Prospecting of electrical logging method

2. Introduction
Well logging
Types of Well Logging
Electrical Logging
Types of Electrical Logging
Spontaneous Potential Logging
Resistivity Logging
Induction Logging
Conclusion
References

3. IntroductIon
•Geophysical exploration-study of physical
properties Geological materials by using appropriate
instruments
•Types of geophysical exploration:
•Electrical
•Magnetic
•Gravity
•Seismic
•Radioactive and
•Well logging

4. Well loggIng
Continuous recording of a physical parameter of the
formation with depth by introducing sonde
First developed by Schlumberger brothers in 1927
To identify the productive zone of hydrocarbon and
its mobility
To define petrophysical parameters
To determine depth, thickness, formation
temperature and pressure of reservoir
To distinguish between oil, gas and water zones in a
reservoir

5. Types of well logging
Electrical method
 Radioactivity method
Sonic logging
Miscellaneous logging

6. electrIc loggIng
Continuous record of the electrical properties
of the fluids and geologic materials
Performed by measuring current through
electrodes in the logging device or sonde
Used in geological investigations to assess the
variation with depth of geologic materials and
associated fluids
Correlate and determine the continuity of
geologic strata
Types- Resistivity, Spontaneous(Self) Potential,
Induction logging

7. Spontaneous Potential Logging
Due to salinity between formation water and mud
filtrate against permeable beds
The measurement is made through a
potential meter
Useful in Establishing correlation of beds from
well to well
To determine bed boundaries and thickness
To evaluate the formation water resistivity
To delineate porous and permeable reservoir rock

10. Resistivity Logging
oAbility to impede the flow of electric current
oFall in the range from 0.2 to 100 ohm meter
o4 electrodes are used
oCarried out by lowering of electrodes
oTypes
Normal and Lateral logs
Laterolog
Microlog
Microlaterolog
Proximity

11. Normal and Lateral log
4 electrodes-2 potential(M and N), 2 power
electrodes(A and B)
Normal device- A and M are closely spaced ,
B is grounded and N is far away from A-M
Lateral device- M and N closely spaced with
electrode A

13. Microlog
The resistivity of a small volume of formation
3 electrodes(A, M1 and M2) in vertical line
Spacing is 1 inch( 2.5cm)
Excellent permeability indicator

14. Microlaterolog
Central electrode very small size and 3 circular
electreodes concentric with 1-2 cm
Accurate estimate of flushed zone resistivity and
hence porosity

15. Proximity log
Used with other resistivity logs
Evaluate permeable zones exhibiting thick (up to
2 cm) mud cakes

16. Induction Logging
In dry boreholes or boreholes containing
nonconducting fluids
Based electromagnetic induction
Parameter is conductivity
Transmitter coil and receiver coil coaxially
supported by an insulating mandrel

18. Laterolog
4 electrodes- one at centre and 3 are
symmetrically placed with centre one

19. Case study 1:

20. Case study 2:

21. Case study 3:

22. Well logging technique is one of the type used in
geophysical exploration
This can be performed by logging devices or SONDE
Electrical logging can be done by measuring current
through electrodes in the logging device
Spontaneous potential, resistivity and induction logging
To identify productive zone of hydrocarbon, to define
petrophysical parameter, to determine depth,
formation temperature and pressure of a reservoir, to
measure hydrocarbon mobility
Conclusion

23. References
M.G. Ramachandra Rao,
Outlines of Geophysical prospecting (1975)
Prasaranga Manasagangotri Mysore pp:343-366
1981,Milton B Dobrin, Introduction to
geophysical prospecting , Third edition,
Mcgraw- HILL Book Company pp:568-622
www.wikipedia.com
www.greatgeophysics.com/logginginfo.html
www.geologging.com/english/products/.../ele tric_log.htm