Unconventional reservoir

By :Salim TAZEROUTAhmed BOUADEL

GEOPHYSICISTS AT SONATRACH P.E.D.

Agenda

1. INTRODUCTION 2. UNCONVENTIONAL RESSOURCES 3. SHALE GAS 4. ROADMAP TO SHALE GAS5. SWEET SPOT6. PRODUCTION 7. CONCLUSION

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

Objective

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

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

Conventional vs. Unconventional

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

SHALE GAS

Shale gas

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

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

ROADMAP TO SHALE PLAY

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.

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

Fracability

Brittelness index equation

Productibility Productibility : Identifying the producing potential of

unconventional reservoir need to know :

Integrated work

Geological & geophysical

geochemical

mineralogicalRock mecanics

Petrophysical log

productivity

Roadmap to shale play

Geochemical approach

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.

TOCThis factor is usualy the majore factor used when judging

the productivity of the shale.

Type of kerogen

Petrolum maturation

Roadmap to shale play

Geological approach

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

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 :

Roadmap to shale play

Geophysical approach

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.

Roadmap to shale play

Geomecanical approach

Roadmap to shale play

FCI, fracture complexity index.SRV stimulated reservoir volume.

natural fructure

Roadmap to shale play

Petrophysical approach

Roadmap to shale play

Potential reservoir to product

logs template

summary

SWEET SPOT

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:

Sweet spot caracteristics

1. Mid to high kerogen content 2. Lower clay content3. Higher effective porosity 4%, and

permeability < 100 md4. Low water saturation5. High youngs modulus 6. Low poisson’s ratio.7. Brettlness index > 25%8. Thickness > 200 pouce

Produce from sweet spot

Horizontal drilling Map productivity

sweet spot

sweet spotsweet spot

sweet spot

sweet spot

Conclusion

Conclusion

approximation of the production rate of a resource over time.

Thank you for your attention