neutron logging presentation

1. Arnab Mallick
M.Sc Applied Geology (3rd Sem)
Durgapur Government College

2.  The Neutron, Density and Acoustic logs are
frequently referred to as Porosity logs.
 Of these, the Neutron log measures porosity
more accurately.
 The Neutron log is sensitive mainly to the
amount of hydrogen atoms in a formation.

3.  The tool operates by bombarding the formation
with high energy neutrons, which emit from a
mixture of Americium and Berillium (Neutron
source )
 These neutrons undergo scattering in the
formation, losing energy and producing high energy
gamma rays.
 The fast neutrons interacts with the nuclei of atoms
in the formation.
 The fast neutrons are then converted to Epithermal
neutrons and then Thermal neutrons.

5.  The Thermal neutrons are absorbed by Hydrogen
and Chlorine in the formation by capture and
emit Gamma rays.
 The presence of hydrogen in the fluid is what we
want to measure. So we measure either γ-ray or
neutron to determine porosity.

6.  Determination of porosity / Lithology
 Delineation of porous formations
 Gas detection (with density log)
 Estimation of shale content

7. The neutron log response to alternation of shales and sandstones.
Neutron unit

8.  H- atom concentration in gas is low than water
and liquid hydrocarbon.
 So bombardment with H-atoms is less.
 Thus, Porosity measured is very low.
 This anomaly can be identified properly with the
help of Gamma-Gamma log.
shale
sandstone
Shale effect

9.  Clays within shales contain bound water.
 This bound water appear as very high
porosity (error)
 NMR log is used to identify the bound and
movable fluid.

10. stands for the separation measured for in 100% sandstone,
100% shale and at the depth of interest in the log.

11.  Ellis, D. V., & Singer, J. M. (2007). Well logging
for earth scientists(Vol. 692). Dordrecht: Springer.
 Darling, T. (2005). Well logging and formation
evaluation. Elsevier.
 Johnson, D. E., & Pile, K. E. (2002). Well logging
in nontechnical language. PennWell Books.

12. THANK
YOU