Produced water from
oil and gas production
Lisa Sumi
Oil and Gas Accountability Project
Presentation at the 2005 People’s Oil and Gas Summit
Farmington, New Mexico October 28, 2005
Produced Water
• Any water that is produced to the
surface along with oil or gas
• It is the largest waste stream
generated by the oil and gas industry
Produced Water Quantity
• On average, about 7 - 10 barrels (bbls),
(which is 280 - 400 U.S. gallons) of
produced water generated per barrel
of crude oil.
• Natural gas wells typically produce
much less water than oil wells.
Water quantity
• Typically, for
conventional oil
and gas wells,
water production
increases over
time.
Source: USGS. 1997. USGS Research on Saline
Waters Co-Produced with Energy Resources
What’s in produced water?
Major components include:
1. hydrocarbons
2. salts
3. metals
4. radionuclides
5. production chemicals
Hydrocarbons and organic
compounds
• Include oil, grease, and dissolved
organic compounds such as:
benzene, naphthalene, toluene,
phenanthrene, and
pentacholorophenol.
• Generally, as the weight of organic
compounds decreases they are
more difficult to remove using
oil/water separators.
Salts
• Salts in produced water are
primarily chlorides and sulfides of
Ca, Mg, and Na. Produced water
may contain high levels of
chlorides - as much as 10 times
more than seawater.
Metals and trace elements
• Lead, chromium and nickel are often
among the most abundant. Also, barium,
manganese, iron, strontium, zinc, silver,
cadmium, lithium, copper, mercury,
arsenic, selenium, boron and antimony
may also be present in produced water.
Total dissolved solids
The U.S. Geological Survey has a database of
produced water constituents from various oil and gas
producing regions across the country
• it contains good information on total
dissolved solids (TDS)
• it does not contain detailed information on
hydrocarbons, radionuclides or metals
http://energy.cr.usgs.gov/prov/prodwat/tds.htm
Comparison of water quality
P
Paarraam
meetteerr D
Drriinnkkiinngg w waatteerr C
CB BM M N
Naattuurraall ggaass
ccrriitteerriiaa pprroodduucceedd pprroodduucceedd
wwaatteerr wwaatteerr
pH 6.5 – 8 7-8 6.5 – 8
TDS (mg/L) 500 (taste) 4,000 – 20,000 20,000 – 100,000
Benzene 5 < 100 1,000 – 4,000
(ppb)
Na+ (mg/L) 200 500 – 2,000 6,000 – 35,000
Barium - 0.001 – 0.1 0.1 - 40
(mg/L)
Cl- (mg/L) - 1,000 – 2,000 13,000 – 65,000
HCO3- - 150 – 2,000 2,000 – 10,000
Source: Hayes, T. and Arthur, D. 2004. Overview of Emerging
Produced Water Treatment Technologies.
Benzene in water after
treatment
3
2.5
1.5
1 Benzene
0.5
0
Concentration Concentration Drinking Water
after Best after Best Standard (ppm)
Practical Available
Technology Technology
(ppm) (ppm)
Source: Argonne National Laboratory. 2004. A White Paper Describing
Produced Water of Crude Oil, Natural Gas and Coalbed Methane.
Produced water
contamination
Prior to the institution of Federal
regulations in the1970's, large
volumes of these waters were
discharged into rivers, streams,and
unlined evaporation ponds,
contaminating surface and ground
waters and soils in energy producing
States.
Source: USGS, 1997. USGS Research on Saline Waters Co-
Produced With Energy Resources.
Produced water incidents
• Study by Fisher and Sublette
• Fluid releases in OK between 1993 - 2003
• An average of 790 releases a year
• 50% were less than 40 bbls; 25% were
between 40 and 100 bbls; the remaining
25% were > 100 bbls (4,000 U.S. gallons).
Source: Fisher, J.B. and Sublette, K.L. 2005. Environmental
Releases from exploration and production operations in
Oklahoma: Type, volume, causes and prevention.
Most frequent source of
produced water release
3000
2500 Flowlines
2000 Wells
# of Tanks
1500
incidents Surface Equ't
1000
Pits
500 Other/Unknown
0
Most frequent cause of
release
500
450
400
Overflows
350
Illegal Activity
300
Storms
250
Fire
200
Accidents
150
Corrosion
100
50
0
overflowing tank
tank corrosion
Accidental cause
of produced
water spill ?
One of the causes of
releases outlined in the
study was livestock or
wildlife opening
produced water valves.
Impact of releases
1000
900
800
Surface water
700
Crop and stock
600
Soil
500
Erosion
400
Groundwater
300
Wildlife
200
100
0
Spills
produced water spill
sterilized soil
Produced water disposal
today
• Surface or stream disposal
• Evaporation pits/ponds
• Underground injection for waterflooding
and maintaining field pressures
• Underground injection for disposal
Pits and ponds
brine pit in SE NM
rips in liner
Injection wells
Diagram credit: NM Oil Conservation Division
Enhanced Recovery Wells
Diagram: EPA
Pathways for
contamination
• leaks or cracks in injection well
casing
• improperly plugged abandoned
oil and gas wells within the radius
of influence created by injection
wells
• natural or induced fractures,
which connect the injection
zone with adjacent water zones
GAO Study
• Study found 23 confirmed cases of
groundwater contamination from
produced water injection wells
• “for most of the 23 confirmed cases, the
drinking water sources that were
contaminated will remain so for years until
natural processes restore water quality.”
GAO. 1989. Safeguards Are Not Preventing Contamination
from Oil and Gas Wells.
Natural fracture?
Simon Land and Cattle Injection Well,
La Plata County, CO
• 1989 - SL&C injection well installed
• 1993 - increase in injection pressure
• 1996 - sharp decrease in injection pressure
• 1997 - flow and temperature at hot springs
• 1999 - (January) injection ceases
• 1999 - (August) hot springs water
temperature and flow rate decrease
Conclusion
• Produced water is the largest volume
waste produced by the industry
• Produced water contains constituents
that are harmful living organisms
• There are risks to human and
environmental health involved with every
method of disposal
