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Unconventional Gas:Shale Gas
Shale Gas Unconventional gas (hydrocarbons) found
in subsurface shale formations Replacement to coal, oil, and natural gas Clean burning 1,744 trillion cubic feet (tcf) of shale gas
estimated reserves 110 year supply…
R.A. Kerr, 2010 and D.O.E., 2009
Shale Gas Basins in the Continental U.S.
U.S. Fuel Energy Consumption 2007
Renewable Energy3%
Hydropower3%
Nuclear8%
Coal23%
Natural Gas22%
Liquids40%
Energy dependence in the U.S. Surge in exploration of shale gas in North
America
Energy dependence in the U.S. Surge in exploration of shale gas in North
America
Gas from Shale Rock?
Two phase process Horizontally Drill Hydraulic fracturing (frac)
Both processes are water
intensive! (>10 million
gallons)
Generating large volumes
of wastewater as flowback
Typical O&G Operation
External SourceWater
Waste Stream
OPEN SYSYTEM
WASTE
FRAC TANKSPrepare fracture fluidsFRAC PUMPS
Pressurize fracture mixture
GAS WELL HEAD
Horizontal drill and
frac
DRILL & FRAC WASTE RESERVOIR
Store drilling and fracturing waste
What is Fracturing?
Hydraulic fracturing of
shale rock Pressurize hydraulic
mixture (up to 1,000 psi)
Up to 5 fractures per
day/crew
2-6 million gallons of
water per well
Fluid Management
Fluid Management Source water
Local or regional freshwater Drill/Frac wastewater
Disposal Deep well injection Costly Environmentally disruptive
Recycling Typically settle and decant Only 50-60% water recovery!
(at times <20%)
Oil & Gas Exploration and ProductionTurning Waste Streams Into Resources
One industry’s waste…
-Appropriate Treatment-Public Perception
-Resource Management
Is another's high value water resource…
Oil & Gas Exploration and ProductionPotential Beneficial Reuses
Drilling Muds
Frac Flowbac
k
Produced Water
Livestock W
aterin
g
Irrigation
Industry
Stream Augmentation
Internal Reuse
Oil & Gas Exploration and ProductionIs Adequate & Effective Treatment Possible?
Drilling Muds
Frac Flowbac
k
Produced Water
Gelling agents, friction reducers, surfactants 10,000 to 30,000 ppm TDS 1,000 to 5,000 mg/L organic constituents Reduced conditions 1 to 6 million gallons of waste produced/well
Addressing tough industrial streams
Robust on-site treatment
Mobile and modular construction
Inexpensive waste stream reduction
Flexible under variable influent compositions
Treat high TDS waste steams
Potential Processes for Treatment of O&G Wastewater
Station 4: Oil and Gas Production Wastewater Pretreatment
Objective Evaluate potential pretreatment of oilfield wastewater
(a mixture of produced water and frac flowback
wastewater)
Focus on maximizing wastewater oxidation and
subsequent turbidity removal through
coagulation/flocculation
Station 4: Oil and Gas Production Wastewater Pretreatment
OXIDATION PROTOCOL
Investigate hydrogen peroxide oxidation of oil and grease, organic
matter, and metals (manganese).
Tests conducted at ambient pH and temperature of approximately
~20 °C.
Hydrogen peroxide (35% and SG of 1.1) will be dosed at various
concentrations (0.5 to 3.0 g/L) into 1L jars.
Oxidation-reduction potential (ORP), manganese concentration, and
pH should be measured after 15 minutes of reaction time.
Station 4: Oil and Gas Production Wastewater Pretreatment
COAGULATION PROTOCOL
Aluminum or iron salts will be added after sample oxidation.
Aluminum (10-60 mg/L) from Al2(SO4)3 (alum), AlCl3 (aluminum
chloride), and iron (10-60 mg/L) from a solution of ferric chloride
(FeCl3) are the chosen coagulants.
Turbidity and pH should be measured in the raw wastewater sample
and each of the settled jars.
Samples for Mn, COD, alkalinity, and hardness analysis should be
taken from the jars showing the greatest turbidity removal.
Station 4: Oil and Gas Production Wastewater Pretreatment
ELECTROCOAGULATION PROTOCOL
Aluminum or iron electrodes will be used after sample oxidation.
Doses will be controlled through current density (Amp./cm2)
Flocculation (jar tester) following electrocoagulation
Turbidity and pH should be measured in the raw wastewater sample
and each of the settled jars.
Samples for Mn, COD, alkalinity, and hardness analysis should be
taken from the jars showing the greatest turbidity removal.