Insights on Density-neutron log porosity

What is density-neutron log porosity and how is it used ?

Density-neutron log porosity is a commonly used technique for measuring the porosity of rocks in the oil and gas industry. This technique involves measuring the density and neutron response of the rock, which can be used to calculate the porosity.

The testing methods for density-neutron log porosity.

• Density Log: The density log measures the density of the rock by measuring the attenuation of gamma rays emitted from a radioactive source. To test for density log porosity, the density log is run in the borehole, and the density values are recorded as a function of depth. The density values are then corrected for the effects of mud filtrate invasion, shale content, and porosity, to obtain the true formation density.
• Neutron Log: The neutron log measures the hydrogen content of the rock by measuring the attenuation of neutrons emitted from a radioactive source. To test for neutron log porosity, the neutron log is run in the borehole, and the neutron values are recorded as a function of depth. The neutron values are then corrected for the effects of mud filtrate invasion, shale content, and porosity, to obtain the true formation neutron response.
• Porosity Calculation: The porosity of the rock is calculated from the density and neutron response using the porosity equations. To test for density-neutron log porosity, the density and neutron values are plotted on a cross plot, and the porosity values are calculated from the porosity equation. The porosity values are then compared to other porosity measurements, such as core measurements, to verify the accuracy of the density-neutron log porosity.

Testing for density-neutron log porosity is important for understanding the porosity of rocks in the oil and gas industry. The density log and neutron log provide continuous measurements of the density and neutron response of the rock, which can be used to calculate the porosity. 

Video 01: Well Logging: Density Neutron

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Video 02: Neutron Porosity Log

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