This document discusses unconventional reservoirs and shale gas. It begins with defining unconventional resources as hydrocarbon reservoirs with low permeability and porosity that are difficult to produce. Shale gas is then introduced as natural gas trapped in shale formations. The document outlines a roadmap for identifying and developing shale plays, including geological, geophysical, geochemical, and geomechanical approaches. Key factors like total organic carbon content, thermal maturity, and brittleness are examined. The concept of a "sweet spot" is introduced as the most prospective volumes within a shale play, characterized by properties like thickness and permeability. The document concludes with thanking the audience.

1. Unconventional reservoir
By :
Salim TAZEROUT
Ahmed BOUADEL
GEOPHYSICISTS AT
SONATRACH P.E.D.

2. Agenda
1. INTRODUCTION
2. UNCONVENTIONAL RESSOURCES
3. SHALE GAS
4. ROADMAP TO SHALE GAS
5. SWEET SPOT
6. PRODUCTION
7. CONCLUSION

3. Introduction
• Shale gas was first extracted in the mid 1800s
expanding uses for oil from coal and shale began
• production became comercially availabale and
produced at large scales in the past decade due to
extraction advancements, horizontal driling and
hydraulic fracturing
• In the following; we will try to answer some critical
question that we asked before to start our work

4. Objective
1. What’s unconventional resource?
2. What’s shale gas ?
3. Finding the sweet spot?
4. How to produce the shale gaz ?

5. Unconventional resources
 Defenition
• Unconventional resources are hydrocarbon reservoirs
that have low permeability and porosity and so are
difficult to produce.
 Characteristic
• Gas- and oil-bearing shales are organically-rich, fine
grained sedimentary rocks capable of producing
commercially important quantities of hydrocarbons

6. Conventional vs. Unconventional

7. Types of unconventional reservoir
1. Tight Gas Sands (TGS)
2. Shale Gas and Shale Oil
3. Coal Bed Methane (CBM)
4. Tar sands
5. Methane hydrate
unconventional

8. SHALE GAS

9. Shale gas
• Shale gas is natural gas that is found
trapped within shale formation.

10. potential shale gas
• Grain size bellow 2 micron
• Clay content > 50%
• Total organic carbon TOC >2%
• Low poisson ratio
• High young modulus
• Thermal maturity R0 1% to 1.1%
• Permeability < 0.1md
• Kerogen typeII/III
• Thickness > 200 pouce

11. ROADMAP TO SHALE PLAY

12. Roadmap to shale play
• It is useful to have a defined strategy for the
discovery, developement, and decline phase of each
individual shale play.
• Each new shale play is unique in nature with respect
to geologic setting, lithology and production
mechanism.
• For that we follow a roadmap to shale play
developement in the last two decade.

13. Roadmap to shale play
 The key factors to defined individual shale play
are:
1. Fracability : capability of the reservoir to
be fracture stimulated effectively
2. Productibility : capability of the completion
plain to sustain commercial production
3. Sustainability: capability to the field
developement to meet both econonomic and
environemental constraints

14. Fracability
Brittelness index equation

15. Productibility
 Productibility : Identifying the producing potential of
unconventional reservoir need to know :
Integrated work
Geological &
geophysical
geochemical
mineralogical
Rock
mecanics
Petrophysical
log
productivity

16. Roadmap to shale play
Geochemical approach

17. Road map to shale play
 The key factor plays in geochemistry study is :
1. TOC % (Total organic carbon)
2. Kerogen type;
3. Thermal maturity Ro.

18. TOC
This factor is usualy the majore factor used when judging
the productivity of the shale.

19. Type of kerogen

20. Petrolum maturation

21. Roadmap to shale play
Geological approach

22. Roadmap to shale play
Shale gas core data
•Shales are typically deposited in
low-energy environments
• The depositions of most shale
formations are a series of thin
laminations wich alter the
advancement of the fracture.
•Collected available data (maps
,logs, and interpretation)
geologist will be able to define
shale formation

23. Roadmap to shale play
• Laminar layers of siliceous or carbonaceous material that can have
conventional porosity storage and flow.
• Natural fractures can contribute when mineral deposition has not taken
place.
• Black organic bulk shale that can feed both the laminated layers and the
natural fractures and desorb gas through the fracture-network surface
area.
 The most common lithology combination in the shale
formation are :

24. Roadmap to shale play
Geophysical approach

25. Roadmap to shale play
 The geophysics study based on the seismic interpretation,
defines the regional extent, mapping the structures and faults.
 this seismic interpretation have to include also:
1. Analyze available well logs with emphasis on full log suites.
2. Run models including fluid substitution to determine the
response of pay in the shales.
3. Determine the applicability of AVO analysis in determining
the location of “sweet spots”.
4. Compare the model to the seismic data.

26. Roadmap to shale play
Geomecanical approach

27. Roadmap to shale play
FCI, fracture complexity index.
SRV stimulated reservoir volume.
natural fructure

28. Roadmap to shale play
Petrophysical approach

29. Roadmap to shale play
Potential reservoir
to product
logs template

30. summary

31. SWEET SPOT

32. Sweet spot
• All what we defined before is under one
name « sweet spot »
• Sweet spot are defined as the most
prospective volumes of the shale play.
Can be described as a formation volume
that has the following characteristics:

33. Sweet spot caracteristics
1. Mid to high kerogen content
2. Lower clay content
3. Higher effective porosity 4%, and
permeability < 100 md
4. Low water saturation
5. High youngs modulus
6. Low poisson’s ratio.
7. Brettlness index > 25%
8. Thickness > 200 pouce

34. Produce from sweet spot
Horizontal drilling Map productivity
sweet spot
sweet spotsweet spot
sweet spot
sweet spot

35. Conclusion

36. Conclusion
approximation of the production
rate of a resource over time.

37. Thank you for your attention