Porosity can be measured using sonic and density logs. Sonic logs measure the interval transit time of a sound wave through rock, with denser rock having faster transit times and more porous rock having slower times. There are two methods to calculate porosity from sonic logs: using an equation involving transit time and mud/rock properties, or using a sonic porosity chart. Similarly for density logs, porosity can be calculated from an equation using bulk and grain densities of the formation and mud, or looked up on a density porosity chart. Together, sonic and density logs provide good indications of porosity when used in combination.

1. Porosity logging
Department of petroleum engineering
Soran university
Present by : Reband azad raza

2. • Porosity Logs
Sonic log Density Log
None of this Logs can directly measures porosity
Combination of these tools ,will give good indication
for porosity

3. • 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

4. How would you find a porosity from sonic curve diagram ?!

5. There is two method to measure porosity from sonic Log :
1- Equation
2-Sonic porosity chart
1-
2-

6. 1-Porosity – By equation method –sonic tool
First step indicate a wanted depth porosity

7. Apply this equation :
From Curve
c
Fresh water mud in well =189𝜇𝑠𝑒𝑐/𝑓𝑡
salt water mud= 185𝜇𝑠𝑒𝑐/𝑓𝑡
Equation method

8. dolomite
43.5𝜇𝑠𝑒𝑐/𝑓𝑡
c
salt water mud= 185𝜇𝑠𝑒𝑐/𝑓𝑡
79 𝜇𝑠𝑒𝑐/𝑓𝑡∆𝑡𝑙𝑜𝑔 =
So, ∅𝑠 =
79−43.5
185−43.5
= 0.3
Dolomite from chart

9. Chart – sonic log - porosity

10. 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

11. There is two method to measure porosity from density Log:
1- Equation 2-density porosity chart

12. Apply this equation :
Equation method
PeMaterial
2.648Sand
3.76Shale
2.71Limestone
2.876Dolomite
2.032Salt
2.977Anhydrite
From curve
Fresh water mud in well =1.0𝑔𝑚/𝑐𝑚3
salt water mud= 1.1𝑔𝑚/𝑐𝑚3

13. dolomite2.876 𝑔𝑚/𝑐𝑚3
salt water mud= 1.1𝑔𝑚/𝑐𝑚3
So, ∅𝑠 =
2.876−2.6
2.876−1.1
= 0.155

14. Chart – density log - porosity

15. Any Question ? !