Porosity logging
Department of petroleum engineering
Soran university
Present by : Reband azad raza
الرحيم الرحمن الله بسم
• Porosity Logs Sonic log Density Log
None of this Logs can directly measures porosityCombination of these tools ,will give good indication
for porosity
• A log that measures interval transit time (Δt) of a compressional sound wave travelling through the formation
Sonic log
• Dense rock – faster travel time• Porous rock – slower travel time
How would you find a porosity from sonic curve diagram ?!
There is two method to measure porosity from sonic Log :
1- Equation 2-Sonic porosity chart
1-
2-
1-Porosity – By equation method –sonic toolFirst step indicate a wanted depth porosity
11500 m
11700 m
Apply this equation :
From Curve
c
Fresh water mud in well =189
salt water mud= 185
Equation method
dolomite
4c
salt water mud= 185
79 ∆ 𝑡𝑙𝑜𝑔=¿
So,
Dolomite from chart
Chart – sonic log - porosity
Density log
The density logging tool is made up of: - a radioactive source of either Cs-137 or Co-60
The gamma rays enter the surrounding rocks where some are absorbed.
It has 2 detectors
• Long range
• Short range
There is two method to measure porosity from density Log:1- Equation 2-density porosity chart
Apply this equation :
Equation method
Pe
Material
2.648
Sand
3.76
Shale
2.71
Limestone
2.876
Dolomite
2.032
Salt
2.977
Anhydrite
From curve
Fresh water mud in well =1.0
salt water mud= 1
dolomite2
2
salt water mud= 1
So,
Chart – density log - porosity
Any Question ? !
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