US3567936A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Multiple neutron detector borehole logging tool
Assignee: Schlumberger Technology Corp
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Filing: 1968-02-07
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Granted: 1971-03-02
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Expires: 1988-02-07
Abstract
Abstract An earth formation porosity logging tool in accordance with an illustrative embodiment of the invention comprises a neutron source and four neutron detectors spaced at different distances from the source for transport through a borehole. Signals are obtained that correspond to the ratios of the counts registered by the two short-spaced detectors and the two long-spaced detectors. The effect of the borehole characteristics on the formation porosity measurement is compensated by directly contrasting these ratio signals with each other. A second illustrative embodiment of the invention using only three neutron detectors also is shown and described.
Inventors
- 👤 Jay Tittman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:15
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/10; G01V5/107
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
280 words
A tool for measuring the porosity of an earth formation comprising a housing, one source of neutrons within said housing for irradiating the earth formation, a short-spaced neutron detector within said housing spaced from said one neutron source in the vicinity of about 16 inches to produce a signal that corresponds to the neutron distribution in the earth formation in response to neutrons from said one source, a long-spaced neutron detector within said housing spaced from said one neutron source in the vicinity of about 25 inches to produce a signal that corresponds to the neutron distribution in the earth formation in response to neutrons from said one source, neutron detecting apparatus within said housing spaced from said one neutron source a distance of less than about 16 inches to produce a signal that corresponds to the neutron distribution in the earth formation in response to neutrons from said one source, signal transmission means within said housing for processing said detector signals and said apparatus signal for transmission to the earth''s surface, amplification means on the earth''s surface for amplifying said processed signals, a first ratio circuit coupled to said amplification means for producing a signal that corresponds to the ratio beTween said long-spaced detector signal and said neutron detecting apparatus signal, a second ratio circuit coupled to said amplification means for producing a signal that corresponds to the ratio between said short-spaced detector signal and said neutron detecting apparatus signal, a function former circuit for combining said ratio signals in accordance with a preestablished response characteristic that produces an output signal that corresponds to the earth formation porosity, and a recorder for establishing a log of said porosity signal.
Claim 2
Dependent Claim
280 words
A tool for measuring the porosity of an earth formation comprising a housing, one source of neutrons within said housing for irradiating the earth formation, a short-spaced neutron detector within said housing spaced from said one neutron source in the vicinity of about 16 inches to produce a signal that corresponds to the neutron distribution in the earth formation in response to neutrons from said one source, a long-spaced neutron detector within said housing spaced from said one neutron source in the vicinity of about 25 inches to produce a signal that corresponds to the neutron distribution in the earth formation in response to neutrons from said one source, neutron detecting apparatus within said housing spaced from said one neutron source a distance of less than about 16 inches to produce a signal that corresponds to the neutron distribution in the earth formation in response to neutrons from said one source, signal transmission means within said housing for processing said detector signals and said apparatus signal for transmission to the earth''s surface, amplification means on the earth''s surface for amplifying said processed signals, a first ratio circuit coupled to said amplification means for producing a signal that corresponds to the ratio beTween said long-spaced detector signal and said neutron detecting apparatus signal, a second ratio circuit coupled to said amplification means for producing a signal that corresponds to the ratio between said short-spaced detector signal and said neutron detecting apparatus signal, a function former circuit for combining said ratio signals in accordance with a preestablished response characteristic that produces an output signal that corresponds to the earth formation porosity, and a recorder for establishing a log of said porosity signal.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |