Changes

===Pulsed neutron tool===

===Pulsed neutron tool===

[[file:basic-cased-hole-tools_fig1.png|thumb|{{figure number|1}}Typical presentation of a pulsed neutron log. © Schlumberger, 1986.]]

[[file:basic-cased-hole-tools_fig1.png|300px|thumb|{{figure number|1}}Typical presentation of a pulsed neutron log. © Schlumberger, 1986.]]

Pulsed neutron devices are electronic devices that generate pulses of high energy neutrons. These high energy neutrons bombard the formation, losing energy as they collide with atoms of the rock. Eventually, the neutrons lose so much energy that they are captured (generally by chlorine that exists as part of the salt dissolved in the formation waters). When a neutron is captured, a gamma ray is emitted. The detectors in the pulsed neutron tool are designed to measure these “capture” gamma rays, thus, a “capture cross section” of the formation through casing can be determined. This formation property allows one to estimate the water saturation when porosity and formation water salinity are known. A typical pulsed neutron log is shown in [[:file:basic-cased-hole-tools_fig1.png|Figure 1]].

Pulsed neutron devices are electronic devices that generate pulses of high energy neutrons. These high energy neutrons bombard the formation, losing energy as they collide with atoms of the rock. Eventually, the neutrons lose so much energy that they are captured (generally by chlorine that exists as part of the salt dissolved in the formation waters). When a neutron is captured, a gamma ray is emitted. The detectors in the pulsed neutron tool are designed to measure these “capture” gamma rays, thus, a “capture cross section” of the formation through casing can be determined. This formation property allows one to estimate the water saturation when porosity and formation water salinity are known. A typical pulsed neutron log is shown in [[:file:basic-cased-hole-tools_fig1.png|Figure 1]].