Transcript Oil Flows Hydraulic Pressure Fractures Rock Sand lodges in fractures FRACKING=HYDRAULIC FRACTURING The Marcellus Shale Formation: • Large Area • Shallow Depth • Lots of Gas Thin formation • Tight Rock • Jointed.

Oil
Flows
Hydraulic Pressure
Fractures Rock
Sand lodges
in fractures
FRACKING=HYDRAULIC FRACTURING
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The Marcellus
Shale Formation:
• Large Area
• Shallow Depth
• Lots of Gas
Thin formation
• Tight Rock
• Jointed formation
http://geology.com/articles/marcellus-shale.shtml
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Marcelus and Utica Shale are Tight
Rocks
•
• Marcellus shale is “tight”, meaning not many
small cracks between joints, so the gas
trapped in the rock needs help to be released
to the surface: artificial fracture is the
solution.
• Open joints using “hydraulic fracturing” or
fracking.
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“Horizontal” Drilling and Fracturing
Not to scale
~ 3500 feet
Cap rock
Cap rock
~ 100 feet
Pay zone
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A Typical Drilling Pad
Let’s watch a movie to see what
happens from such a site
Pumps and Power
Drill Rig
Drilling Mud
Lagoon
Injection Water and Flowback
Lagoon
http://www.glossary.oilfield.slb.com/
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More Than One Well per Pad
~100’s
of feet
Hydraulic fracture
Well (6 here)
Pad
Not to Scale
many 1000’s of feet
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Direction of max
horizontal stress
Geology controls the arragement
Ideal Arrangement of Spacing Units
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Example: Dallas/Fort Worth Airport Property,
Barnett Shale Play
• 53 pads on 18,076 acres
• Almost complete
coverage
• Patchwork, mostly ideal
units
• One developer
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Some chemicals used in the procedure
Proppant: Particles, like sand, transported into the fractures to
keep them open after fracturing pressure release.
Gelling Agents: Increase fluid viscosity to help proppant
transport.
Biocides: Kill bacteria that harm the gelling agents.
Breakers: Decrease viscosity of the fracturing fluid, after the
fracturing process, to improve flowback.
Anti-Corrosives: Protect metallic elements in the well.
Friction Reducers: Allow high pressures and flow rates.
Acid : Clean out perforations, well, fractures
http://www.epa.gov/OGWDW/uic/pdfs/cbmstudy_attach_uic_ch04_hyd_frac_fluids.pdf
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http://www.earthworksaction.org/hydfracking.cfm
Additives to Fracturing Fluids
From NYS DEC’s SGEIS, 2009
PROBLEM
• When the fracturing process is completed, the pressure
is released, and much of the fracturing fluid backflows to
the wellhead*.
• The backflow is:
 highly saline;
 contain some heavy metals (e.g. barium, strontium);
 Toxic fluid additives;
FLUID Recycling can ameliorate this problem but more research is needed to
achieve good results
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Potential Problems
 Contamination of ground water and surface water by fracturing fluids

Water leaks

Gas leaks
 Interconnection of aquifers produced by fractures and alteration of the
underground rock layers
 Destruction of the confining nature of common confined aquifers in SE Ohio.
 Lack of good models to predict expected impacts, more research is needed to
understand water and gas circulation during and after exploitation.
 For zones that are impacted (contaminated water wells, etc.), for how long are
they going to be impacted? Who is going to supply clean water to the affected
users after exploitation ends?