Patent US3705304A successfully refreshed from Google Patents.
US3705304A
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US
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Pulsed neutron well logging apparatus having means to vary the neutron generator pulse repetition rate
Assignee: Western Atlas International Inc
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Filing: 1967-05-31
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Granted: 1972-12-05
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Expires: 1987-05-31
Abstract
Abstract A bistable multivibrator or scale of two circuit is inserted in the sync pulse line before a pulsed neutron generator to reduce the pulse repetition rate by a factor of two. The radiation detection system within the borehole instrument is gated in the conventional manner without the repetition rate of its detection gates being reduced by the factor of two. A second bistable multivibrator circuit is inserted in the sync pulse line before the sync pulse cable driver, the second multivibrator circuit causing the surface electronics to accept signal information during the first half of an elongated cycle which has not been corrected for activation background, and to accept information during the second half of the cycle which relates only to activation background. The signal information is combined with the background information to provide data relating to the decline of the thermal neutron population which is independent of the activation background counting rate.
Inventors
- 👤 Eric C Hopkinson
- 👤 Arthur H Youmans
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:16
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/10; G01V5/101; G01V5/102
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
116 words
A system for radioactivity well logging comprising a source of neutrons, a sync generator having a given pulse repetition rate, pulser means for causing said source to produce a discrete burst of neutrons, a scaler circuit connected between said sync generator and said pulser, whereby said source is caused to pulse at a repetition rate reduced by the scale circuit from said given pulse repetition rate, and radiation detection means including a first and a second gate connected to said sync generator and in spaced relationship to said neutron source, whereby each of said gates in said detection means is opened by the number of said scaler circuit for each time said neutron source is pulsed.
Claim 2
Independent Claim
116 words
A system for radioactivity well logging comprising a source of neutrons, a sync generator having a given pulse repetition rate, pulser means for causing said source to produce a discrete burst of neutrons, a scaler circuit connected between said sync generator and said pulser, whereby said source is caused to pulse at a repetition rate reduced by the scale circuit from said given pulse repetition rate, and radiation detection means including a first and a second gate connected to said sync generator and in spaced relationship to said neutron source, whereby each of said gates in said detection means is opened by the number of said scaler circuit for each time said neutron source is pulsed.
Claim 3
Dependent Claim
15 words
The system according to claim 1 wherein said scaler circuit comprises a scale of two.
Claim 4
Dependent Claim
62 words
The system according to claim 1 including a sync pulse cable driver and a second scaler circuit having the same number as said first mentioned scaler circuit connected between said sync generator and said cable driver, whereby the output of said cable driver has sync pulses having a pulse repetition rate the same as the pulse repetition rate of said neutron source.
Claim 5
Dependent Claim
16 words
The system according to claim 3 wherein said second scaler circuit comprises a scale of two.
Claim 6
Dependent Claim
66 words
The system according to claim 4 including a surface blanking circuit and three counting rate meters, two of said counting rate meters being respectively connected to said first and second gates during one portion of the time following each neutron pulse and the third counting rate meter being connected to at least one of said gates during another portion of the time following each neutron pulse.
Claim 7
Dependent Claim
29 words
The system according to claim 5 including means for subtracting the counting of said third counting rate meter from the respective counting rates of said two counting rate meters.
Claim 8
Dependent Claim
20 words
The system according to claim 5 including means for recording the counting rates from each of said counting rate meters.
Claim 9
Dependent Claim
37 words
The system according to claim 6 including means for recording the counting rates from said two counting rate meters after the counting rate from said third counting rate meter is respectively subtracted from each of the two.
Claim 10
Dependent Claim
32 words
The system according to claim 6 including means for deriving a function of the ratio of the counting rates of said two counting rate meters after subtraction of said third counting rate.
Claim 11
Dependent Claim
16 words
The system according to claim 9 wherein said function is the thermal neutron capture cross section.
References Cited (Backward Citations)
US3358142A
Cited
US3566116A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-12-05 | 1976-06-05 | 1976-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-12-05 | 1980-06-05 | 1980-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-12-05 | 1984-06-05 | 1984-12-05 | $7700.00 | Window Closed / Lapsed |