Oil and gas pipelines

Summary: Oil and gas pipelines are continuous pipe conduits for transporting oil and natural and/or supplemental gas from one point to another. Pipelines provide one of the safest, most efficient, and economical solutions for transporting oil and gas resources.

Pipeline networks are composed of several types of equipment: valves, pumps/compressor stations, communications systems, and meters. The flow of oil is kept in motion by pumps, while natural gas pipelines require special compressors. Both pumps and compressors are installed along the pipeline to maintain the flow of products.

Oil pipelines are made from steel or plastic tubes. Oil pipeline networks usually include crude oil and refined products pipelines. For crude oil, its pipelines can be subdivided into “gathering lines” and “trunk lines.” Gathering lines are small diameter pipelines (2–8 inches) tapping into the oil fields to gather the sources to the trunk lines, which have a larger diameter (8–48 inches) and serve the purpose of delivering crude oil to refineries. Pipelines that deliver refined petroleum products also vary in size (8–42 inches). The end point of the refined products pipeline is not end users but rather large fuel terminals where products are loaded onto tanker trucks and delivered to retail points, such as gas stations.

Natural gas pipelines are usually constructed of carbon steel to withstand the higher pressure of compressed gas. Gas pipeline networks also have small gathering systems and large cross- or inter-country transmission pipelines. Another difference between gas and oil refined product pipelines is that the former is delivered directly to end users through local distribution lines.

The Largest Network in the World

Currently, the United States has the most extensive oil and gas pipeline network in the world, more than 10 times larger than that of Europe as a whole. There are an estimated 55,000 miles of crude oil trunk lines, 30,000 to 40,000 miles of small gathering oil pipelines, and 95,000 miles of refined products pipelines in the United States. The United States also has about 20,000 miles of natural gas gathering lines and approximately 278,000 miles of natural gas transmission lines. The U.S. government ordered the construction of two of its most well-known pipelines, named the Big Inch and Little Big Inch, from 1942–43 to avoid the dangers tankers would face from German submarines during World War II. The Big Inch was 24 inches in diameter and transported crude oil, while the Little Big Inch was 20 inches in diameter and transported refined products. The two pipelines ran from east Texas to the northeastern United States. After the war ended in 1945, the Big Inch was converted to natural gas and leased and later sold to a private corporation.

Although pipeline companies prefer to operate their systems as close to full capacity as possible to maximize their revenues, the average utilization rate (flow rate/design capacity) seldom reaches 100 percent. Several factors contribute to this outcome: scheduled or unscheduled maintenance, temporary decreases in market demand, and weather-related limitations to operations.

Pipeline Safety Issues and Technological Solutions

The flammability of oil and gas raises special concerns for pipeline safety. There are many historical records of oil and gas pipeline exploration accidents. Leakage accidents are usually attributed to pipeline aging and corrosion. Numerous technological solutions to avoid leakage and enhance surveillance have been developed. The most economical method to avoid corrosion is to use pipeline coatings and pipeline monitoring technologies. Some monitoring technologies require walking along the line to detect potential leakage; others use remote satellite surveillance systems. Computation pipeline monitoring systems (CPMs) are the most commonly used technology to monitor pipeline safety. CPMs bring on-field information such as pressures, flows, and temperatures back to control rooms.

The control rooms use a supervisory control and data acquisition (SCADA) system to analyze and control the sensor–based data in order to estimate the status of the pipelines. The estimation is then compared to the baseline scenario to detect anomalies and leaks, as well as plan for preventive maintenance. Sometimes, a video pipeline monitoring system that provides visual assistance to the human operator to facilitate problem attribution and decision making is also incorporated into the CPM. Although a growing number of monitoring technologies have emerged to meet the safety demands, many are not ready for commercialization because of the high costs to install such technologies. Besides monitoring, some pipeline systems suffer from severe aging problems and require replacement.

On-Going Global Oil and Gas Pipeline Expansions

Currently, there are 15 strategically important oil and gas pipelines that are newly operational or under construction in the world: the TAPI Pipeline (starts from Turkmenistan and delivers gas to India through Afghanistan and Pakistan); the Denali Natural Gas Pipeline (delivering from Alaska to Alberta, Canada, then onto the American midwest); the Keystone Pipeline (delivering oil from Alberta, Canada, to Illinois and Oklahoma); the IGI Poseidon Off-Shore Gas Pipeline (connecting Greek and Italian gas transportation systems, expected completion in 2012); the Mozdok Gas Pipeline (which reaches from Azerbaijan to North Ossetia); the Altai Gas Pipeline (which starts from Russia and delivers Gazprom natural gas to China, expected completion in 2011–15); the South Stream Pipeline (delivering gas from Russia to Austria through southeastern Europe, expected completion in 2015); the Nord Stream gas pipeline (delivers from Russia to Germany, expected completion in 2011); the TransCaspian Natural Gas Pipeline (which reaches from Turkmenistan to Azerbaijan); the White Stream Pipelines (which deliver gas from Georgia to Romania and then on to western Europe); the Nabucco Pipeline (which links Turkey’s gas supply to southeastern Europe and eventually Austria, expected completion in 2015); the ESPO pipeline (expected to deliver oil from Russia to China and potentially Japan in 2014); the Pars Pipeline (delivers gas from Iran to Turkey); and the Iran–Pakistan–India Pipeline (that delivers gas from Iran to India and Pakistan, expected completion in 2015).

Bibliography

Goodland, Robert, et al. Oil and Gas Pipelines Social and Environmental Impact Assessment: State of Art. Fargo, ND: International Association of Impact Assessment Conference, 2005.

Herberg, Mikkal E., et al. Pipeline Politics in Asia: The Intersection of Demand, Energy Markets, and Supply Routes. Seattle, WA: National Bureau of Asian Research, 2010.

White, Gregory. “The 15 Oil and Gas Pipelines That Are Changing the World’s Strategic Map.” http://www.businessinsider.com/the-15-oil-and-gas-pipelines-changing-the-worlds-strategic-map-2010-3.

U.S. Energy Information Administration. “International Energy Outlook 2010: Natural Gas.” http://www.eia.doe.gov/oiaf/ieo/nat‗gas.html.

U.S. Energy Information Administration. “Natural Gas Pipeline Capacity & Utilization,” http://www.eia.doe.gov/pub/oil‗gas/natural‗gas/analysis‗publications/ngpipeline/usage.html.