The document discusses conventional and unconventional gas extraction, focusing on shale gas and the technological advancements in drilling that make its extraction economically viable. It highlights concerns about environmental impacts, including groundwater contamination and seismic risks, along with methods for managing these risks. The document also examines the role of shale gas in energy independence for countries like the USA and Poland, and outlines the hydraulic fracturing process used to extract gas from shale formations.

1. SHALE GAS
Bocchinfuso F., Bresciani F., Caprio M.S., Colonnelli A.

2. CONVENTIONAL AND
UNCONVENTIONAL GAS
Conventional Gas
 Free oil and gas
trapped in porous
reservoirs
 (usually
sandstone or
limestone)
 Relatively easy to
extract
Unconventional
Gas:
 Gas trapped in
rocks which is
more difficult to
produce from
such as :
 Tight gas
 Coal bed
methane
 Shale Gas
Why extract
unconventional
oil and gas now?
 Developments in
drilling technology
over the last 20
years have made
it economic to
extract

3. UNCONVENTIONAL GAS

4. WHAT IS SHALE GAS?
Sedimentary
rock and organic
matter (kerogen)
Both source
rock and
reservoir of the
gas
Shale
Stored in three
ways
Thermogenic
and biogenic
generation
Gas

5. ENERGY INDEPENDENCE
Sources: IEA and EIA
USA China
2014 total energy import 25% 19%
Gas percentage produced with shale
in 2015
50% Work in progress

6. USA become a gas
exporter
Shale gas & tight oil
13.6 Tcf in 2015
to 29 Tcf in 2040

7. US NATURAL GAS

8. ECONOMICAL ISSUES
 30% fracking companies went bankrupt in 2015 due to the oil low price
 At the same time technology improvements leads to higher rates of recovery at lower costs
Oil price - WTI [USD/bbl]

9. EUROPE POSITION
 Poland has european largest
reservoirs and those are being
investigating
Independence from
Russia
Environmental
Effects

10. THE WELLBORE
Location of
the site
Vertical drilling
(mud )
Casing (conductor,
surface,
intermediate,
production)
Cement
Kick off point

11. THE WELLBORE
Angle drilling process in
order to get horizontal
mining along the shale
layer (eventually in
several directions)
Again cement to seal the
production casing
The well is complete:
casing and cement isolate
the freshwater zone and
the surroundings from the
wellbore, avoiding any
kind of leakage. The
drilling machine is no
longer needed.

12. HYDRAULIC FRACTURING
It’s a mining technique that is
used to release the gas
trapped in shale formations.
The first step after the drilling
process is the perforation of
the production case using a
perforating gun

13. HYDRAULIC FRACTURING
Fracking can be described as a
sequence of three stages:
1. PAD: high pressure fluid is pumped
down through the well and the
perforation holes in order to
fracture the formation

14. HYDRAULIC FRACTURING
2. PROPPANT STAGE: proppant is
added to the fluid in order to keep
the fissures open (sand, bauxite,
ceramic balls)
2. DISPLACEMENT: flush the
previous sand laden stage in order
to clean the pipe and allow the
extraction of gas.

15. EXTRACTION OF THE GAS
Hydraulic fracturing is completed
Fluid is carried out of the pipe
Permanent production well head is
installed

16. Major concerns:
Contamination
of ground water
wells
Waste water
disposal
Seismic risks
Green house
effect
ENVIRONMENTAL IMPACT

17. CONTAMINATION OF WATER SUPPLIES
Ways of contamination:
 Propagation by fractures
 Wellbore leakages
Solutions:
 Fingerprint and seismic measurments
 API directives

18. WASTE WATER DISPOSAL
•
Flowback water
Methods of
disposal:
Underground
injection
At municipal
facilities
Reuse
147,000 counted injection
wells
Over 250 milion cubic meters
pumped each year

19. SEISMIC RISK
• Caused by fluid injection
• Increased number of earthquakes with
M>3:
• Increase in magnitude
• Most powerful was 5.6 M
24 193

20. Microseismic Diagrams of Typical Hydraulic
Fracturing Job in the Barnett Shale

21. GHG EMISSION
Venti
ng
Flarin
g
Gree
n
comp
letion
3 option to manage
fugitive emissions
during flowbak:

22. BIBLIOGRAPHY
MIT Energy Initiative, http://energy.mit.edu/publication/future-natural-gas/.
EIA, http://www.eia.gov/outlooks/aeo/.
Treccani,
http://www.treccani.it/export/sites/default/Portale/sito/altre_aree/Tecnologia_e_Scienze_appli
cate/enciclopedia/italiano_vol_3/057-084_ita.pdf.
API guidance document first edition, Oct. 2009.
EPA, https://www.epa.gov/natural-gas-star-program.
http://science.sciencemag.org/