after sealing is essential for safe and efficient drilling operations.
This work uses the finite element method to investigate fully coupled stress changes in impermeable and poroelastic permeable formations. Hydraulic fractures are propagated up to 5 m in the toughness-dominated regime and then plugged. Analysis shows that in an impermeable formation, a perfect plug (complete fluid isolation to the fracture tip) can result in a new fracture initiating at the plug location. In contrast, in permeable poroelastic formations, the plug cannot achieve perfection because pressure behind the fracture tip equilibrates with formation pressure and fluid diffusion, generating back stresses. This demonstrates the critical role of diffusion processes in obtaining accurate closure stress predictions, highlighting limitations of standard elasticity-based industrial simulators.
Biography
Dr. Ernestos Sarris is an Assistant Professor at the Engineering Department of the University of Nicosia (UNIC), teaching upstream petroleum courses in Oil & Gas Engineering and Geomechanics in Civil & Environmental Engineering programs. He is also a Visiting Assistant Professor at the School of Applied Sciences, Aristotle University of Thessaloniki (AUTH). Dr. Sarris directs the Petrophysics and Soil Mechanics laboratories at UNIC.
He holds a degree in Mineral Resource Engineering and an MSc in Environmental Geotechnology from the Technical University of Crete, and a PhD in Petroleum Geomechanics with applications in hydraulic fracturing from the University of Cyprus.
His research focuses on mathematical modeling and simulation of petroleum-related rock mechanics phenomena, including hydraulic fracturing, particle flow-back, wellbore stability, sand production, multiphase flows in porous media, CO₂ sequestration, enhanced oil recovery, and environmental applications in mining. Dr. Sarris has served as a principal researcher and completed numerous academic and industrial projects.