Downhole navigation and detection system
First Claim
Patent Images
1. An apparatus for evaluating an earth formation, the apparatus comprising:
- a logging tool configured to be conveyed in a borehole in the earth formation; and
a spinning mass gyroscope configured to provide an indication of an azimuthal orientation of the logging tool, the gyroscope including;
(i) at least one photodiode primarily responsive to light having a wavelength less than about 440 nm, and(ii) a light source configured to have an output matched to a response curve of the at least one photodiode.
1 Assignment
0 Petitions
Accused Products
Abstract
A photodiode whose long-wavelength cutoff is in the short-wavelength range (preferably, between ultraviolet and yellowish-green) having reduced temperature sensitivity is used in downhole applications. It may be matched with scintillation devices having an output matched to the response curve of the photodiode for use with nuclear logging devices. The photodiode may also be used in gyroscopes in which light from an LED matched to the photodiode is reflected from a spinning mass.
-
Citations
23 Claims
-
1. An apparatus for evaluating an earth formation, the apparatus comprising:
-
a logging tool configured to be conveyed in a borehole in the earth formation; and a spinning mass gyroscope configured to provide an indication of an azimuthal orientation of the logging tool, the gyroscope including; (i) at least one photodiode primarily responsive to light having a wavelength less than about 440 nm, and (ii) a light source configured to have an output matched to a response curve of the at least one photodiode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
-
-
12. A method of evaluating an earth formation, the method comprising:
-
conveying a logging tool into a borehole in the earth formation; and using a spinning mass gyroscope having at least one photodiode primarily responsive to light having a wavelength less than about 440 nm and a light source configured to have an output matched to a response curve of the at least one photodiode to provide an indication of an azimuthal orientation of the logging tool. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
-
-
22. A computer-readable medium product having stored thereon instructions that when read by a processor cause the processor to perform a method, the method comprising:
using an output of a formation evaluation sensor on a logging tool and an output of an azimuthal orientation sensor to provide an image of the earth formation wherein the azimuthal orientation sensor comprises a spinning mass gyroscope and at least one photodiode-primarily responsive to light having a wavelength less than about 440 nm and a light source configured to have an output matched to a response curve of the at least one photodiode. - View Dependent Claims (23)
Specification