A fossil fuel, it is formed when large quantities of dead organisms, usually zooplankton and algae, are buried underneath sedimentary rock and undergo intense heat and pressure. Petroleum is recovered mostly through oil drilling. This latter stage comes after the studies of structural geology (at the reservoir scale), sedimentary basin analysis, reservoir characterization (mainly in terms of porosity and permeable structures). It is refined and separated, most easily by boiling point, into a large number of consumer products, from petrol and kerosene to asphalt and chemical reagents used to make plastics and pharmaceuticals. Petroleum is used in manufacturing a wide variety of materials, and it is estimated that the world consumes about 88 million barrels each day.

Natural gas is a fossil fuel used as a source of energy for heating, cooking, and electricity generation. It is also used as a fuel for vehicles and as a chemical feedstock in the manufacture of plastics and other commercially important organic chemicals. Fossil fuel based natural gas is a non-renewable resource. Natural gas is an extremely valued resource in our society and it is believed by many to be the most important energy source for the future. It is not surprising, then, that the natural gas industry generates a great deal of commerce worldwide. The abundance of natural gas coupled with its environmental soundness and multiple applications across all sectors, means that natural gas will continue to play an increasingly important role in meeting demand for energy. It is important to note that there is a steady climb in demand for natural gas which could increase as climate change legislation grows demand for low-carbon fuels such as clean natural gas. Demand for natural gas has traditionally been highly cyclical. Demand for natural gas depends highly on the time of year, and changes from season to season. In the past, the cyclical nature of natural gas demand has been relatively straightforward: demand was highest during the coldest months of winter and lowest during the warmest months of summer. The main driver for this primary cycle of natural gas demand is the need for residential and commercial heating. The relatively recent shift towards use of natural gas for the generation of electricity has resulted in an anomaly in this traditional cyclical behaviour. While requirements for natural gas heating decrease during the summer months, demand for space cooling increases during this warmer season.