The document discusses the petrophysical properties of rocks, focusing on characteristics like porosity, permeability, and electrical conductivity. It explains various well logging methods used to gather data on rock properties during drilling, including gamma ray logs, resistivity logs, and sonic logs. Emphasizing the importance of combining multiple log types for accurate determination of lithology and hydrocarbon content, it concludes with references for further reading.

2. Introduction
Petrophysic of the rocks
It is the study of the physical and chemical properties
of the rocks related to the pores and fluid distribution
• Porosity, is ratio between volume of void to the
total voids of the rock.
• Permeability, is ability of a porous material to
allow fluids to pass through it.
• Electric, most of the sedimentary rocks don’t have
conductivity.
• Radiation, clay rocks have 40K, radiate alpha ray.
• Hardness, it depends on the cementing material
and thickness of the sediments.

3. WELL LOGGING
• The systematic recording of rock properties and
it’s fluid contents in wells being drilled or produced
to obtain various petrophysical parameters and
characteristics of down hole sequences (G.E Archie
1950).
• The measurement versus depth or time, or both,
of one or more physical properties in a well.
• These methods are particularly good when
surface outcrops are not available, but a direct
sample of the rock is needed to be sure of the
lithology.

4. • A wide range of physical parameters can be
measured.
• In some cases, the measurements are not direct,
it require interpretation by analogy or by
correlating values between two or more logs run
in the same hole.
• Provide information on lithology, boundaries of
formations and stratigraphic correlation.
• Determine Porosity, Permeability, water, oil and
gas saturation.
• Reservoir modeling and Structural studies… etc.

5. Types of Well Logging
Logs can be classified into several types under
different category
Permeability and lithology Logs
• Gamma Ray log
• Self Potential [SP] log
• Caliber log
Porosity Logs
• Density log
• Sonic log
• Neutron log
Electrical Logs
• Resistivity Log

6. Permeability
and
lithology
Log

7. Gamma Ray Log (GR)
• Measures the radioactivity of the formation and
evaluation of radioactive minerals, such as
potassium and uranium deposits in clay rocks,
like shale.
• Gamma ray penetrates steel, so the log can be
run in cased holes.
• The log has robust lithostratigraphic indicator
that can be used for correlation and facies
studies.
• Unaffected by fluids
• Evaluation of shale content.

8. • Scale 0 ------- 150
• The base line
(shale line) is
center line = 75
50
100
150
200
----
GR Log
Depth (M)
Clay
Permeable
zone
Sand

9. Where;
V(sh)= shale volume (%),
GR(log)= GR value from log,
GR(max)=GR value from log at shale line,
GR(min)= GR value from log at sand line
Evaluation of the shale content

10. Spontaneous Potential (SP) Log
• Measuring the difference in electrical potential
between two electrodes, a grounded electrode
and an electrode on the sonde (logging tool).
• The SP log is very similar in shape to GR log
(but does not identify thin beds), and both can
be used alternatively for correlation purposes.
• If the fluid is better conductor than the drilling
mud (salt water), the curve will deflect to the
left.
• If the fluid is poor conductor (fresh water or oil),
it will deflect to the right.

11. SP Log
• Scale,
1 line = 20 mV The base line = 0
Hard rock
Saline water
Not clay
Friable rock
Fresh water
Clay

12. Caliber Log
• The logging system provides a continuous
recording of borehole diameter versus depth.
• Can be used in both soft and hard formations,
run in uncased wells.
• The main indicator of the log is:
 Determine hole and casing diameter,
 Locate caved zones,
 Recognition of mud cake
When a hole diameter less than the bit size is an
excellent indicator of permeability.

13. Caliper log
Base line is bit size
Friable rock
Hard rock
permeable zone

14. Porosity Log
Determine the porosity,
And
Type of fluids

15. Density Log
• The log measures the bulk density of the
formation, by tool contains a radioactive source
emitting gamma rays.
• Measure how much radiation returns to a sensor
and that controlled by rock density, porosity,
composition of the formation and fluids.
• The main use of the Log is to determine a value of
porosity.
• It s also useful in the detection of gas-bearing
formations and recognition of evaporites.

16. Density Log
Scale = 0.1
Add the value from left
to right
Or subtract from right
to left

17. Sonic (acoustic) Log
• Is a continuous record of the specific time
required versus depth for a compressed wave to
travel through a given distance of formation in the
borehole. (ms/ft.) or (s/ft.)
• The acoustic travel time in a formation depends
upon lithology and porosity, the more dense the
lower the travel time (∆t) because sound waves
travel through the rock it self rather than the mud
• The main uses, is estimation of porosity (primary)
and the calibration of regional seismic data.

18. Common lithological travel time

19. Sonic Log
∆t log = Reading from sonic log in µs/ft
∆t ma =Transit time of matrix material
∆t f = fluid velocity ~189 s/ft.

20. Neutron Log
• The log design from the fact, hydrogen atom is
consist of proton and electron so it is very needful
to the neutron.
• Using a radioactive source emitting neutrons
which is collide with the hydrogen nuclei of the
formation material.
• The amount of returning radiation will show the
total of the lost, a dry layer will reject all the
neutron and if it is contain a fluids the lost will be
more.
• Most of the gas field discovered by the neutron
Log (when the density is low compare with other
Logs for the water and oil).

21. Neutron Log
Displayed as
(NPHI, PHIN, NPOR)
For the limestone
porosity is direct from
the log
EX: 14%
Whereas other
lithology is from the
other chart

23. Electrical Logs
EX: Resistivity Log
For determine water
and
Hydrocarbons

24. Electrical Logs
• Are the most important tools available and first logs
to be used by Marcel and Conrad Schlumberger
1927
• Widely used in exploration work for water, minerals
, hydrocarbons and engineering purposes.
• The main use of the electrical tools is to calculate
 The water saturation of a reservoir formation
 Electrical conductivity or resistivity of the
materials
 And give an idea about hydrocarbon.

25. Resistivity Log
• Resistivity of the material is resistant in ohms of a unit
cube, (ohms/S) or (ohms/M)
• Most of the rocks are porous and moisture (sandstone), and
other are compacted which they are containing moisture in
the component minerals (granite)
• Resistivity decrease with increase in the moisture content
and for rock with low moisture content resistivity
determined by the component minerals.
• Weathered rocks has lower resistivity than fresh.

26. 1/ Micro for saturated zone
2/ Shallow for transition
zone
3/ Deep for the zone which
is not effected by drilling
mud
Types of Resistivity

27. Resistivity Log
Micro: red Deep: black Shallow: blue
M<S<D
Saline water
M>S>D
Fresh water
M<S<<D
Petroleum
Dry layer when they shows overlap
between them
When the D and M only
overlapping that give an idea about
the reservoir

28. CONCLUSION
• Depending onthe Petrophysic ofthe rocksdifferent type oflogging
have beenusedfordetermine different properties ,porosity,
• Theimportance thing inthe logisheading andbase line.
• Combinationsoftwoormorelogsbetter than onelog fordetermine
lithology,porosity, and hydrocarbon content.

29. REFERENCES
• Andrew D. Miall (2016), Stratigraphy: A modern Synthesis, Springer International
Publishing Switzerland, 454 P.
• Baker Hughes INTEQ (2001), Advanced Wireline & MWD Procedures Manual,
Baker Hughes INTEQ Technical Publications Group, 192P.
• http://www.see.leeds.ac.uk/
• https://www.spec2000.net/

30. Thank
You