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OCR for page 228
Appendix G
Saline Spills
INTRODUCTION
Saline water associated with North Slope oil production
comes from water produced with the oil or from seawater
used for enhanced oil recovery. The produced water is clas-
sified as wastewater and injected into Class I and II waste-
water wells. Drilling fluids and cuttings generated by drill-
ing and associated wastes derived from processing facilities
are also injected into these wells (Maxim and Niebo 2001a).
Seawater has been used in relatively large volumes since
1984 when the Prudhoe Bay waterflood project began. This
is a field-wide enhanced oil recovery system that includes
facilities to extract and treat water from the Beaufort Sea and
then inject it into injection wells. The injected water main-
tains pressure within the oil reservoir and flushes oil toward
recovery wells (Maxim and Niebo 2001a). When this project
began it was estimated to enable the recovery of an addi-
tional billion barrels from the Prudhoe Bay oil fields (ARCO
Alaska 1984~. Seawater is also used other purposes, such as
testing pipelines for leaks.
Produced water is considered saline, though salinity is
highly variable, depending on the field and the amount of
seawater injected into the oil-bearing strata (Maxim and
Niebo 2001a).
Spills of produced water may occur at the wellhead,
along pipelines, and at central processing facilities. They
may also come from leaking tanks or, in the past, leaking
reserve pits.
Reserve pits have been phased out in recent years, and
they are being dewatered and restored. A recent progress
report on the ADEC reserve pit closure program states that
as of mid-January 2002,184 of 329 reserve pits on the North
Slope (56%) have been closed, restored, and approved by
ADEC (J. Peterson, ADEC, unpublished material, 2002~.
Judd Peterson, ADEC Reserve Pit Coordinator, stated that
plans to rehabilitate remaining reserve pits were due in his
office on January 28, 2002. He estimates that completion of
228
remaining pit restorations through closure and ADEC ap-
proval will take 6 to 8 years. Mr. Peterson also stated that
ADEC requires water sampling adjacent to all remaining
reserve pits. According to these data, no substances are be-
ing leached from these pits that exceed state water quality
standards. Some reserve pits contain diesel-based drilling
fluids and produce a visible sheen when muds are disturbed.
ADEC requires that these be excavated, dewatered, and
backfilled on an accelerated timetable even if the diesel can-
not be detected in samples. Accelerated restoration is also
required for pits subject to erosion and possible contamina-
tion of Beaufort Sea waters. Four such sites are currently
being restored, and a fifth site is scheduled for restoration in
2003 (J. Peterson, ADEC, personal communication, 2002~.
Seawater spills from the enhanced oil recovery process
can occur at the seawater extraction plant, the seawater treat-
ment plant, holding tanks, along pipelines, and at seawater
injection wells. Less common sources include fire control
systems, compressors, pig launchers, and meltwater.
Causes of saline water spills along the pipeline include
leaking valves, pump failures, leaking pipes, leaking tanks
and drums, transfer hoses, o-ring and seal failures, leaking
vehicles, and human error. In the past, leaking reserve pits
were also a cause of spills.
SPILL DATA
Maxim and Niebo (2001a) examined water spill data
from an unpublished portion of the TAPS oil spill database
developed by IT Corporation. This spill database contains
information on spills of crude oil, refined petroleum prod-
ucts, water, and other substances from 1977 to 1999. The
database covers exploration and production activities on the
North Slope and the entire Trans-Alaska Pipeline. The crude
oil and products spills data were presented in TAPS Owners
(2001) environmental report. There was some difficulty dis-
tinguishing the saline water spills from freshwater spills.
OCR for page 229
APPENDIX G
Maxim and Niebo (2001a) compiled spills listed as wa-
ter, produced water, seawater, wash water, meltwater, gelled
water (seawater mixed with chemical enhancer to thicken
it used in enhanced oil recovery), and chemical mixtures.
Any spill record that referred to seawater, produced water,
or gelled water was considered to be a saline spill for pur-
poses of the analysis. There was no way to separate out the
low salinity from the higher salinity (seawater) spills. Some
spills did not contain enough information to identify the
material spilled, and those were termed unclassified spills.
There were 17 unclassified spills between 1977 and 1985.
These were excluded from the analysis. Together, they ac-
counted for 0.9% of the total spill volume. In addition, spill
records for that period were less complete, and reporting
appeared to be less rigorous than it has been subsequently.
Therefore, the detailed analysis covers only the period from
1986 through 1999.
Three spills during this period were water mixed with
crude oil. They were considered in the oil spill section; only
the water portion was considered in the analysis of saline
water spill data.
Over the period 1986-1999, there were 929 seawater
spills associated with North Slope exploration and produc-
tion and the North Slope portion of TAPS. Total amount
spilled was 40,849 bbl (1,715,658 gallons). This averages
out to 66 spills per year over the period and an annual spill
volume of 2,918 bbl (122,556 gallons). (See Table G-1.)
Analyses of the TAPS oil spill data have normalized
spills to the amount of oil transported (Maxim and Niebo
2001b). This is appropriate for oil spills in establishing time
trends, but may not be the best choice when normalizing
TABLE G-1 Number and Volume of Saline, Freshwater,
And Unclassified Water Spills on the North Slope
229
saline water spill data. Comparing water spilled with the
amount of crude oil produced suggests only how well water
is being handled in relation to the amount of oil handled, and
it may mask inefficiencies in the ANS water handling sys-
tem. A more useful analysis may be comparing the amount
of water handled on the North Slope with the amount of
water spilled.
Seawater used in the enhanced oil recovery process ac-
counted for the vast majority of water used on the North
Slope during the period. Annual data on the amount of pro-
duced water and water used for enhanced oil recovery is
available from the Alaska Oil and Gas Conservation Com-
mission (AOGCC) (McMains, personal communication,
2001~. These data were used to calculate the volumetric spill
rate (VSR), measured in barrels of water spilled per million
barrels of wastewater handled (bbls/million bbls). Table G-2
lists the annual water handled, the annual brine spill vol-
umes, and the calculated VSR. Figure G-1 (3) plots the VSR
based on volume of water handled (solid line) as well as the
volume of oil transported through TAPS (dotted line). The
lines match until 1990 when the volume of water handled
increased while the amount of oil transported began to
decrease.
Over the period from 1986 through 1999, the average
VSR for saline spills based on water handled was 3.3 bbl/
million bbl of water handled. If based on the volume of oil
transported, the VSR is 5.4 bbl/million bbl transported
(Maxim and Niebo 2001b).
As is the case with oil spills, there is substantial annual
variability in the VSR for saline water spills from 0.25 to
17.85 bbl/million bbl. "Bad" years are the result of a rela-
tively few large spills and "good" years result from the lack
of large spills, not spill numbers. The years 1997 and 1991
TABLE G-2 Alaska North Slope E&P Saline Water Spill
Rates (1986-1999)
Unclassified
Saline Water Freshwater Water Spill Volume of Annual Spill Rate
Volume Water Handled (bbls spilled/
Year no. vol. (bbl) no. vol. (bbl) no. vol. (bbl) Year (bbls) (bbls) million bbls handled)
1986 18 955 8 26,923 16 160 1986 955 588,243,485 1.623
1987 20 177 13 19,758 20 17 1987 177 689,765,315 0.257
1988 52 1,098 15 55 39 45 1988 1,098 726,675,694 1.511
1989 104 3,336 24 231 41 122 1989 3,336 801,407,354 4.163
1990 139 772 36 117 24 17 1990 772 845,450,781 0.914
1991 132 9,295 36 227 25 168 1991 9,295 894,098,366 10.395
1992 80 505 37 227 38 16 1992 505 983,579,753 0.514
1993 73 575 35 52 11 7 1993 575 1,038,007,615 0.554
1994 63 1,728 44 95 12 3 1994 1,728 997,105,134 1.733
1995 63 1,057 21 216 14 52 1995 1,057 1,001,078,993 1.055
1996 56 652 16 32 8 56 1996 652 1,000,648,796 0.651
1997 52 18,407 21 60 17 71 1997 18,407 1,031,291,327 17.849
1998 41 1,910 39 144 8 16 1998 1,910 1,004,600,076 1.901
1999 36 383 26 19 25 58 1999 383 671,552,213 0.571
Totals 929 40,850 371 48,156 298 808 Total 90,290 12,273,505,602 3.30
SOURCE: Modified from Niebo 2001a.
SOURCE: Modified from Maxim and Niebo 2001a.
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230
100-
`~, ~ 10—
cd 0
= c
Q As
U) ~
° lis \
g
Bbls/MM bbls ANS water handled
- - - - - Bbls/MM bbls TAPS throughput
art,
\=_r
, ~
\
\
\
\
0.1~ 1 1 1 1 1 1
1986 1988 1990 1992 1994 1996 1998
Year
FIGURE G-1 Saline water VSR on the North Slope, 1986-1999.
SOURCE: Reprinted with authors' permission from Maxim and
Niebo 2001a.
have the highest spill rates (VSRs). In 1997, 18,040 bbl
(757,680 gal) of freshwater and diluted seawater came to the
surface around several wells. A large spill occurred in 1991
when a valve failed and 8,500 bbl (357,000 gal) of produced
water were spilled at Central Processing Facility 2.
The 20 largest saline water spills from North Slope op-
erations during the 1986-1999 period are listed in Table G-
3. These range in volume from 210 to 18,040 bbl (8,820 to
757,680 gal). Combined, they account for 85% of the total
saline water spill volume.
APPENDIX G
The volume of reported saline water spills range from
0.0024 bbl (approximately 1.6 cups) to 18,040 bbl (757,680
gal). As with oil spills, small spills are frequent, large spills
are rare, and the total volume is dominated by the few large
spills. A Lorenz diagram (Figure G-2) provides a useful de-
piction of these spills. The fraction of spill volume is plotted
against the fraction of spills. If all spills were of equal size,
the plot would be a straight line. There is substantial curva-
ture in the plot, and the computed Lorenz coefficient is 0.97.
It is clear that the relatively few large spills account for the
most of the spill volume. In fact, 50% of North Slope saline
water spills were less than 0.95 bbls (40 gal), and the small-
est 90% of those spills accounted for approximately 3.9% of
the total volume; the smallest 95% accounts for approxi-
mately 8.2% of the total volume spilled (Maxim and Niebo
2001a).
EFFECTS OF SALINE WATER SPILLS
A study that anticipated potential spills associated with
the Prudhoe Bay Waterflood project was sponsored by the
Army Corps of Engineering Cold Regions Research and
Engineering Lab (CRREL) (Simmons et al. 1983~. The pur-
pose was to evaluate the sensitivities of different tundra plant
communities to seawater spills. Eight sites representing the
range of vegetation types along the pipeline route were
treated with single, saturating applications of seawater dur-
ing the summer of 1980. Each site was examined prior to the
experimental spills, monitored closely for 28 days, and vis-
TABLE G-3 Twenty Largest Saline Water Spills from North Slope Operations
Volume
(bbls)
Description
1
4
5
6
7
9
10
11
12
13
14
15
16
17
18
19
20
17 Mar 97
01 Jun 91
16 Dec 89
10 Jan 98
29 Sep 86
28 Jul 89
31 Oct 94
22 Dec 89
25 Jun 92
07 Mar 94
14 Apr 94
15 Mar 95
07 Nov 95
08 Feb 88
30 Mar 88
17 May 88
06 Oct 88
01 Nov 96
12 Dec 91
07 Jan 96
18,040
8,500
1,500
1,500
500
Freshwater and diluted seawater surfaced around nine wells at Drillsite 4.
Valve failed and leaked produced water at Flowstation 2.
Pipeline weld failed, leaking seawater from a seawater injection line along Oliktock Road.
Pipeline leak spilled produced water.
Fiberglass bypass line on heat exchanger failed, spilling seawater to secondary containment at Seawater
Treatment Plant.
500 Flowstation 2 actuator bonnet failed spilling produced water.
385 Crack in pipeline lY-lR spilled mixture of crude oil and produced water. Only the volume of spilled water is
given for this spill.
355
350
320
310
300
300
287
281
250
250
231
230
210
Pipeline leaked seawater to drill pad. Corrosion suspected.
Water tank overflowed seawater to a sump when valve leaked at CPF-3.
Seawater spilled to drill pad at Prudhoe.
Seawater valve in pig launcher module leaked into pigging pit and overflowed.
Produced water was released to a drill pad and reserve pit when equipment failure caused pressure change in
. .
plpelme.
Seawater spilled onto drill pad during equipment malfunction.
Seawater injection line bled water from a pipe rack on a drill pad.
Corrosion caused a produced water leak in a pipeline.
Solonoid on seawater line at seawater treatment plant failed.
Produced water injection line at drillsite failed due to corrosion.
Leak in seawater line at seawater injection plant.
Rod failed on seawater pump at central processing plant.
Produced water spilled from pig launcher after an ice plug melted out of a partially open valve.
SOURCE: Modified from Maxim and Niebo 2001a.
OCR for page 231
APPENDIX G
1.0 -
. .
0.8-
0.6-
0.4 -
0.2 -
0.0 -
0.0 0.2
Actual distribution of saline spills
---- - Curve with all spills the same size
1
0.4 0.6
Fraction of Spills
0.8 1.0
FIGURE G-2 Lorenz diagram of North Slope saline water spills.
SOURCE: Reprinted with authors' permission from Maxim and
Niebo 2001a.
ited less frequently over the following year. Symptoms of
physiological stress were observed 8 days after the experi-
mental spill. Within 12 days, 17 taxa of vascular plants de-
veloped physiological stress attributable to the treatment,
ranging from slight chlorosis to total browning and desicca-
tion of all the plants foliage. The impact of seawater treat-
ment was most severe in the mesic and dry sites. The wet
sites were less severely affected. Within a month of treat-
ment, 30 of 37 taxa of shrubs and fortes in the experimental
plots developed definite symptoms of stress, while the 14
graminoid taxa did not exhibit adverse effects. Live vascular
plant cover was reduced by 89% and 91% in the two dry
sites and by 54%, 74%, and 83% in the three moist sites.
Mosses were unaffected in all but one of the experimental
sites. Two species of foliose lichens showed deterioration,
while other lichen species were not affected. The absorption
and retention of salts by soils is inversely related to soil
moisture. In the wet sites, conductivities reached prespill lev-
els in approximately 30 days. Salts were retained in soils at
the dry sites, concentrating at or near the seasonal thaw line.
Soil enzyme and microfloral activity was reduced for up to
one year after treatment (Simmons et al. 1983~.
In December 1982 approximately 400 bbl (16,800 gal)
of concentrated sodium chloride leaked from a damaged stor-
age tank at a drillsite in the Kuparuk oil field. The spilled
brine spread onto tundra adjacent to the drill pad, covering
an area of approximately 0.3 ha (0.7 acre) before freezing
(Baker 1985~. Soils and vegetation were studied for two
years. By the 1983 growing season all plants within 40 to 60
m (130 to 200 ft) of the center of the spill were dead, and up
to 30 m (100 ft) beyond the dead vegetation, many plants
showed signs of physiological stress. In July 1983, the size
of the affected area was approximately 1.6 ha (4 acres). In
the fall of 1983 a road was constructed across the western
side of the site, altering the local drainage and forming an
impoundment in the spring of 1984. By July 1984, the size
231
of the affected area had increased to approximately 4.5 ha
(11 acres). Vegetation was dead within 90 to 140 m (300 to
460 ft) of the spill center, and signs of stress were found in
plants 40 to 60 m (130 to 200 ft) beyond the dead vegetation
(Baker 1985~. The study was continued and expanded to map
and quantify vegetation types, examine the effects of the spill
on thaw depths, and document salinity levels in soil and
water bodies in the vicinity. Unaffected tundra near the spill
zone was used as a reference area.
The area affected by the spill was divided into high- and
moderate-impact zones. Forbs and shrubs were most se-
verely affected, graminoids and cryptogams less severely.
Some recovery had occurred by 1984; the size of the high-
impact zone was decreasing. There was vigorous growth of
the sedge species Eriphorum angustifolium in the moderate-
impact zone (Jorgenson et al. 1987~.
In June 2000, approximately 1,200 to 1,500 gallons
(28.6 to 35.7 bbls) of low-salinity seawater (Electrical Con-
ductivity = 5,020 ,umhos/cm; salinity = 3.5 ppt) was leaked
from the Alpine oil pipeline during hydrostatic testing. The
tundra at this site is moist tussok and wet sedge. The soil
active layer was only partially thawed at the time of the spill.
The moist tundra was thawed deeper than the wet sedge
meadow. The spill site was studied by J. D. McKendrick
(2000a). As in the previous study, the moist (tussok) com-
munity was affected to a greater degree than the wet (sedge)
community. Elevated salt levels in surface water bodies were
found as far as 58 ft (18 m) from the leak. The area of veg-
etation damaged by the leak was 6.25 ft2 (0.1 m2~. In this
area salt levels in soil were elevated. Even though plants lost
their leaves, they survived and grew normally during the
growing season. McKendrick (2000a) attributes this to the
low salinity of the water spilled. In addition, tundra commu-
nities close to the coast may be exposed to seawater during
storm surges.
McKendrick (1997) has examined many saline water
spill sites, including those treated with fertilizers or flushed
with freshwater or calcium nitrate. He noted much variation
in recovery based on such things as grazing pressure. Those
sites treated by flushing with freshwater or calcium nitrate
recovered faster than non-flushed sites. The calcium nitrate
flush was no more effective than freshwater alone. Recovery
of flushed sites may still take several years; non-flushed sites
may take decades, depending on conditions.
The effects of saline water spills are related to salinity.
As expected, low-salinity water has less severe initial im-
pacts and more rapid recovery than higher-salinity water.
Recovery from higher-salinity spills may take several years.
Effects of saline water spills can be reduced by flushing
with freshwater (Walker 1996~. Joyce (M. Joyce, indepen-
dent consultant, personal communication, 6/7/2001) reports
that the standard response countermeasure in summer is
flushing with warm freshwater. In winter, snow berms are
constructed to contain the spill and the frozen material is
picked up with scrapers.
Representative terms from entire chapter:
produced water
