Offshore drilling


General: Offshore drilling is the extraction of petroleum products, such as oil and natural gas, from deposits in the seabed. These deposits may be located at great depths. Offshore drilling may take place near the shoreline or in a lake or sea. It typically requires sophisticated equipment. Drilling equipment is kept above sea level on large platforms that may be moveable and float on masts or poles anchored to the seafloor. Drilling for oil underwater is usually more challenging than oil extraction on land.

The environmental impact of offshore drilling is due mainly to the production of wastes during oil and natural gas drilling. These wastes take the form of water and solids extracted with the petroleum products. The water and solids produced during drilling may contain radioactivity that may be harmful to humans, animals, and the environment.

Petroleum is a fossil fuel, a non-renewable fuel source made up of the fossilized remains of animals and plants exposed to extreme heat and pressure under the Earth's crust. In its liquid state, petroleum is known as crude oil and natural gas in its gaseous state. The solid form of petroleum may be called bitumen, tar, pitch, or asphalt. Petroleum consists of the elements hydrogen and carbon.

The exact chemical composition of crude oil varies depending on how much hydrogen and carbon the oil contains and in what arrangement. Most oil is composed of 82- 87% carbon by weight and 12-15% hydrogen by weight and a small amount of sulfur, nitrogen, and oxygen. Crude oil can be separated into different products, including gasoline, kerosene, and lubricating oil, under different temperatures. Natural gas consists of mostly methane, and possibly other gases, such as propane and ethane.

History: As early as 4,000 B.C., asphalt was quarried, or dug out of the ground, and used as mortar and for waterproofing in what is now present-day Iraq. In 347 A.D., the Chinese attached drill bits to bamboo poles and drilled the first oil wells 800 feet deep. In 1594, the Persians hand dug oil wells. The first modern oil well was dug in the Aspheron peninsula of Baku in Asia in 1848.

Kerosene, a fuel oil first used to light lamps, was once extracted from petroleum (which replaced whale oil) and created a market for petroleum products. This led to the formation of the first oil company in the United States in 1854 called the Pennsylvania Rock Oil Company. The first commercially successful oil well was drilled in 1859 by Edwin L. Drake, which sparked international interest in oil drilling. The well was 70-feet deep and produced barrels containing 42 gallons of oil, the standard for packing fish established by King Edward IV. This standard was endorsed by the Petroleum Producers Association in 1872 and is the standard of measurement used in the United States to this day.

Today, oil is usually shipped in oil tankers, or ships designed to carry large quantities of oil. The amount of oil a tanker carries varies with the size of the tanker. Smaller tankers can carry as little as 10,000 deadweight tonnage (DWT) and the largest tankers carry as much as 550,000 DWT of crude oil. DWT is a measurement of how much a ship can carry safely with sinking too low in the water.

The oil industry and its products continued to grow throughout the 19th and early 20th centuries, spurred by the development of diversified oil companies such, as John D. Rockerfeller's Standard Oil Trust in Ohio, standardized methods of production that made petroleum products safer and more effective, and new inventions fueled by petroleum, such as the internal combustion engine and gasoline pump.

Transporting petroleum products advanced with the construction of two pipelines in 1942. The pipelines transported crude oil from oil fields in Texas and the Gulf Coast to refineries and distribution centers in New York and Pennsylvania. In the same year, the first off-shore oil well was drilled. In 1960, Iran, Iraq, Kuwait, Saudi Arabia, and Venezuela formed the Organization of Petroleum Exporting Countries (OPEC), an intergovernmental organization that regulates the price of oil.

In 1974, an embargo of Arab oil, wherein Arab countries decreased oil production and increased oil prices in response to the United States and other countries' support of Israel in the Yom Kippur War, caused an energy crisis. This crisis renewed interest in oil resources within the United States. It also sparked interest in developing ways to conserve energy and stockpiling oil via the U.S. Strategic Petroleum Reserve. For instance, the automobile industry began to replace larger vehicles with more energy-efficient models. Oil prices again dropped in the 1980s.

In 1989, the Exxon Valdez oil tanker hit a reef off the coast of Alaska. The resulting oil spill was one of the worst in history, with more than 10.8 million gallons of oil spilled into the ocean, covering 11,000 square miles. As of 2007, more than 26,000 gallons of oil still remained in the contaminated shoreline. It is estimated that 500,000 seabirds, at least 1,000 sea otters, about 12 river otters, 300 harbor seals, 250 bald eagles, 22 orcas, and billions of salmon and herring eggs were killed. The Exxon Valdez oil spill prompted more concern among the public about the adverse effects of the oil industry.

More recently, higher fossil fuel prices and increased interest in protecting the environment has driven the development and steady growth of the renewable energy industry. Petroleum products, though, are still in high demand. More than 63% of energy consumed to heat buildings, power vehicles and machinery, and generate electricity in the United States comes from petroleum products, specifically oil and natural gas. Consumption is estimated to increase by more than 39% by 2025.

Petroleum production: According to U.S. Department of Energy (DOE), more than 30 states in the United States produce oil and/or natural gas. The United States' oil potential is the most thoroughly explored. The United States has the highest number of wells drilled internationally at about 3.5 million. About 25% of these wells are still producing. The United States' continued oil production depends on discovering more oil fields, both giant and more geologically obscure fields, and maximizing their use.

About 50-250 drilled wells contain most of the oil found in a world-class giant field, which consists of 500 million to 500 billion barrels of oil that can be recovered. Most of the oil that has yet to be discovered (an estimated 275 billion to 1.4 trillion barrels) is located in frontier basins, or places that are difficult to explore, such as Polar Regions. About 77% of oil reserves have been discovered, 30% consumed, and at the present rate of consumption, oil shortages and decreased production is expected to occur in the mid-21st Century.

Eighteen countries are responsible for 86% of the world's oil production and are estimated to have 82% of the world's undiscovered oil fields. Saudi Arabia has the largest oil reserve in the world, due in part to the world's largest oil field, the Al-Ghawar field, which contains 82 billion barrels of oil. In 2006, Saudi Arabia, Russia, and the United States were the world's largest petroleum producers.

Petroleum consumption: According to the U.S. Energy Information Administration (EIA), crude oil and natural gas plant liquids were the world's most important primary energy sources from 1980 to 2006 at 35.9% world production, which increased 16.9% from 1996 to 2006. The United States consumed the most petroleum in 2006 (20.7 million barrels daily), followed by China, Japan, Russia, and Germany.

Regulation: Most radionuclides, or unstable compounds that emit radiation, produced during oil processing are regulated by the Atomic Energy Act (AEA), although the AEA only covers source material, which are defined as mined uranium and thorium ore. Under the Clean Water Act, the U.S. Environmental Protection Agency (EPA) has the authority to regulate technologically-enhanced, naturally occurring radioactive materials (TENORM), or the naturally occurring radioactive material exposed and/or concentrated by petroleum production, or naturally occurring radioactivity that is concentrated during petroleum processing. The Safe Drinking Water Act established National Primary Drinking Water Regulations that control the amount of some petroleum processing byproducts that are allowed in drinking water in the United States. The National Oil and Hazardous Substances Pollution Contingency Plan (NCP) regulates cleanup of oil spills and outlines goals for protecting the public and environment. Gulf Coast states such as Louisiana, where oil wells are drilled, may also set limits for exposure to TENORM. The U.S. Occupational Health and Safety Administration (OSHA) also set limits for exposure to radioactive materials.


General: Offshore drilling is the extraction of oil and natural gas from petroleum deposits from the sea or ocean floor and may take place at great depths. Petroleum is a hydrocarbon fuel source made up of the fossilized remains of animals and plants. It exists in liquid (crude oil), gaseous (natural gas), and solid (bitumen, tar, pitch, or asphalt) states.

Oil deposits: The migration and accumulation of petroleum depends on two factors: the porosity of the rocks that surround it and how well they transmit fluid. Most petroleum deposits are found in sandstone and siltstone reservoirs, followed by limestone and dolomite, and rarely in metamorphic, shale, and igneous rocks. From these reservoirs, oil migrates to traps, or rock that curves outwardly like a container and is capped by a dense, impermeable rock. Some petroleum deposits are found near the surface, but most are found 500-25,000 feet below the surface, with the deeper deposits containing the most natural gas.

Large oil deposits: Oil traps congregate together to form oil fields. Most petroleum is found in larger fields. A "super-giant oil field" contains at least five billion barrels of oil that can be recovered. (Each barrel is 42 gallons in size.) Only 40 super-giant fields have been discovered, most of which (20) are located in the Arabian Peninsula, although a few are found in the United States, Russia, Mexico, Libya, Algeria, Venezuela, and China. As more oil fields are discovered, their size and the amount of petroleum they contain decreases.

Oil discovery: Certain geological formations, such as faults or folds, on the surface are indicative of underground oil reserves. Additionally, small changes in the gravitational force or anomalies in the earth's magnetic field surrounding certain rock formations are also a sign of underlying oil reserves. The presence of radioactive elements, such as uranium, thorium, radium, and lead-210, may be found with petroleum deposits.

Seismic surveying: Seismic surveying exploits the ability of rock to transmit and reflect sound. This oil discovery method is used to find smaller reserves or those that are located in more challenging geological locations. Microphones are set up at different distances as a shallow hole is drilled. Sound is emitted into the hole. The sound waves bounce off underground rock formations, usually causing a small explosion that is recorded by the microphones. This is repeated over a wide area. Computers analyze the recordings, which are used to create maps of rock formations.

Exploratory oil drilling: To pinpoint the location of the most productive petroleum deposits, exploratory wells are drilled first by rigs (machines that create small holes in the seabed) that vary in size. Some are portable and can be moved and manned by one person. Others are very large and capable of drilling great distances into the ocean floor. Most exploratory rigs are also moveable offshore drilling rigs, in that they can be moved from one location to another.

Shallow water drilling rigs: Drilling barges are used in swamps, lakes, and inland seas with shallow, still waters. These platforms float at the water's surface and are pulled to a location by a smaller vessel. A jack-up refers to a type of drilling rig that is transported to the proper location and hoisted above water by columns that can be lowered to the ocean floor. A submersible rig is a rig that is weighted to the ocean floor after it is floated to the proper location.

Deep water drilling rigs: A semisubmersible rig is often used in deeper, more turbulent water, where stability is a concern. The floating, above-water structures of the rig are connected with columns to vessels and anchors submerged below the surface. Semisubmersibles may be moved to another location via their own locomotion. Drillships may be completely free-floating vessels that are kept in the same location by propellers that prevent the ship from moving too far off course. Drilling equipment reaches the seabed through a hole in the ship's body.

Oil extraction: Once the drilling rigs locate productive petroleum deposits in the seabed, an offshore oil-drilling platform is towed to the location to begin oil extraction. These platforms are permanent and often expensive structures built to withstand poor weather conditions and turbulent waters. Due to their cost, large platforms are usually built over large petroleum deposits.

Shallow water drilling platforms: Fixed platforms are permanent structures anchored to the seabed by a rigid column. A platform and drilling equipment are located above the water's surface. They are stable structures used in shallow water, up to 1,500 feet deep. Compliant towers are also anchored to the seabed with a platform and equipment located above water. The column that attaches the platform to the seabed is more flexible than that of a fixed platform.

Deep water drilling platforms: SeaStar platforms are used in greater depths (500- 3,500 feet). Their platforms are similar to semisubmersibles, and the two columns anchoring the platform to the seabed are flexible. Floating production systems may be submersibles or ships attached to the seabed by heavy anchors at depths of 1,500-6,000 feet. Tension leg platforms are similar to SeaStars, although, tension legs are used at greater depths (1,500-7,000 feet). A subsea system is located on the ocean floor at depths of up to 7,000 feet. The oil extracted by the subsea system may be transported to an above-water platform by pipelines. Spar platforms are among the largest offshore platforms and are used in the deepest waters (2,000-10,000 feet). A drilling platform is attached to the ocean floor by a single column, with additional support and stability provided by cables that connect the column to the seabed.

When oil is drilled in shallow water, such as wetland, equipment is often mounted on a barge that can be raised over the water on masts (poles). In colder climates where floating ice is a concern, barges are reinforced with materials such as rock or gravel. In water deeper than 15 meters, oil drilling equipment is usually mounted on a free-floating platform that may be a ship or partially submerged vessel. Also, immovable platforms are mounted to the ocean floor by pilings 10-20 meters high or by filled flotation tanks.

Oil drilling: In rotary drilling, the drill bit spins, and the well is filled with mud that prevents liquid from gushing to the surface. It also moves pieces of debris out of the well. Drilling is usually stopped at certain points to insert steel pipes and cement that keep liquids from penetrating the well.

Drill bits: Diffusion bonding, a process of welding two or more substances together, allows manufacturers to adhere diamond cutters to drill bits, creating the polycrystalline diamond drill bit that is now standard. Also, more recently, microwaves have been used to increase the strength of tungsten carbide deep drilling bits by 30%.

Waste from oil drilling: Petroleum can come from the fossilized remains of aquatic organisms found in ancient seas that are now buried under the earth's surface. In this case, petroleum deposits are found with brine (salt water), also called formation water. A mixture of oil, gas, and water is formed during the drilling process. The mixture is pumped to the surface where the water, now called "produced water," is separated into a pond, pit, or tank. As the oil reserves begin to decline, more water is produced.

Radioactive waste: Naturally occurring radioactive material (NORM) is present in the rocks and minerals of the earth's crust. Beneath the earth's crust is the mantle, the movement of which is driven by temperature changes. This movement and other geological processes, such as weathering of rocks by wind and rain, has distributed radioactive chemicals throughout the earth's crust in different concentrations. Geologic formations that contain petroleum deposits may also contain radionuclides, such as uranium, thorium, radium, and lead-210. Radionuclides dissolved in the formation water will separate out into waste.

TENORM (technologically-enhanced, naturally occurring radioactive materials): Petroleum production can expose and/or concentrate naturally-occurring radioactive material that is found at some oil drilling sites, such as the Gulf Coast states. These radioactive materials are collectively referred to as TENORM. This radioactive material is primarily radium-226, radium-228, and radon gas. Radon gas is released into the atmosphere. Other radioactive wastes are found in wastewater, mud, sludge, slime, and evaporation ponds and pits associated with oil and natural gas production. Radium can be placed in ponds to evaporate or for reuse. Radioactive materials may also be found in the pipes, storage tanks, and equipment used in petroleum production. The levels of radiation on produced waters can range from 0.1 pCi/l (picoCurie per liter) to 9,000 pCi/l. Radioactive solids range from less than 0.25 pCi/g (picoCurie per gram) to more than 100,000 In the pipes and tanks.


General: Although it takes 22,000 fewer wells a year to produce the same amount of oil and gas as it did in 1985, pollution from oil production, especially radioactivity, is a widespread international problem. Technological advances in the petroleum industry have reduced air and water pollution, but the threat to ecosystems and human health has deterred the expansion of oil drilling to environmentally sensitive areas, such as the Arctic National Wildlife Refuge in Alaska. But as fossil fuel prices rise, the debate over oil production versus conservation is expected to intensify.

In 1986, scale generated during oil production in Mississippi was found to contain elevated levels of radioactivity, specifically radium-226 and thorium-232, bringing the issue of radioactive contamination to public attention. After the discovery, the U.S. Environmental Protection Agency (EPA) conducted industry surveys and found high radiation levels in some equipment, soil contaminated with radium-226 at some disposal sites, and contamination of nearby ponds, agricultural fields, and vegetation near some oil-processing sites. This led industry and regulatory agencies to change the way wastes were handled.

Waste: The petroleum industry generates about 260,000 metric tons of waste annually in the form of produced water, scales, sludges, and contaminated equipment. Exact amounts vary from site to site and depend on location, type of operation, formation conditions, and age of the well. About 30% of oil and gas wells in the United States produce radioactive waste. Radioactivity was reported at 20-100% of the petroleum facilities in every state that participated in an EPA survey, though the percentage reporting high concentrations of radioactivity varied.

Produced water: For every barrel of oil produced, about 10 barrels of wastewater are also produced. Wastewater compromises 98% of the waste produced by oil and natural gas operations and may be harmful to the environment. More than 18 billion barrels of wastewater are generated annually in the United States. This wastewater may contain high levels of total dissolved solids (TDS), which are the solids suspended in a liquid that make the water unusable, even with treatment. Although the levels of radioactivity in produced waters are low, the volume of water produced is high. Currently, produced waters are either injected into wells, or, in the case of marine oil processing, are discharged into non-potable or untreated coastal waters. Thirty-one states had 166,000 injection wells as of 1992. Cracks or fractures in injection wells could potentially lead to groundwater or drinking water contamination.

Scale: Scale is defined as compounds that settle out of the mixture of petroleum and salt water, also called formation water, during drilling. Scale is composed mainly of barium, calcium, strontium, and radium, with radium-226 in higher concentration than radium-228.

Scale collects in pipes and tubes, with the highest concentrations at the wellhead, water lines that separate gas, water, and oil, heater treaters that divide oil and water, and gas dehydrators. Chemical compounds may be used to inhibit scale formation. The petroleum industry produces 100 tons of scale per oil well annually. Scale increases as oil pumped from the well decreases and water levels rise. Average radium concentration in scale is estimated to be 480pCi/g, although it may be as high as 400,000pCi/g, depending on the location. Currently, scale is removed from pipes with high-pressure water or scraped out and stored in drums for disposal.

Sludge: Sludge is usually an oily material composed of silica, barium, or radium (usually radium-226) that settles out of produced waters. Dried sludge appears similar to soil. The oil industry generates about five million cubic feet of sludge each year. Most sludge is found in the oil stock and water storage tanks. Radium concentration in sludge is estimated to be 75pCi/g, varying from site to site. Concentrations of lead can be more than 27,000pCi/g in sludge. Radiation is typically higher in scales, but sludges are more soluble, readily released into the environment, and pose a higher risk of exposure. Currently, the EPA recommends removing water from radioactive sludge and storing it in tanks. If the sludge contains 50-2,000pCi/g of radium, it is stored at a facility designed to house TENORM waste.

Contaminated equipment: During oil production, equipment may become contaminated with radioactivity, with levels varying depending on geographic location. According to one survey, 57% of the oil production equipment in the United States showed radioactivity at or near background levels micro Roentgens per hour (µR/hr), with higher levels reported in water handling equipment. Levels of radiation for this equipment were five times background levels, or 30-40µR/hr. Currently, equipment can be cleaned, recycled, reused, or disposed of in landfills.

Disposal: According to the EPA, oil processing equipment contaminated with lead and radiation was recycled for use in construction projects in the past. These projects included home building, plumbing for kitchens, fencing, and materials for welding classes. Sludge and other wastes were placed in pits and burned. Produced waters and other wastes were placed in pits, wherein radioactive waste would settle to the bottom. Radionuclides in the pits are reported to range from 270 to 1100pCi/g. This and other practices may have caused ground and surface water and soil contamination in the surrounding environment.

Currently, radioactivity levels of oil processing equipment are detected, and contaminated equipment is cleaned before disposal. If the equipment is smelted (the process of obtaining metal from or by applying heat), radioactive materials vaporize and are released as a gas. Pollution-control devices, such as filters, are installed in stacks at smelter facilities to cut down on air pollution by as much as 99%. The EPA has established voluntary guidelines for disposal sites of radioactive waste. A sanitary landfill contains 3-50pCi/g of radium; low-level sites contain 50- 2,000pCi/g; and sites that contain greater than 2,000pCi/g follow the Atomic Energy Act regulations.


General: Radioactive wastes, or the radioactive byproducts of oil production, may be found in wastewater, air, and solid waste near oil drilling sites. According to the U.S. Environmental Protection Agency (EPA), radioactive contamination from petroleum facilities and practices is a widespread problem throughout the world. Radioactive contamination may affect human, animal, aquatic, plant, and microbial health through contaminated water, air, and soil. Prolonged exposure to or exposure to high concentrations of radioactive wastes and other pollutants, such as polycyclic aromatic hydrocarbons (PAH), may be lethal. Exposure to high levels of radiation or prolonged exposure may increase the risk of cancer in humans and other animals.

Radioactive contamination: Exposure to radioactivity typically occurs in three ways: through onsite disposal of contaminated materials, which may lead to groundwater and air contamination; the improper disposal of wastes that may contaminate surrounding communities, crops, water, and soil; or the reuse of petroleum processing equipment. The public is also at risk of exposure to radioactive materials. Areas near drilling sites are more likely to be contaminated if they were active before regulations controlling radionuclides came into effect the Gulf States, upper Midwest, and some Appalachian states. High levels of radioactive wastes may be found in states where petroleum drilling and processing takes place. Louisiana, Mississippi, and the Persian Gulf are known to have high levels of TENORM.

Oil workers: Oil workers at the processing and disposal sites are most likely to be exposed to radioactive materials, either by inhaling radon gas or radioactive dust, which raises their risk of lung cancer, or exposure to gamma radiation, which can penetrate the skin and may increase the risk of various cancers, such as bone cancer.

According to the International Labour Organization, an offshore oil worker is at risk of injury from the drilling machinery and working at great heights. In some cases, harsh weather conditions and sunlight on the drilling rig or platform may also cause injury, sunstroke, electrocution via lightning, or other health problems. Welders and workers near exhaust pipes are at risk of burns. The rig environment, especially if submerged below water, may be lacking oxygen, which may damage tissues. Workers may also experience stress and anxiety from long shifts on the drilling platforms.

Nearby residents: People working or residing within 100 meters of a disposal site have a similar risk of exposure to radiation as disposal workers. Those risks include inhaling contaminated dust, drinking contaminated water, eating contaminated food, inhaling radon, and direct exposure to gamma radiation. Within a 50-mile radius of disposal sites, there is a risk of exposure to contaminated air, river water, and food. People working in office buildings constructed on oil waste piles may be exposed to contaminated air, dust, and gamma radiation.

One study evaluated the occurrence of a brain tumor cluster among employees at a petroleum facility and found that chemical and physical exposures were not significantly associated with the tumors.

A bulletin from the U.S. Occupational Safety and Health Administration (OSHA), pertaining to health hazards associated with petroleum production in Louisiana, stated that oil production wastewater contained radium levels that exceeded those allowed for other sectors, such as the nuclear power industry. Samples from wastewater of oil platforms contained 605-1215pCi/l (picoCuries/liter). The EPA considers activity levels in excess of 50pCi/liter as hazardous.

Equipment contamination: The public may also be exposed to radioactivity when oil production equipment is reused in other, unrelated construction projects. For instance, pipes contaminated with radioactivity were found in scrap yards in New Orleans, Baton Rouge, and Lake Charles. Contaminated pipes were used to construct bleachers at schools in Mississippi. A pipe yard in Houma, Louisiana, was found to have radioactivity levels similar to that of a nuclear power plant.

Water contamination: According to recent studies, water treatment systems may be contaminated with radionuclides and other byproducts of petroleum processing, although reports of contaminated water negatively affecting public health are lacking. A marsh in coastal Louisiana was contaminated with 1.76 curies of radium in a five-year period by the Leeville Oil Field, and possibly in excess of 10 curies over the lifetime of the field

Soil contamination: Louisiana's Department of Environmental Quality's Nuclear Energy Division states that soil contaminated with radioactive waste at pipe storage sites had radium-226 radioactivity of up to 8,700pCi/gm. Radium-226 has a half-life (the time it takes for half of it to decay) of 1,620 years. Therefore, it may persist in the environment for centuries.

One study examined the effect of crude oil production on the soil composition of Momoge Wetland in China. Oil sites had higher amounts of total petroleum hydrocarbon and total organic carbon and higher pH values, but lower total nitrogen. Amounts of total phosphorous and electrical conductivity showed no significant changes. The length of time the oil well was in production affected the level of soil contamination.

A study in Mexico concluded that soil contamination with total petroleum hydrocarbons occurred in all oil pumping stations included in the evaluation.

A study of PAH contamination in oil exploration and production sites throughout Texas tested the bottom of oil tanks to see if the measurements of PAHs were indicative of the concentrations of PAHs in the surrounding soil. Overall, the PAH concentrations in the tanks were greater than soil concentrations. The fraction of carcinogenic PAHs per total PAHs increased from 12% in tank bottoms to 46% in the soil. Therefore, PAH content in tank bottoms may not be a useful indicator of PAH concentrations in soil.

Aquatic animals: Exposure to radioactivity in produced waters (wastewater produced during petroleum processing) or contaminated soil may impair development, disrupt sex ratios, and cause birth defects in aquatic species.

Additionally, seismic waves are often used to determine the location of oil reserves. These waves may disorientate aquatic mammals that use sonar for communication and navigation. The exact impact of seismic waves has been difficult to determine because experiments often use caged animals that cannot escape stimuli. Recently, the beachings of possibly thousands of whales was reported in Madagascar after seismic testing in the area.

Recent research suggests that air-guns used to produce short, low-frequency noises that aid in petroleum reserve marine exploration may severely damage the ears of aquatic vertebrates. The sensory cells, or epithelia, did not recover up to 58 days after exposure.

A study of the Patoka River watershed in Indiana found that burrowing aquatic species were more sensitive to contamination than land burrowers. Burrowing crayfish species were associated with oil derricks (equipment, including towers and platforms, surrounding an oil drilling site) that contained more strontium, phosphorous, and other associated PAHs.

Plants: Early study suggests that a species of grassland plant, Carex tato, found in the Momoge Wetland in China, was being killed by oil production in the area. Carex tato plants died because the oil production byproducts damaged their roots and leaves. Some microbes in the soil were found to break down crude oil, but alcohol, a byproduct of oil production, was trapped near the roots due to poor permeability of the top soil and deeper layers and had a lethal effect on the root tissue. Additionally, the cuticles of leaf tissues were damaged by crude oil on the top soil that became volatized in the atmosphere during drought conditions. The Carex tato is a staple in the diet of several rare birds and also helps maintain the integrity of the soil in wetlands.

Microbes: Researchers have examined the effect of oil-polluted ice in the Artic fjord on microbial communities. Oil contamination appeared to stimulate microbial growth of microbes that feed on organic material (called heterotrophic prokaryotes), with communities predominated by Gammaproteobacteria, a class containing many disease-causing bacteria, whereas clean ice contained more heterogeneous microbial populations. The study also found the biodegradation of oil in primarily the deeper parts of the ice was slow.

Indigenous populations: Oil exploration and production have the potential to disrupt plant and animal life in the surrounding areas. One study considered the impact of oil and gas exploration in the western Amazon, an area rich in plant and animal species, indigenous (native) populations, and large, untapped petroleum reserves. The areas zoned for oil exploration compose the most species-rich part of the Amazon and overlap lands where many isolated indigenous populations reside. Some of these lands are titled to these groups and some are not. The study concludes that oil extraction without proper assessment and extensive road system could affect the indigenous population profoundly.

Environmentally sensitive areas: Many untapped oil reserves in the United States are located in environmentally sensitive areas, most of which is federal land in the western part of the country. Environmental impacts are currently being assessed in Colorado, Wyoming, Montana, New Mexico, Alaska, and Oklahoma.


Future exploration: New oil and natural gas reserves will likely be discovered in the in the frontier, or more geologically remote regions, making exploration more expensive and challenging. Russia appears to offer the best potential for new reserves. Future exploration is expected to involve the smaller basins as well as the more expensive and difficult frontier basins. Russia, and to a lesser extent Iraq, are thought to possess the best potential for new discoveries. The world's 23% remaining petroleum reserves are thought to be located in Arctic regions or deep underwater. The largest North Sea oil platform has a production cost 40 times that of costs in the Middle East.

Natural gas: According to the U.S. Department of Energy (DOE), about 125 trillion cubic feet of natural gas may be trapped below 15,000 feet. At that depth, rock is much harder to drill due to extreme pressure, heat, and hardness. A drill bit may slow to 2-4 feet per hour, and controlling its path at that depth is difficult. The DOE's Office of Fossil Energy Deep Trek program is currently developing more advanced drilling techniques in deep reservoirs.

Telemetry: Traditionally, the location of a working drill bit was transmitted by the application of pressure to the mud (mud pulse) surrounding the bit. A new technology called IntelliPipe™ sends information 200,000 times faster than mud pulsing and with more efficiency. A coupler is embedded in the small gaps between 30 feet sections of pipe. It allows data to be sent across the gaps to a high-speed data cable attached to the pipe wall. According to the DOE, field trials in the United States and Canada demonstrate the technology's reliability. During 500 drilling hours, 6,400 feet of Intellipipe™ were used in an oil well in Oklahoma. It may also be possible to place sensors along the drill pipe to constantly monitor drilling.

Drill pipes: A recently developed 2.5 inch carbon fiber drill pipe is lighter, stronger, and more flexible than traditional steel pipes. It may play a role in horizontal drilling and deep drilling, where the weight of the pipe is an important consideration. The lighter the pipe, the greater the distance a well can be drilled. The pipe can also better withstand drilling stress and can be reused. In one trial, a carbon pipe was used to drill an additional 1,000 feet in an older well.

Geothermal electricity: Many older oil fields produce hot water at temperatures below 220©F that can be used to generate an estimated 5,000 megawatt (MW) of electricity. Since September 2008, a field test site in Wyoming has been producing 150-250 gross kilowatts of power. The hot water is treated before being released into a nearby stream. The electricity may be used for onsite power generation. According to the DOE, research into exploiting 8,000 similar wells in Texas is currently underway.

Environmental impact: Much of the oil reserves left in the United States lie in environmentally sensitive areas. The U.S. National Energy Technology Laboratory (NETL) supports the development of technologies that reduce the environmental impact of drilling and oil production in general and more specifically in federal lands. Sixty-eight percent of untapped oil resources are located on federal land, most in the western states. Many environmental protection standards were developed without specific data from detailed studies. In 2000, the U.S. Bureau of Land Management and the DOE began 10 joint projects to assess environmental problems from oil production in Colorado, Wyoming, Montana, New Mexico, Alaska, and Oklahoma.

Reducing environmental impact: To reduce impact on environmentally sensitive areas or to access difficult geological areas, oil producers can drill a well in a more suitable site, and then, once underground, turn the well horizontally to drill at a site potentially miles away. Also, from a single well, lateral wells can extend out laterally like spokes of a wheel, so as not to disturb surface habitats.

Wastewater: Currently, most of the wastewater generated from oil production is unsuitable for use, a fact that has hampered the growth of oil production in the United States. Discovering beneficial uses of wastewater could reduce the cost of oil production, making the U.S. oil industry more economically viable. If these waters could be properly treated and released into the environment safely, the water could be used to offset drought and develop habitats, as well as be used by industries and residences. The U.S. Bureau of Land Management, Forest Service, Fish and Wildlife Service, Minerals Management Service, and U.S. National Energy Technology Laboratory (NETL) are working in conjunction to develop new water treatment technologies and research the benefits of wastewaters.


This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

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