Iran is an energy superpower and the Petroleum industry in Iran plays an important part in it. In 2004 Iran produced 5.1 percent of the world’s total crude oil (3.9 million barrels (620,000 m3) per day), which generated revenues of US$25 billion to US$30 billion and was the country’s primary source of foreign currency. At 2006 levels of production, oil proceeds represented about 18.7 percent of gross domestic product (GDP). However, the importance of the hydrocarbon sector to Iran’s economy has been far greater. The oil and gas industry has been the engine of economic growth, directly affecting public development projects, the government’s annual budget, and most foreign exchange sources. In FY 2009, for example, the sector accounted for 60 percent of total government revenues and 80 percent of the total annual value of both exports and foreign currency earnings. Oil and gas revenues are affected by the value of crude oil on the international market. It has been estimated that at the Organization of the Petroleum Exporting Countries (OPEC) quota level (December 2004), a one-dollar change in the price of crude oil on the international market would alter Iran’s oil revenues by US$1 billion. In 2010, Iran, which exports around 2.6 million barrels of crude oil a day, was the second-largest exporter among the Organization of Petroleum Exporting Countries. In the same year, officials in Iran estimate that Iran's annual oil and gas revenues could reach $250 billion by 2015. According to IHS CERA estimate, oil revenue of Iran will increase by a third to USD 100 billion in 2011 even though the country is under an extended period of U.S. sanctions. Iran plans to invest a total of $500 billion in the oil sector before 2025

In addition to the natural gas associated with oil exploration and extraction, an estimated 62 percent of Iran’s 32.3 trillion cubic meters of proven natural gas reserves in 2006 were located in independent natural gas fields, an amount second only to those of Russia. In 2006 annual production reached 105 billion cubic meters, with fastest growth occurring over the previous 15 years. In 2006 natural gas accounted for about 50 percent of domestic energy consumption, in part because domestic gas prices were heavily subsidized. Natural gas production will reach 700 million cubic meter/day by 2012 and 900 million cubic meter/day by 2015. Since 1979, infrastructure investment by Iranian and foreign oil firms has increased pipeline capacity to support the Iranian gas industry. Between 1979 and 2003, pipelines to transport natural gas to refineries and to domestic consumers increased from 2,000 kilometers to 12,000 kilometers. In the same period, natural gas distribution pipelines increased from 2,000 kilometers to 45,000 kilometers in response to growing domestic consumption. Gas processing plants are located at Ahvaz, Dalan, Kangan, and Marun, in a corridor along the northern Persian Gulf close to the major gas fields. South Pars, Iran’s largest natural gas field, has received substantial foreign investment. With its output intended for both export and domestic consumption, South Pars is expected to reach full production in 2015. The output of South Pars is the basis of the Pars Special Economic Energy Zone, a complex of petrochemical and natural gas processing plants and port facilities established in 1998 on the Persian Gulf south of Kangan. Iran is able to produce all the parts needed for its gas refineries. Iran is now the third country in the world to have developed Gas to liquids (GTL) technology. In the 1980s, Iran began to replace oil, coal, charcoal, and other fossil-fuel energy sources with natural gas, which is environmentally safer. The share of natural gas in household energy consumption, which averaged 54 percent in 2004, was projected to increase to 69 percent by 2009. Overall, natural gas consumption in Iran was expected to grow by more than 10 percent per annum between 2005 and 2009. With international oil prices increasing and projected to continue increasing, international demand for natural gas and investment in production and transportation of natural gas to consumer markets both increased in the early 2000s. Iran set a goal of increasing its natural gas production capacity to 300 billion cubic meters by 2015 while keeping oil production stable. To achieve this capacity, the government has planned a joint investment worth US$100 billion in the oil and gas industry through 2015. Market value of Iran's total natural gas reserves at comparative international energy price of $75 per barrel of oil stands at ~US $4 trillion. Following the discovery of a large gas deposit in the Caspian sea in 2011, Iran could rank first in the world in terms of gas reserves. The Sardar Jangal field holds at least 50 trillion cubic feet (some 1.4 trillion cubic meters) of gas reserves.[38] In addition, Iranian media have reported in 2012 the discovery of gas field "as big as South Pars gas field".

Shielded metal arc welding (SMAW), also known as manual metal arc welding (MMA or MMAW), flux shielded arc welding or informally as stick welding, is a manual arc welding process that uses a consumable electrode coated in flux to lay the weld. An electric current, in the form of either alternating current or direct current from a welding power supply, is used to form an electric arc between the electrode and the metals to be joined. As the weld is laid, the flux coating of the electrode disintegrates, giving off vapors that serve as a shielding gas and providing a layer of slag, both of which protect the weld area from atmospheric contamination. Because of the versatility of the process and the simplicity of its equipment and operation, shielded metal arc welding is one of the world's most popular welding processes. It dominates other welding processes in the maintenance and repair industry, and though flux-cored arc welding is growing in popularity, SMAW continues to be used extensively in the construction of steel structures and in industrial fabrication. The process is used primarily to weld iron and steels (including stainless steel) but aluminium, nickel and copper alloys can also be welded with this method. Though SMAW is almost exclusively a manual arc welding process, one notable process variation exists, known as gravity welding or gravity arc welding. It serves as an automated version of the traditional shielded metal arc welding process, employing an electrode holder attached to an inclined bar along the length of the weld. Once started, the process continues until the electrode is spent, allowing the operator to manage multiple gravity welding systems. The electrodes employed (often E6027 or E7024) are coated heavily in flux, and are typically 28 in (0.8 m) in length and about 0.25 in (6 mm) thick. As in manual SMAW, a constant current welding power supply is used, with either negative polarity direct current or alternating current. Due to a rise in the use of semiautomatic welding processes such as flux-cored arc welding, the popularity of gravity welding has fallen as its economic advantage over such methods is often minimal. Other SMAW-related methods that are even less frequently used include firecracker welding, an automatic method for making butt and fillet welds, and massive electrode welding, a process for welding large components or structures that can deposit up to 60 lb (27 kg) of weld metal per hour.

Offshore drilling refers to a mechanical process where a wellbore is drilled through the seabed. It is typically carried out in order to explore for and subsequently extract petroleum which lies in rock formations beneath the seabed. Most commonly, the term is used to describe drilling activities on the continental shelf, though the term can also be applied to drilling in lakes, inshore waters and inland seas. Offshore drilling presents environmental challenges, both from the produced hydrocarbons and the materials used during the drilling operation. Controversies include the ongoing US offshore drilling debate. There are many different types of facilities from which offshore drilling operations take place. These include bottom founded drilling rigs (jackup barges and swamp barges), combined drilling and production facilities either bottom founded or floating platforms, and deepwater mobile offshore drilling units (MODU) including semi-submersibles and drillships. These are capable of operating in water depths up to 10,000 ft. In shallower waters the mobile units are anchored to the seabed, however in deeper water (>5,000 ft) the semisubmersibles or drillships are maintained at the required drilling location using dynamic positioning. Offshore oil production involves environmental risks, most notably oil spills from oil tankers or pipelines transporting oil from the platform to onshore facilities, and from leaks and accidents on the platform. Produced water is also generated, which is excess water from oil or gas production and includes varying amounts of oil, or other chemicals used in, or resulting from, oil production. According to the organization Culture Change, a Gulf of Mexico rig dumps about 90,000 tons of drilling fluid and cuttings over its lifetime, with its wells also contributing with heavy metals.