(19)
(11) EP 0 387 055 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
10.06.1992 Bulletin 1992/24

(43) Date of publication A2:
12.09.1990 Bulletin 1990/37

(21) Application number: 90302472.7

(22) Date of filing: 08.03.1990
(51) International Patent Classification (IPC)5G01V 5/06, E21B 47/10, E21B 43/26, E21B 33/14
(84) Designated Contracting States:
DE FR GB IT NL

(30) Priority: 10.03.1989 US 321307

(71) Applicant: HALLIBURTON LOGGING SERVICES, INC.
Houston, Texas 77042 (US)

(72) Inventors:
  • Gadeken, Larry L.
    Houston, Texas 77079 (US)
  • Smith, Harry D., Jr.
    Houston, Texas 77079 (US)

(74) Representative: Wain, Christopher Paul 
A.A. THORNTON & CO. Northumberland House 303-306 High Holborn
London WC1V 7LE
London WC1V 7LE (GB)


(56) References cited: : 
   
       


    (54) Gamma ray well logging for radial tracer distances


    (57) Gamma ray well logging to obtain relative distance indications of tracers from the well bore comprises separating a measured gamma ray spectrum into component parts attributable to individual tracers, using standard spectra, and then obtaining the relative distance indicators from those parts of the spectrum. For cased borehole, using standard spectra as a guide, the proportions of the borehole component and the formation component can be determined and a composite spectrum obtained for each individual tracer by adding the borehole and formation components together. A Compton ratio Rc of gamma ray counts in an energy region of the spectrum which is sensitive to Compton scattering to gamma ray counts in an energy region of the spectrum which is not sensitive to Compton scattering is then obtained. By a linear transformation which parameterizes the Compton ratio Rc with the inverse square of the annulus diameter of a distributed region of tracer surrounding the well bore, a relative distance indication of the distribution of each tracer with respect to the well bore is obtainable for each tracer.





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