Perenco UK Ltd Annual Environmental Report 2012 – Southern Sector SNS
Introduction
This report outlines the environmental performance of Perenco UK Ltd’s offshore operations in the
southern sector of the Southern North Sea (SNS) during 2012. Following Perenco’s acquisition of
operations in the northern sector of the SNS during 2012, these assets are the subject of a separate
report. This report consists of




a description of the company’s activities in the SNS S,
a summary of the ISO 14001-certified environmental management system (EMS) that
provides the framework for the control of the environmental aspects of these activities
a description of our environmental policy, including our environmental objectives and targets
that we have set for significant environmental aspects and impacts, and
a summary of our performance in relation to the environmental policy, objectives and targets,
and any relevant legislative requirements
Perenco UK Ltd’s activities
Perenco has been an operator in the Southern North Sea (SNS) since September 2003. Offshore
Perenco are responsible for four installations that are classified as “manned” (Indefatigable 23A &
23C, Thames 28A, Leman 27A) and a total of 26 normally unattended installations (NUIs) producing
gas and liquids that are tied back through pipelines to onshore terminals. We operate three of these
NUIs on behalf of other oil and gas companies and these are included in this report where
appropriate.
The environmental management system
Our EMS is designed to identify and assess the risks associated with the environmental impacts of
our activities, and to apply and monitor the effectiveness of the controls required to minimise these
risks. The EMS forms an integral part of Perenco’s Business Management System (BMS) and is
certified by BVQI as meeting the requirements of ISO 14001. A new Certificate was issued in 2012
following a successful re-certification audit of the EMS.
The environmental policy
Our Environmental Policy is reproduced below. It informs the definition of our significant
environmental aspects that are the focus of our environmental management activities.
Aspects and Objectives
Offshore, our significant routine environmental aspects and associated objectives for 2012 were:
Aspect
Objective
Emissions of CO2
Retain CO2 emissions within allocations set for
permitted installations
Ensure the monthly average concentration of oil
discharged in produced water does not exceed 30
ppm
Reduce the use and/or discharge of production
chemicals that carry substitution warnings
Identify opportunities for the reduction in HC venting
Monitor and where reasonably practicable reduce
NOx emissions from relevant combustion equipment
<6 reportable spills (NB. Any spill to sea, irrespective
of size, is reported to the regulator, DECC).
Discharge of Oil in Produced water
Discharge of Production Chemicals
Emissions of hydrocarbon gases
Emissions of other combustion products
Hydrocarbon and chemical spills to sea
Performance and programmes
Emissions of CO2
CO2 emissions from our major offshore installations are subject to control under the Greenhouse
Gases Emissions Trading Scheme (ETS) Regulations 2005. Each installation (Indefatigable 23A,
Leman 27A, Thames 28A and Trent) has an allocation of CO 2 and we seek to ensure that our
emissions stay within these totals. The table shows our verified emissions for 2012 together with the
corresponding allowances for each installation. Emissions remain well within the total allocations
across the installations.
Installation
Emissions (ktonnes)
Allocations (ktonnes)
Indefatigable 23A
147,206
224,886
Leman 27A
163,630
123,797
Trent
38,074
51,603
Thames
18,407
97,703
Total
367,317
497,989
Discharge of Oil in Produced Water (OIPW)
Discharge of OIPW is subject to control under the Oil Pollution Prevention and Control Regulations
that require that the monthly average concentration of aliphatic hydrocarbons in any discharge is <30
ppm.
After treatment, OIPW is currently discharged from Indefatigable 23A, Trent, Tyne and all 6 of the
LAPS installations (Lancelot, Excalibur, Guinevere, Galahad, Malory and Waveney). OIPW was
discharged from Leman 27A until November 2004 when Perenco introduced a re-cycling process to
re-inject produced water into a depleted subterranean gas reservoir. Since that time no produced
water has been discharged from Leman 27A. Similarly, on Thames, produced water is injected into
two wells, providing the injection wells’ capacity is not exceeded. Under such conditions, produced
water is treated through a tilted plate separator and discharged to sea. During 2012, discharges of
produced water from Thames were limited to 20% of total production, and towards the end of the
year, injection capacity was increased following an acid wash of the installation’s disposal wells such
that all produced water can now be injected.
Annual mean monthly
concentration in
produced water (ppm)
Total Hydrocarbons
discharged
(kg)
Volume of produced
water discharged
3
(m )
32.4
9
21
5
17
593
507
445
117
25
19,636
54,953
22,077
23,811
1,419
Tyne
58
79
1,880
Lancelot
Malory
Guinevere
Waveney
17
13
7
11
12
8
3
7
917
610
368
629
19.6
1,796
126,300
Installation
Thames
Galahad
Trent
Inde
Excalibur
Total
Galahad accounts for 44% of all our produced water discharges and about 28% of the hydrocarbons
discharged, but the concentration of the discharge averaged as little as 2 ppm during 2012.
Discharges of hydrocarbons from Indefatigable 23A accounted for 6.5% of total hydrocarbon
discharges. A new OIPW treatment technology was installed in November 2005 which proved
extremely effective in reducing the concentration of hydrocarbons in the PW which had averaged
about 290 ppm during 2004. From installation to the end of April 2006, discharges from 23A
averaged 29 ppm. In May 2006, additional production requiring the use of mono ethylene glycol
(MEG) for hydrate inhibition significantly affected the performance of the OIPW separation processes
resulting in poor quality discharges such that our average discharge in 2007 was 55 ppm,
considerably higher than the 30 ppm target. With lower MEG use, performance was improved with
many fewer process upsets, but further new tiebacks, requiring the continued use of MEG continued
to present a challenge. Improvements to control over the separation process and reductions in MEG
use combined to improve our 2009 performance to an annual average of 18 ppm. During 2012, Inde
23A’s discharge quality averaged 5 ppm. Confronted with declining field pressures, there are plans to
reduce field suction pressures and promote production from water-laden wells using assisted foam lift.
Trials completed during 2012 provided the assurance that residual concentrations of foaming
chemicals in the produced water will not compromise the performance of Inde 23A’s separation
processes and the hydrocarbon concentration in the discharge should remain unaffected.
In 2009, the discharge from Trent averaged above the 30 ppm limit. This was because the MEG
laden liquids coming from Kilmar and Garrow were too saline to permit their export to Bacton for
recovery and had to be discharged from Trent. The volumes involved were higher than Trent’s
treatment capacity at the time and this necessitated the utilisation of redundant storage vessels on
Trent to increase separation capacity. Further improvements to increase effective gravity separation
were completed in the 2009 shutdown and for the remainder of that year, Trent’s PW averaged 16
ppm. The improvement in processing capacity, however, remains less than the potential PW flow
from Kilmar and as a result, ATP have been required to restrict gas production from Kilmar. This was
addressed during 2012 with the installation of a topsides water separation capacity on Kilmar capable
of treating the produced water to achieve a local discharge of hydrocarbons <30 ppm. Following
commissioning in Q3 2013, the separation technology has consistently achieved a discharge of <5
ppm.
The high average for Tyne is attributable to one month’s upset when the treatment system did not
perform to specification. Excluding that result, Tyne’s mean discharge was <30 ppm.
During 2012 the Thames OIPW averaged 32 ppm. However, this was due to one instance in
December when, during an intervention to improve the performance of the Titled Plate Separator
(TPS), a small volume of produced water (about 15% of the monthly total) was discharged at a
concentration in excess of 100 ppm. The average figure from January to November was 25 ppm,
comfortably below the 30 ppm target.
Discharge of Production Chemicals
The use and discharge of production chemicals is subject to control under the Offshore Chemicals
Regulations.
This requires regulatory approval following an assessment of the predicted
environmental impacts of any proposed discharges. In addition, only chemicals that have been
registered by the Centre for Environment, Fisheries and Aquaculture Science (CEFAS) may be used.
Gas production requires only a limited range of production chemicals, mainly for the purposes of
hydrate inhibition, corrosion control and separation of liquid hydrocarbons. Production chemical
usage is limited to Inde 23A, Leman 27A, Trent, Tyne, Thames, Pickerill and the LAPS assets
together with their associated tie-backs. Such chemicals are generally used in closed systems that
provide for their recovery and re-use, so minimising discharges to the marine environment.
Chemical use for gas production is dominated by the need for hydrate inhibition. Mono Ethylene
Glycol (MEG) is routinely used for this purpose. It is a “PLONOR” chemical (i.e. it Poses Little or No
Risk” to the environment, OCNS category “E”) and it is usually recovered, recycled and reused unless
its salinity precludes this in which case it is discharged offshore with the associated corrosion inhibitor
with which it is dosed. Modelling indicates that this discharge presents a negligible risk to the
environment.
The use and discharge of chemicals that carry a CEFAS-imposed “substitution warning” is minimised
and justified to the regulator by reference to technical and environmental risk criteria while actively
seeking to find viable replacements. None of the production chemicals that we routinely use carry a
SUB warning, and programmes to “minimise harm” ensure that such chemicals when used
occasionally and, where replacement is not feasible, are contained and shipped ashore or, as on
Thames and Leman, injected with the PW.
Emissions of hydrocarbon gases
The venting of hydrocarbon gases is subject to regulatory control as part of our production licences
issued under the Energy Act 1976.
The loss of gas to the atmosphere results from routine and upset conditions. We monitor and report
the amounts released and this is summarised for 2011 in the table below. Very little gas is lost as a
result of upset conditions. Most is due to the requirement to purge and start and stop compressors
and other engines as well as losses of seal gas from the compressors equipped with wet gas seals.
Installation
Gas emitted (tonnes)
Leman 27A
Thames
Inde 23A
Trent
Total
1230
452
2476
538
4696
The Greenhouse Warming Potential (GWP) of the methane in the vented gas amounts to about 21%
of the GWP of the CO2 emitted from our combustion processes. As part of our continuous
improvement program Perenco are currently planning to introduce improvements to controls which
are designed to reduce the number of plant upsets that contribute to unplanned emissions of
hydrocarbon gases.
Emissions of other combustion products
Onshore, the environmental impacts of concern attributable to combustion processes include the
emissions to atmosphere of oxides of nitrogen (NOx). These have the potential to cause health
impacts, and also contribute to acid rain. Offshore receptors are broadly insensitive to the amounts of
NOx that are emitted from combustion of gas. Nonetheless, combustion processes with an installed
capacity >50 MW(th) are subject to regulatory control under the Offshore Combustion Regulations.
Perenco currently have such capacity installed on Indefatigable 23A, Leman 27A, Thames and Trent.
When in 2004 Perenco commenced work on a new compression platform for the Trent installation the
compression turbines were designed to include the latest technology to minimise their emissions of
NOx (SoLoNOx technology). The environmental assessment that accompanied the permit application
under the Offshore Combustion Regulations predicted that the NOx emissions from the compressors
would be 38 – 50 ppm. Emission tests since installation have shown performance in the range 18 –
30 ppm.
Indefatigable 23A, Thames and Leman 27A were also permitted under these regulations during 2007
and an assessment of the environmental impacts associated with their combustion activities was
submitted in support of our an application for a permit. Total NOx emissions from Indefatigable 23A,
Thames and Leman 27A in 2012 are shown in the table below.
Installation
NOx (tonnes)
Leman 27A
Thames
Inde 23A
Trent
Total
92
127
96
13
328
The remote location of the installations and the small proportion to total loading from the offshore
industry means that the environmental effects of the NOx emissions are minimal and the cost of
retrofitting low NOx emission combustion equipment is prohibitive in the circumstances of old fields
and declining assets.
Waste
We generated a total of 770 tonnes of waste from our operations offshore (excluding drilling) and
around 81% of this was reused, recycled, or otherwise managed rather than consigned to landfill.
Less than 2% of the 181 tonnes of special waste was sent to landfill.
The Tyne T6 platform well drilled during 2012 largely used Low Toxicity Oil-Based mud (LTOBM),
cuttings associated with which are not discharged to sea, but are recovered and shipped ashore for
treatment. This treatment entails the thermal recovery of the oil adhering to the cuttings, and although
not included in the figures below, would add to the total fraction of the waste classified as “waste to
energy”.
Installation
Inde 23A
LAPS
Pickerill
Leman 27A
Thames 28A
Trent
Tyne
Total
Waste
group
General
Special
General
Special
General
Special
General
Special
General
Special
General
Special
General
Special
General
Special
All
Reuse
Recycle
Landfill
231
Waste to
energy
0
60
Other
route
0
Total
disposed
291
0
0
0
4.7
23
52
0
1
14
0
0
57
37
0
0
1
3.2
0
0
1
4.5
0
0
9.7
7.7
0
0
0.1
112
11.8
0
0
52.7
0
0
11.9
165
0
0
1.4
38
66.56
0.4
0.4
0
0
16.9
68
55.44
0
0
0.34
14.1
23.5
0
0.29
7.8
0
0
24.1
22
0
0
0.29
8.17
8.1
0
0.1
2.22
0
0
8.5
10.39
0
0
0
0
429.47
7.83
2.02
0.4
163.98
0
141.22
2.79
0
16.9
0
2.02
588.53
181.22
0
437.3
164.38
144.01
16.9
769.75
Hydrocarbon and chemical spills to sea
The Oil Pollution Prevention and Control Regulations apply to hydrocarbon and chemical spills to sea
and these have to be reported and are subject to detailed investigation to ascertain the cause and
prevent recurrence. A total of 14 events were reported during 2012. This was more than those
reported in 2011 and remained greater than the target of 6 that was set for the year. Brief details of
the spills are given in the table below.
We have substantially reduced the spills during bunkering operations, but maintenance-related issues
remain significant root causes. The importance of the latter has been addressed through the
identification of environmentally critical equipment to prioritise maintenance and a focus on
maintaining the integrity of diesel storage and distribution systems.
Location
18B
Date
29/01/12
Loss (litres)
10
17/06/12
31/08/12
Description
Diesel bunkering hose failure during bunkering operations
Contamination of the potable water system with
hydrocarbon substance
Hydraulic fluid leak from Bure Oscar subsea well
Suspected communication between the 13 3/8” & 20”
casing
Oil spill to sea from air compressor drier water auto dump
Loss of Aqualink hydraulic fluid from well 6 wellhead supply
to SSSV.
Diesel leak from generator fuel priming pump resulting in
spill to sea
Diesel spill to sea from well C5 Annulus
Diesel leak to sea from ruptured filter on generator
27A
25/02/12
Thames
14/03/12
Tyne
29/03/12
Thames
04/04/12
Thames
20/04/12
Excalibur
24/04/12
27C
18A
3 Party
rd
07/09/12
Release of Barite to sea from ENSCO80.
250 kg
23C
03/10/12
10
27C
15/10/12
Thames
19/10/12
Oil released under pressure from well swab cap after WHM
Crane hydraulic return filter housing lid lifted from housing
allowing oil to spill into cab and then to sea
Hydraulic fitting failure on well 1 control line and Aqualink
spill to sea
Ensco 80 Oil base mud spill to sea
rd
3 Party
21/10/12
negligible
10,245
2
1
400
500
2
1,000
150
178
45
Two spills were of a scale or seriousness that prompted comprehensive investigation (shown in green
above). On presentation, the Regulator accepted the actions and closed the file on the incidents.