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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