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:
Apr. 18, 1995
Filed:
Nov. 29, 1993
Peter D Wraight, Missouri City, TX (US);
Donald C McKeon, Houston, TX (US);
Schlumberger Technology Corporation, Houston, TX (US);
Abstract
A method and apparatus for detecting natural gamma-ray signals of an earth formation and correcting these gamma-ray signals for effects from borehole gamma-rays. Gamma-ray signals are detected at two detector locations in the borehole. The borehole effects are derived from the differences between the detected signals. After the borehole effects are determined, the detected gamma-ray signal is corrected for these effects and measurements of the formation elements are derived. A differential signal between the two detectors is created by excluding a small volume of borehole fluid from one of the detectors from the borehole fluid, before detecting gamma-rays at both detectors. The excluder displaces a known volume of borehole fluid equal to the volume of the excluder. Both detectors record gamma-ray generated from the formation and borehole. The additional volume of borehole fluid at one detector causes the detected signals to be different. This difference in signals is caused by the detection of the gamma-rays from the extra volume of fluid by the exposed detector. From this differential signal, correction parameters are derived to correct the signal for borehole effects caused by potassium in the borehole fluid, and thereby leave a signal indicative of natural gamma-rays from the earth formation.