US4950892A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and tool for gravel pack evaluation
Assignee: Schlumberger Technology Corp
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Filing: 1989-03-13
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Granted: 1990-08-21
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Expires: 2009-03-13
Abstract
Abstract A method for investigating a gravel pack located in the annulus between the tubing/screen and the casing of a borehole, comprising the steps of: moving a logging tool through the tubing/screen over the depth region of the gravel pack, said logging tool including a neutron source able to emit neutrons at such an energy that their interaction with a first set of atoms indicative of the gravel pack quality causes the production of gamma rays, and at least one gamma ray detector; and deriving a measurement of the number of gamma rays resulting from the interaction of said neutrons and said first set of atoms of the gravel pack material, and which are detected by said detector over a predetermined counting time interval.
Inventors
- 👤 Jean-Remy Olesen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 18:10
CPC Classifications
E; E21; E21B; E21B43/00; E21B43/02; E21B43/04; E21B47/00
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
123 words
A method for investigating a gravel pack located in the annulus between the tubing/screen and the casing of a borehole, comprising the steps of: moving a logging tool through the tubing/screen over the depth region of the gravel pack, said logging tool including a neutron source able to emit neutrons at such an energy that their interaction with a first set of atoms indicative of the gravel pack quality causes the production of gamma rays, and at least one gamma ray detector; and deriving a measurement of the number of gamma rays resulting from the interaction of said neutrons and said first set of atoms of the gravel pack material, and which are detected by said detector over a predetermined counting time interval.
Claim 2
Independent Claim
123 words
A method for investigating a gravel pack located in the annulus between the tubing/screen and the casing of a borehole, comprising the steps of: moving a logging tool through the tubing/screen over the depth region of the gravel pack, said logging tool including a neutron source able to emit neutrons at such an energy that their interaction with a first set of atoms indicative of the gravel pack quality causes the production of gamma rays, and at least one gamma ray detector; and deriving a measurement of the number of gamma rays resulting from the interaction of said neutrons and said first set of atoms of the gravel pack material, and which are detected by said detector over a predetermined counting time interval.
Claim 3
Dependent Claim
15 words
A method according to claim 1, wherein said first set of atoms includes silicon (Si).
Claim 4
Dependent Claim
69 words
A method according to claim 1, including the step of moving the tool in the well at a speed related to the half life of the gamma rays characteristic of a second set of atoms non representative of the gravel pack, the influence of said second set of atoms having to be minimized in the total count of gamma rays related to said first and second sets of atoms.
Claim 5
Dependent Claim
19 words
A method according to claim 3, in which said second set of atoms includes oxygen (O 16 ) atoms.
Claim 6
Independent Claim
47 words
A method according to one of claims 1 or 3, wherein said interaction is of the activation type, where emitted neutrons transmute the nucleus of atoms of said first set in an unstable isotope which in turn decays back to a stable state while emitting gamma rays.
Claim 7
Dependent Claim
16 words
A method according to claim 1 wherein said first set of atoms includes aluminum (Al) atoms.
Claim 8
Independent Claim
214 words
A method for investigating a gravel pack located in the annulus between the tubing/screen and the casing of a borehole, comprising the steps of: (a) moving a first logging tool, including a neutron source adapted to emit neutrons at such an energy that their interaction with a first set of atoms of gravel pack material produces gamma rays, and at least one first gamma ray detector, through the tubing/screen over the depth region of the gravel pack; (b) deriving a first measurement of the number of gamma rays resulting from the interaction of said neutrons and said first set of atoms of the gravel pack material, and detected by said first detector over a predetermined count time interval; (c) moving a second tool through the tubing/screen over the depth region of the gravel pack, said second logging tool including a gamma ray source adapted to emit gamma rays able to interact with said first set of atoms so that said emitted gamma rays are deviated and redirected, and at least a second gamma ray detector; (d) deriving a second measurement of the number of gamma rays deviated and redirected following their interaction with said first set of atoms, and detected by said second gamma ray detector; and (e) comparing said first and second measurements.
Claim 9
Independent Claim
214 words
A method for investigating a gravel pack located in the annulus between the tubing/screen and the casing of a borehole, comprising the steps of: (a) moving a first logging tool, including a neutron source adapted to emit neutrons at such an energy that their interaction with a first set of atoms of gravel pack material produces gamma rays, and at least one first gamma ray detector, through the tubing/screen over the depth region of the gravel pack; (b) deriving a first measurement of the number of gamma rays resulting from the interaction of said neutrons and said first set of atoms of the gravel pack material, and detected by said first detector over a predetermined count time interval; (c) moving a second tool through the tubing/screen over the depth region of the gravel pack, said second logging tool including a gamma ray source adapted to emit gamma rays able to interact with said first set of atoms so that said emitted gamma rays are deviated and redirected, and at least a second gamma ray detector; (d) deriving a second measurement of the number of gamma rays deviated and redirected following their interaction with said first set of atoms, and detected by said second gamma ray detector; and (e) comparing said first and second measurements.
Claim 10
Independent Claim
19 words
A method according to one of claims 1 or 7, wherein said neutron source is of the electronic type.
Claim 11
Dependent Claim
95 words
A tool for investigating a gravel pack located in the annulus between the tubing/screen and the casing of a borehole, comprising: a neutron source adapted to emit neutrons at such an energy that their interaction with a first set of atoms indicative of the gravel pack generates gamma rays; at least one gamma ray detector; and means for deriving a measurement of the number of gamma rays resulting from the interaction of said neutrons and said atoms of the gravel pack material, and which are detected by said detector over a predetermined counting time interval.
Claim 12
Dependent Claim
95 words
A tool for investigating a gravel pack located in the annulus between the tubing/screen and the casing of a borehole, comprising: a neutron source adapted to emit neutrons at such an energy that their interaction with a first set of atoms indicative of the gravel pack generates gamma rays; at least one gamma ray detector; and means for deriving a measurement of the number of gamma rays resulting from the interaction of said neutrons and said atoms of the gravel pack material, and which are detected by said detector over a predetermined counting time interval.
Claim 13
Dependent Claim
43 words
A tool according to claim 9, wherein said interaction is of the activation type, where emitted neutrons transmute the nucleus of atoms of said first set in an unstable isotope which in turn decays back to a stable state while emitting gamma rays.
Claim 14
Dependent Claim
15 words
A tool according to claim 9, wherein said neutron source is of the electronic type.
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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) | 1993-08-20 | 1994-02-19 | 1994-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-20 | 1998-02-19 | 1998-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-20 | 2002-02-19 | 2002-08-21 | $7700.00 | Window Closed / Lapsed |