US3665195A
Expired / Lapsed
US
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Thermal neutron activation radioactivity logging method
Assignee: Western Atlas International Inc
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Filing: 1969-10-16
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Granted: 1972-05-23
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Expires: 1989-10-16
Abstract
Abstract A method of determining the existence and quantity of an element in a formation. A portion of the formation is irradiated with neutrons and the gamma rays emanating from the formation due to induced radio-activity, or ''''activation'''' from thermal neutron capture by the element of interest are detected and recorded. The thermal neutron capture cross section of the formation is determined. The product of the gamma ray emission and the thermal neutron capture cross section is obtained as a quantitative indication of the element''s abundance in the formation.
Inventors
- 👤 Arthur H Youmans
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:55
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/10; G01V5/101; G01V5/107
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
87 words
A method of thermal neutron activation logging for determining the existence and quantity of at least one specific element in subsurface earth formations penetrated by a borehole comprising the steps of: irradiating the formations surrounding the borehole with neutrons, measuring activation radiation resulting from thermal neutron capture by an element of the formation, measuring the thermal neutron capture cross section of the formation, and deriving a quantity proportional to the product of the measured activation radiation and the measured thermal neutron capture cross section of the formation.
Claim 2
Independent Claim
87 words
A method of thermal neutron activation logging for determining the existence and quantity of at least one specific element in subsurface earth formations penetrated by a borehole comprising the steps of: irradiating the formations surrounding the borehole with neutrons, measuring activation radiation resulting from thermal neutron capture by an element of the formation, measuring the thermal neutron capture cross section of the formation, and deriving a quantity proportional to the product of the measured activation radiation and the measured thermal neutron capture cross section of the formation.
Claim 3
Dependent Claim
21 words
The method of claim 1 wherein the measured activation radiation is that resulting from thermal neutron capture by a preselected element.
Claim 4
Dependent Claim
11 words
The method of claim 2 wherein said preselected element is aluminum.
Claim 5
Dependent Claim
25 words
The method of claim 1 wherein the measured activation radiation is specific gamma radiation resulting from activation of a specific element by thermal neutron capture.
Claim 6
Dependent Claim
35 words
The method of claim 1 wherein the activation radiation is from a specific element and is measured to the exclusion of other radiation by selectively measuring gamma rays having energies characteristic of said specific element.
Claim 7
Dependent Claim
61 words
The method of claim 1 including the steps of determining the effect of natural gamma radiation from said formations on the measurement of activation radiation and subtracting said effect from the measurement of activation radiation, said subtraction being done prior to the step of deriving a quantity proportional to the product of the activation radiation and the neutron capture cross section.
Claim 8
Dependent Claim
79 words
The method of claim 1 wherein the step of measuring the thermal neutron capture cross section of the formation comprises the steps of: irradiating the formations surrounding the borehole with neutrons, detecting radiations from the formations during a first time interval, detecting radiations from the formations during a second time interval, and comparing the radiations detected during the first time interval with those detected during the second time interval as an indication of thE thermal neutron capture cross section.
Claim 9
Independent Claim
90 words
A method of activation logging in an earth borehole comprising the steps of: irradiating the formations surrounding the borehole with neutrons, measuring activation radiation resulting from thermal neutron capture by elements of the formations, correlated with depth in the borehole, measuring the thermal neutron capture cross section of the formations, correlated with depth in the borehole, deriving a quantity proportional to the product of the depth correlated activation radiation and the corresponding thermal neutron capture cross section for that depth, and recording said quantity correlated with depth in the borehole.
Claim 10
Independent Claim
90 words
A method of activation logging in an earth borehole comprising the steps of: irradiating the formations surrounding the borehole with neutrons, measuring activation radiation resulting from thermal neutron capture by elements of the formations, correlated with depth in the borehole, measuring the thermal neutron capture cross section of the formations, correlated with depth in the borehole, deriving a quantity proportional to the product of the depth correlated activation radiation and the corresponding thermal neutron capture cross section for that depth, and recording said quantity correlated with depth in the borehole.
Claim 11
Dependent Claim
19 words
The method of claim 8 wherein the measured activation radiation results from thermal neutron capture by a specific element.
Claim 12
Dependent Claim
11 words
The method of claim 9 wherein said specific element is aluminum.
Claim 13
Dependent Claim
24 words
The method of claim 10 including the steps of obtaining a silicon log and correcting the activation radiation measurement for the effect of silicon.
Claim 14
Dependent Claim
18 words
The method of claim 11 wherein the irradiating neutrons are predominantly neutrons having energies less than 3.9 mev.
Claim 15
Dependent Claim
15 words
The method of claim 12 wherein the neutrons are obtained from a californium-252 neutron source.
Claim 16
Dependent Claim
15 words
The method of claim 13 wherein a scintillation counter is employed as the radiation detector.
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) | 1975-05-23 | 1975-11-22 | 1976-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-23 | 1979-11-22 | 1980-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-23 | 1983-11-22 | 1984-05-23 | $7700.00 | Window Closed / Lapsed |