Petroleum and natural gas often are found in the same fields, and they often are extracted using similar methods and by the same companies. When it comes to oil, after geologists and geophysicists turn in their reports and recommendations, a petroleum company decides whether to drill. Petroleum engineers explore the area, recommend the type of derrick and drilling equipment to be used, and supervise the work of drilling. If the well strikes oil, a petroleum engineer oversees its production.
The primary goal is not the immediate production of large quantities of oil. Rather, the goal is to recover the greatest total amount of oil over a long period of time. With careful management, wells may produce oil for more than 30 years of operation.
Preparing the site for drilling is an important part of the oil-production process. Rig builders put up the tall, open towers called rigs or derricks. Drillers bore holes in the ground, often two or three miles deep, and then they bring up new oil or gas.
The rig houses the hoisting equipment that lifts and lowers the heavy tools, pipe, and casing used in drilling a well. Many rigs are portable so they can be moved more easily from one drilling site to another. For deep drilling, a permanent rig is usually built. It is made of structural steel parts fastened together.
The rig-builder supervisor directs work on the rig, and crews vary in size according to the job. A small rig may require only three or four workers, whereas a rig for a large drilling project may need as many as 25 workers.
Most wells are drilled by the rotary method. The rotary drilling crew bores a hole in the ground, much as a hole is bored in a wooden plank by a hand drill. They use a steel bit with sharp teeth, called the drill stem. Power applied to the drill stem at the surface of the well rotates the bit and its teeth, chewing a hole through the earth’s layers. As the hole is bored deeper, new pipe lengths are put on at the top.
A typical rotary drilling crew consists of a rotary driller and four or five helpers, often called roughnecks. An engine operator runs the engine that keeps the pipe and bit rotating. A derrick operator works on a platform high up on the rig and is busiest when a drilling bit grows dull and must be replaced, as then the whole string of pipe has to be pulled up out of the hole. As each pipe section comes up, the roughnecks disconnect it; the derrick operator snares the upper end and pulls the pipe over to a rack beside the platform. Several miles of pipe often are racked up in the derrick before the worn bit is brought to the surface.
An average-sized rig-building or drilling job has another group of workers called roustabouts. They clear drilling sites, clean the derrick floor, and help in other ways.
In offshore drilling, divers handle much of the work that must be done. In exploration work, they frequently dive for observation purposes or to retrieve lost cables or other equipment. Divers also do underwater construction work, put up platforms, and complete underwater pipelines. Such divers must be skilled in welding, cutting, pile driving, and riveting.
Other skilled workers are also needed at drilling sites. For example, the tractor driver operates the tractor, rooting out tree stumps, leveling the ground, and preparing a rough path. The ditching-machine operator cuts a trench through the earth for the pipeline. The spacer sees that the pipe lengths are spaced end to end with precision, so they can be joined together by the welder. If the pipe has not already been coated at the mill with material to limit corrosion, a crew applies it on the job.
More than half of all refinery workers are maintenance workers. Their job is to keep the complex equipment running smoothly. Maintenance workers also are employed in exploration, production, transportation, and even in marketing, where they repair service station pumps, home oil burners, and other types of mechanical equipment.
Refining is done by heating crude oil in a fractionating tower at the refinery. The lightest elements of the oil, gases, and gasoline fractions vaporize first and are carried off at the top of the tower. Other fractions, such as those of kerosene and lubricating oil, are separated from the crude oil and drawn off through pipes farther down in the column. In later, more complex refining operations, these various fractions are processed into such products as gasoline, kerosene, jet fuels, diesel oil, home heating oil, motor oil and other lubricants, waxes, asphalt, and basic ingredients for thousands of petrochemicals.
In the oil field, almost all the work in mechanical trades is outdoors. Since drilling goes on around the clock, drillers work in three shifts, with three complete crews. Most oil fields are in isolated regions, and crews live in quarters furnished by the company.
Oil wells, pipelines, and refineries are in operation 24 hours a day, seven days a week. Control workers are usually assigned on a rotating basis to one of three shifts, and they take turns on weekends and holidays.
Transportation of crude oil and refined products is carried out by pipeline, barge and ship, railroad tank car, and highway tank truck. Most of the crude oil and oil products move through a network of pipelines totaling over 200,000 miles.
Tank-truck drivers deliver oil products to service stations and dealers, to farms and factories, and to airlines and surface transportation companies. Trailer truck drivers haul gasoline and other products from refineries to distributing points, particularly in regions not served by pipelines.
Marketing consists of the sale and distribution of petroleum products. The largest portion of these products is sold through more than 150,000 service stations in the country. Thousands of other outlets, such as garages and auto repair shops, also sell gasoline and lubricants. Large volumes of these and other products are sold directly to trucking fleets, airline companies, bus lines, federal, state, and municipal governments, public utilities, steamship companies, and other large users.
The structure of the natural gas industry is similar to that of the petroleum industry up to a point. Scientists discover the natural gas reserves, and wells are constructed and operated. However, today, since the industry was deregulated in the 1980s and 1990s, wholesale gas marketers often drive the sale and flow of natural gas to transportation companies and end users. Marketers may sell their own natural gas, or perform this service as brokers. When natural gas is sold to end users it is typically used by utility companies or other distributors for use in homes and businesses for heat and cooking. It is also becoming more widely used at power plants for generating electricity. Another use of natural gas that is gaining in popularity is as an alternative transportation fuel in vehicles. For example, many city transportation companies have begun to use buses that run on compressed natural gas, or CNG. Companies are choosing to use these buses because they are becoming less costly to operate than those running on diesel fuel, and they are less harmful to the environment. Today many cities have transit bus fleets that run on compressed natural gas, and according to the American Public Transit Association, many diesel buses have been replaced by natural gas and diesel hybrid drivetrains.