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:
Feb. 24, 1998
Filed:
Dec. 01, 1995
Melis Van Der Horst, GD Rijswijk, NL;
Shell Oil Company, Houston, TX (US);
Abstract
A method is provided for determining an electric conductivity of an earth formation formed of different earth layers, whereby a wellbore containing a wellbore fluid extends through said formation. The method includes lowering an induction logging tool into the wellbore to a location surrounded by a selected one of the earth layers, the tool including a magnetic field transmitter suitable to induce magnetic fields of different frequencies in said earth layers, and magnetic field receiver suitable to receive response magnetic fields at different spacings from the transmitter and to provide a signal representative of each response magnetic field. At least two of the different frequencies and at least two of the different spacings are selected, and for different combinations of each selected frequency and each selected spacing, the transmitter is operated so as to induce a magnetic field of the selected frequency in said earth layers, which magnetic field induces a corresponding response magnetic field near the tool. The receiver is operated at the selected spacing from the transmitter so as to provide a signal representing the response magnetic field. The signals are combined in a manner so as to create a combined signal having a reduced dependency on the electric conductivity in the wellbore region and the electric conductivity of an earth layer adjacent the selected layer.