SHALE GAS RECOVERY TECHNIQUES

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SHALE GAS Natural gas from shale.

Trapped in shale formations.

Organic matter broken down by high temperature.

Thermogenic gas.

Reabsorbed by shale and trapped.

Composition varies with the method of extraction and shale type.

COMPOSITIONComponent Typical Analysis

(mole%)

Range

(mole%)

Methane 95.2 87.0-96.0

Ethane 2.5 1.5-5.1

Propane 0.2 0.1-1.5

iso-Butane 0.03 0.01-0.3

normal Butane 0.03 0.01-0.3

iso-Pentane 0.01 Trace-0.14

normal Pentane 0.01 Trace-0.04

Hexane plus 0.01 Trace-0.06

Nitrogen 1.3 0.7-5.6

Carbon Dioxide 0.7 0.1-1.0

Oxygen 0.02 0.01-0.1

Hydrogen Trace Trace-0.02

Specific Gravity 0.58 0.57-0.62Shanthipriya.N

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HYDRAULIC FRACTURING Propagation of fractures by a pressurized fluid.

Injection of fracturing fluid.

Opening up of thin cracks.

Expansion of gas from rock.

Old technology which is now used in conjunction with other technologies like horizontal drilling.

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HYDRAULIC FRACTURING FLUID Major part of it is water, with sand and chemical additives.

Reduces friction, protects rock formation.

Increases the efficiency of the process.

Water is used only for a short-term periodof drilling.

Local geology, hydrology and geography affect the water requirements.

Proppant : primarily to provide a permeable and permanent filler to fill the void created during the fracturing process.

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Additive Chemical Ingredient Purpose Common Use Of Chemical

Ingredient

Acid Hydrochloric Acid or muriatic acid Dissolve minerals &

initiate cracks in rock

Swimming pool chemical &

cleaner

Antibacterial Agent Glutaraldehyde Eliminates bacteria in

water

Disinfectant, Sterilizer

Corrosion Inhibitor Formamide Prevents corrosion of well

casing

Acrylic fibres, plastics

Crosslinker Borate salts Maintains fluid viscosity Laundry detergents, soaps

Friction Reducer Petroleum distillate Slicks water to minimize

friction

Used in cosmetics

Gel Guar gum or hydroxyethyl

cellulose

Thickens water to

suspend sand

Thickener

Iron Control Citric Acid Prevents precipitation of

metal oxide

Food additive

Clay Stabilizer Potassium chloride Creates brine carrier Medicines, IV fluids

pH Adjusting Agent Sodium or potassium

carbonate

Maintains effectiveness of

other components

Laundry detergent, water

softener

Proppant Silica, quartz sand Keeps fracture open Drinking water filtration

Scale Inhibitor Ethylene glycol Prevents scale deposits in

pipes

Household cleansers

Surfactant Isopropanol Reduce surface tension Glass cleanser, deodorants

Water Water To expand fracture &

deliver proppants

Landscaping, manufacturing

HORIZONTAL DRILLING A type of inclined drilling.

Kick-off Point : subsurface location just above the target oil or gas.

Entry Point : Intersection of the drill pipe with the gas bed.

Most reservoirs have a vast extent in horizontal direction.

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Shale Basins – Site Of Recovery Shale plays are formations containing significant amount of natural gas.

Geographic structures with favorable conditions for production.

Surveyors and geologists analyze the location using surface and subsurface techniques – LOGGING.

Usual physical properties detected are porosity, permeability, saturation, etc.

The shale matrix permeability is usually low. Thus requires fracturing for production.

Surveying, Logging & Analysis Extensive surveillance study carried out to determine the location of underground reservoir.

Ensures minimal impact of operations on local community.

Makes comply with government regulations.

Latest development is computer simulation.

Use of the collected data of producing formation and create a model, using mathematical formulas of fracture propagation, to predict possible fracture propagations.

Simulators allow engineers to alter the stimulation programs (volumes and types of proppants, fluids, and additives) to evaluate how fractures could develop within the reservoir.

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RECOVERY PROCESSES There are four stages involved in recovery process:

1. Preparing for drilling. (4 to 8 weeks)

2. Rig Work. (4 to 5 weeks)

3. Hydraulic fracturing. (2 to 5 days)

4. Production. (25 to 40 years)

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PREPARING FOR DRILLING Clearing of drilling area.

Vehicle access to site and infrastructure for water.

Final assessment for environmental, human health safety plans and operational procedures.

Regulations by government.

Assembling the rig.

RIG WORK

Construction of the rig and drilling of well.

Steel casing, cementing.

Horizontal drilling.

Production casing.

End of drilling phase.Shanthipriya.N

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HYDRAULIC FRACTURING

Use of perforated guns for fracturing.

Fracking fluid is pressurized through the well.

The rock cracks and fluid flows farther to open up the cracks.

Fractures are held open by the proppant.

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Fracture Monitoring Techniques The proceedings of the well are to be monitored for efficient process.

Pumping rate, pressure, proppant are monitored.

Wellbore pressure.

Commonly pressure, pumping rate, fluid properties & proppants are important for hydraulic fracturing.

Gases released into atmosphere during fracturing.

Micro seismic monitoring.

Eddy covariance flux.

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ENVIRONMENTAL EFFECTS Contamination of groundwater, risks to air quality, mishandling of wastes, migration of gases and chemicals to surface and health problems due to these

Air Emissions:Particulate matter, nitrogen oxide, sulfur oxide, carbon dioxide,

carbon monoxide, methane, ethane, liquid condensates, volatile organic compounds like BTEX.

Groundwater Pollution:Indirect effect-evaporation ponds-runoff due to rain-poor

pipelines carrying chemicals-breakage in waste water pipe.

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CONCLUSION Fuel powers the world. Unconventional gas recovery is easier and economical than coal.

Electricity Generation – reliable, cost competitive, cleaner technology.

Horizontal drilling in conjunction with hydraulic fracturing has made development of shale gas resource an economically viable venture.

Less water consumption (60 to 40%) for production of electricity from natural gas than in coal.

A step towards cleaner technology – less carbon emissions from shale gas compared to coal.

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THANK YOU

THANK YOU

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REFERENCES Canadian Society for Unconventional Gas.

The Institute for Energy and Environmental Research for Northeastern Pennsylvania.

National Bureau of Asian Research.

International Energy Agency.

Exxon Mobil.

www.hydraulic fracturing.com

Evaluating the Environmental Implications of Hydraulic Fracturing in Shale Gas Reservoirs BY: J. Daniel Arthur.

American petroleum Institute.

The Hindu.