Modelagem acoplada hidro-mecÃnica da perfuraÃÃo de poÃos em rochas frÃgeis

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

The thesis presents the first results of a research theme that is now going on the Civil Engineering Department of the Federal University of Pernambuco, which deals with wellbore stability in brittle rocks. The aim is to implement in a finite element code which solves simultaneously the stress equilibrium and the mass balance equation of pore fluid more realistic models, as Drucker-Prager and Mohr-Coulomb, for the rock stress-strain behaviour. The implementation of elastoplastic stress integration was based on modified Euler algorithm with error control proposed by Sloan (1987). In brittle rocks, as shales and some sandstones, drilling process changes mechanical and hydraulic properties of the material. After unloading in situ stress, due to excavation, this kind of material increases volume, developing fissures and decreasing strength (softening). Fissures development increases rock permeability, affecting the pore pressure distribution during and after excavation, which in turns, will influence the effective stress computation. The coupled hydro-mechanical modeling using more realistic models to describe the material stress-strain behaviour helps to a better comprehension of permeability variation induced by drilling process, that is explained consistent with the basic laws of continuum mechanics. Examples of laboratory tests and boundary value problems are presented showing the applicability of the numerical tool to well stability in brittle rocks

ASSUNTO(S)

permeabilidade mÃtodo dos elementos finitos elastoplasticidade permeability finite element method engenharia civil brittle rocks elasto-plasticity rochas frÃgeis hydro-mechanical coupling acoplamento hidro-mecÃnico

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