Simulação numerica do comportamento mecanico do sal em poços de petroleo

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

Drilling incidents such as stuck pipe and collapsed casing string take place when some type of salt formations are drilled because of the high pronounced plastic behavior of the salt and the creep behavior as a function of time of this type of rock. The creep behavior becomes faster and more severe if temperature and/or pressure acting on the salt go up. The deeper the salt is found, the earlier and more intense the troubles caused by salt creep will be evident. A compute r program was written to estimate the borehole closure rate in front of a salt zone. It simulates the relevant physical conditions expected to be found in the well that influence the salt mechanical behavior. The program can assist the drilling personnel during the design and the execution phases of the well. The computer program uses the finite element theory. The static behavior of the salt was approached by using the linear elastic laws over triangular elements in Plane Strain state. The quasi-static behavior, or the salt deformation with time (salt creep), was approached by a power law empirical equation of creep, used by most of the researchers in underground excavations projects of salt mines or atomic waste repositories. The equation mentioned above is used to represent the primary or transient creep and fits very good to the physical conditions considered in this work. The quasi-static equilibrium differential equations were derived from the virtual work principIe and were integrated over the time by the use of Euler s Explicit AIgorithm. The material isotropy and geometric linearity were assumed in this work. Simulations were done covering most of the drilling situations found while drilling through moving salt formations. The results are showed through graphical outputs with some pertinent comments

ASSUNTO(S)

poços de petroleo - perfuração sal viscoelasticidade

ACESSO AO ARTIGO

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