Energy Exploration International - EEI Inc

Exploration - Production & Transportation

If commercial levels of oil and gas for onshore production are found when drilling at a reservoir, a plan is designed to get maximum production rates for the lowest cost. Once the decision to bring the reservoir onstream is made, wells are drilled and linked to the processing plant via a pipeline.

Flowing wells complete production by using cemented steel casing and pipes called 'tubes.' At the top of the tubing is a wellhead called a 'Christmas tree' which is made up of a cluster of valves to control the flow of oil or gas.

To increase the flow of the processing plant, pumps and other devices are often used at the wellhead. A flowing well however, normally has enough pressure for oil and gas to flow to the surface naturally.

The crude oil and natural gas that flows to the surface can have impurities. For instance, oil, gas and water may come out of the same well along with sand or other solid material.

There could also be hydrogen sulphide or carbon dioxide present in the effluent. If this is the case, the oil or gas is referred to as 'sour.' If there is no hydrogen sulphide or carbon dioxide, it is referred to as 'sweet.'
The different fields in onshore production require different methods for separation, transportation and processing.

Processing - Making Marketable Commodities

Most crude oil and natural gas requires some processing to remove undesirable components before the commodity goes to market. There are hundreds of products and by-products of crude oil which are separated and refined at an oil refinery. A combination of physical separation and chemical conversion processes are used to create products with the correct odour, colour, stability and other specifications required by the market.

Some processing facilities are basically just settling tanks for removing sand and water, while others are billion-dollar plants treating large volumes of sour gas or bitumen. The most important process in the refinery is fractional distillation which uses the different boiling points of the components of crude oil to separate them by evaporation and condensation.

Processing facilities separate the raw petroleum into the major products sold by the upstream sector:

• Crude oil, a mixture of liquid hydrocarbons
• Market-ready natural gas, composed mainly of methane, the simplest hydrocarbon molecule.
• Natural gas liquids (NGLs), the heavier gaseous hydrocarbons, including ethane, propane and butane.
• Condensate, liquid hydrocarbons obtained from processing natural gas for market.
• Sulphur, obtained from processing natural gas and transported as liquid, pellets or cakes.

About two-thirds of Texas oil and gas production does not require extensive processing.

Gas Processing

The natural gas purchased by consumers consists almost entirely of methane, the simplest hydrocarbon. In gas reservoirs, however, methane is typically found in mixtures with heavier hydrocarbons - such as ethane, propane, butane and pentanes - as well as water vapour, hydrogen sulphide (H2S), which is found in sour gas, carbon dioxide, nitrogen and other gases. Almost all of these substances are removed from the gas stream at processing plants located near production areas.

Transportation - Moving and Selling Products

America's oil and natural gas supplies are mainly located in rural and remote areas of America’s Southeast, and offshore. Consumers are concentrated in capital cities concentrated along America’s sprawling coastline.

Supply and demand are linked together in America by about 550,000 miles of pipelines. Some are massive steel conduits more than a metre in diameter, while others are plastic tubes approximately an inch in diameter. They form delivery systems as vast and complex as the railroads, highways or electric utilities. However, pipelines are largely invisible, buried a metre or more underground.

Pipelines fall into four general categories:

• Gathering lines move raw oil and gas from wellheads to processing plants and transmission facilities
• Trunk lines transport crude oil, natural gas liquids and refined petroleum products to refineries and petrochemical plants, and some trunk lines transport refine products to consumer areas.


• Gas transmission systems carry natural gas at high pressure from producing areas to consuming areas
• Local distribution companies deliver natural gas at low pressure to homes and businesses.

About 95 per cent of America's crude oil and natural gas is transported by pipelines. Regulators set strict safety and environmental standards for pipeline construction and operation.

Crude oil, gas liquids and refined products are also transported by tanker, barge, railway and truck. Pipelines are the only method used to deliver natural gas in America today.

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