Petroleum is the most widely used form of mobile energy and now supplies approximately three-fourths of the total energy used in the United States. It is also a major raw material from which a wide variety of products are manufactured. Petroleum is found in porous rock formations in the upper strata of some areas of the Earth's crust.

It consists of a complex mixture of hydrocarbons, mostly alkanes, but may vary greatly in appearance and composition. Petroleum Journals Online (PJO) publishes the first fully refereed e-journals of petroleum engineering. This initiative is designed to make it possible for petroleum engineers to rapidly publish peer-reviewed articles online while retaining their copyright.

Petroleum contains gaseous, liquid, and solid elements. The consistency of petroleum varies from liquid as thin as gasoline to liquid so thick that it will barely pour. Petroleum products are used to produce synthetic fibers such as nylon, orlon, and dacron, and other polymers such as polystyrene, polyethylene and synthetic rubber.

They also serve as raw materials in the production of refrigerants, aerosols, antifreeze, detergents, dyes, adhesives, alcohols, explosives, weed killers, insecticides, and insect repellents. Petroleum engineers develop extensive knowledge about the world of oil production, and many become industry analysts. A number use their economics skills?all oil production is a cost-benefit analysis'to enter companies as in-house economists.

Petroleum licences the Petroleum (Consolidation) Act 1928 (as amended by DSEAR) requires that anyone operating a petrol filling station should have a licence issued by their local Petroleum Licensing Authority.

The licence is renewed at regular intervals, currently annually. Petroleum engineers are the scientists behind the oil industry. They're the ones who help determine where those big oil rigs should go, and where we should and should not drill for more of that black gold, Texas tea.

Oil and natural gas still underpin almost all aspects of modern society. Transport is almost solely reliant on oil.

State well regulations require that petroleum storage tanks be at least 100 feet from a water well. Minimum separation distances regulate only new well installation. Statewide oil production has declined to levels not seen since 1943. In 2005, the total receipts to refineries of roughly 674 million barrels came from in-state oil production (39.4%), combined with oil from Alaska (20.1%), and foreign sources (40.4%).

Petroleum engineeris design and operate wells and well systems to produce crude oil and natural gas resources fromthe earth. Responsiblities fo the engineeer include the design, construction, operation, and management of drilling, production, and field processing systems to economically recover and utilize the world's principle source of fuels and chemical feed-stocks.

Petroleum provides the energy necessary for the transportation of people and goods. California is the third largest manufacturer of petroleum products, SIC 2911, with value of shipments just under $26 billion dollars.

Petroleum engineers must implement high technology plans with the use of manpower, highly coordinated and often in dangerous conditions. The drilling rig crew and machines they use become the remote partner of the petroleum engineer in implementing every drilling program.