US3858037A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Well-logging measuring apparatus and method
Assignee: Schlumberger Technology Corp
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Filing: 1973-01-18
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Granted: 1974-12-31
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Expires: 1993-01-18
Abstract
Abstract A specific embodiment of the invention provides a technique for identifying the mineral composition of an earth formation masked by a barite mudcake. The gamma radiation intensities on both sides of the K absorption limit for the barium in the mudcake are contracted with a normalized gamma radiation spectrum of the formation. The contrast indicates the nature of the mineral composition and some characteristics of the mudcake.
Inventors
- 👤 D Moore
- 👤 J Tittman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 04:36
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/12
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
121 words
A computer for analyzing characteristics of an earth formation traversed by a borehole wherein measurements for use by said computer are derived from a logging tool adapted to pass through a borehole while emitting gamma radiation into and detecting gamma radiation from a formation, comprising a first source of signals corresponding to detected gamma radiation and representative of detected photons of energies within a predetermined range which is less than about 33 keV and substantially greater than 0 keV, a second source of signals corresponding to detected gamma radiation and representative of detected photons of energies greater than about 39 keV, and circuit means for combining signals from said sources to produce a first output signal representative of a subsurface characteristic.
Claim 2
Dependent Claim
121 words
A computer for analyzing characteristics of an earth formation traversed by a borehole wherein measurements for use by said computer are derived from a logging tool adapted to pass through a borehole while emitting gamma radiation into and detecting gamma radiation from a formation, comprising a first source of signals corresponding to detected gamma radiation and representative of detected photons of energies within a predetermined range which is less than about 33 keV and substantially greater than 0 keV, a second source of signals corresponding to detected gamma radiation and representative of detected photons of energies greater than about 39 keV, and circuit means for combining signals from said sources to produce a first output signal representative of a subsurface characteristic.
Claim 3
Dependent Claim
89 words
A computer according to claim 1 and further including discriminator means responsive to said second source signals for producing a first group of signals that correspond to photon energies from about 39 keV to about 120 keV and a second group of signals that correspond to photon energies from about 240 keV to about 300 keV, and further circuit means for combining said first and second groups of signals to produce a second output signal for use with said first output signal for identifying characteristics of an earth formation.
Claim 4
Dependent Claim
22 words
A computer according to claim 1 wherein said first output signal is indicative of a mudcake on the wall of a borehole.
Claim 5
Dependent Claim
47 words
A computer according to claim 1 wherein said first source signals corresponds to photons of energies in the range of about 24 keV to about 33 keV and said second source signals correspond to photons of energies in the range of about 39 keV to 51 keV.
Claim 6
Dependent Claim
44 words
A computer according to claim 4 wherein said signals from said first and second sources are combined in accordance with a predetermined relationship to produce said first output signal, which first output signal is indicative of barite mudcake on the wall of a borehole.
Claim 7
Dependent Claim
30 words
A computer according to claim 2 and further including means for combining said first and second output signals to produce a signal representative of given characteristics of an earth formation.
Claim 8
Dependent Claim
23 words
A computer according to claim 5 wherein said predetermined relationship is the ratio of said first and second source signals to one another.
Claim 9
Dependent Claim
44 words
A computer according to claim 1 and further including discriminator means responsive to said second source signals for producing a first group of signals representative of a specified energy range for use with said first output signal in identifying characteristics of an earth formation.
Claim 10
Independent Claim
101 words
A method of analyzing characteristics of an earth formation traversed by a borehole from measurements derived from a logging tool adapted to pass through a borehole while emitting gamma radiation into and detecting gamma radiation from a formation, cOmprising deriving first measurements corresponding to detected gamma radiation and representative of detected photons of energies less than about 33 keV, deriving second measurements corresponding to detected gamma radiation and representative of detected photons of energies within at least one predetermined range greater than about 39 keV, combining said first and second measurements to produce a first output representative of a subsurface characteristic.
Claim 11
Independent Claim
101 words
A method of analyzing characteristics of an earth formation traversed by a borehole from measurements derived from a logging tool adapted to pass through a borehole while emitting gamma radiation into and detecting gamma radiation from a formation, cOmprising deriving first measurements corresponding to detected gamma radiation and representative of detected photons of energies less than about 33 keV, deriving second measurements corresponding to detected gamma radiation and representative of detected photons of energies within at least one predetermined range greater than about 39 keV, combining said first and second measurements to produce a first output representative of a subsurface characteristic.
Claim 12
Dependent Claim
90 words
The method of claim 9 and further including selecting only those of said second measurements which correspond to photon energies from about 39 keV to about 120 keV to produce a first group of measurements, and selecting only those of said second measurements which correspond to photon energies from about 240 keV to about 300 keV to produce a second group of measurements, and combining said first and second groups of measurements to produce a second output for use with said first output for identifying characteristics of an earth formation.
Claim 13
Dependent Claim
20 words
The method of claim 9 wherein said first output is indicative of a mudcake on the wall of said borehole.
Claim 14
Dependent Claim
44 words
The method of claim 9 wherein said first measurements correspond to photons of energies in the range of about 24 keV to about 33 keV and said second measurements correspond to photons of energies in the range of about 39 keV to 51 keV.
Claim 15
Dependent Claim
37 words
The method of claim 12 wherein said first and second measurements are combined in accordance with a predetermined relationship to produce said first output, which first output is indicative of mudcake on the wall of a borehole.
Claim 16
Dependent Claim
25 words
The method of claim 10 and further including combining said first and second outputs to produce a representation of given characteristics of an earth formation.
Claim 17
Dependent Claim
23 words
The method of claim 13 wherein said predetermined relationship is the ratio of representations of said first and second measurements to one another.
Claim 18
Dependent Claim
32 words
The method of claim 9 and further including selecting those of said second measurements within a specified energy range for use with said first output in identifying characteristics of an earth formation.
Claim 19
Dependent Claim
14 words
The method of claim 13 wherein said first output is indicative of mudcake thickness.
Claim 20
Dependent Claim
89 words
The method of claim 13 and further including the steps of selecting those of said second measurements which correspond to photon energies from about 39 keV to about 120 keV to produce third measurement representations, selecting those of said second measurements which correspond to photon energies from about 240 keV to 300 keV to produce fourth measurement representations, combining said third and fourth measurement representations to produce a second output, and combining said first and second outputs to produce an output representation of the constituents of the earth formation.
References Cited (Backward Citations)
US3108188A
Cited
US3139528A
Cited
US3435217A
Cited
US3368075A
Cited
US3521064A
Cited
US3532885A
Cited
US3514598A
Cited
US3465151A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-30 | 1978-07-01 | 1978-12-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-30 | 1982-07-01 | 1982-12-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-30 | 1986-07-01 | 1986-12-31 | $7700.00 | Window Closed / Lapsed |