US4096385A
Expired / Lapsed
US
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Clay content determination by natural gamma ray spectrometry
Assignee: Schlumberger Technology Corp
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Filing: 1977-02-14
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Granted: 1978-06-20
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Expires: 1997-02-14
Abstract
Abstract In accordance with an illustrative embodiment of the present invention, a technique is provided for automatically processing measurements of the total natural gamma radioactivity and the thorium, uranium, potassium contents of formations surrounding a borehole to obtain a representation of the clay content of said formations in a zone of the borehole where the presence of one of said elements, called a disturbing element, is not related to clay. First, reference values of the total radioactivity and the thorium, uranium, potassium contents in the zone are determined. Then, at least two of these measurements are combined in accordance with a function determined from the reference values to produce a representation of the clay content of the formations corrected for the effect of the disturbing element.
Inventors
- 👤 Graham Marett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:42
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/06
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
110 words
A method for automatically processing measurements of the total natural gamma radioactivity and the contents of three natural radioactive elements of a formation surrounding a borehole to obtain a representation of the clay content of said formation in a zone of the borehole where the presence of one of said elements, called a disturbing element, is not related to clay, comprising the steps of: determining reference values of said measurements in said zone; and combining at least two of said measurements in accordance with a function determined from said reference values to produce a representation of the clay content of the formation corrected for the effect of said disturbing element.
Claim 2
Independent Claim
110 words
A method for automatically processing measurements of the total natural gamma radioactivity and the contents of three natural radioactive elements of a formation surrounding a borehole to obtain a representation of the clay content of said formation in a zone of the borehole where the presence of one of said elements, called a disturbing element, is not related to clay, comprising the steps of: determining reference values of said measurements in said zone; and combining at least two of said measurements in accordance with a function determined from said reference values to produce a representation of the clay content of the formation corrected for the effect of said disturbing element.
Claim 3
Dependent Claim
26 words
The method of claim 1, wherein said combining step includes combining the measurements of the contents of the two radioactive elements other than the disturbing element.
Claim 4
Dependent Claim
45 words
The method of claim 2, wherein said step of determining reference values comprises the determination of first and second reference values of the contents of said two radioactive elements for the zone, respectively in substantially pure clay formations and in formations containing substantially no clay.
Claim 5
Dependent Claim
32 words
The method of claim 3, wherein said first and second reference values are respectively statistical maxima and statistical minima of the contents of each of said two radioactive elements in said zone.
Claim 6
Dependent Claim
62 words
The method of claim 3, wherein the determination of said function comprises: forming a linear combination of the contents of said two radioactive elements which takes on a first and second predetermined value for said first and second reference values respectively; and determining coefficients to be assigned to said two contents so that the statistical variations of said linear combination are minimized.
Claim 7
Dependent Claim
40 words
The method of claim 5, wherein the step of determining said coefficients includes: computing the standard deviation of said linear combination in substantially pure clay formations; and determining the value of said coefficients for which said standard deviation is minimum.
Claim 8
Dependent Claim
26 words
The method of claim 1, wherein said combining step includes combining the measurements of the total natural gamma radioactivity and the content of the disturbing element.
Claim 9
Dependent Claim
82 words
The method of claim 7, wherein said step of determining reference values comprises: the determination of first and second reference values of the total natural gamma radioactivity and the content of said disturbing element for the zone, respectively in substantially pure clay formations and in formations containing substantially no clay; and the determination of third reference values of the total natural gamma radioactivity and the content of said disturbing element for the zone within a calibration interval that contains the disturbing element.
Claim 10
Dependent Claim
59 words
The method of claim 8, wherein: said first and second reference values are respectively statistical maxima and minima of the total natural gamma radioactivity and the content of the disturbing element in said zone; and said third reference values are average values of the total natural gamma radioactivity and the content of the disturbing element in said calibration interval.
Claim 11
Dependent Claim
88 words
The method of claim 8, wherein the determination of said function comprises: forming a linear combination of the total natural gamma radioactivity and the content of said disturbing element which takes on a first and second predetermined value for said first and second reference values respectively; and determining coefficients to be assigned to the total natural gamma radioactivity and the content of the disturbing element so that said linear combination takes on an average value of the clay content within the calibration interval for said third reference values.
Claim 12
Dependent Claim
43 words
The method of claim 10, wherein said average value is obtained by combining the contents of the two radioactive elements other than the disturbing element in said calibration interval in accordance with a linear function determined from said first and second reference values.
Claim 13
Dependent Claim
63 words
The method of claim 11, wherein the determination of said linear function includes: forming a linear combination of the contents of said two radioactive elements which takes on a first and second predetermined value for said first and second reference values respectively; and determining coefficients to be assigned to said two contents so that the statistical variations of said linear combination are minimized.
Claim 14
Dependent Claim
28 words
The method of claim 10, wherein said average value is determined from the content of one of the elements other than the disturbing element in said calibration interval.
Claim 15
Dependent Claim
64 words
The method of claim 1, wherein said combining step includes combining, in accordance with a given function, a first function of at least the content of one of the two radioactive elements other than the disturbing element, determined from said reference values, and a second function of the total natural gamma radioactivity and the content of said disturbing element, determined from said reference values.
Claim 16
Dependent Claim
84 words
The method of claim 14, wherein said step of determining reference values comprises: the determination of first and second reference values of the total natural gamma radioactivity and the contents of the three radioactive elements for the zone, respectively in substantially pure clay formations and in formations containing substantially no clay; and the determination of third reference values of the total natural gamma radioactivity and the contents of the three radioactive elements for the zone within a calibration interval that contains the disturbing element.
Claim 17
Dependent Claim
62 words
The method of claim 15, wherein: said first and second reference values are respectively statistical maxima and statistical minima of the total natural gamma radioactivity and the contents of the three radioactive elements for the zone; and said third reference values are average values of the total natural gamma radioactivity and the contents of the three radioactive elements in said calibration interval.
Claim 18
Dependent Claim
73 words
The method of claim 15, wherein the determination of said first function comprises: forming a first linear combination of the contents of said two radioactive elements other than the disturbing element which takes on a first and second predetermined value for the first and second reference values respectively; and determining coefficients to be assigned to the contents of said two elements so that the statistical variations of said first linear combination are minimized.
Claim 19
Dependent Claim
41 words
The method of claim 17, wherein the step for determining said coefficients includes: computing the standard deviation of said first linear combination in substantially pure clay formations; and determining the value of said coefficients for which said standard deviation is minimum.
Claim 20
Dependent Claim
90 words
The method of claim 15, wherein the determination of said second function comprises: forming a linear combination of the total natural gamma radioactivity and the content of said disturbing element which takes on a first and second predetermined value for the first and second reference values respectively; and determining coefficients to be assigned to the total natural gamma radioactivity and the content of the disturbing element so that said second linear combination takes on an average value of the clay content within the calibration interval for said third reference values.
Claim 21
Dependent Claim
67 words
The method of claim 19, wherein said average value is obtained by: forming a linear combination of the contents of the two radioactive elements other than the disturbing element which takes on a first and second predetermined value for said first and second reference values respectively; and determining coefficients to be assigned to said two contents so that the statistical variations of said linear combination are minimized.
Claim 22
Dependent Claim
63 words
The method of claim 14, wherein the determination of said given function includes: forming a linear function of said first and second functions which takes on a first and second predetermined value for said first and second reference values respectively; and determining coefficients to be assigned to said first and second functions so that the statistical variations of said given function are minimized.
Claim 23
Independent Claim
118 words
A method for automatically processing natural gamma ray well logging data to obtain a representation of the clay content of a formation surrounding a borehole in a zone where the presence of a radioactive element, called a disturbing element, is not related to clay, comprising the steps of: deriving from said well logging data measurements of the total natural gamma radioactivity and the contents of three natural radioactive elements for said formation; determining reference values of said measurements in said zone; and combining at least two of said measurements in accordance with a function determined from said reference values to produce a representation of the clay content of the formation corrected for the effect of the disturbing element.
Claim 24
Independent Claim
118 words
A method for automatically processing natural gamma ray well logging data to obtain a representation of the clay content of a formation surrounding a borehole in a zone where the presence of a radioactive element, called a disturbing element, is not related to clay, comprising the steps of: deriving from said well logging data measurements of the total natural gamma radioactivity and the contents of three natural radioactive elements for said formation; determining reference values of said measurements in said zone; and combining at least two of said measurements in accordance with a function determined from said reference values to produce a representation of the clay content of the formation corrected for the effect of the disturbing element.
Claim 25
Dependent Claim
29 words
The method of claim 22, wherein said combining step includes combining in accordance with a linear function the contents of the two radioactive elements other than the disturbing element.
Claim 26
Dependent Claim
29 words
The method of claim 22, wherein said combining step includes combining in accordance with a linear function the total natural gamma radioactivity and the content of said disturbing element.
Claim 27
Dependent Claim
65 words
The method of claim 22, wherein said combining step includes combining in accordance with a linear function a first function of at least the content of one of the two radioactive elements other than the disturbing element determined from said reference values, and a second function of the total natural gamma radioactivity and the content of said disturbing element, also determined from said reference values.
Claim 28
Independent Claim
108 words
An apparatus for automatically processing measurements of the total natural gamma radioactivity and the contents of three natural radioactive elements of a formation surrounding a borehole to obtain a representation of the clay content of said formation in a zone where the presence of one of said elements, called a disturbing element, is not related to clay, comprising: means for determining reference values of said measurements in said zone; and means for combining at least two of said measurements in accordance with a function determined from said reference values to produce a representation of the clay content of the formation corrected for the effect of the disturbing element.
Claim 29
Independent Claim
108 words
An apparatus for automatically processing measurements of the total natural gamma radioactivity and the contents of three natural radioactive elements of a formation surrounding a borehole to obtain a representation of the clay content of said formation in a zone where the presence of one of said elements, called a disturbing element, is not related to clay, comprising: means for determining reference values of said measurements in said zone; and means for combining at least two of said measurements in accordance with a function determined from said reference values to produce a representation of the clay content of the formation corrected for the effect of the disturbing element.
Claim 30
Dependent Claim
31 words
The apparatus of claim 26, wherein said combining means includes means for combining in accordance with a linear function the contents of the two radioactive elements other than the disturbing element.
Claim 31
Dependent Claim
31 words
The apparatus of claim 26, wherein said combining means includes means for combining in accordance with a linear function the total natural gamma radioactivity and the content of said disturbing element.
Claim 32
Dependent Claim
55 words
The apparatus of claim 26, wherein said combining means includes means for combining in accordance with a linear function a function of at least the content of one of the two radioactive elements other than the disturbing element and a second function of the total natural gamma radioactivity and the content of said disturbing element.
Claim 33
Independent Claim
121 words
An apparatus for automatically processing natural gamma ray well logging data to obtain a representation of the clay content of a formation surrounding a borehole in a zone where the presence of a radioactive element, called a disturbing element, is not related to clay, comprising: means for deriving from said well logging data measurements of the total natural gamma radioactivity and the contents of three natural radioactive elements for said formation; means for determining reference values of said measurements in said zone; and means for combining at least two of said measurements in accordance with a function determined from said reference values to produce a representation of the clay content of the formation corrected for the effect of the disturbing element.
Claim 34
Independent Claim
121 words
An apparatus for automatically processing natural gamma ray well logging data to obtain a representation of the clay content of a formation surrounding a borehole in a zone where the presence of a radioactive element, called a disturbing element, is not related to clay, comprising: means for deriving from said well logging data measurements of the total natural gamma radioactivity and the contents of three natural radioactive elements for said formation; means for determining reference values of said measurements in said zone; and means for combining at least two of said measurements in accordance with a function determined from said reference values to produce a representation of the clay content of the formation corrected for the effect of the disturbing element.
References Cited (Backward Citations)
US3336476A
Cited
US3976878A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-06-19 | 1981-12-19 | 1982-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-19 | 1985-12-19 | 1986-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-19 | 1989-12-19 | 1990-06-20 | $7700.00 | Window Closed / Lapsed |