unconventional gas: shale gas shale gas unconventional gas (hydrocarbons) found in subsurface shale...

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.