WELL LOGGING BY QAISAR KHAN MS GEOLOGY XIAN SHIYOU UNIVERSITY CNINA

1. Prepared By: Qaisar Khan
MS Geological Engineering,2022
Xi’an Shiyou university

2.  Petrophysics of the rocks
It is the study of the physical and chemical properties of the rocks related to the
pores and fluid distribution
• Porosity:
Porosity is ratio between volume of void to the total voids of the rock.
• Permeability:
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.  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. 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

7. • 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.

10. • 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.

12. • 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.

14. Determine the porosity,
And
Type of fluids

15. • 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.

17. • 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.

20. • 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).

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

24. • 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 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.

28. • 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. • 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/

31. The End