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:
Oct. 22, 2002
Filed:
Jul. 14, 2000
Steven Martin Hudson, Dorset, GB;
Flight Refuelling Ltd., Dorset, GB;
Abstract
A data transmission system for use in extracting data from a downhole location in a well is disclosed. The well has electrically conductive downhole structure ( ,C) which together with an earth return forms a signal circuit which is used to transmit data. A current source ( ) is provided at the wellhead for applying a reference signal to the downhole structure ( ,C). Effective impedance varying means ( ) are located downhole and used for varying the effective impedance of the signal circuit in dependence on data to be transmitted to the wellhead. Monitoring means ( ) for monitoring changes in the reference signal caused by varying the effective impedance of the signal circuit are located at the wellhead. Monitoring these changes allows data to be extracted. A separate reference earthing point may be provided for the monitoring means to alleviate the effect of imperfections in the earth connection (S) used to complete the signal circuit.