The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 09, 2000
Filed:
Jan. 14, 1998
Leonty A Tabarovsky, Houston, TX (US);
Antonio Fabris, Houston, TX (US);
Alberto G Mezzatesta, Houston, TX (US);
Gregory B Itskovich, Houston, TX (US);
Western Atlas International, Inc., Houston, TX (US);
Abstract
An apparatus for determining radial distribution of resistivity of earth formations surrounding a wellbore. The apparatus includes a sonde mandrel having an insulating exterior surface and electrodes disposed on the insulating surface at spaced apart locations. The electrodes are connected to circuits for measuring a focused current resistivity within a predetermined longitudinal span. The electrodes are also connected to circuits for measuring electrical impedance between pairs of electrodes spaced apart at a plurality of different longitudinal spacings. The preferred embodiment includes a voltage measuring circuit interconnected between a pair of electrodes which is positioned between a closest spaced pair of electrodes connected to the impedance measuring circuits, so that a vertical resolution of the impedance measurements can be limited to approximately the axial spacing of the pair of electrodes connected to the voltage measuring circuit. A method according to the invention for determining the distribution of resistivity of earth formations surrounding a wellbore includes the steps of measuring a focused current resistivity of the earth formations to determine a composite resistivity of an uninvaded zone, an invaded zone and a flushed zone. Impedance is measured between pairs of electrodes, each pair having a different longitudinal spacing, and resistivity of the flushed zone and the invaded zone are determined from the measurements of impedance. The resistivity of the uninvaded zone can then be determined from the measurement of focused current resistivity.