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:
Dec. 22, 1998
Filed:
Oct. 18, 1996
Jan W Smits, Paris, FR;
Schlumberger Technology Corporation, Ridgefield, CT (US);
Abstract
A method and apparatus for determining the geometrical characteristics of a well, including insertion of a sonde of elongate shape into the well, the sonde including azimuth electrodes (A.sub.azi), an annular current electrode (A.sub.0), and at least one annular current return electrode (A). The annular current electrode (A.sub.0) emits a current I.sub.0, which flows essentially in a column of mud situated inside the well and returns to the annular current return electrodes. Signals are induced in response to the current I.sub.0 from which can be determined the geometrical characteristics of the well. Alternative embodiments include an apparatus which is symmetrical about the azimuth electrodes. High resolution measurements are obtained by computed focusing. In a first effective operating mode, currents i.sub.1 and i'.sub.1 are emitted from guard electrodes A.sub.1 and A'.sub.1 located on either side of the current electrode (A.sub.0,A'.sub.0), the current I.sub.0,1 emitted by the annular current electrode being equal to 0. In a second effective operating mode, a current I.sub.0,2 is emitted from the current electrode (A.sub.0,A'.sub.0) towards the guard electrodes, the total current I.sub.t,2 emitted from the sonde into the formation being equal to 0. Computed focusing is performed on the basis of the above two effective operating modes to simulate an operating mode in which (i) a current I.sub.0.c is emitted into the surrounding formation from the current electrode (A.sub.0,A'.sub.0); and (ii) the current I.sub.0,c is focused in the formation by emitting two currents I.sub.1,c and I'.sub.1,c from respectively the guard electrodes (A.sub.1,A'.sub.1).