	US 11,906,690 B2
	Obtaining inelastic spectra free of detector born gamma rays induced by neutrons
Feyzi Inanc, Houston, TX (US); Toyli Anniyev, Houston, TX (US); Peng Yuan, Houston, TX (US); Maxim Vasilyev, Houston, TX (US); and David Chace, Houston, TX (US)
Assigned to BAKER HUGHES OILFIELD OPERATIONS LLC, Houston, TX (US)
Filed by Baker Hughes Oilfield Operations LLC, Houston, TX (US)
Filed on Oct. 9, 2019, as Appl. No. 16/596,871.
Claims priority of provisional application 62/743,831, filed on Oct. 10, 2018.
Prior Publication US 2020/0116891 A1, Apr. 16, 2020
Int. Cl. G01V 5/10 (2006.01); G01V 5/04 (2006.01); G01T 3/06 (2006.01); G01V 5/12 (2006.01)

CPC G01V 5/045 (2013.01) [G01T 3/06 (2013.01); G01V 5/12 (2013.01)]

20 Claims

1. A method of measuring properties of a formation or well structure, comprising:

receiving a first measurement of gamma rays from the formation or well structure via a detector during a first period of time;

receiving a second measurement of gamma rays from the formation or well structure via the detector during a second period of time;

removing the second measurement from the first measurement to produce an inelastic spectrum;

determining a spectral slope from the inelastic spectrum;

determining a scaling factor based on the spectral slope;

determining a spectral shape associated with the detector;

determining a detector-induced spectrum by applying the scaling factor to the spectral shape; and

removing the detector-induced spectrum from the inelastic spectrum to produce a clean inelastic spectrum for use in evaluating properties of the formation or well structure.