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2.3 Applications in level measurement

Storage tank in oil and gas industry is usually made
from a huge structure of welded steel plate. It is used
to contain and store a large volume of crude oil or set-
tling sludge layer depending on the undergone pro-
cess. Since it is the tank for oil or crude oil, there are
some fraction consists of other materials co-exists with
the crude oil such as water, vapor and organic com-
pound and etc. These will form several layers of ma-
terials depending on the density of each fraction.

This is because the crude oil from drilling usually
contains different hydrocarbon and sand materials that
creates various layers inside the storage tank. The
thickness of each layer is depending on the volume
of mixed oil with other materials. The heavier one will
drop and settle at the lower layer while the lighter will
move up remain in the middle and float at some levels
within the top site in the storage tank. In this case, the
concentration of hydrogen in each layer plays an im-
portant role where, layer with large volume of hydro-
gen molecules will scattered neutron more. This will
provides significant effect on the capability of making
neutron back scattering phenomenon. Figure 2.3 illus-
trates the neutron detection gauge applied in neutron
backs-scattered technique.

Thermal neutrons from the gauge head will pene-
trate the wall of storage tank and reach the hydrocar-

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