Cícero Roberto Teixeira Régis

Numerical integration in the calculation of the 2.5‐D response of a very large loop

This work presents the details of a procedure for the numerical integration of Hankel transforms in the calculation of the electromagnetic fields generated by a large horizontal loop over a 2D earth. The method performs the integration by deforming the integration path into the complex plane and applying Cauchy’s theorem on a modified version of the integrand. The modification is the replacement of the Bessel functions J0 and J1 by the Hankel functions H (1) 0 and H (1) 1 . The integration on a path going up the complex plane allows us to take advantage of the vanishing properties of the Hankel functions, so that we can calculate on very small segments, instead of the infinite line of the original improper integrals. We have applied the method to calculate the fields of very large loops, at distances and depths which are prohibitive for the traditional numerical integration methods.

REVISITING SOME OLD UNEXPLAINED EFFECTS IN INDUCTION LOGS WITHIN LAMINATED FORMATIONS WITH THE TRIAXIAL INDUCTION TOOL

ABSTRACT . Modern induction triaxial or multicomponent well logging tools provide resistivity anisotropy logs, and estimates of the electrical resistivity of sand laminae in thinly laminated formations. In this paper, coaxial and coplanar vertical logs were modeled in one-dimensional (1D) laminated packages and in their equivalent anisotropic beds, neglecting the presence of the borehole and the invasion... Keywords: well logging, multicomponent induction tool, laminated reservoirs, electrical anisotropy. RESUMO. As atuais ferramentas de perfilagem em poco por inducao eletromagnetica, denominadas triaxias ou multicomponentes, fornecem perfis de anisotropia eletrica e permitem estimar a resistividade de lâminas de areia em ambientes finamente laminados. Neste artigo, os perfis dos arranjos coaxial e coplanar de bobinas foram simulados em modelos... Palavras-chave: perfilagem de poco, ferramentas multicomponetes, reservatorios laminados, anisotropia eletrica.