US5021653A
Expired / Lapsed
US
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Geochemical logging apparatus and method for determining concentrations of formation elements next to a borehole
Assignee: Schlumberger Technology Corp
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Filing: 1990-02-07
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Granted: 1991-06-04
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Expires: 2010-02-07
Abstract
Abstract Logging method and tool string for identifying and determining the concentrations of subsurface formation elements next to a borehole, by (i) using a low energy neutron source (either a chemical source, e.g. a 252 Cf, or a deuterium-deuterium electronic source), and (ii) detecting and counting the delayed gamma rays resulting from the activation by the neutrons of atoms of at least one element of interest (e.g. aluminum). Two gamma ray detectors may also be disposed on either side of the low energy neutron source, for detecting and counting the prompt gamma rays resulting from the capture of neutrons by atoms of elements, such as Si, Ca, Fe, S, H, or Cl, Gd, Ti, or K. The low energy neutron source is used for both the "activation" and the "capture" measurements. The tool string may also include a natural gamma ray tool for the determination of uranium, thorium and potassium, and for measuring the background to be subtracted from the gross Al activation measurement.
Inventors
- 👤 Brad Roscoe
- 👤 James Grau
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 23:37
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/10; G01V5/101
Claims Analysis
Total Claims: 45
Claim 1
Independent Claim
141 words
A method for identifying and determining the concentrations of subsurface formation elements, next to a borehole, including the steps of: (1) irradiating the formations with neutrons from a low energy neutron source disposed in a logging tool lowered in the borehole, said neutron source being the only neutron source disposed in the said logging tool; (2) and counting the delayed gamma rays resulting from the activation of atoms of at least of a first element by the neutrons emitted by said source; (3) deducing from the counts of activation gamma rays the concentration of said first element; (4) detecting and counting the prompt gamma rays resulting from the capture of the neutrons emitted by said source by atoms of at least a second element; and (5) deducing from the count rates of capture gamma rays the concentration of said second element.
Claim 2
Independent Claim
141 words
A method for identifying and determining the concentrations of subsurface formation elements, next to a borehole, including the steps of: (1) irradiating the formations with neutrons from a low energy neutron source disposed in a logging tool lowered in the borehole, said neutron source being the only neutron source disposed in the said logging tool; (2) and counting the delayed gamma rays resulting from the activation of atoms of at least of a first element by the neutrons emitted by said source; (3) deducing from the counts of activation gamma rays the concentration of said first element; (4) detecting and counting the prompt gamma rays resulting from the capture of the neutrons emitted by said source by atoms of at least a second element; and (5) deducing from the count rates of capture gamma rays the concentration of said second element.
Claim 3
Dependent Claim
31 words
The method according to claim 1 wherein the energy of said neutrons is such that the activation of atoms of an element which might interfere with said first element, is minimized.
Claim 4
Dependent Claim
17 words
The method according to claim 1 wherein said low energy neutron source is a chemical neutron source.
Claim 5
Dependent Claim
16 words
The method according to claim 3 wherein said chemical neutron source is a 252 Cf source.
Claim 6
Dependent Claim
12 words
The method according to claim 1 wherein said first element is aluminum.
Claim 7
Dependent Claim
12 words
The method according to claim 2 wherein said interfering element is silicon.
Claim 8
Dependent Claim
44 words
The method according to claim 1 further including the steps of detecting and counting the gamma rays resulting in count rates from the background natural activity, and subtracting said count rates from the count rates of the activation of atoms of said first element.
Claim 9
Dependent Claim
40 words
The method according to claim 1 wherein the step of deducing from the capture gamma rays the concentration of said second element, and the step of deducing from the activation gamma rays the concentration of said first element, are simultaneous.
Claim 10
Dependent Claim
175 words
A method according to claim 8 wherein said concentration of said first element and said concentration of said second element are derived from the respective elemental weight fractions "Wt i " which are expressed as: F Σ.sub.i [X.sub.i (C R.sub.i /S.sub.i)]+X.sub.k Wt.sub.k =1 where "Σ i " is a summation operator over the elements "i", "Wt i " is equal to F (CR i /S i ) and is the weight fraction of the element "i" determined from capture and activation measurements, "F" is a depth dependent normalization factor, "X i " is the ratio of the weight of the associated oxide or carbonate to the weight of the element "i", "CR i " is the total count rate from activation and capture, corrected for dead time and logging speed, and attributed to the element "i", "X k " and "Wt k " are inferred from natural activity measurements, "S i " is a relative spectral sensitivity factor of the corresponding element "i", and wherein said first element is included in said summation operator Σ.
Claim 11
Dependent Claim
26 words
The method according to claim 1 wherein said second element consists of Si, Ca, Fe, S, H, Cl, Gd, Ti, or K, or any combination thereof.
Claim 12
Dependent Claim
31 words
The method according to claim 1 wherein said step of detecting the capture gamma rays is carried out by two detectors disposed on either side of said low energy neutron source.
Claim 13
Dependent Claim
27 words
The method according to claim 1 further including detecting and counting the gamma rays resulting from the natural activity of atoms of at least a third element.
Claim 14
Dependent Claim
30 words
The method according to claim 1 further comprising detecting and counting the thermal or epithermal neutrons resulting from the interaction of the emitted neutrons with hydrogen atoms of the formation.
Claim 15
Dependent Claim
24 words
The method according to claim 1 further comprising surrounding said source with a shield comprising a material of high density, for absorbing gamma rays.
Claim 16
Dependent Claim
24 words
The method according to claim 1 further comprising surrounding said source with a shield comprising a material of low density for slowing down neutrons.
Claim 17
Independent Claim
99 words
A method for identifying and determining the concentrations of subsurface formation elements next to a borehole, including the steps of: (1) irradiating the formations with neutrons emitted by a low energy neutron electronic source disposed in a logging tool lowered in the borehole, said neutron source being the only neutron source disposed in the said logging tool; (2) detecting and counting the delayed gamma rays resulting from the activation of atoms of at least a first element by the neutrons emitted by said source; and (3) deducing from the counts of gamma rays the concentration of said first element.
Claim 18
Independent Claim
99 words
A method for identifying and determining the concentrations of subsurface formation elements next to a borehole, including the steps of: (1) irradiating the formations with neutrons emitted by a low energy neutron electronic source disposed in a logging tool lowered in the borehole, said neutron source being the only neutron source disposed in the said logging tool; (2) detecting and counting the delayed gamma rays resulting from the activation of atoms of at least a first element by the neutrons emitted by said source; and (3) deducing from the counts of gamma rays the concentration of said first element.
Claim 19
Dependent Claim
32 words
The method according to claim 16 wherein the energy of said neutrons is of such that the activation of atoms of an element which might interfere with said first element, is minimized.
Claim 20
Dependent Claim
14 words
The method according to claim 16 wherein said electronic source is a deuterium-deuterium source.
Claim 21
Dependent Claim
18 words
The method according to claim 17 wherein said first element is aluminum and said interfering element is silicon.
Claim 22
Dependent Claim
150 words
A logging tool for identifying and determining the concentrations of subsurface formation elements next to a borehole, comprising: (1) means for irradiating the formations with neutrons from a low energy neutron source disposed in a logging tool lowered in the borehole, said neutron source being the only neutron source disposed in the said logging tool; (2) means for detecting and means for counting the delayed gamma rays resulting from the activation by the neutrons of atoms of at least of a first element; (3) means for deducing from the counts of activation gamma rays the concentration of said first element; (4) means for detecting and means for counting the prompt gamma rays resulting from the capture of the neutrons emitted by said source by atoms of at least a second element; and (5) means for deducing from the count rates of capture gamma rays the concentration of said second element.
Claim 23
Dependent Claim
150 words
A logging tool for identifying and determining the concentrations of subsurface formation elements next to a borehole, comprising: (1) means for irradiating the formations with neutrons from a low energy neutron source disposed in a logging tool lowered in the borehole, said neutron source being the only neutron source disposed in the said logging tool; (2) means for detecting and means for counting the delayed gamma rays resulting from the activation by the neutrons of atoms of at least of a first element; (3) means for deducing from the counts of activation gamma rays the concentration of said first element; (4) means for detecting and means for counting the prompt gamma rays resulting from the capture of the neutrons emitted by said source by atoms of at least a second element; and (5) means for deducing from the count rates of capture gamma rays the concentration of said second element.
Claim 24
Dependent Claim
31 words
The tool according to claim 20 wherein the energy of said neutrons is such that the activation of atoms of an element which might interfere with said first element, is minimized.
Claim 25
Dependent Claim
13 words
The tool according to claim 20 wherein said source is a chemical source.
Claim 26
Dependent Claim
15 words
The tool according to claim 22 wherein said chemical source is a 252 Cf source.
Claim 27
Dependent Claim
18 words
The tool according to claim 20 wherein said first element is aluminum and said interfering element is silicon.
Claim 28
Dependent Claim
25 words
The tool according to claim 20 further comprising a shield surrounding said neutron source and comprising a material of high density, for absorbing gamma rays.
Claim 29
Dependent Claim
25 words
The tool according to claim 20 further comprising a shield surrounding said neutron source and comprising a material of low density, for slowing down neutrons.
Claim 30
Dependent Claim
47 words
The tool according to claim 20 further comprising means for detecting and means for counting the gamma rays resulting in count rates from the background natural activity, and means for subtracting said count rates from the count rates of the activation of atoms of said first element.
Claim 31
Dependent Claim
54 words
The tool according to claim 20 further comprising means for detecting and means for counting the gamma rays resulting from the capture of neutrons by atoms of a first plurality of elements, and means for deducing from the respective count rates of capture gamma rays relative to each element, the concentration of each element.
Claim 32
Dependent Claim
28 words
The tool according to claim 28 wherein said first plurality of elements consists of Si, Ca, Fe, S, H, Cl, Gd, Ti, or K, or any combination thereof.
Claim 33
Dependent Claim
29 words
The tool according to claim 28 wherein said means for detecting capture gamma rays includes two gamma ray detectors disposed on either side of said low energy neutron source.
Claim 34
Dependent Claim
31 words
The tool according to claim 20 further comprising means for detecting and means for counting the gamma rays resulting from the natural activity of atoms of at least a third element.
Claim 35
Dependent Claim
32 words
The tool according to claim 20 further comprising means for detecting and counting the thermal or epithermal neutrons resulting from the interaction of the emitted neutrons with hydrogen atoms of the formation.
Claim 36
Dependent Claim
102 words
A Logging tool for identifying and determining the concentrations of subsurface formation elements next to a borehole, including a housing comprising: (1) means for irradiating the formations with neutrons, in the form of a low energy neutron electronic source, said neutron source being the only neutron source disposed in the said logging tool; (2) means for detecting and means for counting the delayed gamma rays resulting from the activation of atoms of at least of a first element by the neutrons emitted by said source; and (3) means for deducing from the counts of gamma rays the concentration of said first element.
Claim 37
Dependent Claim
102 words
A Logging tool for identifying and determining the concentrations of subsurface formation elements next to a borehole, including a housing comprising: (1) means for irradiating the formations with neutrons, in the form of a low energy neutron electronic source, said neutron source being the only neutron source disposed in the said logging tool; (2) means for detecting and means for counting the delayed gamma rays resulting from the activation of atoms of at least of a first element by the neutrons emitted by said source; and (3) means for deducing from the counts of gamma rays the concentration of said first element.
Claim 38
Dependent Claim
31 words
The tool according to claim 33 wherein the energy of said neutrons is such that the activation of atoms of an element which might interfere with said first element, is minimized.
Claim 39
Dependent Claim
15 words
the tool according to claim 33 wherein said neutron electronic source is a deuterium-deuterium source.
Claim 40
Dependent Claim
168 words
A Logging tool for identifying and determining the concentrations of subsurface formation elements next to a borehole, comprising a housing in which are successively disposed, from top to bottom: (1) means for detecting and means for counting the gamma rays resulting from the natural activity of atoms of at least one element; (2) first means for detecting and means for counting the prompt gamma rays resulting from the capture of neutrons by atoms of at least another element; (3) means, in the form of a chemical neutron source, said neutron source being the only neutron source disposed in the said logging tool, for irradiating the formations with low energy neutrons; (4) second means for detecting and means for counting the prompt gamma rays resulting from the capture of neutrons by atoms of said another element; and (5) means for detecting and means for counting the delayed gamma rays resulting from the activation, by the neutrons emitted by said irradiating means, of atoms of at least a further element.
Claim 41
Dependent Claim
168 words
A Logging tool for identifying and determining the concentrations of subsurface formation elements next to a borehole, comprising a housing in which are successively disposed, from top to bottom: (1) means for detecting and means for counting the gamma rays resulting from the natural activity of atoms of at least one element; (2) first means for detecting and means for counting the prompt gamma rays resulting from the capture of neutrons by atoms of at least another element; (3) means, in the form of a chemical neutron source, said neutron source being the only neutron source disposed in the said logging tool, for irradiating the formations with low energy neutrons; (4) second means for detecting and means for counting the prompt gamma rays resulting from the capture of neutrons by atoms of said another element; and (5) means for detecting and means for counting the delayed gamma rays resulting from the activation, by the neutrons emitted by said irradiating means, of atoms of at least a further element.
Claim 42
Dependent Claim
166 words
A Logging tool for identifying and determining the concentrations of subsurface formation elements next to a borehole, comprising a housing including successively from top to bottom: (1) means for detecting and means for counting the gamma rays resulting from the natural activity of atoms of at least one element; (2) means for detecting and means for counting the prompt gamma rays resulting from the capture of neutrons by atoms of at least another element; (3) a chemical neutron source means, said neutron source being the only neutron source disposed in the said logging tool, for irradiating the formations with low energy neutrons; (4) means for detecting and counting, at two longitudinally spaced locations, the thermal or epithermal neutrons resulting from the interaction of the emitted neutrons with hydrogen atoms of the formation; and (5) means for detecting and means for counting the delayed gamma rays resulting from the activation, by the neutrons emitted by said chemical neutron source, of atoms of at least a further element.
Claim 43
Dependent Claim
166 words
A Logging tool for identifying and determining the concentrations of subsurface formation elements next to a borehole, comprising a housing including successively from top to bottom: (1) means for detecting and means for counting the gamma rays resulting from the natural activity of atoms of at least one element; (2) means for detecting and means for counting the prompt gamma rays resulting from the capture of neutrons by atoms of at least another element; (3) a chemical neutron source means, said neutron source being the only neutron source disposed in the said logging tool, for irradiating the formations with low energy neutrons; (4) means for detecting and counting, at two longitudinally spaced locations, the thermal or epithermal neutrons resulting from the interaction of the emitted neutrons with hydrogen atoms of the formation; and (5) means for detecting and means for counting the delayed gamma rays resulting from the activation, by the neutrons emitted by said chemical neutron source, of atoms of at least a further element.
Claim 44
Dependent Claim
177 words
A Logging tool for identifying and determining the concentrations of subsurface formation elements next to a borehole, comprising a housing including: (1) means for detecting and counting the gamma rays resulting from the natural activity of atoms of at least one element; (2) means for irradiating the formations with neutrons in the form of a low energy neutron electronic source, said neutron source being the only neutron source disposed in the said logging tool; (3) first means for detecting and counting the thermal or epithermal neutrons resulting from the interaction of said neutrons with hydrogen atoms of the formation; (4) means for detecting and means for counting the prompt gamma rays resulting from the capture of neutrons by atoms of at least another element; (5) second means for detecting and counting the thermal or epithermal neutrons resulting from the interaction of said neutrons with hydrogen atoms of the formation; and (6) means for detecting and means for counting the delayed gamma rays resulting from the activation by said neutrons of atoms of at least a further element.
Claim 45
Dependent Claim
177 words
A Logging tool for identifying and determining the concentrations of subsurface formation elements next to a borehole, comprising a housing including: (1) means for detecting and counting the gamma rays resulting from the natural activity of atoms of at least one element; (2) means for irradiating the formations with neutrons in the form of a low energy neutron electronic source, said neutron source being the only neutron source disposed in the said logging tool; (3) first means for detecting and counting the thermal or epithermal neutrons resulting from the interaction of said neutrons with hydrogen atoms of the formation; (4) means for detecting and means for counting the prompt gamma rays resulting from the capture of neutrons by atoms of at least another element; (5) second means for detecting and counting the thermal or epithermal neutrons resulting from the interaction of said neutrons with hydrogen atoms of the formation; and (6) means for detecting and means for counting the delayed gamma rays resulting from the activation by said neutrons of atoms of at least a further element.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-06-03 | 1994-12-03 | 1995-06-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-06-03 | 1998-12-03 | 1999-06-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-06-03 | 2002-12-03 | 2003-06-04 | $7700.00 | Window Closed / Lapsed |