When talking about oil and gas, we must say that they range as sources of energy for domestic and industrial purposes, used as fuel, containing mainly combustible gaseous mixture. The amount of gas brought to the surface with the oil during drilling procedures generally labels as casing-head gas. However, there are certain wells in which we can find only natural gas.

One of the reasons for which the oil and gas are so popular worldwide is their composition. They contain valuable organic elements that are important raw materials of the oil and chemical industries. Before the actual usage, natural gas passes through a number of chemical processes in which heavy hydrocarbons result extracted as liquids.

In the past, natural gas recovered from the oil extraction could not make the object of trade at a good price. This is why people simply burned it at the oil field (a process called flaring). This wasteful practice has not met banning rules in many countries, particularly since scientists have discovered that it brings its contribution in warming up the atmosphere through the greenhouse effect.

In addition, the companies now recognize that value for the gas may increase with liquefied natural gas, compressed natural gas or other transportation methods to end-users in the future. The gas now undergoes a process of re-injection into the soil, for later recovery. This also helps oil production by keeping underground pressures higher. In Saudi Arabia, during the late 1970s, a "Master Gas System" emerged, bringing the flaring to an end. The natural gas is useful for generating electricity and caloric power for desalinization. At the same time, some landfills that also discharge methane gases have developed to stock the methane and produce electricity.

The usual places in which natural gas stores are subterranean caverns formed inside old gas reservoirs from previous gas wells, salt domes, or in tanks as liquefied natural gas. The primary utilization of gas is energy production, generated with gas and steam turbines. The general estimation is that the natural supply of gas will last until approximately the year 2030, 20 years after the peak of oil. Supplementary estimation concerns a world's supply of natural that should be finished around the year 2085.

Due to its wide range of utilizations, because of the location, and of the companies that use natural gas, its price can vary worldwide. An example is the price per 1000 cubic feet in the United States of America estimated somewhere around the value of $10. Such variations have also led to a financial crisis in North America in the past few years, because of the continuous increase of their price.

Another way of looking at this very powerful industry is that of publicity. Particularly during the past few years, the oil and gas industries have had an increasingly higher publicity. That is because specific companies have benefited from funding for development purposes. The transport, storage and use of oil and gas, which are highly flammable and destroying substances, oblige the companies to have special equipment and of course of qualified personnel only to handle them. Small accidents such as explosions do occur annually, but their number is decreasing year by year, as people are constantly developing specific measures to prevent such accidents.

However, when referring to oil and gas we must say that they are not renewable sources of energy. That is why, no matter how much it helps us improve our lives by giving us forms of electric, mechanical and caloric energy, we will eventually have to find ways to replace them.

Natural gas is one of the most useful sources of energy for our society. Nowadays, oil and gas provide us with the basic means for conducting our daily activities.