BENEFICIAL USE OF PRODUCED WATER SOUNDS SIMPLE ENOUGH. Rick McCurdy, Ground Water Protection Council s Annual UIC Conference February 21-23, 2017

Transcription

1 BENEFICIAL USE OF PRODUCED WATER SOUNDS SIMPLE ENOUGH Rick McCurdy, Ground Water Protection Council s Annual UIC Conference February 21-23, 2017

2 BUT FIRST A MOST PRECIOUS COMMODITY

3 AGENDA What s In Produced Water? What Do We Need To Remove in Order To Beneficially Use? How Do We Remove the Various Components?

4 WHAT S IN PRODUCED WATER? Various salts Various minerals Various metals Dissolved gasses VOC s, TSS, NORM Other organic compounds Production and completion chemicals

5 WHAT NEEDS TO BE REMOVED TO BENEFICIALLY USE? Depends on the end use: Enhanced oil recovery Typically little change outside of minimization of total suspended solids and oil & grease Offset fresh water in hydraulic fracturing Land application Requirements can vary by State Oklahoma: Water table >6 from surface Soil Exchangeable Sodium Percentage no greater than 15 Soil conductivity <4,000 micromhos/cm (topsoil) Minimum of 100 from any stream (as defined by OK Water Quality Standards) Total dissolved solids <5,000 mg/l Oil and Grease <1,000 mg/l Beneficial use Wildlife and/or Irrigation (west of the 98 Meridian) Direct discharge with a NPDES permit

6 DISCHARGE LIMITATIONS (EXAMPLE) Pennsylvania WGR-123 Permit Appendix A Constituent Limit Constituent Limit Constituent Limit Constituent Limit Aluminum 0.2 mg/l Chloride 25 mg/l Manganese 0.2 mg/l Silver 1.2 µg/l Ammonia 2 mg/l COD 15 mg/l MBAS 0.5 mg/l Sodium 25 mg/l Arsenic 10 µg/l Chromium 10 µg/l Methanol 3.5 mg/l Strontium 4.2 mg/l Barium 2 mg/l Copper 5 µg/l Molybdenum 0.21 mg/l Sulfate 25 mg/l Benzene 0.12 µg/l Ethylene Glycol 13 µg/l Nickel 30 µg/l Toluene 0.33 mg/l Beryllium 4 µg/l Gross Alpha 15 pci/l NO2-NO3-N 2 µg/l TDS 500 mg/l Boron 1.6 mg/l Gross Beta 1,000 pci/l O & G Non-detect TSS 45 mg/l Bromide 0.1 mg/l Iron 0.3 mg/l ph Uranium 30 µg/l Butoxyethanol 0.7 mg/l Lead 1.3 µg/l Ra226/228 5 pci/l (combined) Cadmium 0.16 µg/l Magnesium 10 mg/l Selenium 4.6 µg/l Zinc 65 µg/l

7 LIMITS FOR HYDRAULIC FRACTURING FLUIDS General Water Quality Requirements Source - PetroWiki

8 LIMITS FOR HYDRAULIC FRACTURING FLUIDS General Water Quality Requirements Constituent Slickwater Guar (Lin) Chlorides Total Hardness 140K (anionic) No Limit (cationic) Guar (XL) Other (XL) 60K 60K 60K 50K 20K 20K 20K Iron Oil&Grease TSS Boron No Limit No Limit Bacteria * All units are mg/l except bacteria which is cfu/ml

9 MEETING HYDRAULIC FRACTURING REQUIREMENTS Dilution You don t have to dilute with fresh water! Brackish or other produced may be an acceptable diluent Consider mixing any of the above to lower troublesome constituent levels Other alternative sources? (treated municipal waste, RO reject from a municipal plant, industrial water such as boiler blowdown) Caution make sure you understand compatibility of any mixture (more on this later) If you are targeting a sour reservoir and produced water from that formation is abundant consider using it. Depending on quantity of hydrogen sulfide present, economics of scavenging or physically removing may be favorable. It has been done!

10 MEETING HYDRAULIC FRACTURING REQUIREMENTS Chemical Chelation Bind the troublesome constituent in the matrix of another compound and prevent it from reacting with, and causing issues with, your hydraulic fracturing additives Example Iron Can be chelated with citric acid or THPS If using an EPA-registered THPS, you can control bacteria as well!

11 TREATING PRODUCED WATER FOR BENEFICIAL USE Chemical Removal Iron Removal Oxidation (H 2 O 2, ClO 2, O 3 ) ph adjustment (careful ph of ~10 sufficient for iron to come out of solution as Fe(OH) 3 however, a ph of 11 will result in Ca ++ coming out of solution as well) Total Hardness reduction / removal Lime softening Ca(OH) 2 is added to raise ph Ca ++ precipitates as CaCO 3 Mg ++ precipitates as Mg(OH) 2 May also precipitate Ba ++, Sr ++ and Ra ++ Potential for disposal of large quantities of solids Example removing 5,000 mg/l of Ca ++ and 1,000 mg/l of Mg ++ from 10,000 bwpd will generate 26.4 tons of solids per day

12 TREATING PRODUCED WATER FOR BENEFICIAL USE Chemical Removal Barium / Strontium removal thru addition of sodium sulfate Both will precipitate as their sulfate species Potential for large solids disposal Removing 5,000 mg/l Ba ++ and 1,000 mg/l of Sr ++ from 10,000 bwpd will generate 18.5 tons of solids per day Bigger concern is for the potential of Ra ++ to precipitate as well TENORM technically enhanced, naturally occurring radioactive material

13 TREATING PRODUCED WATER FOR BENEFICIAL USE Chemical Removal Alkalinity Will exist as either CO 2, H 2 CO 3, HCO 3, or CO 3 Raising ph (>8.3) will precipitate as CaCO 3 (with Ca ++ present) Lowering the ph (<4.5) will allow majority to escape as CO 2 Sulfates Can precipitate with the addition of BaCl 2 Considerable reactant addition plus solids disposal Example removing 2,000 mg/l of SO 4= from 10,000 bwpd: Will require 7.6 tons of BaCl 2 per day Will create 8.5 tons of BaSO 4 disposal (unless you can find a market) TENORM should not be a concern

14 TREATING PRODUCED WATER FOR BENEFICIAL USE Chemical Removal Bacteria Non-oxidizing biocides (glut, glut/quats, THPS, DBNPA, etc) Usually no compatibility issues Oxidizing biocides (ClO 2, HOCl, NaClO, Peracetic acid, O 3 ) Potential compatibility issues FIFRA Regulations

15 TREATING PRODUCED WATER FOR BENEFICIAL USE Chemical Removal TSS (total suspended solids) Traditional floc and drop or floc and float Typically, polymer added to agglomerate solids and then either dropped to bottom and pulled off, or floated to the top and skimmed Solids can be disposed as a sludge, but generally more economical to dehydrate (filter press, belt press, etc) before disposal

16 TREATING PRODUCED WATER FOR BENEFICIAL USE Mechanical Removal Hydrocyclones Can be used for hydrocarbon and solids removal Electro-coagulation Good for removal of TSS, iron and bacteria Some hardness removal, as well Requires filtration downstream of unit

17 TREATING PRODUCED WATER FOR BENEFICIAL USE Mechanical Removal DAF / IGF Works well with limited hydrocarbons, TSS and iron (if oxidized) Can be used with filtration Polymer addition usually improves efficiency Filtration Works well with TSS and with iron if oxidized Consider back-washable systems if TSS is considerable as sock / cartridge exchange can be burdensome and expensive

18 TREATING PRODUCED WATER FOR BENEFICIAL USE Mechanical Removal Filtration Ultra-filtration Membrane-Solutions Nano-filtration Ceramic membranes Photo copyright Tonka Water Photo copyright Waterworld Photo copyright Water online

19 TREATING PRODUCED WATER FOR BENEFICIAL USE Mechanical Removal Reverse Osmosis Uses pressure to push water molecules through a permeable membrane Requires extensive pretreatment, but removes all minerals, salts and metals Easy to foul media (hydrocarbons and bacteria are troublesome) Inefficient with brines exceeding 50K TDS Forward Osmosis Uses a draw solution to pull water through a permeable membrane More robust and less prone to fouling Most systems push permeate though an RO membrane for a polishing effect Can handle brines >50K TDS

20 TREATING PRODUCED WATER FOR BENEFICIAL USE Mechanical Removal Resin bed ion exchange Total Hardness removal from low TDS brines and relatively fresh water Boron removal Photo is the property of ROK Water

21 TREATING PRODUCED WATER FOR BENEFICIAL USE Mechanical Removal Distillation Requires pretreatment to remove hydrocarbons, TSS, iron and divalent cations Energy intensive A 50,000 bwpd plant will have the energy demand of a city of 25,000-34,000 people High temperature systems require corrosion resistant alloys ($$) Usually has a clean, concentrated brine stream that can be used as a kill fluid Photo copyright 212 Resources Diagram copyright Fountain Quail Photo copyright GE Corporation

22 AGENDA What s In Produced Water? What Do We Need To Remove in Order To Beneficially Use? How Do We Remove the Various Components?

23 BENEFICIAL USE OF PRODUCED WATER SOUNDS SIMPLE ENOUGH Rick McCurdy, Ground Water Protection Council s Annual UIC Conference February 21-23, 2017