Finite element simulation of hydraulic fracturing using mesh fragmentation technique

• Grant number: 14/06906-4
• Support Opportunities: Scholarships abroad - Research Internship - Master's degree
• Start date: July 14, 2014
• End date: January 13, 2015
• Field of knowledge: Engineering - Civil Engineering - Structural Engineering
• Principal Investigator: Osvaldo Luís Manzoli
• Grantee: Michael Andrade Maedo
• Supervisor: Marcelo Javier Sanchez Castilla
• Host Institution: Faculdade de Engenharia (FE). Universidade Estadual Paulista (UNESP). Campus de Bauru. Bauru , SP, Brazil
• Institution abroad: Texas A&M University, United States
• Associated to the scholarship: 13/01468-6 - Finite element simulation of multiple cracks in solids using mesh fragmentation technique, BP.MS

Abstract

The demand for energy has increased significantly in recent years. Oil companies has sought new alternatives and under increasingly adverse conditions. The injection and extraction projects of fluids under high depths in reservoirs increase significantly the risks, since they change the rock properties. Thus, computer simulation allows analyzing the behavior of geological system assuming the interaction between the naturally fractured mass and flux of fluids. Thereby, formulations considering the pressure as unknowns for the fluids phase, and displacement for the mechanical part are necessary. This project intends to contribute for advances in numerical simulation of hydro-mechanical problems related to the behavior of fractured geological media under hydraulic loads. Modeling will be performed using the mesh fragmentation technique, which consists in the introduction of finite elements with high aspect ratio between bulk elements from the original mesh. Such elements have constitutive models consistent with the strong discontinuity regime. Since the tension is the main mechanism of opening fractures in rocks induced by fluids injection, the hydro-mechanical coupled problem will allow the analysis using the proposed technique. In addition to the stress-strain problem, the effect of the hydraulic coupling must be considered, introducing the formulation for the fluid transportation, constitutive laws for the flux (Darcy's Law) and laws that establish the relation between mechanical and hydraulic problems. Thus, the fluid pressure field is introduced as a new unknown to the problem. The project is aimed to assist the developments that are being done with UFPE and TAMU's group, with the purpose to adapt the methodology of mesh fragmentation for problems involving hydro-mechanic coupling, extending the applicability of the computer tool. In this context, basic tests (benchmarks) will be developed and analyses will be performed to validate the methodology, contrasting the obtained results from experiments or from other existing methodologies for the same purpose. (AU)