This document is intended to provide an introduction for non-specialists to the key activities and potential sources of environmental effects associated with oil and gas exploration and production. It forms part of the information base for the Department of Trade and Industry's (now Department of Energy and Climate Change) Strategic Environmental Assessment (SEA2) process in the North Sea.

This report is a contribution to the Strategic Environmental Assessment (SEA6) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). This report considers the major sources of contamination to the Irish Sea from offshore energy installations and puts them in the context of other sources of contamination to the region. The report also considers contamination of the wider environment, making use of data provided by monitoring programmes and other specific studies. The oil and gas industry in the Irish Sea is small by comparison to that of the North Sea, but bears comparison to that of the Southern North Sea which is dominated by gas production and for which many of the platforms are in relatively shallow water. The discharge of production and drilling chemicals, residual oil and compounds derived from the formation water co-produced with the oil or gas contribute to the contamination concentration in sediments and water. However, in Liverpool Bay and Morecambe Bay, where the oil and gas fields are located, the riverine inputs of major groups of organic contaminants and metals are found to be several orders of magnitude greater than those from the offshore oil and gas industry. Inputs of artificial radionuclides into the Irish Sea are dominated by discharges from Sellafield on the Cumbrian coast. The distribution of radionuclides in seawater, in the sediment and in biota are reviewed.

This report is a contribution to the Strategic Environmental Assessment (SEA5) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). The SEA5 review differs from previous assessments in that the zone includes a large coastal fringe, along the whole east coast of Scotland and the Northern Isles, and contains a diverse range of habitats, from inter-tidal rocky shores and sandy beaches, to the shallow sub-littoral and deepwater mud basins offshore. These habitats support a wide range of invertebrate resources, of which six species of crustacean, four species of bivalve mollusc and two species of gastropod mollusc form the basis of a thriving shellfish fishing industry in Scotland. The landings are dominated by the Norway lobster, Nephrops norvegicus which occurs in four main areas, one of which, the Fladen ground, is in close proximity to mature oil fields. The fishery for this species in the North Sea is likely to increase, with diversion of effort from the demersal fisheries for cod and other whitefish. Much of this expansion should take place at Fladen where the stock is at present under-exploited. It is likely, however, that trawl gear used in the Norway lobster (and pink shrimp) fisheries will be required to be more selective in order to reduce the by-catch of demersal fish, especially cod, and the wastage through discarding of under-sized fish. Relevant aspects of the biology of each species are described, including habitat preference, distribution, feeding, life-cycle, reproduction and spawning. Details are given about the fishing methods used, assessments of the state of stocks, and the management regime and legislation currently used to control each fishery.

This report is a contribution to the Strategic Environmental Assessment (SEA3) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). This study provides forecast information on probable activity levels, capital expenditure, tax revenues and employment resulting from exploration and production in the SEA3 area. The SEA3 area comprises 330 blocks or part blocks in the Central and Southern North Sea. Estimates were made of the reserves which might be discovered or developed. A cautious view was taken of the number of new developments which might emanate from licensing the area. The related exploration, appraisal, development and decommissioning costs were then estimated. Economic modelling was undertaken for different oil and gas prices to calculate for each development gross revenues, development costs, operating costs, and decommissioning costs. The taxation implications were also calculated. The impact of licensing the SEA3 area on the level of employment in the UK has been calculated. The proposed licensing would make a modest but worthwhile contribution towards moderating the downward trend of employment in the North Sea industry.

This report is a contribution to the Department of Trade and Industry's (now Department of Energy and Climate Change) Strategic Environmental Assessment SEA2. Eight marine mammal species occur regularly over large parts the North Sea: harbour seal, grey seal, harbour porpoise, bottlenose dolphin, white-beaked dolphin, Atlantic white-sided dolphin, killer whale and minke whale. A further 15 cetacean species and five pinniped species are reported less frequently in the region. This report describes the distribution and abundance of these mammals and their ecological importance. The harbour porpoise is the most numerous marine mammal in the North Sea, with a population estimated at 268,000 in summer 1994. The northern and central SEA2 areas are particularly important areas for the harbour porpoise. Marine mammals make use of sound for a variety of purposes: finding prey, detecting predators, communication and probably navigation. The offshore oil and gas industry generates underwater noise at every stage of the process: during exploration seismic surveys, drilling, production and decommissioning. The effects of these different sources of underwater noise on marine mammals are discussed. The use of explosives for underwater cutting and demolition during the decommissioning of platforms and installations may pose a serious threat to some marine mammals. The effects of pollution on seals and cetaceans are discussed, including the effects of oil spills. Large whales can be killed by being struck by ships; increased shipping traffic in an area would increase this threat.

This report is a contribution to the Strategic Environmental Assessment (SEA5) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). A review of the coastal distribution and abundance of swans and geese in the SEA 5 area, including migration routes, key feeding areas and roosting areas was carried out. A review of the potential impacts of offshore wind farms on swans and geese was also conducted. The study area was defined as the east coast of Scotland from the English border north to John O' Groats, including Orkney and Shetland, and the offshore waters in the SEA 5 area. The review considered nine species: mute swan, Bewick's swan, whooper swan, bean goose, pinkfooted goose, white-fronted goose, greylag goose, barnacle goose and brent goose. Offshore wind farms may impact birds directly by mortality from collisions or indirectly by displacement from migratory flyways or local flight paths. At present there are very little data on the effects of offshore wind farms on swans and geese. Of the nine species reviewed, five species, whooper swan, mute swan, pink-footed goose, greylag goose and barnacle goose occur in internationally important numbers at coastal sites in the SEA5 area. Greenland white-fronted goose occur in nationally important numbers.

This report is a contribution to the Department of Trade and Industry's (now Department of Energy and Climate Change) Strategic Environment Assessment SEA2 for the North Sea. It draws on a wide range of data sources to provide an overview of the chemicals used in the offshore oil and gas industry, of the chemicals already in the environment and of those released into the environment from other sources. Considering the whole sea area, it should be noted that the water samples with the highest levels of chemical contamination are found at inshore estuary and coastal sites subject to high industrial usage. Approximately 2,000 chemical products are used by the offshore oil and gas industry. In 1999 some 180,000 tonnes of chemicals were discharged into the UK sector of the North Sea. Produced water is now the main source of contaminants, having overtaken drill cuttings since oil-based muds were replaced by less harmful alternatives. 24,286 tonnes of chemicals were reported as discharged to the UKCS in produced water in 1999. As oilfields mature, the amount of produced water increases. The range of chemicals used by the offshore oil and gas industry, the means of regulating them and of monitoring their use, are discussed. Evidence of biological effects caused by the release of contaminants into the sea is reviewed.

This report is a contribution to the Strategic Environmental Assessment (SEA4) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). The SEA4 area includes the most northerly part of the UK continental shelf, north of the Shetland Islands between the international boundaries with Norway and the Faroe Islands, and the area to the west of Shetland and the Orkney Islands. Starting with scenarios of possible exploration and development activity in the area provided by the Department of Trade and Industry, this study provides forecasts of oil and gas production, expenditure, employment and tax revenues. The impacts of future oil and gas developments in the SEA4 area on the local economies of Shetland and Orkney will be small in comparison to what has happened in the past. The main impact will be to postpone or to slow down the decline in UK oil production. Nevertheless, production from fields in the area could make significant contributions to overall UKCS production, employment and tax revenues, as well as extending the lives of facilities such as the Sullom Voe and Flotta terminals. It could help to retain employment and population in the area.

This report is a contribution to the Strategic Environmental Assessment (SEA5) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). This report assesses the socio-economic implications of licensing the SEA 5 area and sets out the results in relation to: oil and gas production, and reserves; capital, operating and decommissioning expenditure; employment; tax revenue; social impacts. The Department of Trade and Industry provided scenarios of possible exploration and development activity in the area and these scenarios were converted into optimistic and pessimistic scenarios. They were then used to produce forecasts of: oil and gas production; oil and gas reserves; expenditure; employment; and tax revenues. The implications for existing facilities in the area are discussed and the potential social impacts.

This report is a contribution to the Strategic Environmental Assessment (SEA2) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). SEA2 focuses on the mature areas of the North Sea UK continental shelf which is divided into 3 areas - Northern, Central and Southern North Sea. The socio-economic effects of licensing the SEA2 area are discussed. The scope of the study includes estimates of the reserves which might be discovered and developed, and the related exploration, appraisal, development and decommissioning costs. The possible phasing of these activities through time is also examined. The effects of the development of new fields in extending the lives of existing ones and the implications for the provision of necessary infrastructure onshore are also examined. The employment generated directly and indirectly in the 3 sub-areas is estimated. The distinction is made between employment at the various stages in the exploration, development and production activities. The significance of the employment opportunities provided for the long-term maintenance of a skilled workforce is also considered.