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:
Aug. 05, 2003
Filed:
Dec. 11, 2000
Paul L. Sinclair, Austin, TX (US);
CBG Corporation, Austin, TX (US);
Abstract
An apparatus and method is disclosed for induction logging of electrical properties of earth formations that operates at low frequencies while remaining resistant to skin effect and maintaining mutual balancing. The apparatus includes a plurality of transmitter coils that are at a plurality of distances from a measure point located at an end of the apparatus, and a receiver coil array coupled to receive induced voltages resulting from currents induced in the earth formations by one or more transmitters of the plurality of transmitter coils, wherein the common measure point is located within the receiver coil array, and wherein one or more of the plurality of distances from the measure point are determined according to a function of one or more frequencies associated with one or more transmitters of the plurality of transmitters. According to an embodiment, the function includes determining the distance that is inversely proportional to a square root of the frequency associated with the one or transmitter. In another embodiment, the distances include {square root over (2)}*N, {square root over (2)}/2*N, {square root over (2)}/4*N, 2N, N, N/2 and N/4, wherein N is a fixed distance such as one meter. An embodiment of the method includes subtracting signals received from a borehole compensation array disposed at the end of the tool from signals received at the receiver coil array, the subtracting reducing the influence of local changes in borehole diameter.