US4381449A
Expired / Lapsed
US
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Neutron-inelastic gamma radiation well logging method and apparatus with background radiation accounted for
Assignee: Texaco Inc
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Filing: 1974-12-26
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Granted: 1983-04-26
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Expires: 1994-12-26
Abstract
Abstract Methods and apparatus are provided for making improved pulsed neutron derived measurements of the carbon: oxygen ratio in subsurface earth formations. Plural radiation measurements are made as a function of time from the initiation of the neutron pulse to distinguish inelastic and thermal neutron interactions. These measurements are then combined in several different manners to provide an improved carbon:oxygen ratio measurement and multiple porosity and formation lithology indication measurements.
Inventors
- 👤 Harry D. Smith, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:25
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/10; G01V5/101; G01V5/102
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
108 words
A system for observing earth formation properties comprising: means for irradiating the earth formation with a pulse of high energy neutrons; means for detecting over a broad energy band gamma radiation produced by the inelastic scattering of neutrons by nuclei of the formation elements during an interval of 10μ seconds or less in the early part of said neutron pulse and for producing signals in response thereto; and circuit means for converting said inelastic gamma ray signals to an output signal functionally related to inelastic gamma rays over a selected, broad energy band to provide an indication of the hydrogenous matter content of the earth formations under observation.
Claim 2
Independent Claim
108 words
A system for observing earth formation properties comprising: means for irradiating the earth formation with a pulse of high energy neutrons; means for detecting over a broad energy band gamma radiation produced by the inelastic scattering of neutrons by nuclei of the formation elements during an interval of 10μ seconds or less in the early part of said neutron pulse and for producing signals in response thereto; and circuit means for converting said inelastic gamma ray signals to an output signal functionally related to inelastic gamma rays over a selected, broad energy band to provide an indication of the hydrogenous matter content of the earth formations under observation.
Claim 3
Dependent Claim
26 words
A system according to claim 1, wherein said inelastic gamma radiation signal producing means comprises a radiation detector spaced several inches from said neutron irradiating means.
Claim 4
Dependent Claim
16 words
A system according to claim 1, wherein said output signal is an indication of formation porosity.
Claim 5
Independent Claim
107 words
A method for observing earth formation properties comprising the steps of: irradiating an earth formation with pulses of high energy neutrons; detecting over a wide energy band the gamma radiation produced by inelastic scattering of said neutrons by nuclei of earth formation elements during the time interval commencing after the initiation of each neutron pulse and terminating before thermal neutron absorption gamma radiation becomes predominant and generating signals in response thereto; and converting said inelastic gamma radiation signals to an output signal functionally related to inelastic gamma rays over a selected, broad energy band to provide an indication of hydrogenous matter content of earth formations under observation.
Claim 6
Independent Claim
107 words
A method for observing earth formation properties comprising the steps of: irradiating an earth formation with pulses of high energy neutrons; detecting over a wide energy band the gamma radiation produced by inelastic scattering of said neutrons by nuclei of earth formation elements during the time interval commencing after the initiation of each neutron pulse and terminating before thermal neutron absorption gamma radiation becomes predominant and generating signals in response thereto; and converting said inelastic gamma radiation signals to an output signal functionally related to inelastic gamma rays over a selected, broad energy band to provide an indication of hydrogenous matter content of earth formations under observation.
Claim 7
Dependent Claim
35 words
A method according to claim 4 wherein the time interval during which said inelastic scattering gamma radiation as detected is early in each neutron pulse and is of a duration not greater than 10μ seconds.
Claim 8
Independent Claim
100 words
A system for observing earth formation properties comprising: means for irradiating the earth formation with a pulse of high energy neutrons; means for detecting over a broad energy band gamma radiation produced by the inelastic scattering of said neutrons by nuclei of the formation elements during an interval of 10μ sec or less in the early part of said neutron pulse and for producing signals in response thereto; and circuit means responsive to detector signals produced by inelastic gamma rays over a selected, broad energy band, for providing an output signal indicative of a characteristic of the formation under observation.
Claim 9
Independent Claim
100 words
A system for observing earth formation properties comprising: means for irradiating the earth formation with a pulse of high energy neutrons; means for detecting over a broad energy band gamma radiation produced by the inelastic scattering of said neutrons by nuclei of the formation elements during an interval of 10μ sec or less in the early part of said neutron pulse and for producing signals in response thereto; and circuit means responsive to detector signals produced by inelastic gamma rays over a selected, broad energy band, for providing an output signal indicative of a characteristic of the formation under observation.
Claim 10
Dependent Claim
24 words
A system according to claim 6 wherein said inelastic gamma radiation signal producing means comprises a radiation detector spaced from said neutron irradiating means.
Claim 11
Independent Claim
101 words
A method for observing earth formation properties comprising the steps of: irradiating an earth formation with pulses of high energy neutrons; detecting over a wide energy band the gamma radiation produced by the inelastic scattering of said neutrons by nuclei of the earth formation elements during the time interval commencing after the initiation of each neutron pulse and terminating before thermal neutron absorption gamma radiation becomes predominant and generating signals in response thereto; and providing an output signal indicative of a characteristic of the formation under observation responsive to detector signals produced by gamma rays over a selected, broad energy band.
Claim 12
Independent Claim
101 words
A method for observing earth formation properties comprising the steps of: irradiating an earth formation with pulses of high energy neutrons; detecting over a wide energy band the gamma radiation produced by the inelastic scattering of said neutrons by nuclei of the earth formation elements during the time interval commencing after the initiation of each neutron pulse and terminating before thermal neutron absorption gamma radiation becomes predominant and generating signals in response thereto; and providing an output signal indicative of a characteristic of the formation under observation responsive to detector signals produced by gamma rays over a selected, broad energy band.
Claim 13
Dependent Claim
18 words
The method of claim 8 wherein said selected, broad energy band is at least 3 M.E.V. in width.
Claim 14
Dependent Claim
33 words
The method of claim 8 wherein said selected, broad energy band includes a carbon energy band at least 1.5 M.E.V. in width and an oxygen energy band at least 1.5 M.E.V. in width.
Claim 15
Dependent Claim
22 words
The method of claim 10 wherein said output signal is functionally related to the ratio of carbon to oxygen in the formation.
Claim 16
Dependent Claim
81 words
The method of claim 8 further comprising the steps of: deriving from said gamma radiation signals, a first indicating signal functionally related to carbon in the formation as indicated by carbon gamma rays between 3 and 4.7 M.E.V.; deriving from said gamma radiation signals, a second indicating signal functionally related to oxygen in the formation as indicated by oxygen gamma rays between 5 and 6.5 M.E.V.; and deriving as said output signal a ratio of said first and second indicating signals.
Claim 17
Dependent Claim
19 words
The method described in claim 8, wherein said output signal is functionally related to the porosity of said formation.
Claim 18
Dependent Claim
19 words
The method described in claim 8, wherein said output signal is functionally related to the lithology of said formation.
Claim 19
Dependent Claim
17 words
The method of claim 8, wherein said output signal is functionally related to hydrocarbons in said formation.
Claim 20
Dependent Claim
85 words
The method described in claim 8, including the steps of: deriving from said detected gamma radiation a first indicating signal functionally related to said detected inelastic scattering gamma rays; deriving from said first indicating signal a second indicating signal functionally related to a first element in said formation; deriving from said first indicating signal a third indicating signal functionally related to a second element in said formation; and deriving from said second and third indicating signals a functional representation of said characteristic of said formation.
Claim 21
Dependent Claim
30 words
The method described in claim 16, further including: deriving and recording a ratio of said second and third indicating signals as a functional representation of said characteristic of said formation.
Claim 22
Dependent Claim
60 words
The method described in claim 17, further including: deriving said second indicating signal as a functional indication of carbon in said formation; deriving said third indicating signal as a functional indication of oxygen in said formation; and deriving and recording a ratio of said second and third indicating signals as a functional representation of the hydrocarbon content of said formation.
Claim 23
Dependent Claim
88 words
The method described in claim 8, including the steps of: deriving from said detected gamma radiation a first indicating signal functionally related to said detected inelastic scattering gamma rays; deriving from said first indicating signal a second indicating signal functionally related to a first element in said formation; deriving from said first indicating signal a third indicating signal functionally related to a second element in said formation; and deriving and recording a ratio of said second and third indicating signals as a functional representation of a formation characteristic.
Claim 24
Dependent Claim
49 words
The method described in claim 19, including the steps of: deriving from said first indicating signal a fourth indicating signal functionally related to a third element in said formation; and deriving from said first indicating signal a fifth indicating signal functionally related to a fourth element in said formation.
Claim 25
Dependent Claim
32 words
The method described in claim 20, further including: deriving and recording the sum of said second, third, fourth and fifth indicating signals as a functional representation of the porosity of said formation.
Claim 26
Dependent Claim
30 words
The method described in claim 20, including the step of: deriving and recording a ratio of said fourth and fifth indicating signals as a functional representation of another formation characteristic.
Claim 27
Dependent Claim
60 words
The method described in claim 22, further comprising: deriving said second indicating signal as a functional indication of carbon in said formation; deriving said third indicating signal as a functional indication of oxygen in said formation; and deriving and recording a ratio of said second and third indicating signals as a functional representation of the hydrocarbon content of said formation.
Claim 28
Dependent Claim
59 words
The method described in claim 23, further comprising: deriving said fourth indicating signal as a functional indication of calcium in said formation; deriving said fifth indicating signal as a functional indication of silicon in said formation; and deriving and recording a ratio of said fourth and fifth indicating signals as a functional representation of the lithology of said formation.
Claim 29
Dependent Claim
82 words
The method described in claim 24, further comprising: deriving said second indicating signal as a functional indication of carbon in said formation; deriving said third indicating signal as a functional indication of oxygen in said formation; deriving a ratio of said second and third indicating signals; and deriving and recording a representation of the hydrocarbon content of said formation as a function of said ratio of said second and third indicating signals and said ratio of said fourth and fifth indicating signals.
Claim 30
Dependent Claim
44 words
The method described in claim 25, further including: deriving a functional representation of the porosity of said formation; and deriving and recording a representation of the hydrocarbon saturation of said formation as a function of said hydrocarbon content and the porosity of said formation.
Claim 31
Dependent Claim
67 words
The method described in claim 8, including the steps of: deriving a ratio of carbon to oxygen in said formation as a function of said output signal generated in response to said detected gamma rays produced by inelastic scattering of said neutrons; and deriving and recording a representation of the hydrocarbon content of said formation as a function of said ratio and the lithology of said formation.
Claim 32
Dependent Claim
48 words
The method described in claim 27, including the steps of: deriving a functional representation of the porosity of said formation; and deriving and recording a representation of the hydrocarbon saturation of said formation as a function of said representations of the porosity and hydrocarbon content of said formation.
Claim 33
Independent Claim
170 words
A system for observing earth formation properties comprising: means for irradiating the earth formation with a pulse of high energy neutrons; means for detecting gamma radiation produced by the inelastic scattering of said neutrons by nuclei in the earth formation during the time interval commencing after the initiation of each neutron pulse and terminating before thermal neutron absorption gamma radiation becomes predominant and generating a signal in response thereto; circuit means for deriving from said inelastic gamma radiation signal, a first indicating signal functionally related to carbon in the formation as indicated by gamma radiation detected over an energy band including 3 to 4.7 M.E.V.; circuit means for deriving from said inelastic gamma radiation signal, a second indicating signal functionally related to oxygen in the formation as indicated by gamma radiation detected over an energy band including 5 to 6.5 M.E.V.; and circuit means for deriving as an output signal a ratio of said first and second indicating signals as an indication of a characteristic of the formation under observation.
Claim 34
Independent Claim
170 words
A system for observing earth formation properties comprising: means for irradiating the earth formation with a pulse of high energy neutrons; means for detecting gamma radiation produced by the inelastic scattering of said neutrons by nuclei in the earth formation during the time interval commencing after the initiation of each neutron pulse and terminating before thermal neutron absorption gamma radiation becomes predominant and generating a signal in response thereto; circuit means for deriving from said inelastic gamma radiation signal, a first indicating signal functionally related to carbon in the formation as indicated by gamma radiation detected over an energy band including 3 to 4.7 M.E.V.; circuit means for deriving from said inelastic gamma radiation signal, a second indicating signal functionally related to oxygen in the formation as indicated by gamma radiation detected over an energy band including 5 to 6.5 M.E.V.; and circuit means for deriving as an output signal a ratio of said first and second indicating signals as an indication of a characteristic of the formation under observation.
Claim 35
Dependent Claim
19 words
The system of claim 29 wherein said first and second indicating signals are compensated for inelastic background gamma radiation.
Claim 36
Independent Claim
227 words
A method for observing earth formation properties comprising the steps of: (a) irradiating an earth formation with pulses of high energy neutrons; (b) detecting over a wide energy band the gamma radiation produced by the inelastic scattering of said neutrons by nuclei of the earth formation elements during the time interval commencing after the initiation of each neutron pulse and terminating before thermal neutron absorption gamma radiation becomes predominant and generating signals in response thereto; (c) detecting the gamma radiation produced by thermal neutron absorption by nuclei of the earth formation elements during another time interval during which said thermal neutron absorption gamma radiation predominates over said gamma radiation produced by the inelastic scattering of said neutrons and generating signals in response thereto; (d) providing an output signal indicative of a characteristic of the formation under observation responsive to detector signals produced by gamma rays over a selected, broad energy band by converting detector signals generated in response to said gamma radiation produced by inelastic scattering to a signal functionally related to the ratio of carbon to oxygen in the formation; and (e) providing another output signal indicative of a characteristic of the formation under observation by converting detector signals generated in response to said gamma radiation produced by thermal neutron capture to a signal functionally related to the ratio of silicon to calcium in the formation.
Claim 37
Independent Claim
227 words
A method for observing earth formation properties comprising the steps of: (a) irradiating an earth formation with pulses of high energy neutrons; (b) detecting over a wide energy band the gamma radiation produced by the inelastic scattering of said neutrons by nuclei of the earth formation elements during the time interval commencing after the initiation of each neutron pulse and terminating before thermal neutron absorption gamma radiation becomes predominant and generating signals in response thereto; (c) detecting the gamma radiation produced by thermal neutron absorption by nuclei of the earth formation elements during another time interval during which said thermal neutron absorption gamma radiation predominates over said gamma radiation produced by the inelastic scattering of said neutrons and generating signals in response thereto; (d) providing an output signal indicative of a characteristic of the formation under observation responsive to detector signals produced by gamma rays over a selected, broad energy band by converting detector signals generated in response to said gamma radiation produced by inelastic scattering to a signal functionally related to the ratio of carbon to oxygen in the formation; and (e) providing another output signal indicative of a characteristic of the formation under observation by converting detector signals generated in response to said gamma radiation produced by thermal neutron capture to a signal functionally related to the ratio of silicon to calcium in the formation.
References Cited (Backward Citations)
US3833809A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-04-25 | 1986-10-25 | 1987-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-04-25 | 1990-10-25 | 1991-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-04-25 | 1994-10-25 | 1995-04-26 | $7700.00 | Window Closed / Lapsed |