Technologies for Removing Contaminants from Produced Water

Transcription

1 Technologies for Removing Contaminants from Produced Water RICK MCCURDY SR. ENGINEERING ADVISOR CHEMICALS & WATER Ground Water Protection Council Annual UIC Conference February 12-14, 2018 Tulsa, Oklahoma

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

3 CONSTITUENTS OF PRODUCED WATER Chlorides Salinity, salt content Total Hardness Divalent cations Ca ++, Mg ++, Ba ++, Sr ++, Ra ++ Iron Fe 2 O 3, Fe 3 O 4 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

4 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

5 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 ppm Paraffin compounds (solvents/dispersants) BTEX (toluene, xylene) typically batched at 2,500 ppm Scale Inhibitors Phosphonates, polymers typically ppm Biocides Glutaraldehyde, quaternary amines, THPS Typically batched at 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

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

7 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

8 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

9 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.

10 ELECTROCOAGULATION 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 Photos courtesy of Rick McCurdy

11 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

12 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 Ethylene Glycol aka antifreeze Freeze point suppressor Moderately toxic Acrylamide aka precursor to polyacrylamide Known carcinogen Human consumption through burnt toast Compound structures from Wikipedia

13 FILTRATION - SIZE DOES MATTER! Copyright enprom.eu

14 STAGED SEPARATION Copyright German Technology for Water and Energy

15 FILTRATION Particle filtration Sock / cartridge (>2 micron) Microfiltration micron Ultrafiltration micron Nanofiltration micron Reverse Osmosis micron Forward Osmosis Membrane Distillation Top photo copyright TanMar Corp.,bottom right photo copyright Pure Aqua, Inc., bottom left diagram copyright ScienceDirect.com

16 REVERSE OSMOSIS Only water molecules pass thru Easily fouled by other materials Hydrocarbons Bacteria Mineral scale Energy Demand WaterTectonics, SlideShare

17 FORWARD OSMOSIS 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 Right diagram HTI Water, bottom diagram Engineering.com

18 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

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

20 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

21 Technologies for Removing Contaminants from Produced Water RICK MCCURDY SR. ENGINEERING ADVISOR CHEMICALS & WATER Ground Water Protection Council Annual UIC Conference February 12-14, 2018 Tulsa, Oklahoma