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OFFSHORE ENVIRONMENTAL PERFORMANCE
An insight in the environmental performance of the UK offshore oil and gas industry as measured by the EBT benchmark indicators is provided in the following table.
Emission and discharge type
Benchmark indicator
UKCS Performance
Oil in produced water
mg of oil per kg of produced water or
Only a few gas platforms with small water discharge volumes have trouble meeting the legal 40 mg/kg discharge limit. Most installations have oil in water discharge figures below 30 mg/kg; some even below 10 mg/kg.
Tons of oil per million BOE
For oil fields this ratio goes up as the fields deplete and as less oil is produced while water production increases, and is therefore more an indicator of the maturity of the field than of its environmental performance. A few oil platforms discharge more than 50 tons of oil for every million barrels they produce. The average for the UKCS fluctuates around 3.4 tons per million barrels of oil equivalent.
Accidental release of oil
Grams of oil spilled per TOE produced or
Efforts to reduce the amounts of oil spilled have been very successful on the UKCS and only 0.5 grams of oil is spilled these days for every ton of oil and gas produced.
Production chemicals
Grams of OCNS group A equivalents per ton of gross production (oil + gas + water)
This benchmark indicator shows a slow increase in the use/toxicity of production chemicals since 1997. The introduction of the Chemicals Regulation 2002 and the subsequent revision of the method for calculating Group A equivalents has led to a sharp increase. Generally less than 50 grams of OCNS Group A equivalents are used per ton of gross production.
Drilling chemicals
kg of OCNS group A equivalents per meter drilled
Drilling chemical discharges differ significantly per well, ranging between 4 grams and 0.3 kg of OCNS Group A equivalents per meter drilled. Generally less than 0.05 kg of OCNS Group A equivalents are discharged per meter drilled.
Flaring and venting
Tons of CO2 equivalents per ton of oil produced
Most of the gas that is flared offshore is flared by oil platforms. This practice results in about 0.04 tons of CO2 for every ton of oil produced.
Fuel consumption
Tons of CO2 per ton of gross production
The amounts of energy required to produce oil and gas from the UKCS is slowly increasing as a result of depleting reservoirs. Even when taking account of the amount of water that has to be lifted with the oil, this benchmark indicator is slowly increasing. To lift a single ton of fluids will currently result in about 0.035 tons of CO2.
Tons of CO2 per ton of oil and gas production per km from shore
The amount of energy required to pump a ton of crude oil to shore is fairly consistent across the UKCS; generally ranging between 0.05 and 0.4 kg of fuel for a km of pipeline distance.
The amount of energy required to pump a ton of gas to shore ranges more widely; typically between 0.1 and 2.5 kg of fuel per km of pipeline distance.
Flaring, venting and fuel consumption
Exported TOE as a percentage of produced TOE
The production of oil is generally less energy efficient than the production of gas. Gas production from the UKCS is about 98.3% efficient, whereas oil production is about 93.5% efficient.
Waste generation
kg of waste per manday
The amounts of waste generated on offshore installations ranges typically between 2 and 15 kg per person per day.
kg of waste per TOE produced
The relative amounts of waste generated offshore per TOE produced have increased steadily since 1997. Waste generation ranges per offshore installation; typically between 0.2 and 2 kg per TOE.
