Patent US4540399A successfully refreshed from Google Patents.
Patent US4208580A successfully refreshed from Google Patents.
US4208580A
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Lithology determination from the calcium and magnesium activation lines
Assignee: Schlumberger Technology Corp
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Filing: 1978-12-26
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Granted: 1980-06-17
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Expires: 1998-12-26
Abstract
Abstract In the illustrative embodiments of the invention disclosed, the lithology of an earth formation traversed by a well bore is investigated by irradiating the formation with a neutron source and generating an energy spectrum of the activation gamma rays resulting therefrom. From the spectrum thus obtained, the levels of the activation gamma radiation emitted by 27 Mg and that emitted by 49 Ca are determined. The two intensity measurements are then combined, e.g. by forming a cross-plot or ratio thereof, to provide an indication of the lithology of the earth formation and, in particular, of the extent of dolomitization of the formation.
Inventors
- 👤 Jeffrey S. Schweitzer
- 👤 Ralph M. Tapphorn
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:57
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/10; G01V5/101
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
116 words
A method for investigating the lithology of an earth formation traversed by a well bore, comprising the steps of: (a) irradiating an earth formation with neutrons of sufficient energy to produce therein the neutron activation reactions 26 Mg(n,γ) 27 Mg and 48 Ca(n,γ) 49 Ca; (b) measuring the level of gamma ray activity resulting from the decay of 27 Mg using a high resolution gamma ray detector; (c) measuring the level of gamma ray activity resulting from the decay of 49 Ca using a high resolution gamma ray detector; and (d) combining said 27 Mg gamma ray measurement and said 49 Ca gamma ray measurement to provide an indication of the lithology of the earth formation.
Claim 2
Independent Claim
116 words
A method for investigating the lithology of an earth formation traversed by a well bore, comprising the steps of: (a) irradiating an earth formation with neutrons of sufficient energy to produce therein the neutron activation reactions 26 Mg(n,γ) 27 Mg and 48 Ca(n,γ) 49 Ca; (b) measuring the level of gamma ray activity resulting from the decay of 27 Mg using a high resolution gamma ray detector; (c) measuring the level of gamma ray activity resulting from the decay of 49 Ca using a high resolution gamma ray detector; and (d) combining said 27 Mg gamma ray measurement and said 49 Ca gamma ray measurement to provide an indication of the lithology of the earth formation.
Claim 3
Dependent Claim
40 words
The method of claim 1 wherein the combining step comprises forming a ratio function of the 27 Mg gamma ray measurement and the 49 Ca gamma ray measurement, the value of said function providing an indication of the formation lithology.
Claim 4
Dependent Claim
33 words
The method of claim 2 further comprising the step of recording the 27 Mg and 49 Ca gamma ray measurements and the value of said ratio function as a function of tool depth.
Claim 5
Dependent Claim
41 words
The method of claim 2 wherein the numerator of said ratio function comprises one of said 27 Mg and 49 Ca gamma ray measurements and the denominator thereof comprises the sum of said 27 Mg and 49 Ca gamma ray measurements.
Claim 6
Dependent Claim
44 words
The method of claim 2 wherein the numerator of said ratio function comprises one of said 27 Mg and 49 Ca gamma ray measurements and the denominator thereof comprises the sum of said 27 Mg and 49 Ca gamma ray measurements plus another quantity.
Claim 7
Dependent Claim
40 words
The method of claim 5, further comprising the step of measuring the level of gamma ray activity resulting from the decay of an unstable isotope of Al, and wherein said another quantity is proportional to said Al gamma ray measurement.
Claim 8
Independent Claim
122 words
A method for investigating the lithology of an earth formation traversed by a well bore, comprising the steps of: (a) providing representations in the form of signals of the gamma ray activity resulting from the decay of 27 Mg following the activation thereof by neutron irradiation; (b) providing representations in the form of signals of the gamma ray activity resulting from the decay of 49 Ca following the activation thereof by neutron irradiation; (c) deriving separate measurements of the levels of said 27 Mg and said 49 Ca gamma ray activities from said respective representations; and (d) combining said 27 Mg gamma ray measurement and said 49 Ca gamma ray measurement to provide an indication of the lithology of the earth formation.
Claim 9
Independent Claim
122 words
A method for investigating the lithology of an earth formation traversed by a well bore, comprising the steps of: (a) providing representations in the form of signals of the gamma ray activity resulting from the decay of 27 Mg following the activation thereof by neutron irradiation; (b) providing representations in the form of signals of the gamma ray activity resulting from the decay of 49 Ca following the activation thereof by neutron irradiation; (c) deriving separate measurements of the levels of said 27 Mg and said 49 Ca gamma ray activities from said respective representations; and (d) combining said 27 Mg gamma ray measurement and said 49 Ca gamma ray measurement to provide an indication of the lithology of the earth formation.
Claim 10
Dependent Claim
40 words
The method of claim 7 wherein the combining step comprises forming a ratio function of the 27 Mg gamma ray measurement and the 49 Ca gamma ray measurement, the value of said function providing an indication of the formation lithology.
Claim 11
Dependent Claim
41 words
The method of claim 8 wherein the numerator of said ratio function comprises one of said 27 Mg and 49 Ca gamma ray measurements and the denominator thereof comprises the sum of said 27 Mg and 49 Ca gamma ray measurements.
Claim 12
Dependent Claim
44 words
The method of claim 8 wherein the numerator of said ratio function comprises one of said 27 Mg and 49 Ca gamma ray measurements and the denominator thereof commprises the sum of said 27 Mg and 49 Ca gamma ray measurements plus another quantity.
Claim 13
Dependent Claim
64 words
The method of claim 10 further comprising the steps of: providing representations in the form of signals of the level of gamma ray activity resulting from the decay of an unstable isotope for Al following the neutron irradiation thereof; deriving a measurement of the level of said Al gamma ray activity; and wherein said another quantity is proportional to said Al gamma ray measurement.
Claim 14
Dependent Claim
130 words
Apparatus for investigating the lithology of an earth formation traversed by a well bore comprising: (a) means for irradiating an earth formation with neutrons of sufficient energy to produce therein the neutron activation reactions 26 Mg(n,γ) 27 Mg and 48 Ca(n,γ) 49 Ca; (b) high resolution gamma ray detector means for detecting gamma rays resulting from the decay of unstable isotopes of the formation; (c) means coupled to said detector means for separately measuring the level of gamma ray activity resulting from the decay of 27 Mg and the level of gamma ray activity resulting from the decay of 49 Ca; and (d) means for combining the 27 Mg gamma ray measurement and the 49 Ca gamma ray measurement to provide an indication of the lithology of the earth formation.
Claim 15
Dependent Claim
130 words
Apparatus for investigating the lithology of an earth formation traversed by a well bore comprising: (a) means for irradiating an earth formation with neutrons of sufficient energy to produce therein the neutron activation reactions 26 Mg(n,γ) 27 Mg and 48 Ca(n,γ) 49 Ca; (b) high resolution gamma ray detector means for detecting gamma rays resulting from the decay of unstable isotopes of the formation; (c) means coupled to said detector means for separately measuring the level of gamma ray activity resulting from the decay of 27 Mg and the level of gamma ray activity resulting from the decay of 49 Ca; and (d) means for combining the 27 Mg gamma ray measurement and the 49 Ca gamma ray measurement to provide an indication of the lithology of the earth formation.
Claim 16
Dependent Claim
41 words
The apparatus of claim 12 wherein said combining means includes means for forming a ratio function of the 27 Mg gamma ray measurement and the 49 Ca gamma ray measurement, the value of said function providing an indication of formation lithology.
Claim 17
Dependent Claim
32 words
The apparatus of claim 13 further comprising means for recording the 27 Mg and 49 Ca gamma ray measurements and the value of said ratio function as a function of tool depth.
Claim 18
Dependent Claim
75 words
The apparatus of claim 13 wherein said combining means includes: means for forming the sum of said 27 Mg gamma ray measurement and said 49 Ca gamma ray measurement; and said ratio function forming means is operative to form said ratio function with one of said 27 Mg and 49 Ca gamma ray measurements as the numerator thereof and the sum of said 27 Mg and 49 Ca gamma ray measurements as the denominator thereof.
Claim 19
Dependent Claim
78 words
The apparatus of claim 13 wherein: said combining means includes means for forming the sum of said 27 Mg and 49 Ca gamma ray measurements plus another quantity; and said ratio function forming means is operative to form said ratio function with one of said 27 Mg and 49 Ca gamma ray measurements as the numerator thereof and the sum of said 27 Mg and 49 Ca gamma ray measurements and said another quantity as the denominator thereof.
Claim 20
Dependent Claim
44 words
The apparatus of claim 16 further comprising means coupled to said detector means for measuring the level of gamma ray activity resulting from the decay of an unstable isotope of Al, and wherein said another quantity is proportional to said Al gamma ray measurement.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1983-06-17 | 1983-12-17 | 1984-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-06-17 | 1987-12-17 | 1988-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-06-17 | 1991-12-17 | 1992-06-17 | $7700.00 | Window Closed / Lapsed |