CONCENTRATE MANAGEMENT ISSUES: GENERAL & A FOCUS ON DEEP WELL INJECTION. Mike Mickley. P.E., Ph.D. Mickley & Associates Boulder, CO

Transcription

1 CONCENTRATE MANAGEMENT ISSUES: GENERAL & A FOCUS ON DEEP WELL INJECTION Mike Mickley. P.E., Ph.D. Mickley & Associates Boulder, CO RO ROUNDTABLE MEETING Brighton February 7,

2 EVOLUTION OF CONCENTRATE DISPOSAL More, larger plants More challenges More awareness of issues Issues / concerns in background Documentation and definition; clarity of issues disposal Focus on improvements & solutions management ZLD, beneficial use, volume reduction sustainability Significant local challenges; Desalination Roadmap 2

3 FOCUS Municipal desalination plants of size > 4 MGD Year-round operation 3

4 REVIEW: some incorrect but often held perceptions Multiple disposal options exist at a given site DWI is feasible in many locations Evaporation ponds and land applications are generally viable options where climate permits Cost reduction for concentrate disposal is similar to cost reduction for water production Concentrate management provides more concentrate disposal options Volume reduction is helpful with regards to facilitating concentrate disposal Beneficial uses are widely available and offer a solution to concentrate disposal New desalination technologies may solve concentrate disposal challenges There are uses for concentrate, brine (obtained from concentrate), and mixed solids (obtained from concentrate) that will alleviate disposal challenges Concentrate disposal should not be considered waste disposal There may be a silver bullet it just requires more attention and research 4

5 NUMBER OF DESALTING PLANTS BY STATE (through 2004)

6 DISPOSAL METHOD BY PLANT SIZE U.S. municipal desalting plants built through 2002 of size > MGD (95 m3/d) 60 % of Desalting Plants < 1 MGD (3,785 m3/d) 1-6 MGD (3,785-22,710 m3/d) 6 MGD (22,710 m3/d) 10 0 Surface water Sewer Subsurface injection Evaporation pond Land Recycle Reuse system 6

7 BRACKISH CONCENTRATE DISPOSAL (plants built by 2003) Disposal type Largest size (MGD) # plants # states Surface 36 (RO), 20 (RO), 15 (RO) Sewer 36 (NF), 15 (RO), 9.5 (NF) Deep well 23 (NF), 20 (RO), 12 (NF, RO) 26 2 (FL-25, CA-1) Land 12 (NF), 1.5 (RO) 20 2 (FL-18, TX-2) Evap. pond 1.5 (EDR), 0.2 (RO) 9 3 (TX-5, FL-3, AZ-1) Disposal types have size limitations Disposal types have location limitations of 25 states use only surface water or sewer disposal 7

8 ASIDE Salt loading Example Thornton: Even though nitrate was the only receiving water standard in question, several other constituents would increase receiving water levels for those constituents yet to levels still below the level of the standard >>> future discharges are limited; eventually, new discharges not possible Salt loading can occur with: Discharge to surface water Discharge to sewer Discharge to land application (salt loading of ground water) 8

9 TRADITIONAL DISPOSAL OPTIONS -- surface water discharge -- discharge to sewer -- land application -- concentrate 'communicates' with receiving water salt loading -- evaporation ponds -- land intensive -- climate dependent -- location dependent -- costly limited application -- subsurface injection -- location dependent limited application 9

10 RELATIVE COST OF CONCENTRATE DISPOSAL OPTIONS Evaporation Pond Brine Concentrator ZLD Capital Cost Spray Irrigation Deep Well Injection Surface Water Sewer Concentrate Flow Rate 10

11 INJECTION WELL CLASSES 11

12 SOME DWI POSSIBILITIES (in theory) Discharge to new Class I well Discharge to existing Class I well Rework an abandoned Class II well into a Class I well Discharge to Class II well (maintain reservoir pressure) Discharge to Class V well 12

13 SUBSURFACE INJECTION by CLASS I WELLS Possible limitations: Hydro-geological May not find isolated aquifer below USDW zone (10,000 mg/l) May not have sufficient capacity for the life of the desal plant May not have sufficient injection rate so as to avoid many wells and resulting distribution system Regulatory Cost Class I wells may be prohibited Expensive for small desal plants (< 1 MGD capacity) 13

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15 CLASS I - Deep well injection in Colorado Only 1 active Class 1 well in Eastern Colorado; very small (0.042 MGD) Class 2 wells small (diameter, flow) Need for investigations costly Available aquifer characterizations suggest wells in Denver Basin would be deep (9000 ft?); individual wells small; adjacent wells not close Would need distribution system to deliver concentrate to many wells >>> likely not feasible Largest capacity Class I wells (in MGD): FL 22 TX 3 ND 0.9 OK 0.7 IL 0.6 WY 0.5 LA 0.43 MI 0.36 KS

16 CLASS I VS. CLASS II CONTROVERSY Class I (hazardous and non-hazardous industrial wastes) vs. Class II (oil and gas wells) Can inject high salinity produced water into Class II wells but not RO concentrate that may be of lower salinity In Colorado Class I wells overseen by USEPA; Class II wells by Colorado Oil and Gas Conservation Commission (COGCC) Formation pressures have been reduced by past oil/gas production Can oil and gas fields accept injected concentrate? Investigate formation pressures Model interaction of concentrate with formation fluids Analyze water sensitivity of formation fines and clays Model injectivity 16

17 RECOMMENDED RESOURCE Bureau of Reclamation report 17

18 FINDINGS Many wells in depleted O&G fields had formation pressures much less than the lowest-most source of DW (thus no potential for fluids in these wells to move into overlying aquifers) Concentrate could be injected into O&G fields without causing the precipitation of minerals In some cases concentrate would need a pre-treatment Mean injections rates of aquifers considered about 10 gpm or one area and about 280 and 470 gpm in the southern Gulf Coast and East Texas basins >>> injection of concentrate would likely not be a problem if the injection water and the formation are appropriately pretreated, as is done routinely by the oil industry in the injection of produced waters 18

19 FINDINGS (continued) Need changes in statutes Would be helpful if non-hazardous Class I requirements were less than hazardous Class I requirements (but still Class I) Create a special category of Class I allowing disposal into Class II wells? Concentrate could be injection directly into a Class II well with no additional permits it the concentrate was used in enhanced oil recovery as make-up water BUT would need assurances that concentrate would be accepted over a period of time 19

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22 OIL AND GAS FIELDS IN DENVER METRO REGION Red area = gas field; Green area = oil field; Red dots = oil or gas wells 22

23 FT. BLISS, TEXAS (Class V example) System under construction Concentrate 3 MGD; 6,000 mg/l 3 disposal wells; each permitted for 1100 gpm; one drilled 22 miles from desalination plant Class V wells permitted with no rule changes Formation water is USDW of 7,000 to 8,000 mg/l Wells will be drilled and completed to Class I requirements (not necessary but done for environmental concerns) Depths: bottom hole 3,700 to 4,000 Costs (approximate): Step 1: overall evaluation of disposal options $0.1 M Step 2: drill 4 test holes; complete EIS $1.8 M Step 3: geophysics studies $0.15 M Step 4: drilled pilot well (well #1) $1.4 M + 0.2M (consulting) Step 5: authorization application $0.13 M Step 6: drill 2 more wells; equip all 3 $4.5 M drilling, testing TOTAL $1.0 M equiping $9.2 M 23

24 SOME ISSUES OF DWI Finding an appropriate confining layer (Melbourne, FL spent $11MM) Potential lost transmissivity of receiving formation with time due to plugging or precipitation Regulator familiarity with UIC program Tubing and packer requirement Corrosion Cost 24

25 POTENTIAL IN COLORADO LIMITED Available information suggests formation permeabilities are relatively low which limit injection rates and thus well size >>> need for several widely spaced wells There is less information available about formation / reservoir capacities but low permeability may imply low capacity 25

26 OTHER RECENT DWI SITUATIONS NEVADA Class I through IV are prohibited ARIZONA no Class I wells currently; one permit application for natural gas storage in a salt dome FLORIDA continued use in certain locations WYOMING possible solution (?) for CBD produced water disposal HAWAII unique situation 26

27 Possible plant sites are in regions below the UIC line and thus eligible for the exemption. 27

28 OPERATING COSTS FOR HIGH RECOVERY ZLD OPTIONS 1 Thermal evap. + evap. pond 2 High recovery RO + thermal evap. + evap. Pond 3 High recovery RO + evap. pond labor Energy Chemical Sludge disposal Evap. pond TOTAL

29 COMPARISON OF DISPOSAL APPROACHES (HYPOTHETICAL PHOENIX CASE) Pipeline to Sea of Cortez Evap. ponds 1 Thermal evap.+ evap. pond 2 High recovery RO + thermal evap.+ evap. pond 3 High recovery RO + Evap. pond Capital $ 310 MM 410 MM 136 MM 76 MM 92 MM Operating $/yr 0.8 MM 1.6 MM 33 MM 29 MM 21 MM Annual $/yr 24 MM 33 MM 43 MM 35 MM 27 MM Water lost 20 mgd 20 mgd 0.8 mgd 0.8 mgd 2.5 mgd Pipeline and evaporation pond analysis from Bureau of Reclamation study Thermal options by Mickley & Associates Thermal options assume $30/ton for solids disposal and $0.05/kwhr Annual costs figured at 40 years and 7.125% interest 29

30 OVERVIEW still the mainstay in many locations limited in number Traditional concentrate disposal options increasing challenges limited cost reduction possibilities ZLD volume reduction consideration of other management tools new desalination technologies need to minimize water resource loss other factors limited in availability further limited by increase volumes severe limitations in some locations beneficial use need to maximize resource use very limited use for concentrate, brine, mixed solids goal of 1) maximum water recovery and 2) development of products meeting application requirements (SUSTAINABILITY) limited impact on improving concentrate disposal feasibility findings environmental limitations of salt loading growing requirement for concentrate (& brine, mixed solids) to meet environmental and application standards 30