Technologies for Removing Contaminantsfrom Produced Water

RICK MCCURDYSR. ENGINEERING ADVISOR – CHEMICALS & WATER

Ground Water Protection CouncilAnnual UIC ConferenceFebruary 12-14, 2018Tulsa, Oklahoma

Agenda• Constituents of Produced Water• Technologies to Remove Constituents or Extract Water• Gaps

CONSTITUENTS OF PRODUCED WATER

• Chlorides ˃ Salinity, salt content

• Total Hardness ˃ Divalent cations

• Ca++, Mg++, Ba++, Sr++, Ra++

• Iron ˃ Fe2O3, Fe3O4

˃ FeOH˃ FeS

• Hydrocarbons˃ Dispersed liquids˃ Dissolved gases

• Sulfates

• Boron

• Alkalinity˃ Bicarbonates (HCO3-)

• Suspended Solids (TSS)

• Bacteria˃ Aerobic

˃ Anaerobic• SRB• APB

• Desirable salts / metals˃ Iodine

˃ Lithium

• Heavy metals˃ Copper

˃ Zinc

CONSTITUENTS OF PRODUCED WATER

• Naturally occurring radioactive materials (NORM)˃ Minimal exposure risk but can be concentrated through some treatment processes

˃ Radium most common

˃ Often found in waters high in either barium or strontium

Left photo - fqechemicals

CONSTITUENTS OF PRODUCED WATER

• Hydraulic fracturing additives˃ Anionic polyacrylamides˃ Guar gels˃ pH adjusting agents (sodium hydroxide)˃ Oxidizers (potassium persulfate, sodium persulfate)˃ Typically only seen during initial flowback phase ˃ Potential for hundreds of assorted chemicals

• e.g. – sodium tetraborate, petroleum distillates, methanol

• Chemicals used during production (not all wells)˃ Corrosion inhibitors

• Amines, quaternary amines, imodazolines typically 30-50 ppm

˃ Paraffin compounds (solvents/dispersants)• BTEX (toluene, xylene) – typically batched at 2,500 ppm

˃ Scale Inhibitors• Phosphonates, polymers – typically 15-25 ppm

˃ Biocides• Glutaraldehyde, quaternary amines, THPS• Typically batched at 250-500 ppm

˃ Foamers• Surfactants typically at 500-1,000 ppm but limited

number of wells

Top photo copyright Halliburton Energy Services, bottom photo courtesy Rick McCurdy

Agenda• Constituents of Produced Water

• Technologies to Remove Constituents

or Extract Water

• Gaps

AVAILABLE TECHNOLOGIES

• Contaminant Removal

˃ Absorptive media

˃ Oxidation

˃ Electrocoagulation

˃ Resin bed extraction

˃ Filtration

• Water Extraction

˃ Reverse Osmosis

˃ Forward Osmosis

˃ Membrane Distillation

˃ Evaporation

Photo copyright The American Oil and Gas Reporter

ABSORPTIVE MEDIA

• Granular Activated Carbon (GAC)

˃ Organics are absorbed onto surface of GAC

˃ Material eventually is fully spent and must be removed from service and treated to

restore absorptive capability

Left photo – Activated Granular Carbon Exporter, right photo – Water Online

OXIDATION

• Chemical oxidizers

˃ Ozone, chlorine dioxide, hydrogen peroxide, potassium persulfate

˃ Break up suspended organic particles

˃ Shear bonds on larger organic molecules

˃ Reacts and removes volatile organic compounds (VOC)

˃ Reacts and removes hydrogen sulfide

˃ Sanitizes fluid

• Thermal oxidative processes

˃ Less chemical consumption

˃ Quicker reactions than most chemical oxidizers

˃ Especially effective against organic molecules

˃ Reacts and removes hydrogen sulfide

Top photo copyright Hydrozonix, bottom photo copyright Siemens Corp.

ELECTROCOAGULATION

Photos courtesy of Rick McCurdy

• Alternating current changes polarity of stacked plates

• Plate material designed to be sacrificial and aids in pulling metals from solution

• Primarily used for removal of calcium, magnesium and iron, but can be used for

some degree of salt removal (sodium chloride) with proper plate material

RESIN BED EXCHANGE

• Divalent cation removal

˃ Ca, Mg, Ba, Sr, Ra

˃ Bed material is regenerated once fully loaded

˃ Regenerate is a sodium chloride solution (standard home water softener)

• As it is passed through the bed the divalent cations are released for disposal

• Resins also available for sulfate and boron removal

Left diagram copyright inserv Company, right phot copyright Bosque Systems

FILTRATION - A TALE OF FOUR MOLECULES

• Dihydrogen Oxide

˃ aka water

˃ While it can kill you, being necessary

for life, it is generally considered a

good thing

• 2-butoxyethano l

˃ aka 2-BE, EGMBE, Butyl Cellosolve

˃ Fantastic mutual solvent

˃ Suspected endocrine disrupter

Compound structures from Wikipedia

• Ethylene Glycol

˃ aka antifreeze

˃ Freeze point suppressor

˃ Moderately toxic

• Acrylamide

˃ aka precursor to polyacrylamide

˃ Known carcinogen

˃ Human consumption through burnt toast

FILTRATION - SIZE DOES MATTER!

Copyright enprom.eu

STAGED SEPARATION

Copyright German Technology for Water and Energy

FILTRATION

• Particle filtration

˃ Sock / cartridge (>2 micron)

• Microfiltration

˃ .05-4.0 micron

• Ultrafiltration

˃ 0.005-0.1 micron

• Nanofiltration

˃ 0.0007-0.008 micron

• Reverse Osmosis

˃ 0.0001-0.003 micron

• Forward Osmosis

• Membrane Distillation

Top photo copyright TanMar Corp.,bottom right photo copyright Pure Aqua, Inc., bottom left diagram copyright ScienceDirect.com

REVERSE OSMOSIS

• Only water molecules pass thru

• Easily fouled by other materials

˃ Hydrocarbons

˃ Bacteria

˃ Mineral scale

• Energy Demand

WaterTectonics, SlideShare

FORWARD OSMOSIS

Right diagram HTI Water, bottom diagram Engineering.com

• Dehydrated or anhydrous

solution used to draw water

molecules through the

membrane

• Low pressure means less

fouling potential

• Still requires pressure demand

(energy) for water removal from

draw solution via RO

EVAPORATION

• Falling film evaporators

• Vacuum distillation / mechanical vapor recompression

• Primarily used to recover water vapor while concentrating the remaining brine

• High temperature operations requires most constituents other that sodium

chloride be removed prior to processing in the evaporator

• VOC’s with boiling points less than 100C will carry with water vapor if not

removed upstream

Left photo copyright 212 Resources, middle drawing copyright Buflovak, right drawing copyright Fountain Quail

Agenda• Constituents of Produced Water

• Technologies to Remove Constituents

or Extract Water

• Gaps

GAPS – WHAT’S NEEDED?

• Conformational Analysis of Treated Water

˃ Periodically or Real-time?

˃ Resistivity?

• 18.2 megohm water - Ultrapure

˃ Groups or families?

• If a test for all VOC’s is non-detect, can’t we assume that any one individual would also be non-detect?

• Cost of Treatment

˃ Previous slides indicate the technology to recover pure water exists but many less

expensive alternatives for produced water reuse or disposal currently exist

˃ Reverse osmosis (for brines < 50k TDS) produces very clean water but extensive

pretreatment required

˃ Membrane distillation has the promise of very clean water from higher TDS streams

with much less pretreatment

Technologies for Removing Contaminantsfrom Produced Water

RICK MCCURDYSR. ENGINEERING ADVISOR – CHEMICALS & WATER

Ground Water Protection CouncilAnnual UIC ConferenceFebruary 12-14, 2018Tulsa, Oklahoma