USRE28477E
Expired / Lapsed
US
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Method and apparatus for measuring neutron characteristics of a material surrounding a well bore
Assignee: Sensus Spectrum LLC
•
Filing: 1973-02-23
•
Granted: 1975-07-08
•
Expires: 1993-02-23
Abstract
Abstract In the particular embodiments of the invention described herein, the formation surrounding a well bore is irradiated with a burst of neutrons and the neutron concentration is observed during selected time intervals after irradiation to determine the thermal neutron decay time characterizing the formation. In one embodiment, the neutron concentration is observed during a first interval one decay time long and during a second and subsequent interval two decay times long which starts immediately after the first interval. In another embodiment the two intervals are spaced by one decay time.
Inventors
No inventors recorded.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 01:50
CPC Classifications
G; G01; G01V; G01V5/00; G01V5/04; G01V5/08; G01V5/10; G01V5/101; G01V5/102; G01V5/107; G01V5/108
Claims Analysis
Total Claims: 81
Claim 1
Independent Claim
119 words
A method for logging a characteristic of an unknown material comprising irradiatinG the material with neutrons during at least two spaced irradiation intervals, detecting indications of the neutron concentration in the material during first and second periods, respectively, after commencement of the corresponding irradiation interval, determining a neutron characteristic of the material from the detected indications occurring during at least one measurement interval during the respective periods, the time of occurrence of at least one measurement interval during the second period being variable, and controlling automatically the variable time of at least one measurement interval during the second period in accordance with the neutron characteristic determined from the indications detected during the first period in the same logging run.
Claim 2
Independent Claim
119 words
A method for logging a characteristic of an unknown material comprising irradiatinG the material with neutrons during at least two spaced irradiation intervals, detecting indications of the neutron concentration in the material during first and second periods, respectively, after commencement of the corresponding irradiation interval, determining a neutron characteristic of the material from the detected indications occurring during at least one measurement interval during the respective periods, the time of occurrence of at least one measurement interval during the second period being variable, and controlling automatically the variable time of at least one measurement interval during the second period in accordance with the neutron characteristic determined from the indications detected during the first period in the same logging run.
Claim 3
Dependent Claim
76 words
A method according to claim 1 including the steps of detecting indications of the thermal neutron concenetration in the material during the first and second periods, determining the thermal neutron decay time of the material from indications detected during the first period, and controlling the time of at least one measurement interval during the second period in a manner tending to optimize the measurement of neutron concentration indications for determination of the thermal neutron decay time.
Claim 4
Independent Claim
77 words
A method according to claim (3) 1 including the steps of detecting indications of the concentration in the material of neutrons having greater than thermal energy during the first and second periods, determining the neutron slowing down time from indications detected during the first period, and controlling the time of at least one measurement interval during the second period so as to optimize the measurement of neutron concentration indications for determination of the neutron slowing down time.
Claim 5
Independent Claim
187 words
A method for logging a characteristic of an unknown material comprising irradiating the material with neutrons during at least two spaced irradiation intervals, detecting indications of the neutron concentration in the material during first and second periods, respectively, after commencement of the corresponding irradiation interval, measuring the detected indications at least during a first measurement interval occurring at first times during the respective periods and during a second measurement interval occurring at second times during the respective periods, at least one of the second irradiation interval, the first and second times in the second period, and the first and second measurement intervals during the second period being variable, determining a neutron characteristic of the material from the measurements made during the first and second measurement intervals in the first period, and controlling automatically the duration of at least one of the second irradiation interval, the first and second times in the second period, and the first and second measurement intervals in the second period, in accordance with the neutron characteristic of the material determined from the measurements made during the first period of the same logging run.
Claim 6
Independent Claim
187 words
A method for logging a characteristic of an unknown material comprising irradiating the material with neutrons during at least two spaced irradiation intervals, detecting indications of the neutron concentration in the material during first and second periods, respectively, after commencement of the corresponding irradiation interval, measuring the detected indications at least during a first measurement interval occurring at first times during the respective periods and during a second measurement interval occurring at second times during the respective periods, at least one of the second irradiation interval, the first and second times in the second period, and the first and second measurement intervals during the second period being variable, determining a neutron characteristic of the material from the measurements made during the first and second measurement intervals in the first period, and controlling automatically the duration of at least one of the second irradiation interval, the first and second times in the second period, and the first and second measurement intervals in the second period, in accordance with the neutron characteristic of the material determined from the measurements made during the first period of the same logging run.
Claim 7
Dependent Claim
34 words
A method according to claim 4 wherein the duration of the first time in the second period is controlled in accordance with the neutron characteristic determined from the measurements made during the first period.
Claim 8
Dependent Claim
34 words
A method according to claim 4 wherein the duration of the second time in the second period is controlled in accordance with the neutron characteristic determined from the measurements made during the first period.
Claim 9
Dependent Claim
35 words
A method according to claim 4 wherein the duration of the first measurement interval in the second period is controlled in accordance with the neutron characteristic determined from the measurements made during the first period.
Claim 10
Dependent Claim
35 words
A method according to claim 4 wherein the duration of the second measurement interval in the second period is controlled in accordance with the neutron characteristic determined from the measurements made during the first period.
Claim 11
Dependent Claim
35 words
A method according to claim 4 wherein the duration of the seconD irradiation interval in the second period is controlled in accordance with the neutron characteristic determined from the measurements made during the first period.
Claim 12
Dependent Claim
37 words
A method according to claim 4 wherein the durations of the first and second selected times in the second period are controlled in accordance with the neutron characteristic determined from the measurements made during the first period.
Claim 13
Dependent Claim
37 words
A method according to claim 4 wherein the durations of the first and second measurement intervals in the second period are controlled in accordance with the neutron characteristic determined from the measurements made during the first period.
Claim 14
Dependent Claim
42 words
A method according to claim 4 wherein the neutron characteristic of the material is determined by comparing the measurement made during the first measurement interval of the first period with the measurement made during the second measurement interval of the first period.
Claim 15
Dependent Claim
46 words
A method according to claim 4 wherein the first measurement interval has a duration approximately equal to a neutron characteristic time constant of the material and the second measurement interval has a duration approximately equal to twice the same neutron characteristic time constant of the material.
Claim 16
Dependent Claim
16 words
A method according to claim 4 wherein the first and second measurement intervals are substantially contiguous.
Claim 17
Dependent Claim
29 words
A method according to claim 4 wherein the first and second measurement intervals are spaced by an interval approximately equal to a neutron characteristic time constant of the material.
Claim 18
Dependent Claim
51 words
A method according to claim 4 wherein the first and second measurement intervals are within a time period extending from about twice the characteristic time constant of the material after the corresponding irradiation interval to about six times the neutron characteristic time constant of the material after the corresponding irradiation interval.
Claim 19
Dependent Claim
26 words
A method according to claim 4 wherein the duration of the irradiation intervals is approximately equal to twice the neutron characteristic time constant of the material.
Claim 20
Independent Claim
240 words
A method for logging a characteristic of an unknown material comprising irradiating the material with neutrons during at least two spaced irradiation intervals, detecting indications of the neutron concentration in the material during first and second periods, respectively, after commencement of the corresponding irradiation interval, measuring the detected indications at least during a first measurement interval occurring at first times during the respective periods and during a second measurement interval occurring at second times during the respective periods, at least one of the second irradiation interval, the first and second times in the second period, and the first and second measurement intervals during the second period being variable, determining a neutron characteristic of the material from the measurements made during the first and second measurement intervals in the first period, controlling automatically the duration of at least one of the second irradiation interval, the first and second times in the second period, and the first and second measurement intervals in the second period, in accordance with the neutron characteristic of the material determined from the measurements made during the first period of the same logging run, measuring detected indications representative of background radiation during a third measurement interval occurring at third times during the first and second periods, respectively, and subtracting the measurement obtained during the third measurement interval from the measurements obtained during the first and second measurement intervals in the same logging run in determining the neutron characteristic.
Claim 21
Independent Claim
240 words
A method for logging a characteristic of an unknown material comprising irradiating the material with neutrons during at least two spaced irradiation intervals, detecting indications of the neutron concentration in the material during first and second periods, respectively, after commencement of the corresponding irradiation interval, measuring the detected indications at least during a first measurement interval occurring at first times during the respective periods and during a second measurement interval occurring at second times during the respective periods, at least one of the second irradiation interval, the first and second times in the second period, and the first and second measurement intervals during the second period being variable, determining a neutron characteristic of the material from the measurements made during the first and second measurement intervals in the first period, controlling automatically the duration of at least one of the second irradiation interval, the first and second times in the second period, and the first and second measurement intervals in the second period, in accordance with the neutron characteristic of the material determined from the measurements made during the first period of the same logging run, measuring detected indications representative of background radiation during a third measurement interval occurring at third times during the first and second periods, respectively, and subtracting the measurement obtained during the third measurement interval from the measurements obtained during the first and second measurement intervals in the same logging run in determining the neutron characteristic.
Claim 22
Independent Claim
269 words
A method for logging a characteristic of an unknown material comprising irradiating the material with neutrons during at least two spaced irradiation intervals, detecting indications of the neutron concentration in the material during first and second periods, respectively, afteR commencement of the corresponding irradiation interval, measuring the detected indications at least during a first measurement interval occurring at first times during the respective periods and during a second measurement interval occurring at second times during the respective periods, at least one of the second irradiation interval, the first and second times in the second period, and the first and second measurement intervals during the second period being variable, determining a neutron characteristic of the material from the measurements made during the first and second measurement intervals in the first period, controlling automatically the duration of at least one of the second irradiation interval, the first and second times in the second period, and the first and second measurement intervals in the second period, in accordance with the neutron characteristic of the material determined from the measurements made during the first period of the same logging run, measuring detected indications representative of background radiation during a third measurement interval occurring at third times during the first and second periods, respectively, subtracting the measurement obtained during the third measurement interval from the measurements obtained during the first and second measurement intervals in the same logging run in determining the neutron characteristic, and controlling automatically the third time in the second period in accordance with the neutron characteristic determined from the measurements made during the first period of the same logging run.
Claim 23
Independent Claim
269 words
A method for logging a characteristic of an unknown material comprising irradiating the material with neutrons during at least two spaced irradiation intervals, detecting indications of the neutron concentration in the material during first and second periods, respectively, afteR commencement of the corresponding irradiation interval, measuring the detected indications at least during a first measurement interval occurring at first times during the respective periods and during a second measurement interval occurring at second times during the respective periods, at least one of the second irradiation interval, the first and second times in the second period, and the first and second measurement intervals during the second period being variable, determining a neutron characteristic of the material from the measurements made during the first and second measurement intervals in the first period, controlling automatically the duration of at least one of the second irradiation interval, the first and second times in the second period, and the first and second measurement intervals in the second period, in accordance with the neutron characteristic of the material determined from the measurements made during the first period of the same logging run, measuring detected indications representative of background radiation during a third measurement interval occurring at third times during the first and second periods, respectively, subtracting the measurement obtained during the third measurement interval from the measurements obtained during the first and second measurement intervals in the same logging run in determining the neutron characteristic, and controlling automatically the third time in the second period in accordance with the neutron characteristic determined from the measurements made during the first period of the same logging run.
Claim 24
Independent Claim
94 words
A method for logging a characteristic of an unknown material comprising irradiating the material with neutrons during at least two spaced irradiation intervals, measuring the rate of change of neutron concentration in the material during corresponding first and second measuring intervals occurring after commencement of the respective irradiation intervals, the time of occurrence of the second measuring interval being variable, and controlling automatically the time of the second measuring interval in accordance with a neutron characteristic of the material determined from a measurement made during the first measuring interval in the same logging run.
Claim 25
Independent Claim
94 words
A method for logging a characteristic of an unknown material comprising irradiating the material with neutrons during at least two spaced irradiation intervals, measuring the rate of change of neutron concentration in the material during corresponding first and second measuring intervals occurring after commencement of the respective irradiation intervals, the time of occurrence of the second measuring interval being variable, and controlling automatically the time of the second measuring interval in accordance with a neutron characteristic of the material determined from a measurement made during the first measuring interval in the same logging run.
Claim 26
Dependent Claim
176 words
Apparatus for logging a characteristic of an unknown material based upon successive detected indications of the neutron concentration in the material following successive irradiations of the material with neutrons during the same logging run comprising conductor means for receiving signals representing the detected indications and synchronizing signals related to the time of initiation of each neutron irradiation, at least one variable gate means responsive to the synchronizing signals and the neutron concentration indication signals for transmitting neutron concentration indication signals during at least one corresponding measurement interval occurring at at least one measurement time after receipt of a synchronizing signal, comparing means responsive to the neutron concentration indication signals transmitted by the gate means to produce a comparison signal related to the neutron concentration in the material at the measurement time, and control means responsive to the comparison signal to produce a control signal for controlling automatically the operation of the gate means, wherein the control means includes variable frequency oscillator means responsive to the comparison signal to produce a control signal having a controlled frequency.
Claim 27
Dependent Claim
176 words
Apparatus for logging a characteristic of an unknown material based upon successive detected indications of the neutron concentration in the material following successive irradiations of the material with neutrons during the same logging run comprising conductor means for receiving signals representing the detected indications and synchronizing signals related to the time of initiation of each neutron irradiation, at least one variable gate means responsive to the synchronizing signals and the neutron concentration indication signals for transmitting neutron concentration indication signals during at least one corresponding measurement interval occurring at at least one measurement time after receipt of a synchronizing signal, comparing means responsive to the neutron concentration indication signals transmitted by the gate means to produce a comparison signal related to the neutron concentration in the material at the measurement time, and control means responsive to the comparison signal to produce a control signal for controlling automatically the operation of the gate means, wherein the control means includes variable frequency oscillator means responsive to the comparison signal to produce a control signal having a controlled frequency.
Claim 28
Dependent Claim
153 words
Apparatus for logging a characteristic of an unknown material based upon successive detected indications of the neutron concentration in the material following successive irradiations of the material with neutrons during the same logging run comprising conductor means for receiving signals representing the detected indications and synchronizing signals related to the time of initiation of each neutron irradiation, at least one variable gate means responsive to the synchronizing signals and the neutron concentration indication signals, for transmitting neutron concentration indication signals during at least one corresponding measurement interval occurring at at least one measurement time after receipt of a synchronizing signal, comparing means responsive to the neutron concentration indication signals transmitted by the gate means to produce a comparison signal related to the neutron concentration in the material at the measurement time, and control means responsive to the comparison signal to produce a control signal for controlling automatically the operation of the gate means.
Claim 29
Dependent Claim
153 words
Apparatus for logging a characteristic of an unknown material based upon successive detected indications of the neutron concentration in the material following successive irradiations of the material with neutrons during the same logging run comprising conductor means for receiving signals representing the detected indications and synchronizing signals related to the time of initiation of each neutron irradiation, at least one variable gate means responsive to the synchronizing signals and the neutron concentration indication signals, for transmitting neutron concentration indication signals during at least one corresponding measurement interval occurring at at least one measurement time after receipt of a synchronizing signal, comparing means responsive to the neutron concentration indication signals transmitted by the gate means to produce a comparison signal related to the neutron concentration in the material at the measurement time, and control means responsive to the comparison signal to produce a control signal for controlling automatically the operation of the gate means.
Claim 30
Dependent Claim
42 words
Apparatus according to claim 22 including second gate means responsive to the synchronizing signals and the neutron concentration signals for transmitting neutron concentration indication signals during a second measurement interval occurring at a second measurement time after receipt of a synchronizing signal.
Claim 31
Dependent Claim
28 words
Apparatus according to claim 23 wherein the control means includes means for producing a control signal for controlling the selected measurement time of at least one gate means.
Claim 32
Dependent Claim
27 words
Apparatus according to claim 23 wherein the control means includes means for producing a control signal for controlling the measurement interval of at least one gate means.
Claim 33
Dependent Claim
29 words
Apparatus according to claim 23 wherein the control means includes means for producing control signals for controlling the selected measurement time and the measurement intervals of both gate means.
Claim 34
Dependent Claim
23 words
Apparatus according to claim 22 including output means responsive to the control means for providing indications of a characteristic of the unknown material.
Claim 35
Dependent Claim
136 words
Apparatus for logging a characteristic of an unknown material comprising neutron source means for irradiating the material with neutrons for an irradiation interval upon receipt of a control signal, at least one of the time and duration of the irradiation interval being variable, detector means for producing indications of the neutron concentration in the material following each irradiation signal during the same logging run, at least one gate means for transmitting signals from the detector means during at least one measurement interval, comparing means responsive to the neutron concentration indication signals transmitted by the gate means to produce a comparison signal related to the neutron concentration in the material at the measurement time, and control means responsive to the comparison signal to produce a control signal for controlling automatically the operation of the neutron source means.
Claim 36
Dependent Claim
136 words
Apparatus for logging a characteristic of an unknown material comprising neutron source means for irradiating the material with neutrons for an irradiation interval upon receipt of a control signal, at least one of the time and duration of the irradiation interval being variable, detector means for producing indications of the neutron concentration in the material following each irradiation signal during the same logging run, at least one gate means for transmitting signals from the detector means during at least one measurement interval, comparing means responsive to the neutron concentration indication signals transmitted by the gate means to produce a comparison signal related to the neutron concentration in the material at the measurement time, and control means responsive to the comparison signal to produce a control signal for controlling automatically the operation of the neutron source means.
Claim 37
Dependent Claim
25 words
Apparatus according to claim 28 wherein the control means (include) includes means for producing a control signal which controls the duration of the irradiation interval.
Claim 38
Dependent Claim
24 words
Apparatus according to claim 28 wherein the control means includes means for producing a control signal which controls the spacing of successive irradiation intervals.
Claim 39
Dependent Claim
140 words
Apparatus for logging a characteristic of an unknown material comprising neutron source means for irradiating the material with neutrons for an irradiation interval upon receipt of a control signal, detector means for producing indications of the neutron concentration in the material following each irradiation signal during the same logging run, at least one variable gate means for transmitting signals from the detector means during at least one measurement interval at a measurement time, at least one of the measurement interval and the measurement time being variable, comparing means responsive to the neutron concentration indication signals transmitted by the gate means to produce a comparison signal related to the neutron concentration in the material at the measurement time, and control means responsive to the comparison signal to produce a control signal for controlling automatically the operation of the variable gate means.
Claim 40
Dependent Claim
140 words
Apparatus for logging a characteristic of an unknown material comprising neutron source means for irradiating the material with neutrons for an irradiation interval upon receipt of a control signal, detector means for producing indications of the neutron concentration in the material following each irradiation signal during the same logging run, at least one variable gate means for transmitting signals from the detector means during at least one measurement interval at a measurement time, at least one of the measurement interval and the measurement time being variable, comparing means responsive to the neutron concentration indication signals transmitted by the gate means to produce a comparison signal related to the neutron concentration in the material at the measurement time, and control means responsive to the comparison signal to produce a control signal for controlling automatically the operation of the variable gate means.
Claim 41
Dependent Claim
24 words
Apparatus according to claim 31 wherein the control means includes means for producing a control signal which controls the duration of the measurement interval.
Claim 42
Dependent Claim
22 words
Apparatus accoRding to claim 31 wherein the control means includes means for producing a control signal which controls the selected measurement time.
Claim 43
Independent Claim
107 words
A method for logging a characteristic of material adjacent a well bore, comprising: irradiating the material with neutrons during an irradiation interval; measuring detected indications of the concentration of neutrons in the material during each of first and second measuring intervals occurring at first and second times, respectively, after commencement of the irradiation interval; measuring detected indications of background radiation in the material during a third measuring interval occurring in the same logging run at a third time after commencement of the irradiation interval; and combining the measurements made during the first, second and third measuring intervals to determine a background corrected neutron characteristic of the material.
Claim 44
Independent Claim
107 words
A method for logging a characteristic of material adjacent a well bore, comprising: irradiating the material with neutrons during an irradiation interval; measuring detected indications of the concentration of neutrons in the material during each of first and second measuring intervals occurring at first and second times, respectively, after commencement of the irradiation interval; measuring detected indications of background radiation in the material during a third measuring interval occurring in the same logging run at a third time after commencement of the irradiation interval; and combining the measurements made during the first, second and third measuring intervals to determine a background corrected neutron characteristic of the material.
Claim 45
Dependent Claim
27 words
A method according to claim 34 wherein the time of occurrence of the third measuring interval is after the termination of the first and second measuring intervals.
Claim 46
Dependent Claim
50 words
A method according to claim 35 wherein: the times of occurrence of the first and second measuring intervals are set to provide measurements of gamma rays resulting from capture of thermal neutrons and indicative of the concentration of thermal neutrons in the material during the first and second measuring intervals.
Claim 47
Dependent Claim
43 words
A method according to claim 36 wherein the neutron characteristic determined is the thermal neutron decay time of the material, and the time of occurrence of at least said third measuring interval is varied as a function of the thermal neutron decay time.
Claim 48
Dependent Claim
41 words
A method according to claim 34 wherein the combining of the first, second and third interval measurements includes subtracting a function of the third interval measurement from the first and second interval measurements to provide background-corrected first and second interval measurements.
Claim 49
Dependent Claim
37 words
A method according to claim 38 wherein the combining of the first, second and third interval measurements further includes deriving a ratio function of the background-corrected first and second interval measurements to determine the background-corrected neutron characteristic.
Claim 50
Dependent Claim
35 words
A method according to claim 38 wherein the third interval measurement is subtracted from each of the first and second interval measurements in proportion to the respective durations of the first and second measuring intervals.
Claim 51
Dependent Claim
71 words
A method according to claim 34 wherein the step of combining the first, second and third interval measurements comprises: determining an indication of the rate of decay of at least a portion of the neutron population in the material from the first and second interval measurements; and correcting the indication of the neutron decay rate in accordance with the third interval measurement to provide a background-corrected indication of the decay rate.
Claim 52
Dependent Claim
35 words
A method according to claim 41 wherein the neutron decay rate indication is corrected by subtracting a function of the third interval measurement from the neutron concentration measurements of the first and second measuring intervals.
Claim 53
Independent Claim
116 words
A method for logging a characteristic of material adjacent a well bore, comprising: irradiating the material with neutrons during a timed sequence of time-spaced irradiation intervals; measuring detected indications of the concentration of neutrons in the material during each of first and second measuring intervals occurring at first and second times, respectively, after corresponding irradiation intervals; measuring detected indications of background radiation in the material during a third measuring interval at a third time occurring after first and second measuring intervals following each irradiation interval and prior to the next successive irradiation interval; and combining the measurements made during the first, second and third measuring intervals to determine a background corrected neutron chracteristic of the material.
Claim 54
Independent Claim
116 words
A method for logging a characteristic of material adjacent a well bore, comprising: irradiating the material with neutrons during a timed sequence of time-spaced irradiation intervals; measuring detected indications of the concentration of neutrons in the material during each of first and second measuring intervals occurring at first and second times, respectively, after corresponding irradiation intervals; measuring detected indications of background radiation in the material during a third measuring interval at a third time occurring after first and second measuring intervals following each irradiation interval and prior to the next successive irradiation interval; and combining the measurements made during the first, second and third measuring intervals to determine a background corrected neutron chracteristic of the material.
Claim 55
Dependent Claim
19 words
A method according to claim 43 wherein the third measuring interval occurs immediately before the next successive irradiation interval.
Claim 56
Dependent Claim
52 words
A method according to claim 43 wherein the neutron characteristic determined is the thermal neutron decay time of the material, the timing of at least one of said irradiation internal and first, second and third measuring intervals in successive sequences being varied as a function of decay time determined in prior sequences.
Claim 57
Independent Claim
141 words
A method for logging a characteristic of material adjacent a well bore, comprising: irradiating the material with discrete bursts of neutrons in a timed sequence; measuring detected indications of the concentration of neutrons in the material during each of first and second measuring intervals occurring at first and second times, respectively, during the time period between the commencement of each neutron burst and the commencement of the next successive neutron burst; suppressing a subsequent neutron burst in the timed sequence; measuring detected indications of background radiation in the material during a third measuring interval occurring during the time period between the predetermined time of commencement of the suppressed neutron burst and the commencement of the next unsuppressed neutron burst; and combining the measurements made during the first, second and third measuring intervals to determine a background-corrected neutron characteristic of the material.
Claim 58
Independent Claim
141 words
A method for logging a characteristic of material adjacent a well bore, comprising: irradiating the material with discrete bursts of neutrons in a timed sequence; measuring detected indications of the concentration of neutrons in the material during each of first and second measuring intervals occurring at first and second times, respectively, during the time period between the commencement of each neutron burst and the commencement of the next successive neutron burst; suppressing a subsequent neutron burst in the timed sequence; measuring detected indications of background radiation in the material during a third measuring interval occurring during the time period between the predetermined time of commencement of the suppressed neutron burst and the commencement of the next unsuppressed neutron burst; and combining the measurements made during the first, second and third measuring intervals to determine a background-corrected neutron characteristic of the material.
Claim 59
Dependent Claim
41 words
A method according to claim 46 wherein the combining of the first, second and third interval measurements includes subtracting a function of the third interval measurement from the first and second interval measurements to provide background-corrected first and second interval measurements.
Claim 60
Dependent Claim
35 words
A method according to claim 47 wherein the third interval measurement is subtracted from each of the first and second interval measurements in proportion to the respective durations of the first and second measuring intervals.
Claim 61
Dependent Claim
26 words
A method according to claim 46 wherein the second measuring interval immediately precedes the time of commencement of suppressed or unsuppressed neutron bursts in the sequence.
Claim 62
Dependent Claim
110 words
Apparatus for logging a characteristic of material adjacent a well bore, comprising: control means for timing a sequence of intervals during which the material is irradiated with neutrons; means for measuring detected indications of the concentration of neutrons in the material during each of rist and second measuring intervals occurring at first and second times, respectively, after commencement of respective irradiation intervals; means for measuring detected indications of background radiation in the material during a third measuring interval occurring at a third time between successive irradiation intervals; and means for combining the measurements made during the first, second and third intervals to determine a background-corrected neutron chracteristic of the material.
Claim 63
Dependent Claim
110 words
Apparatus for logging a characteristic of material adjacent a well bore, comprising: control means for timing a sequence of intervals during which the material is irradiated with neutrons; means for measuring detected indications of the concentration of neutrons in the material during each of rist and second measuring intervals occurring at first and second times, respectively, after commencement of respective irradiation intervals; means for measuring detected indications of background radiation in the material during a third measuring interval occurring at a third time between successive irradiation intervals; and means for combining the measurements made during the first, second and third intervals to determine a background-corrected neutron chracteristic of the material.
Claim 64
Dependent Claim
92 words
Apparatus according to claim 50 wherein the means for measuring detected indications of neutron concentration includes first and second gate means for transmitting detected indications of the neutron concentration during said first and second measuring intervals, respectively, and means for measuring detected indications of background radiation includes third gate means for transmitting detected indications of background radiation during said third measuring interval, the third gate means being operative to place the time of occurrence of the third measuring interval in sequence following the first and second measuring intervals between successive irradiation intervals.
Claim 65
Dependent Claim
35 words
Apparatus according to claim 50 wherein the combining means includes means for subtracting a function of the third interval measurement from the first and second interval measurements to provide background-corrected first and second interval measurements.
Claim 66
Dependent Claim
64 words
Apparatus according to claim 52 wherein the subtracting means is operative to subtract the third interval measurement from the first and second interval measurements in proportion to the respective durations of the first and second measuring intervals; and wherein the combining means further includes means for deriving a ratio function of the background-corrected first and second interval measurements to determine a background-corrected neutron characteristic.
Claim 67
Dependent Claim
67 words
Apparatus according to claim 50 wherein the combining means includes: means responsive to the first and second interval measurements for determining an indication of the rate of decay of at least a portion of the neutron population in the material; and means for correcting the indication of the neutron decay rate in accordance with the third interval measurement to provide a background-corrected indication of the decay rate.
Claim 68
Dependent Claim
32 words
Apparatus according to claim 54 wherein the correcting means is operative to subtract a function of the third interval measurement from the neutron concentration measurements of the first and second measuring intervals.
Claim 69
Dependent Claim
50 words
Apparatus according to claim 50 wherein the combining means determines the thermal neutron decay time of the material; and wherein the timing means varies the occurrence of at least one of the measuring intervals in successive sequences as a function of the thermal neutron decay time determined in prior sequences.
Claim 70
Dependent Claim
34 words
Apparatus according to claim 56 wherein said timing means varies the occurrence of each of the measuring intervals in successive sequences as a function of the thermal neutron decay time determined in prior sequences.
Claim 71
Dependent Claim
33 words
Apparatus according to claim 56 wherein said timing means also varies the occurrence of the irradiation intervals in successive sequences as a function of the thermal neutron decay time determined in prior sequences.
Claim 72
Dependent Claim
37 words
Apparatus according to claim 50 wherein the timing means controls the timed sequence of at least said measuring intervals to place the third measuring interval after the second measuring interval and immediately before the next irradiation interval.
Claim 73
Dependent Claim
151 words
Apparatus for logging a characteristic of a material adjacent a well bore, comprising: means for irradiating the material with discrete bursts of neutrons in a predetermined sequence; means for measuring detected indications of the concentration of neutrons in the material during each of first and second measuring intervals occurring at first and second times, respectively, during the time period between the commencement of each neutron burst and the commencement of the next successive neutron burst; means for suppressing a subsequent neutron burst in the timed sequence; means for measuring detected indications of background radiation in the material during a third measuring interval occurring during the time period between the predetermined time of commencement of the suppressed neutron burst and the commencement of the next unsuppressed neutron burst; and means for combining the measurements made during the first, second and third measuring intervals to determine a background-corrected neutron characteristic of the material.
Claim 74
Dependent Claim
151 words
Apparatus for logging a characteristic of a material adjacent a well bore, comprising: means for irradiating the material with discrete bursts of neutrons in a predetermined sequence; means for measuring detected indications of the concentration of neutrons in the material during each of first and second measuring intervals occurring at first and second times, respectively, during the time period between the commencement of each neutron burst and the commencement of the next successive neutron burst; means for suppressing a subsequent neutron burst in the timed sequence; means for measuring detected indications of background radiation in the material during a third measuring interval occurring during the time period between the predetermined time of commencement of the suppressed neutron burst and the commencement of the next unsuppressed neutron burst; and means for combining the measurements made during the first, second and third measuring intervals to determine a background-corrected neutron characteristic of the material.
Claim 75
Dependent Claim
43 words
Apparatus according to claim 60 wherein the third interval measuring means includes means for commencing and terminating the third measuring interval in substantial coincidence with the time of commencement of the suppressed neutron burst and the commencement of the next unsuppressed neutron burst.
Claim 76
Dependent Claim
44 words
Apparatus according to claim 60 wherein the third interval measuring means includes means for commencing the third measuring interval at the predetermined time of termination of the suppressed neutron burst and terminating it at the time of commencement of the next unsuppressed neutron burst.
Claim 77
Dependent Claim
63 words
Apparatus according to claim 22 including variable gate means responsive to the synchronizing signals and the neutron concentration indication signals for transmitting background indication signals during a measurement interval occurring at a time after receipt of a synchronizing signal later than the one measurement time; said comparing means being responsive to the background indication signals to provide background correction for said comparison signal.
Claim 78
Dependent Claim
49 words
Apparatus according to claim 31 including variable gate means for transmitting background indication signals from the detector means during a background measurement interval at a time later than said measurement time; said comparing means being responsive to the background indication signals to provide background correction for said comparison signal.
Claim 79
Dependent Claim
30 words
Apparatus according to claim 64 wherein the comparing means includes means for subtracting a function of the background indication signals from the neutron concentration indication signals to provide background correction.
Claim 80
Dependent Claim
34 words
Apparatus according to claim 65 wherein the subtracting means is operative to subtract the background indication signals from the neutron concentration indication signals in proportion to the duration of the neutron concentration measurement interval.
Claim 81
Dependent Claim
41 words
A method according to claim 18 wherein the measurement obtained during the third measurement interval is subtracted from the measurements obtained during the first and second measurement intervals in proportion to the respective durations of the first and second measurement intervals.
References Cited (Backward Citations)
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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) | 1978-07-07 | 1979-01-06 | 1979-07-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-07 | 1983-01-06 | 1983-07-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-07 | 1987-01-06 | 1987-07-08 | $7700.00 | Window Closed / Lapsed |