US3887805A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Measuring apparatus
Assignee: SLB NV
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Filing: 1973-04-16
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Granted: 1975-06-03
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Expires: 1993-04-16
Abstract
Abstract An illustrative embodiment of the invention discloses a borehole effects compensation technique for a neutron logging tool. A third neutron detector (or its physical equivalent) is joined to a two-neutron detector formation porosity logging tool. The third detector equivalent is positioned within the tool a distance relative to the neutron source and the other detectors that enables changes in the signal from the third detector caused by variations in the borehole environment to be generally distinguishable from changes in the signal from at least one of the other detectors. The signals from the third detector and one of the two other detectors are combined in order to compensate for the influence of the borehole environment.
Inventors
- 👤 Nick A Schuster
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:58
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/14; G01V5/10; G01V5/107
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
153 words
A borehole logging system for measuring the porosity of an earth formation comprising a housing, a first neutron source within said housing for establishing a neutron distribution in which the neutron intensity decreases with increasing separation from said source at rates that correspond to the formation and borehole conditions, a short-spaced neutron detector within said housing spaced from said source a sufficient distance to produce signals related to the earth formation porosity, a second neutron detector within said housing positioned beyond said first neutron source and said short-spaced detector to produce signals related to the earth formation porosity, a second neutron source within said housing for establishing an individual neutron distribution that characterizes the formation and borehole conditions, said second neutron source positioned within said housing adjacent to said second neutron detector a sufficiently short distance to at least a portion of said neutron detector to compensate said detector for the borehole conditions.
Claim 2
Dependent Claim
153 words
A borehole logging system for measuring the porosity of an earth formation comprising a housing, a first neutron source within said housing for establishing a neutron distribution in which the neutron intensity decreases with increasing separation from said source at rates that correspond to the formation and borehole conditions, a short-spaced neutron detector within said housing spaced from said source a sufficient distance to produce signals related to the earth formation porosity, a second neutron detector within said housing positioned beyond said first neutron source and said short-spaced detector to produce signals related to the earth formation porosity, a second neutron source within said housing for establishing an individual neutron distribution that characterizes the formation and borehole conditions, said second neutron source positioned within said housing adjacent to said second neutron detector a sufficiently short distance to at least a portion of said neutron detector to compensate said detector for the borehole conditions.
Claim 3
Dependent Claim
153 words
A borehole logging system for measuring the porosity of an earth formation comprising a housing, a first neutron source within said housing for establishing a neutron distribution in which the neutron intensity decreases with increasing separation from said source at rates that correspond to the formation and borehole conditions, a short-spaced neutron detector within said housing spaced from said source a sufficient distance to produce signals related to the earth formation porosity, a second neutron detector within said housing positioned beyond said first neutron source and said short-spaced detector to produce signals related to the earth formation porosity, a second neutron source within said housing for establishing an individual neutron distribution that characterizes the formation and borehole conditions, said second neutron source positioned within said housing adjacent to said second neutron detector a sufficiently short distance to at least a portion of said neutron detector to compensate said detector for the borehole conditions.
Claim 4
Dependent Claim
153 words
A borehole logging system for measuring the porosity of an earth formation comprising a housing, a first neutron source within said housing for establishing a neutron distribution in which the neutron intensity decreases with increasing separation from said source at rates that correspond to the formation and borehole conditions, a short-spaced neutron detector within said housing spaced from said source a sufficient distance to produce signals related to the earth formation porosity, a second neutron detector within said housing positioned beyond said first neutron source and said short-spaced detector to produce signals related to the earth formation porosity, a second neutron source within said housing for establishing an individual neutron distribution that characterizes the formation and borehole conditions, said second neutron source positioned within said housing adjacent to said second neutron detector a sufficiently short distance to at least a portion of said neutron detector to compensate said detector for the borehole conditions.
Claim 5
Dependent Claim
31 words
The logging system of claim 1 wherein said second neutron source is positioned on the opposite side of said second neutron detector from said first neutron source and short spaced detector.
Claim 6
Dependent Claim
21 words
The logging system of claim 2 wherein said second neutron source strength is less than that of said first neutron source.
Claim 7
Dependent Claim
21 words
The logging system of claim 1 wherein said second neutron source strength is less than that of said first neutron source.
Claim 8
Dependent Claim
155 words
A borehole logging tool for measuring the porosity of an earth formation comprising a housing, a first neutron source within said housing for establishing a neutron distribution in the earth formation characterized by neutron populations that decrease with increasing distance from said source at rates determined largely by the borehole and earth formation conditions, a pair of neutron detectors within said housing Spaced at different distances from said source for producing signals that indicate the earth formation porosity, and means responsive to changes primarily in said borehole conditions for correcting said formation porosity signals for said changes in the borehole conditions, said responsive means further comprising a second source of neutrons within said housing to establish a neutron distribution characterized by neutron populations that decrease with increasing distance from said second source, said second source being spaced from one of the neutron detectors in said detector pair a distance less than said first neutron source.
Claim 9
Dependent Claim
155 words
A borehole logging tool for measuring the porosity of an earth formation comprising a housing, a first neutron source within said housing for establishing a neutron distribution in the earth formation characterized by neutron populations that decrease with increasing distance from said source at rates determined largely by the borehole and earth formation conditions, a pair of neutron detectors within said housing Spaced at different distances from said source for producing signals that indicate the earth formation porosity, and means responsive to changes primarily in said borehole conditions for correcting said formation porosity signals for said changes in the borehole conditions, said responsive means further comprising a second source of neutrons within said housing to establish a neutron distribution characterized by neutron populations that decrease with increasing distance from said second source, said second source being spaced from one of the neutron detectors in said detector pair a distance less than said first neutron source.
Claim 10
Dependent Claim
28 words
The logging tool of claim 5 wherein said second neutron source is positioned on the opposite side of said pair of neutron detectors from said first neutron source.
Claim 11
Dependent Claim
29 words
The logging tool of claim 5 wherein the intensities of neutrons produced by said second neutron source are less than the intensities of neutrons produced by said first source.
Claim 12
Dependent Claim
15 words
The logging tool of claim 7 wherein both of said sources are continuous and unpulsed.
Claim 13
Dependent Claim
29 words
The logging tool of claim 5 wherein the intensities of neutrons produced by said second neutron source are less than the intensities of neutrons produced by said first source.
Claim 14
Dependent Claim
69 words
A tool for measuring the properties of an earth formation traversed by a borehole comprising: a housing, a first source of neutrons for establishing a first neutron distribution within the borehole and the earth formation, a second source means within said housing for establishing a second neutron distribution primarily influenced by the borehole environment, and detector means within said housing for responding to the first and second neutron distributions.
Claim 15
Dependent Claim
69 words
A tool for measuring the properties of an earth formation traversed by a borehole comprising: a housing, a first source of neutrons for establishing a first neutron distribution within the borehole and the earth formation, a second source means within said housing for establishing a second neutron distribution primarily influenced by the borehole environment, and detector means within said housing for responding to the first and second neutron distributions.
Claim 16
Dependent Claim
19 words
The logging tool of claim 10 wherein said neutron detector means is positioned between said primary and second sources.
Claim 17
Dependent Claim
23 words
The logging tool of claim 10 wherein said second source produces neutrons of lower intensities than the neutrons produced by said first source.
Claim 18
Dependent Claim
99 words
A well logging tool adapted for investigating an earth formation surrounding a borehole, said borehole having an environment which has an influence on the investigation of said earth formation, comprising neutron generating source means adapted for generating high energy neutrons having energy sufficient to penetrate in substantial numbers beyond the borehole and into the formation, said source means also adapted to generate low energy neutrons having energy sufficiently low to penetrate into said borehole environment in substantial numbers and into said earth formation in relatively insubstantial numbers, and first and second radioactive detectors adapted to respond to said neutrons.
Claim 19
Dependent Claim
99 words
A well logging tool adapted for investigating an earth formation surrounding a borehole, said borehole having an environment which has an influence on the investigation of said earth formation, comprising neutron generating source means adapted for generating high energy neutrons having energy sufficient to penetrate in substantial numbers beyond the borehole and into the formation, said source means also adapted to generate low energy neutrons having energy sufficiently low to penetrate into said borehole environment in substantial numbers and into said earth formation in relatively insubstantial numbers, and first and second radioactive detectors adapted to respond to said neutrons.
Claim 20
Dependent Claim
46 words
The apparatus of claim 13 wherein said first and second radioactive detectors produce first and second output signals in response to said neutrons and said apparatus further includes means for combining said first and second signals to produce a representation of at least one formation parameter.
Claim 21
Dependent Claim
32 words
The apparatus of claim 13 wherein said second detector responds to said high and low energy neutrons to produce an output signal which is compensated for the effects of the borehole environment.
Claim 22
Dependent Claim
108 words
A well logging tool adapted for investigating an earth formation surrounding a borehole that has a layer of material between said formation and borehole which has a disturbing influence on the investigation of said earth formation, comprising neutron generating source means adapted for generating high energy neutrons having energy sufficient to penetrate in substantial numbers beyond the material of disturbing influence and into the formation, said means also adapted to generate low energy neutrons having energy sufficiently low to penetrate said material of disturbing influence in substantial numbers and said earth formation in relatively insubstantial numbers, and first and second radioactive detectors adapted to respond to said neutrons.
Claim 23
Dependent Claim
108 words
A well logging tool adapted for investigating an earth formation surrounding a borehole that has a layer of material between said formation and borehole which has a disturbing influence on the investigation of said earth formation, comprising neutron generating source means adapted for generating high energy neutrons having energy sufficient to penetrate in substantial numbers beyond the material of disturbing influence and into the formation, said means also adapted to generate low energy neutrons having energy sufficiently low to penetrate said material of disturbing influence in substantial numbers and said earth formation in relatively insubstantial numbers, and first and second radioactive detectors adapted to respond to said neutrons.
Claim 24
Independent Claim
81 words
A method of investigating an earth formation surrouNding a borehole, said borehole having an environment which has an influence on the investigation of said earth formation, comprising generating high energy neutrons having energy sufficient to penetrate in substantial numbers beyond the borehole and into the formation, generating low energy neutrons having energy sufficiently low to penetrate into said borehole environment to substantial numbers and said earth formation in relatively insubstantial numbers, and producing first and second signals responsive to said neutrons.
Claim 25
Independent Claim
81 words
A method of investigating an earth formation surrouNding a borehole, said borehole having an environment which has an influence on the investigation of said earth formation, comprising generating high energy neutrons having energy sufficient to penetrate in substantial numbers beyond the borehole and into the formation, generating low energy neutrons having energy sufficiently low to penetrate into said borehole environment to substantial numbers and said earth formation in relatively insubstantial numbers, and producing first and second signals responsive to said neutrons.
Claim 26
Dependent Claim
27 words
The method of claim 17 further including the step of combining said first and second signals to produce a representation of at least one earth formation parameter.
Claim 27
Dependent Claim
41 words
The method of claim 17 wherein the step of producing first and second signals includes the step of producing a second signal in response to said high and low energy neutrons which is compensated for the effects of the borehole environment.
References Cited (Backward Citations)
US3240938A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-02 | 1978-12-02 | 1979-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-02 | 1982-12-02 | 1983-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-02 | 1986-12-02 | 1987-06-03 | $7700.00 | Window Closed / Lapsed |