Environmental Impacts of Oil Fields

Development of oil fields—sites containing oil and gas reserves—may cause various changes to the natural and human environment of large geographic areas. The environmental impacts arise during the offshore or onshore oil field operation phases, which are exploration, development, production, and transportation. Environmental impacts may be direct if caused by the actual oil field operations, for example, water contamination by drilling wastes, or indirect if they result from other activities arising from oil field developments, for example, job-related migration. An overview of basic direct environmental impacts of oil field operations is essential to understand the nature, scope, and gravity of their influence on both biophysical and sociocultural environments.

Oil field development starts with broadscale geological and geophysical surveys to identify exploration targets. Offshore exploration usually consists of aerial geosurveys, ship traverses, bottom sampling, seismic surveys with explosives, and test drilling for geological data. These activities may result in disturbance of marine mammals, benthic communities, coral reefs, seafloor, and sediments as well as increase in water turbidity. Onshore seismic exploration may trigger environmental impacts such as noise, vibration, air emissions, and intensive surface and ground disturbance from explosive charges, transport traffic, access roads, and drilling of exploratory wells. Whether offshore or onshore, exploration may lead to the degradation of air, water, and soil quality by discharges of drilling fluids contaminated with mud, formation water, and oil. Despite being a nonintense land use with minor effects on existing activities, the exploration phase [Page 947]may still cause land use conflicts, for example, interfering with fishing and boat use in coastal areas. It may also carry a risk of negatively affecting native communities or damaging cultural resources and sensitive ecosystems.

The onshore development phase consists of construction of roads, airfields, well sites, and production facilities that might modify topography through erosion, sedimentation, and compaction and cause vegetation loss/damage. These impacts may further reduce wildlife habitats, timber yield, and so on, and harm sensitive ecological areas (e.g., wetlands or endangered species). Air pollution might result from wind erosion and soil disturbance due to construction and traffic as well as from burning of fuel fossils that emit CO (carbon monoxide) and NOx (nitrogen oxides), which in high concentrations are harmful to health. Offshore, the seafloor may be disturbed by anchor dragging, drill ship and platform siting, production facility installation, and pipeline trenching. This alongside the possible discharges of drill mud, cuttings, disturbed bottom sediments, and solid wastes may contribute to bottom contamination and increased mortality of benthic and coral communities. Offshore and onshore installations are commonly accompanied by noise and vibrations, potentially harmful for humans and buildings close to construction sites. Installed facilities may affect natural and cultural landscapes, thereby producing different-scale visual impacts and aesthetic damage. The development phase may accidentally damage cultural resources and historical or religious sites. Labor immigration may overtax community services and cause economic, social, or cultural conflicts.

An offshore production complex includes various types of platforms with production and injection wells, transport pipelines, storage, and primary processing facilities. Platforms are self-contained facilities with helipads, accommodation for work crews, power supplies, storage tanks, and so on.

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