Aditya Moralwar, Kerry Sublette, Cherie Almeida, and Laura Ford

University of TulsaJosh Brokaw

Oklahoma State UniversityKathleen Duncan

University of OklahomaGreg Thoma

University of Arkansas

Remediation of a Spill of Crude Oil and Brine Without Gypsum

Study Site• Gibbs #5 – Three parallel spills on 4.5o slope

(within three months in late 1999) of produced fluid from a gathering line –about 10% crude oil and 90% brine(about 130,000 mg/L NaCl)

• Tallgrass Prairie Preserve in Osage County, OK• The three spills:

– North 600 m2

– Middle 230 m2

– South 960 m2

• Remediation began June 2000

Soil Textures of Impacted Plots and Control

0

5

10

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30

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45

50

North Middle South Control

Plot

Perc

ent b

y W

eigh

t

ClaySiltSand

Initial TPH Concentrations(Estimated from 1st order model at t = 0

0

5000

10000

15000

20000

25000

30000

North Middle South

Initi

al T

PH (m

g/kg

)

Initial Na+ Concentrations(Estimated from 1st order model at t = 0

0

500

1000

1500

2000

2500

3000

North Middle South

Plot

[Na]

, mg/

kg

Initial Cl- Concentrations(Estimated from 1st order model at t = 0

0

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1000

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3000

3500

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4500

North Middle South

Plot

[Cl],

mg/

kg

G5 Remediation Protocol

North Middle South

Hay (bales)

NH4NO3 (kg)

P2O5 (kg) 7 3.5

K2O (kg)

32 – 36 48 – 54

90.7 45.4

3.7 1.5

Only Ripped

• Soil was ripped and amendments added on June 14 and 15, 2000

• Interception Trench: Dug perpendicular to north and middlesite at the bottom

Natural Precipitation Was the Only Source of Moisture

Precipitation Data

0.00

5.00

10.00

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30.00

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00Ju

l-00

Aug

-00

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00O

ct-0

0N

ov-0

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ec-0

0Ja

n-01

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ar-0

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pr-0

1M

ay-

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l-01

Aug

-01

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ct-0

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n-02

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ar-0

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ay-

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-02

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n-03

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ar-0

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pr-0

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ay-

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03Ju

l-03

Aug

-03

Months

Rai

nfal

l(cm

)

ActualNormal

Significant periods

of drought

TPH BiodegradationFirst order rate constants (and TPH half-lives) for TPH biodegradation in the brine impacted sites.Site 1st order rate t1/2 (days)

constants(days-1)

North 2.0 X 10-3 348

Middle 2.5 X 10-3 273

South 3.9 X 10-3 177

TPH Biodegradation• No difference in first-order rate constants by ANOVA

even at 80% confidence level

• TPH concentration continuously reduced in the presence of brine

• Average half-life 266 days (8.9 months)

R2 = 0.8536

6.00

6.20

6.40

6.60

6.80

7.00

7.20

7.40

7.60

0 200 400 600 800 1000 1200

Days Since Initiation of Remediation

ln[m

g/kg

Na]

Nor

th

R2 = 0.8691

6.00

6.50

7.00

7.50

8.00

8.50

0 200 400 600 800 1000 1200

Days Since Initiation of Remediation

ln[m

g/kg

Cl]

Nor

th

G5 North

Removal of Brine Components

First order rate constants for removal of brine components

Site 1st order rate constant 1st order rate constantNa+ removal (days-1) Cl- removal (days-1)

North 1.1 X 10-3 1.3 X 10-3

Middle 3.0 X 10-5 0

South 5.0 X 10-4 5.0 X 10-4

Comparison of First-order Rate Constants for Na+ and Cl- Removal Within Treatments

N M SStudent’s t 0.44 0.46 0.02

• No significant differences in the rates of Na+ andCl- removal within any treatment (p>0.20)

• Na+ not retarded by clays?

Comparison of First-order Rate Constants for Na+ and Cl- Removal Between Treatments

Na+ removal Cl- removalN-M 3.51*, p<0.05 3.00, p<0.05

N-S 1.7, 0.10<p<0.02 1.91, 0.10<p<0.02

M-S 0.95, p>0.20 1.41, 0.10<p<0.02

*Student’s t-test

Comparison of First-order Rate Constants for Na+ and Cl- Removal Between Treatments

Na+ removal rates: N > S, M Cl- removal rates: N > S > M

Na+ Cl- (mg/kg)Concentrations after 36 months: N 420 640

M 1060 1600S 900 1740

36-month reductions in salt inventory:

N 73% H/F+ ripped + interception trenchM < 3% ripped only + interception trenchS 40% H/F + ripped

What was the effect of fertilizer?

NO3--N (mg/kg)* NH4

+-N (mg/kg)North 22.7 ± 10.8 9.7 ± 5.7

Middle** 20.0 ± 5.1 14.8 ± 6.3

South 31.9 ± 6.8 12.3 ± 7.5

Control 2.2 ± 1.4 8.1 ± 4.4

* Mean ± std. dev. over period of March 2002 through August 2003

** Effect of transfer from N and S and of bison

South (6/04)

Middle (6/04)

North (6/04)

Conclusions

• There was no effect of treatment on the biodegradation of crude oil. However, TPH reduction clearly proceeded in the presence of brine contamination.

• The combination of hay addition, ripping, and downslopeinterception trench was superior to hay addition with ripping, or ripping plus an interception trench in terms of rates of removal of sodium and chloride

• The remediation of produced fluids spills with ripping (or tilling), hay and fertilizer addition, and an interception trench has been shown to be effective in both the bioremediation of crude oil and removal of brine components. This methodology can easily and inexpensivelyimplemented by small independent oil and gas producers without hiring outside contractors and without the purchase, transportation, and spreading of gypsum.

ACKNOWLEDGEMENTS

• We thank The Nature Conservancy for access to the site

• Funded by the National Energy Technology Office of U.S. Department of Energy (DE-FC26-01BC15332)