Environmental Impact Factor (EIF) simulations related to
Dagny field
Classification: Internal
Status: Final
Expiry date: 2012-05-02
Page 1 of 9
Classification: Internal
Status: Final
Expiry date: 2012-05-02
Page 2 of 9
Environmental Impact Factor (EIF) simulations
Doc. No.
related to Dagny field
Valid from
Rev. no.
Table of contents
1
Introduction ................................................................................................................................................... 4
2
Scope of work ............................................................................................................................................... 4
3
Input data....................................................................................................................................................... 4
3.1
Field data ........................................................................................................................................................ 4
3.2
Scenarios for produced water amounts and oil in water concentrations......................................................... 4
3.3
Produced Water Composition ......................................................................................................................... 5
4
Results ........................................................................................................................................................... 6
5
References..................................................................................................................................................... 9
Classification: Internal
Status: Final
Expiry date: 2012-05-02
Page 3 of 9
Environmental Impact Factor (EIF) simulations
Doc. No.
related to Dagny field
Valid from
1
Rev. no.
Introduction
The Environmental Impact Factor (EIF) is an environmental index quantifying the environmental risk of produced water
discharges and is used for identification and prioritisation of alternative measures for risk reduction. The EIF is based on
a combined environmental risk and hazard assessment, accounting for both composition and amount of the produced
water discharge. A thorough description of the EIF and its practical application is given in Frost et al., 2009 (1) and Smit
et al. 2011 (2).
2
Scope of work
In this document the EIF tool is applied for discharges of produced water from the Dagny Oil and Gas Field, which is
under development. The EIF tool is used in order to compare the potential environmental benefit of alternative measures
to reduce the potential impact of produced water discharges, and to form a basis for a cost-effective total approach to
produced water management.
3
Input data
3.1
Field data
The Dagny Field is located in the Norwegian Sea with geographical coordinates 58° 34' 19,848" North and
01° 41' 48,436" East. The discharge depth is 10 m below sea surface.
3.2
Scenarios for produced water amounts and oil in water concentrations
For this study, EIF is calculated for 8 different scenarios listed in Table 1 below. These alternatives differ in oil (aliphatic
hydrocarbons) concentration and produced water management solutions, as re-injection (E) and discharge to sea (A – D)
being the two options. The daily discharge rates for produced water amounts and the oil in water concentrations for
Dagny presented in Table 1 are used for calculating the annual Environmental Impact Factor (EIF) for Dagny.
Table 1: Produced water amounts and oil in water concentrations for Dagny
Scenario
A1
A2
B1
B2
C1
C2
D1
D2
E
Classification: Internal
Produced water
discharge rate [Sm3/d]
4000
4000
1000
1000
500
500
100
100
0
Oil in Water
concentration [ppm]
29
10
29
10
29
10
29
10
Re-injection
Status: Final
Expiry date: 2012-05-02
Page 4 of 9
Environmental Impact Factor (EIF) simulations
Doc. No.
related to Dagny field
Valid from
Rev. no.
The oil in water concentrations were set based on both the maximum concentration, which is the upper limit of discharge
by the authorities (29 ppm) and the probable lowest concentration, which can be obtained through an optimal design of
the produced water handling (10 ppm).
3.3
Produced Water Composition
For the EIF simulation, man-made chemicals are selected among the tentative products used for Gudrun Design basis,
which were chosen from the project as comparable, for a worst case scenario – i.e. products with highest potential
environmental impact (i.e. hazardous properties) are selected and presented in Table 2 together with their injection rate,
which equals their concentrations in produced water.
Table 2: Chemicals and their concentrations in produced water
Type of chemical to be
used at Dagny
Scale inhibitor
Emulsion breaker
Flocculant
Selected products for simulation
based on products used at Gudrun
SI 4610
DMO 86701
WT-1099
Proposed injection rate in
ppmv (mg/L) for Dagny
50
50
10
Concentrations of natural occurring compounds for Dagny, are listed in Table 3, excluding the aliphatic hydrocarbon
concentrations since it will vary for each scenario. In cooperation with the discipline ladder Flow Assurance the project
came to the result that Norne oil will be the most representative oil regarding the natural occurring compounds.
Therefore the values for 2009 for Norne were taken as input data for the EIF model for Dagny.
Classification: Internal
Status: Final
Expiry date: 2012-05-02
Page 5 of 9
Environmental Impact Factor (EIF) simulations
Doc. No.
related to Dagny field
Valid from
Rev. no.
Table 3: Natural occurring compounds concentrations for Norne 2009 used in the EIF model for Dagny
Compound
Sum BTEX
4
Concentration (mg/L)
23,3968
Sum Naphtalen
1,53441
2-3 ring PAH
0,05309
4+ ring PAH
0,00066
Fenol C0-C3
8,81394
Alkylfenoler C4-C5
0,22522
Alkylfenoler C6-C9
0,00126
Zn
0,0063
Cu
0,00022
Ni
0,00117
Cd
0,00005
Pb
0,00028
Hg
0,00004
Results
The EIF results for all 8 scenarios for Dagny are presented in Table 4.
Table 4: EIF results for Dagny
Scenario
A1
A2
B1
B2
C1
C2
D1
D2
E
PW discharge
3
rate [Sm /d[
4000
4000
1000
1000
500
500
100
100
0
Oil in Water
concentration [ppm]
29
10
29
10
29
10
29
10
Re-injection
EIF
13
10
0
0
0
0
0
0
0
As can be seen in table 4, the maximum EIF value (EIF = 13) occurs for scenario A1, which has the highest discharge
rate for produced water combined with the highest oil in water content. The EIF value for scenario A2 with the same
discharge rate, but lower oil in water concentration (10 ppm) has been calculated to EIF = 10. Generally these EIF values
are low. For all other scenarios EIF has been calculated to EIF = 0.
Classification: Internal
Status: Final
Expiry date: 2012-05-02
Page 6 of 9
Environmental Impact Factor (EIF) simulations
Doc. No.
related to Dagny field
Valid from
Rev. no.
Figure 1 shows, which components are contributing to EIF = 13 in scenario A1. Generally the natural occurring
compounds are dominating the contribution to EIF with about 98 %. Main contributor is aliphates (42 %) followed by
phenols C4-C5 (17 %) and 2-3 ring PAH (10 %). Added chemicals are just contributing with about 2 %.
Dagny 4000/29 EIF = 13
SI 1 KII
1%
Em 1 KVI
1%
BTEX
7%
Naphthalenes
9%
2-3 ring PAH
10 %
Alifater
42 %
4-ring+ PAH
1%
Phenol C0-C3
9%
Phenol C4-C5
17 %
Phenol C6-C9
1%
Figure 1: Contribution to EIF for Dagny scenario A1
Classification: Internal
Status: Final
Expiry date: 2012-05-02
Page 7 of 9
Environmental Impact Factor (EIF) simulations
Doc. No.
related to Dagny field
Valid from
Rev. no.
Figure 2 shows, which components are contributing to EIF = 10 in scenario A2. Also here the natural occurring
compounds are dominating the contribution to EIF with about 98 %. Main contributor is phenols C4-C5 (25 %) followed by
aliphates (18 %) and 2-3 ring PAH (14 %). Added chemicals are just contributing with about 2 %.
Dagny 4000/10 EIF = 10
SI 1 KII
1%
Em 1 KVI
1%
Alifater
18 %
BTEX
11 %
Naphthalenes
13 %
Phenol C6-C9
2%
2-3 ring PAH
14 %
4-ring+ PAH
1%
Phenol C4-C5
25 %
Phenol C0-C3
13 %
Figure 2: Contribution to EIF for Dagny scenario A2
The maximum EIF for Dagny is 13 (scenario A1). This is a low EIF and figure 3 gives an indication how the EIF for
Dagny can be evaluated related to EIF values for 2009 for Statoil’s existing fields on the Norwegian Continental
Shelf (NCS).
Classification: Internal
Status: Final
Expiry date: 2012-05-02
Page 8 of 9
Environmental Impact Factor (EIF) simulations
Doc. No.
related to Dagny field
Valid from
Rev. no.
EIF 2009, Statoil Norwegian Continental Shelf
700
600
500
300
200
Heimdal
Kvitebjørn
Njord
Troll A
Sleipner T/Vest
Visund
Oseberg Sør
Oseberg Øst
Huldra
Oseberg F
Åsgard B
Åsgard A
Oseberg C
Sleipner A/Øst
Grane
Dagny
Snorre B
Kristin
Heidrun
Brage
Troll B
Troll C
Glitne
Snorre A/Vigdis
Norne
Veslefrikk
Statfjord A
Gullfaks A
Gullfaks B
Statfjord B
0
Gullfaks C
100
Statfjord C
EIF
400
Figure 3: EIF 2009, Statoil Norwegian Continental Shelf
Dagnys contribution to the environmental risk on the NCS is very limited. The impact on the environment is small.
5
References
(1) Frost, T. K., Johnsen, S. Torvik, H. and Eide, T.E. (2009). Application of the Environmental Impact Factor (EIF) as a
risk management tool to discharges forproduced water on the Norwegian Continental Shelf. NEL Produced Water
Workshop Aberdeen, October 29-30th 2009.
(2) Smit, M.G.D, Frost, T.K. and S. Johnsen (2011). Achievements of risk-based produced water management on
the Norwegian continental shelf (2002-2008). Integrated Environmental Assessment and Management (IEAM),
Society of Environmental Toxicology and Chemistry (SETAC).
Classification: Internal
Status: Final
Expiry date: 2012-05-02
Page 9 of 9