US4317993A
Expired / Lapsed
US
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Methods and apparatus for constituent analysis of earth formations
Assignee: Schlumberger Technology Corp
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Filing: 1979-05-18
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Granted: 1982-03-02
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Expires: 1999-05-18
Abstract
Abstract In the illustrative embodiments of the invention disclosed, the composition of an earth formation is investigated by repetitively irradiating the formation with bursts of fast neutrons and generating an energy spectrum of the gamma rays resulting from the inelastic scattering of such neutrons by nuclei of the formation. The inelastic scattering gamma ray spectrum is analyzed by comparing it with a composite spectrum, made up of standard spectra of constituents postulated to comprise the formation, to determine the proportions in the formation of the postulated constituents. A background energy spectrum is generated from gamma rays detected during periods between neutron bursts and is utilized to provide one or more standard background spectra for use in the analysis of the inelastic scattering gamma ray spectra. The standard background spectrum or spectra are preferably updated on a repetitive basis to reflect the current background component in the detected inelastic scattering gamma ray spectrum. More reliable information is thereby obtained of the presence of oil in the formation through the derivation of such indicators as the carbon/oxygen ratio, calcium/silicon ratio and the like. Constituent analysis may also be made of the detected background gamma ray spectrum to determine the proportions of the formation constituents contributing to such spectrum, and the standards for the most significant background contributors or the composite spectrum produced by such standard spectra may be used among the standard spectra for the inelastic scattering spectrum analysis in lieu of the detected background spectrum itself.
Inventors
- 👤 Russel C. Hertzog, Jr.
- 👤 William B. Nelligan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 00:16
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/10; G01V5/104; G01V5/105
Claims Analysis
Total Claims: 64
Claim 1
Independent Claim
206 words
A method for investigating the composition of an earth formation traversed by a well bore, comprising the steps of: (a) repetitively irradiating the formation with time-spaced bursts of fast neutrons; (b) detecting gamma rays during first time periods related to the occurrence of the neutron bursts such that the detected gamma rays result predominately from inelastic scattering interactions between the incident neutrons and constituents of the formation; (c) detecting background gamma rays during second time periods between neutron bursts during which the detected gamma rays result predominately from interactions between incident neutrons and constituents of the formation other than inelastic scattering interactions; (d) generating an energy spectrum of the predominately inelastic scattering gamma rays detected in step (b); (e) generating an energy spectrum of the background gamma rays detected in step (c); (f) utilizing the background gamma ray spectrum to provide one or more standard background gamma ray spectra; and (g) comparing the predominately inelastic scattering gamma ray spectrum with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to said inelastic scattering gamma ray spectrum and including among said standard spectra said one or more standard background spectra, to determine the proportions in the formation of the postulated constituents.
Claim 2
Independent Claim
206 words
A method for investigating the composition of an earth formation traversed by a well bore, comprising the steps of: (a) repetitively irradiating the formation with time-spaced bursts of fast neutrons; (b) detecting gamma rays during first time periods related to the occurrence of the neutron bursts such that the detected gamma rays result predominately from inelastic scattering interactions between the incident neutrons and constituents of the formation; (c) detecting background gamma rays during second time periods between neutron bursts during which the detected gamma rays result predominately from interactions between incident neutrons and constituents of the formation other than inelastic scattering interactions; (d) generating an energy spectrum of the predominately inelastic scattering gamma rays detected in step (b); (e) generating an energy spectrum of the background gamma rays detected in step (c); (f) utilizing the background gamma ray spectrum to provide one or more standard background gamma ray spectra; and (g) comparing the predominately inelastic scattering gamma ray spectrum with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to said inelastic scattering gamma ray spectrum and including among said standard spectra said one or more standard background spectra, to determine the proportions in the formation of the postulated constituents.
Claim 3
Dependent Claim
27 words
The method of claim 1 wherein: said standard spectra include spectra for carbon and oxygen; and the comparing step includes determining the proportions of carbon and oxygen.
Claim 4
Dependent Claim
42 words
The method of claim 2 wherein: said standard spectra include a spectrum for each of one or more postulated constituents representative of the lithology of the formation; and the comparing step includes determining the proportion of each of the said lithology constituents.
Claim 5
Dependent Claim
13 words
The method of claim 3 wherein the lithology constituents comprise calcium and silicon.
Claim 6
Dependent Claim
46 words
The method of claim 1 further comprising comparing the background gamma ray spectrum with a composite spectrum, made up of weighted standard spectra of formation constituents postulated to have contributed to said background spectrum, to determine the proportions in the formation of the postulated background-contributing constituents.
Claim 7
Dependent Claim
27 words
The method of claim 5 further comprising the step of recording the proportions of the background-contributing constituents and the proportions of the inelastic scattering gamma ray-contributing constituents.
Claim 8
Dependent Claim
109 words
The method of claim 1 wherein: the repetition rate of the neutron bursts is sufficiently high that the background gamma ray occurring during the first detection periods result predominately from thermal neutron capture interactions between formation constituents and incident neutrons from the preceding neutron bursts; and the second time periods between neutron bursts during which the background gamma rays are detected are related to the preceding bursts such that the background gamma rays detected therein result predominately from thermal neutron capture interactions between formation constituents and incident neutrons from the preceding bursts, whereby the background gamma ray spectrum generated in step (e) predominately represents thermal neutron capture gamma rays.
Claim 9
Dependent Claim
55 words
The method of claim 7 further comprising comparing the predominately thermal neutron capture gamma ray spectrum with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to said predominately thermal neutron capture spectrum, to determine the proportions in the formation of the postulated thermal neutron capture gamma ray-contributing constituents.
Claim 10
Dependent Claim
49 words
The method of claim 1 wherein step (f) comprises: (1) normalizing the background gamma ray spectrum to the same total count as the other standard spectra; and (2) including the normalized background gamma ray spectrum among said standard spectra in step (g) as the standard background gamma ray spectrum.
Claim 11
Dependent Claim
76 words
The method of claim 1 wherein step (f) comprises: (1) comparing the background gamma ray spectrum with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to the background spectrum, to identify the constituents which have contributed significantly to the background spectrum; and (2) including among said standard spectra in step (g) the standard spectra of step (f) (1) for the background-contributing constituents identified as significant in step (f) (1).
Claim 12
Dependent Claim
58 words
The method of claim 10 wherein step (f) (1) comprises: determining the proportions in the formation of the postulated background-contributing constituents which produce a composite spectrum which most nearly matches the background spectrum; and determining which constituents have proportions at or greater than a predetermined level to identify the constituents which have contributed significantly to the background spectrum.
Claim 13
Dependent Claim
40 words
The method of claim 1 wherein step (e) further comprises repetitively updating the background gamma ray spectrum to account for variations during the detection and generation of the background spectrum in factors which affect the shape of the background spectrum
Claim 14
Dependent Claim
98 words
The method of claim 1 wherein step (f) comprises: (1) comparing the background gamma ray spectrum with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to the background spectrum, to determine the proportions in the formation of the postulated background-contributing constituents which produce a composite spectrum which most nearly matches the background spectrum; and (2) including among said standard spectra in step (g) as the standard background spectrum a composite spectrum produced from some or all of the background-constituent proportions determined in step (f) (1) and the corresponding background-constituent standard spectra.
Claim 15
Independent Claim
174 words
A method of investigating the composition of an earth formation, comprising the steps of: (a) providing an energy spectrum of gamma rays detected during first time periods related to a succession of time-spaced bursts of fast neutrons such that the detected gamma rays result predominately from inelastic scattering interactions between the incident neutrons and constituents of the formation; (b) providing an energy spectrum of background gamma rays detected during second time periods between said neutron bursts during which the detected gamma rays result predominately from interactions between the incident neutrons and constituents of the formation other than inelastic scattering interactions; (c) utilizing the background gamma ray spectrum to provide one or more standard background gamma ray spectra; and (d) comparing the predominately inelastic scattering gamma ray spectrum with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to said inelastic scattering gamma ray spectrum and including among said standard spectra said one or more standard background spectra, to determine the proportions in the formation of the postulated constituents.
Claim 16
Independent Claim
174 words
A method of investigating the composition of an earth formation, comprising the steps of: (a) providing an energy spectrum of gamma rays detected during first time periods related to a succession of time-spaced bursts of fast neutrons such that the detected gamma rays result predominately from inelastic scattering interactions between the incident neutrons and constituents of the formation; (b) providing an energy spectrum of background gamma rays detected during second time periods between said neutron bursts during which the detected gamma rays result predominately from interactions between the incident neutrons and constituents of the formation other than inelastic scattering interactions; (c) utilizing the background gamma ray spectrum to provide one or more standard background gamma ray spectra; and (d) comparing the predominately inelastic scattering gamma ray spectrum with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to said inelastic scattering gamma ray spectrum and including among said standard spectra said one or more standard background spectra, to determine the proportions in the formation of the postulated constituents.
Claim 17
Dependent Claim
27 words
The method of claim 14 wherein: said standard spectra include spectra for carbon and oxygen; and the comparing step includes determining the proportions of carbon and oxygen.
Claim 18
Dependent Claim
41 words
The method of claim 15 wherein: said standard spectra include a spectrum for each of one or more postulated constituents representative of the lithology of the formation; and the comparing step includes determining the proportion of each of the lithology constituents.
Claim 19
Dependent Claim
13 words
The method of claim 16 wherein the lithology constituents comprise calcium and silicon.
Claim 20
Dependent Claim
46 words
The method of claim 14 further comprising comparing the background gamma ray spectrum with a composite spectrum, made up of weighted standard spectra of formation constituents postulated to have contributed to said background spectrum, to determine the proportions in the formation of the postulated background-contributing constituents.
Claim 21
Dependent Claim
27 words
The method of claim 18 further comprising the step of recording the proportions of the background-contributing constituents and the proportions of the inelastic scattering gamma ray-contributing constituents.
Claim 22
Dependent Claim
110 words
The method of claim 14 wherein: the repetition rate of the neutron bursts was sufficiently high such that the background gamma rays which occurred during the first detection periods resulted predominately from thermal neutron capture interactions between formation constituents and incident neutrons from the preceding neutron bursts; and the second time periods between neutron bursts during which the background gamma rays were detected were related to the preceding bursts such that the background gamma rays detected resulted predominately from thermal neutron capture interactions between formation constituents and incident neutrons from the preceding bursts, whereby the background gamma ray spectrum provided in step (b) predominately represents thermal neutron capture gamma rays.
Claim 23
Dependent Claim
54 words
The method of claim 20 further comprising comparing the predominately thermal neutron capture gamma ray spectrum with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to said thermal neutron capture spectrum, to determine the proportions in the formation of the postulated thermal neutron capture gamma ray-contributing constituents.
Claim 24
Dependent Claim
46 words
The method of claim 14 wherein step (c) comprises: (1) normalizing the background gamma ray spectrum to the same total count as the other standard spectra; and (2) including the normalized background gamma ray spectrum among said standard spectra as the standard background gamma ray spectrum.
Claim 25
Dependent Claim
75 words
The method of claim 14 wherein step (c) comprises: (1) comparing the background gamma ray spectrum with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to the background spectrum, to identify the constituents which have contributed significantly to the background spectrum; and (2) including among said standard spectra in step (d) the standard spectra of step (c) (1) for the background-contributing constituents identified pursuant to step (c) (1).
Claim 26
Dependent Claim
58 words
The method of claim 23 wherein step (c) (1) comprises: determining the proportions in the formation of the postulated background-contributing constituents which produce a composite spectrum which most nearly matches the background spectrum; and determining which constituents have proportions at or greater than a predetermined level to identify the constituents which have contributed significantly to the background spectrum.
Claim 27
Dependent Claim
40 words
The method of claim 14 wherein step (b) further comprises repetitively updating the background gamma ray spectrum to account for variations during the detection and generation of the background spectrum in factors which affect the shape of the background spectrum.
Claim 28
Dependent Claim
98 words
The method of claim 14 wherein step (c) comprises: (1) comparing the background gamma ray spectrum with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to the background spectrum, to determine the proportions in the formation of the postulated background-contributing constituents which produce a composite spectrum which most nearly matches the background spectrum; and (2) including among said standard spectra in step (d) as the standard background spectrum a composite spectrum produced from some or all of the background-constituent proportions determined in step (c) (1) and the corresponding background-constituent standard spectra.
Claim 29
Dependent Claim
268 words
Apparatus for investigating the composition of an earth formation traversed by a well bore, comprising: (a) means for repetitively irradiating the formation with time-spaced bursts of fast neutrons; (b) means for detecting gamma rays resulting from interactions between the incident neutrons and constituents of the formation and for generating pulses representative of the energies of the detected gamma rays; (c) means responsive to the pulses from the detector means for segregating them into a plurality of channels according to the energies of the corresponding gamma rays, thereby to generate an energy spectrum of said corresponding rays; (d) means for controlling the operation of the spectrum generating means so as (1) to generate an energy spectrum of gamma rays detected during first time periods related to the occurrence of the neutron bursts such that the gamma rays detected therein result predominately from inelastic scattering neutron interactions and (2) to generate an energy spectrum of background gamma rays detected during second time periods between neutron bursts during which the detected gamma rays result predominately from neutron interactions other than inelastic scattering interactions; (e) means for utilizing signals representing the background gamma ray spectrum to provide signals representing one or more standard background gamma ray spectra; and (f) spectra-comparing means responsive to signals representing the predominately inelastic scattering gamma ray spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to said inelastic scattering gamma ray spectrum and including among said standard spectra said one or more standard background spectra, for determining the proportions in the formation of the postulated constituents.
Claim 30
Dependent Claim
268 words
Apparatus for investigating the composition of an earth formation traversed by a well bore, comprising: (a) means for repetitively irradiating the formation with time-spaced bursts of fast neutrons; (b) means for detecting gamma rays resulting from interactions between the incident neutrons and constituents of the formation and for generating pulses representative of the energies of the detected gamma rays; (c) means responsive to the pulses from the detector means for segregating them into a plurality of channels according to the energies of the corresponding gamma rays, thereby to generate an energy spectrum of said corresponding rays; (d) means for controlling the operation of the spectrum generating means so as (1) to generate an energy spectrum of gamma rays detected during first time periods related to the occurrence of the neutron bursts such that the gamma rays detected therein result predominately from inelastic scattering neutron interactions and (2) to generate an energy spectrum of background gamma rays detected during second time periods between neutron bursts during which the detected gamma rays result predominately from neutron interactions other than inelastic scattering interactions; (e) means for utilizing signals representing the background gamma ray spectrum to provide signals representing one or more standard background gamma ray spectra; and (f) spectra-comparing means responsive to signals representing the predominately inelastic scattering gamma ray spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to said inelastic scattering gamma ray spectrum and including among said standard spectra said one or more standard background spectra, for determining the proportions in the formation of the postulated constituents.
Claim 31
Dependent Claim
54 words
The apparatus of claim 27 further comprising spectra-comparing means responsive to signals representing the background gamma ray spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of formation constituents postulated to have contributed to said background spectrum, for determining the proportions in the formation of the postulated background-contributing constituents.
Claim 32
Dependent Claim
26 words
The apparatus of claim 28 further comprising means for recording the proportions of the background-contributing constituents and the proportions of the inelastic scattering gamma ray-contributing constituents.
Claim 33
Dependent Claim
109 words
The apparatus of claim 27 wherein: the irradiating means includes means for repeating the neutron bursts at a rate sufficiently high that the background gamma rays occurring during said first time periods result predominately from thermal neutron capture interactions between formation constituents and incident neutrons from the preceding neutron bursts; and the means for controlling the operation of the spectrum generating means so controls the occurrence of the second time periods that the background gamma rays detected therein result predominately from thermal neutron capture interactions between formation constituents and incident neutrons from the preceding neutron bursts, whereby the background gamma ray spectrum predominately represents thermal neutron capture gamma rays.
Claim 34
Dependent Claim
62 words
The apparatus of claim 30 further comprising spectra-comparing means responsive to signals representing the predominately thermal neutron capture gamma ray spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to said thermal neutron capture spectrum, for determining the proportions in the formation of the postulated thermal neutron capture gamma ray-contributing constituents.
Claim 35
Dependent Claim
59 words
The apparatus of claim 27 wherein the utilizing means of paragraph (e) comprises: (1) means for normalizing the signals representing the background gamma ray spectrum to the same total count as the other standard spectra; and (2) means for including signals representing the normalized background gamma ray spectrum among said standard spectra as the standard background gamma ray spectrum.
Claim 36
Dependent Claim
106 words
The apparatus of claim 27 wherein the utilizing means of paragraph (e) comprises: (1) spectra-comparing means responsive to the signals representing the background gamma ray spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to the background spectrum, for identifying the constituents which have contributed significantly to the background spectrum; and (2) means for including among said standard spectra employed by the spectra-comparing means of paragraph (f) signals representing the standard spectra employed by the spectra-comparing means of paragraph (e) (1) for the background-contributing constituents identified as significant by the means of paragraph (e) (1).
Claim 37
Dependent Claim
66 words
The apparatus of claim 33 wherein the spectra-comparing means of paragraph (e) (1) comprises: means for determining the proportions in the formation of the postulated background-contributing constituents which produce a composite spectrum which most nearly matches the background spectrum; and means for determining which constituents have proportions at or greater than a predetermined level to identify the constituents which have contributed significantly to the background spectrum.
Claim 38
Dependent Claim
45 words
The apparatus of claim 27 wherein the controlling means of paragraph (d) includes means for repetitively updating the background gamma ray spectrum to account for variation during the detection and generation of the background spectrum in factors which affect the shape of the background spectrum.
Claim 39
Dependent Claim
118 words
The apparatus of claim 27 wherein the utilizing means of paragraph (e) comprises: (1) spectra-comparing means responsive to signals representing the background gamma ray spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to the background spectrum, for determining the proportions in the formation of the postulated background-contributing constituents which produce a composite spectrum which most nearly matches the background spectrum; and (2) means for including among said standard spectra employed by the spectra-comparing means of paragraph (f) signals representing a composite spectrum produced from some or all of the background-constituent proportions determined by the spectra-comparing means of paragraph (e) (1) and the corresponding background-constituent standard spectra.
Claim 40
Dependent Claim
193 words
Apparatus for investigating the composition of an earth formation, comprising: (a) means for providing signals representing an energy spectrum of gamma rays detected during first time periods related to a succession of time-spaced bursts of fast neutrons such that the detected gamma rays result predominately from inelastic scattering interactions between the incident neutrons and constituents of the formation; (b) means for providing signals representing an energy spectrum of background gamma rays detected during second time periods between said neutron bursts during which the detected gamma rays result predominately from interactions between the incident neutrons and constituents of the formation other than inelastic scattering interactions; (c) means for utilizing the signals representing the background gamma ray spectrum to provide signals representing one or more standard background gamma ray spectra; and (d) spectra-comparing means responsive to signals representing the predominately inelastic scattering gamma ray spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to said inelastic scattering gamma ray spectrum and including among said standard spectra said one or more standard background spectra, for determining the proportions in the formation of the postulated constituents.
Claim 41
Dependent Claim
193 words
Apparatus for investigating the composition of an earth formation, comprising: (a) means for providing signals representing an energy spectrum of gamma rays detected during first time periods related to a succession of time-spaced bursts of fast neutrons such that the detected gamma rays result predominately from inelastic scattering interactions between the incident neutrons and constituents of the formation; (b) means for providing signals representing an energy spectrum of background gamma rays detected during second time periods between said neutron bursts during which the detected gamma rays result predominately from interactions between the incident neutrons and constituents of the formation other than inelastic scattering interactions; (c) means for utilizing the signals representing the background gamma ray spectrum to provide signals representing one or more standard background gamma ray spectra; and (d) spectra-comparing means responsive to signals representing the predominately inelastic scattering gamma ray spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to said inelastic scattering gamma ray spectrum and including among said standard spectra said one or more standard background spectra, for determining the proportions in the formation of the postulated constituents.
Claim 42
Dependent Claim
54 words
The apparatus of claim 37 further comprising spectra-comparing means responsive to signals representing the background gamma ray spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of formation constituents postulated to have contributed to said background spectrum, for determining the proportions in the formation of the postulated background-contributing constituents.
Claim 43
Dependent Claim
26 words
The apparatus of claim 38 further comprising means for recording the proportions of the background-contributing constituents and the proportions of the inelastic scattering gamma ray-contributing constituents.
Claim 44
Dependent Claim
59 words
The apparatus of claim 37 wherein the utilizing means of paragraph (c) comprises: (1) means for normalizing the signals representing the background gamma ray spectrum to the same total count as the other standard spectra; and (2) means for including signals representing the normalized background gamma ray spectrum among said standard spectra as the standard background gamma ray spectrum.
Claim 45
Dependent Claim
107 words
The apparatus of claim 37 wherein the utilizing means of paragraph (c) comprises: (1) spectra-comparing means responsive to the signals representing the background gamma ray spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to the background spectrum, for identifying the constituents which have contributed significantly to the background spectrum; and (2) means for including among the standard spectra employed by the spectra-comparing means of paragraph (d) signals representing the standard spectra employed by the spectra-comparing means of paragraph (c) (1) for those background-contributing constituents identified as significant by the spectra-comparing means of paragraph (c) (1).
Claim 46
Dependent Claim
66 words
The apparatus of claim 41 wherein the spectra-comparing means of paragraph (c) (1) comprises: means for determining the proportions in the formation of the postulated background-contributing constituents which produce a composite spectrum which most nearly matches the background spectrum; and means for determining which constituents have proportions at or greater than a predetermined level to identify the constituents which have contributed significantly to the background spectrum.
Claim 47
Dependent Claim
46 words
The apparatus of claim 37 wherein the spectrum providing means of paragraph (b) includes means for repetitively updating the background gamma ray spectrum to account for variations during the detection and generation of the background spectrum in factors which affect the shape of the background spectrum.
Claim 48
Dependent Claim
119 words
The apparatus of claim 37 wherein the utilizing means of paragraph (c) comprises: (1) spectra comparing means responsive to signals representing the background gamma ray spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to the background spectrum, for determining the proportions in the formation of the postulated background-contributing constituents which produce a composite spectrum which most nearly matches the background spectrum; and (2) means for including among said standard spectra employed by the spectra-comparing means of paragraph (d) signals representing a composite spectrum produced from some or all of the background-constituent proportions determined by the spectra-comparing means of paragraph (c) (1) and the corresponding background-constituent standard spectra.
Claim 49
Independent Claim
130 words
A method for investigating the composition of an earth formation traversed by a well bore, comprising the steps of: (a) generating an energy spectrum of radiation detected in the well bore and including (1) a component representative of the composition of the formation and (2) a component representative of background radiation; (b) generating an energy spectrum of said background component; (c) utilizing the background spectrum of step (b) to provide one or more standard background spectra; and (d) comparing the spectrum of step (a) with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to the spectrum of step (a) and including among said standard spectra said one or more standard background spectra, to determine the proportions in the formation of the postulated constituents.
Claim 50
Independent Claim
130 words
A method for investigating the composition of an earth formation traversed by a well bore, comprising the steps of: (a) generating an energy spectrum of radiation detected in the well bore and including (1) a component representative of the composition of the formation and (2) a component representative of background radiation; (b) generating an energy spectrum of said background component; (c) utilizing the background spectrum of step (b) to provide one or more standard background spectra; and (d) comparing the spectrum of step (a) with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to the spectrum of step (a) and including among said standard spectra said one or more standard background spectra, to determine the proportions in the formation of the postulated constituents.
Claim 51
Dependent Claim
47 words
The method of claim 45 further comprising comparing the background spectrum of step (b) with a composite spectrum, made up of weighted standard spectra of formation constituents postulated to have contributed to said background spectrum, to determine the proportions in the formation of the postulated background-contributing constituents.
Claim 52
Dependent Claim
43 words
The method of claim 45 wherein step (c) comprises: (1) normalizing the background spectrum to the same total count as the other standard spectra; and (2) including the normalized background spectrum among said standard spectra in step (d) as the standard background spectrum.
Claim 53
Dependent Claim
74 words
The method of claim 47 wherein step (c) comprises: (1) comparing the background spectrum with a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to the background spectrum, to identify the constituents which have contributed significantly to the background spectrum; and (2) including among said standard spectra in step (d) the standard spectra of step (c) (1) for the background-contributing constituents identified as significant in step (c) (1).
Claim 54
Dependent Claim
58 words
The method of claim 48 wherein step (c) (1) comprises: determining the proportions in the formation of the postulated background-contributing constituents which produce a composite spectrum which most nearly matches the background spectrum; and determining which constituents have proportions at or greater than a predetermined level to identify the constituents which have contributed significantly to the background spectrum.
Claim 55
Dependent Claim
61 words
The method of claim 45 further comprising: (e) repetitively generating the spectrum of step (a); (f) repetitively updating the background spectrum of step (b) to account for the variation in factors which affect the shape of the background spectrum; and (g) utilizing the updated background spectrum of step (f) in step (c) to provide said one or more standard background spectra.
Claim 56
Dependent Claim
62 words
The method of claim 45 wherein step (a) comprises: (1) repetitively irradiating the formation with time-spaced bursts of fast neutrons; and (2) generating said energy spectrum of gamma rays detected during time periods related to the occurrence of the neutron bursts such that the detected gamma rays result predominately from inelastic scattering interactions between the incident neutrons and constituents of the formation.
Claim 57
Dependent Claim
140 words
Apparatus for investigating the composition of an earth formation traversed by a well bore, comprising: (a) means for generating an energy spectrum of radiation detected in the well bore including (1) a component representative of the composition of the formation and (2) a component representative of background radiation; (b) means for generating an energy spectrum of said background component; (c) means for utilizing signals representing the background spectrum to provide signals representing one or more standard background spectra; and (d) spectra-comparing means responsive to signals representing the spectrum of step (a) and to signals representing a composite spectrum, made up of weighted standard spectra or constituents postulated to have contributed to the spectrum of step (a) and including among said standard spectra said one or more standard background spectra, for determining the proportions in the formation of the postulated constituents.
Claim 58
Dependent Claim
140 words
Apparatus for investigating the composition of an earth formation traversed by a well bore, comprising: (a) means for generating an energy spectrum of radiation detected in the well bore including (1) a component representative of the composition of the formation and (2) a component representative of background radiation; (b) means for generating an energy spectrum of said background component; (c) means for utilizing signals representing the background spectrum to provide signals representing one or more standard background spectra; and (d) spectra-comparing means responsive to signals representing the spectrum of step (a) and to signals representing a composite spectrum, made up of weighted standard spectra or constituents postulated to have contributed to the spectrum of step (a) and including among said standard spectra said one or more standard background spectra, for determining the proportions in the formation of the postulated constituents.
Claim 59
Dependent Claim
52 words
The apparatus of claim 52 further comprising spectra-comparing means responsive to signals representing the background spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of formation constituents postulated to have contributed to said background spectrum, for determining the proportions in the formation of the postulated background-contributing constituents.
Claim 60
Dependent Claim
53 words
The apparatus of claim 52 wherein the utilizing means of paragraph (c) comprises: (1) means for normalizing the signals representing the background spectrum to the same total count as the other standard spectra; and (2) means for including signals representing the normalized background spectrum among said standard spectra as the standard background spectrum.
Claim 61
Dependent Claim
104 words
The apparatus of claim 52 wherein the utilizing means of paragraph (c) comprises: (1) spectra-comparing means responsive to the signals representing the background spectrum and to signals representing a composite spectrum, made up of weighted standard spectra of constituents postulated to have contributed to the background spectrum, for identifying the constituents which have contributed significantly to the background spectrum; and (2) means for including among said standard spectra employed by the spectra-comparing means of paragraph (d) signals representing the standard spectra employed by the spectra-comparing means of paragraph (c) (1) for the background-contributing constituents identified as significant by the means of paragraph (c) (1).
Claim 62
Dependent Claim
66 words
The apparatus of claim 55 wherein the spectra-comparing means of paragraph (c) (1) comprises: means for determining the proportions in the formation of the postulated background-contributing constituents which produce a composite spectrum which most nearly matches the background spectrum; and means for determining which constituents have proportions at or greater than a predetermined level to identify the constituents which have contributed significantly to the background spectrum.
Claim 63
Dependent Claim
70 words
The apparatus of claim 52 further comprising: (e) means for repetitively generating the spectrum of paragraph (a); (f) means for repetitively updating the background spectrum of paragraph (b) to account for the variations in factors which affect the shape of the background spectrum; and (g) means for utilizing the updated background spectrum of paragraph (f) in the means of paragraph (c) to provide said one or more standard background spectra.
Claim 64
Dependent Claim
71 words
The apparatus of claim 52 wherein the spectrum generating means of paragraph (a) comprises: (1) means for repetitively irradiating the formation with time-spaced bursts of fast neutrons; and (2) means for generating said energy spectrum of gamma rays detected during time periods related to the occurrence of the neutron bursts such that the detected gamma rays result predominately from inelastic scattering interactions between the incident neutrons and constituents of the formation.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-03-01 | 1985-08-31 | 1986-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-03-01 | 1989-08-31 | 1990-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-03-01 | 1993-08-31 | 1994-03-02 | $7700.00 | Window Closed / Lapsed |