Environmental Statement 2008.FH10


Environmental Statement 2008.FH10

3.3 The Environmental Aspects of our Operations

Environmental aspects are elements of our activities, products

or services that can interact with the environment. Figure

3 illustrates the main environmental aspects we have identified

for our offshore locations. We have grouped our significant

environmental aspects into four areas:

• Atmospheric emissions

• Energy use

• Discharges to water including spills

• Waste

3.3.1 Atmospheric Emissions

We burn natural gas and sometimes diesel as fuel on our

facilities to generate the power that is required to run our

operations. In addition, our facilities are designed to ‘flare’

(burn) and ‘vent’ (release unignited) a certain amount of

hydrocarbon gas for safety reasons. Most locations have a

continuous stream of gas to flare or vent designed to stop

the ingress of air into the facilities that could cause explosive

mixtures in the process. Additional amounts are also released

through this route during installation shutdown, when all

hydrocarbon gas systems are depressurised and when certain

equipment items are out of service (either planned or


The majority of our emissions to air are the products of

these combustion processes. The emissions include carbondioxide,

nitrogen oxides, sulphur dioxide, carbon monoxide,

unburnt hydrocarbons and particulates. These atmospheric

pollutants have global (climate change), regional (acidification)

and local (air quality) effects.

3.3.2 Energy Use

In addition to atmospheric emissions, consumption of diesel

and gas to provide energy is an important issue from the

point of view of depletion of natural resources. We are

currently developing GHG and Energy Management Plans

for each of our major installations.

3.3.3 Discharges to water

Most of our discharges to water consist of surplus water

from our oil and gas wells. This "produced water" is a mixture

of naturally occurring water in the reservoir, and seawater

that has been injected into the reservoir to support the

pressure and sweep oil towards the production wells. We

separate the produced water from the oil and gas, and discharge

most of it into the sea. The separated water contains a small

amount of residual oil as well as chemicals both naturally

occurring such as salts, and others such as corrosion inhibitors

and de-oilers.

As well as produced water, many of our wells produce sand

and scale which accumulates in pipework and vessels and

needs to be cleaned out from time to time. When pipework

and vessels are cleaned, the sand and scale is also cleaned to

remove as much oil as possible before it is discharged.

Produced sand contains similar materials to produced water

and may also contain small amounts of Naturally Occurring

Radioactive Material (NORM) which may occur naturally in

an oil or gas reservoir. All discharges are monitored and


We also use seawater for cleaning purposes. After use any

‘wash water’ is cleaned before being discharged back into the

sea via specially designed drains. Legally permitted levels of

cleaning chemicals and some oil may remain in the water

when it is discharged. Other drains on our installations

discharge surface water, such as accumulated rainwater or

seawater, which do not normally contain any oil or chemicals,

as well as emergency fire-fighting water and foam, directly

into the sea.

Finally the smallest contribution to our discharges to the sea

comes from leaks and spills from our wells and equipment.

Such spills may consist of oil, gas, chemicals, or a mixture of

the three. Continuous monitoring, adherence to procedures

and rehearsal of emergency response keeps these unintended

discharges to a minimum.

3.3.4 Waste

A variety of solid and liquid wastes are produced from both

our on and offshore operations including drilling waste such

as cuttings and spent muds; wastes such as oily rags, fluorescent

tubes and batteries, and also office and packaging wastes such

as paper, card and wood.

Some wastes can be treated and re-injected into reservoirs

e.g. drill cuttings under the appropriate legal licences. However

the majority of wastes are shipped to shore for onshore

disposal. All waste, irrespective of where it is produced, is

transferred to licensed facilities for either treatment and

disposal; or sorting and bulking prior to transportation for

final disposal.

All waste is transported and disposed of in accordance with

our European waste management policy, in particular through

application of the waste hierarchy to prevent and reduce

waste as far as possible and minimise the volume of waste

to landfill.

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