NeutronNeutron Log LogPenilaian Formasi Penilaian Formasi

STT MIGAS BalikpapanSTT MIGAS Balikpapan20132013

Theorytical Theorytical BBackgroundackground It measures hydrogen concentration in the formationIt measures hydrogen concentration in the formation Hydrogen is mostly in water, oil and gas.Hydrogen is mostly in water, oil and gas. Neutron log can be recorded in cased or open holeNeutron log can be recorded in cased or open hole Neutron log will record all of the hydrogen ionNeutron log will record all of the hydrogen ion

Neutron Log ApplicationNeutron Log Application

• As a porosity log• Lithology identification• Gas identification

Neutron Log Format DisplayNeutron Log Format Display

Neutron Log InterpretationNeutron Log Interpretation

The compensated neutron logging tool does NOT measure porosity. It measures a hydrogen index. The hydrogen index is related to porosity, but is affected by lithology and fluid properties.

The measurement is displayed as porosity.

Porosity is usually computed with limestone matrix.

After all borehole corrections, the measurement only represents true formation porosity in a clean limestone formation filled with fresh water.

Neutron Log InterpretationNeutron Log Interpretation

Porosity vs. MatrixPorosity vs. Matrix

Schlumberger Chart Por-13b

Apparent Limestone Porosity (p.u.)

True

Por

osity

for I

ndic

ated

Mat

rix

20 p.u.

25 p.u.

17 p.u.

20 p.u.

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