FR2279118A1 - Detecting gullies and cavities behind a borehole tube - strata irradiated with rapid neutrons emit inelastic gamma rays - Google Patents

Detecting gullies and cavities behind a borehole tube - strata irradiated with rapid neutrons emit inelastic gamma rays

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Publication number
FR2279118A1
FR2279118A1 FR7425004A FR7425004A FR2279118A1 FR 2279118 A1 FR2279118 A1 FR 2279118A1 FR 7425004 A FR7425004 A FR 7425004A FR 7425004 A FR7425004 A FR 7425004A FR 2279118 A1 FR2279118 A1 FR 2279118A1
Authority
FR
France
Prior art keywords
strata
signals
gamma rays
irradiated
representing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
FR7425004A
Other languages
French (fr)
Other versions
FR2279118B1 (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Texaco Development Corp
Original Assignee
Texaco Development Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Texaco Development Corp filed Critical Texaco Development Corp
Priority to FR7425004A priority Critical patent/FR2279118A1/en
Publication of FR2279118A1 publication Critical patent/FR2279118A1/en
Application granted granted Critical
Publication of FR2279118B1 publication Critical patent/FR2279118B1/fr
Granted legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V5/00—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity
    • G01V5/04—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging
    • G01V5/08—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays
    • G01V5/10—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays using neutron sources
    • G01V5/101—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays using neutron sources and detecting the secondary Y-rays produced in the surrounding layers of the bore hole
    • G01V5/102—Prospecting or detecting by the use of ionising radiation, e.g. of natural or induced radioactivity specially adapted for well-logging using primary nuclear radiation sources or X-rays using neutron sources and detecting the secondary Y-rays produced in the surrounding layers of the bore hole the neutron source being of the pulsed type

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  • Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)

Abstract

A procedure of detecting the existence of cavities in an oil well borehole, esp. behind the tube above the cementation, consists in irradiating strata in the proximity of the hole, with gusts of high energy neutrons for relatively brief intervals; in detecting immediately before each burst, the basic gamma radiation due to a number of thermic neutrons delayed in the neighbourhood of the strata irradiated, in four energy zones at least of the spectrum of gamma rays, and in producing signals representing them. During each repeated gust of neutrons, the gamma rays are detected which can be attributed to the inelastic diffusion of rapid neutrons in the four different energy zones of the gamma ray spectrum, and signals are produced representing them. The basic gamma radiation is suppressed by subtracting the signal representing it in each of the regions mentioned, in order to set up signals representing at least four corrected measurements of inelastic gamma radiation. In particular the technique consists in generating an output signal representing the hydrogen index of the strata irradiated, by the addition of the four corrected signals and in putting out the corresponding signal. Second and third output signals are produced by forming ratios of the chosen pairs of the signals representing the four corrected measurements of inelastic gamma rays, and in combining the first, second and third output signals according to the functional relationships given so as to obtain an estimate of the presence of cavities in the bore behind the tube. Enables corrections to be made of the effects on the readings of pockets surrounding the tube, filled with the fluids draining through the strata.
FR7425004A 1974-07-18 1974-07-18 Detecting gullies and cavities behind a borehole tube - strata irradiated with rapid neutrons emit inelastic gamma rays Granted FR2279118A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
FR7425004A FR2279118A1 (en) 1974-07-18 1974-07-18 Detecting gullies and cavities behind a borehole tube - strata irradiated with rapid neutrons emit inelastic gamma rays

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7425004A FR2279118A1 (en) 1974-07-18 1974-07-18 Detecting gullies and cavities behind a borehole tube - strata irradiated with rapid neutrons emit inelastic gamma rays

Publications (2)

Publication Number Publication Date
FR2279118A1 true FR2279118A1 (en) 1976-02-13
FR2279118B1 FR2279118B1 (en) 1979-08-24

Family

ID=9141434

Family Applications (1)

Application Number Title Priority Date Filing Date
FR7425004A Granted FR2279118A1 (en) 1974-07-18 1974-07-18 Detecting gullies and cavities behind a borehole tube - strata irradiated with rapid neutrons emit inelastic gamma rays

Country Status (1)

Country Link
FR (1) FR2279118A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998058278A1 (en) * 1997-06-19 1998-12-23 Computalog U.S.A., Inc. Formation density measurement utilizing pulsed neutrons

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998058278A1 (en) * 1997-06-19 1998-12-23 Computalog U.S.A., Inc. Formation density measurement utilizing pulsed neutrons
AU733374B2 (en) * 1997-06-19 2001-05-10 Precision Energy Services, Inc. Formation density measurement utilizing pulsed neutrons
AU733374C (en) * 1997-06-19 2001-11-22 Precision Energy Services, Inc. Formation density measurement utilizing pulsed neutrons

Also Published As

Publication number Publication date
FR2279118B1 (en) 1979-08-24

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