Natural gas is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane (95%) in addition to various smaller amounts of other higher alkanes. Traces of carbon dioxide, nitrogen, hydrogen sulfide, and helium are also usually present. Methane is colorless and odorless, and the second largest greenhouse gas contributor to global climate change after carbon dioxide. Because natural gas is odorless, odorizers such as mercaptan are commonly added to it for safety so that leaks can be readily detected.
Petroleum is a naturally occurring yellowish-black liquid mixture. It consists mainly of hydrocarbons, and is found in geological formations. The term petroleum refers both to naturally occurring unprocessed crude oil, as well as to petroleum products that consist of refined crude oil.
Petroleum engineering is a field of engineering concerned with the activities related to the production of hydrocarbons, which can be either crude oil or natural gas. Exploration and production are deemed to fall within the upstream sector of the oil and gas industry. Exploration, by earth scientists, and petroleum engineering are the oil and gas industry's two main subsurface disciplines, which focus on maximizing economic recovery of hydrocarbons from subsurface reservoirs. Petroleum geology and geophysics focus on provision of a static description of the hydrocarbon reservoir rock, while petroleum engineering focuses on estimation of the recoverable volume of this resource using a detailed understanding of the physical behavior of oil, water and gas within porous rock at very high pressure.
Petroleum geology is the study of the origins, occurrence, movement, accumulation, and exploration of hydrocarbon fuels. It refers to the specific set of geological disciplines that are applied to the search for hydrocarbons.
An oil well is a drillhole boring in Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produce only gas may be termed a gas well. Wells are created by drilling down into an oil or gas reserve and if necessary equipped with extraction devices such as pumpjacks. Creating the wells can be an expensive process, costing at least hundreds of thousands of dollars, and costing much more when in difficult-to-access locations, e.g., offshore. The process of modern drilling for wells first started in the 19th century but was made more efficient with advances to oil drilling rigs and technology during the 20th century.
North Sea oil is a mixture of hydrocarbons, comprising liquid petroleum and natural gas, produced from petroleum reservoirs beneath the North Sea.
Gas reinjection is the reinjection of natural gas into an underground reservoir, typically one already containing both natural gas and crude oil, in order to increase the pressure within the reservoir and thus induce the flow of crude oil or else sequester gas that cannot be exported. This is not to be confused with gas lift, where gas is injected into the annulus of the well rather than the reservoir. After the crude has been pumped out, the natural gas is once again recovered. Since many of the wells found around the world contain heavy crude, this process increases their production. The basic difference between light crude and heavy crude is its viscosity and pumpability—the lighter the crude the easier it is to pump. Recovery of hydrocarbons in a well is generally limited to 50% and 75–80%. Recycling of natural gas or other inert gases causes the pressure to rise in the well, thus causing more gas molecules to dissolve in the oil lowering its viscosity and thereby increasing the well's output. Air is not suitable for repressuring wells because it tends to cause deterioration of the oil, thus carbon dioxide or natural gas is used to repressure the well. The term 'gas-reinjection' is also sometimes referred to as repressuring—the term being used only to imply that the pressure inside the well is being increased to aid recovery.
A drilling rig is an integrated system that drills wells, such as oil or water wells, or holes for piling and other construction purposes, into the earth's subsurface. Drilling rigs can be massive structures housing equipment used to drill water wells, oil wells, or natural gas extraction wells, or they can be small enough to be moved manually by one person and such are called augers. Drilling rigs can sample subsurface mineral deposits, test rock, soil and groundwater physical properties, and also can be used to install sub-surface fabrications, such as underground utilities, instrumentation, tunnels or wells. Drilling rigs can be mobile equipment mounted on trucks, tracks or trailers, or more permanent land or marine-based structures. The term "rig" therefore generally refers to the complex equipment that is used to penetrate the surface of the Earth's crust.
Heavy crude oil is highly viscous oil that cannot easily flow from production wells under normal reservoir conditions.
A petroleum reservoir or oil and gas reservoir is a subsurface accumulation of hydrocarbons contained in porous or fractured rock formations. Such reservoirs form when kerogen is created in surrounding rock by the presence of high heat and pressure in the Earth's crust.
Enhanced oil recovery, also called tertiary recovery, is the extraction of crude oil from an oil field that cannot be extracted otherwise. Whereas primary and secondary recovery techniques rely on the pressure differential between the surface and the underground well, enhanced oil recovery functions by altering the physical or chemical properties of the oil itself in order to make it easier to extract. When EOR is used, 30% to 60% or more of a reservoir's oil can be extracted, compared to 20% to 40% using only primary and secondary recovery.
Steam-assisted gravity drainage is an enhanced oil recovery technology for producing heavy crude oil and bitumen. It is an advanced form of steam stimulation in which a pair of horizontal wells are drilled into the oil reservoir, one a few metres above the other. High pressure steam is continuously injected into the upper wellbore to heat the oil and reduce its viscosity, causing the heated oil to drain into the lower wellbore, where it is pumped out. Dr. Roger Butler, engineer at Imperial Oil from 1955 to 1982, invented the steam assisted gravity drainage (SAGD) process in the 1970s. Butler "developed the concept of using horizontal pairs of wells and injected steam to develop certain deposits of bitumen considered too deep for mining". In 1983 Butler became director of technical programs for the Alberta Oil Sands Technology and Research Authority (AOSTRA), a crown corporation created by Alberta Premier Lougheed to promote new technologies for oil sands and heavy crude oil production. AOSTRA quickly supported SAGD as a promising innovation in oil sands extraction technology.
The Shengli Oil Field is the second-largest oil field in China. Located in the delta of the Yellow River, it was discovered in 1961, and oil production began in earnest in 1964. Oil output quickly increased, peaking in 1991 at 33.55 million tons. While output has decreased since then, enhanced oil recovery techniques have maintained oil production at high levels, producing around 650,000 barrels (103,000 m3) per day.
Reservoir engineering is a branch of petroleum engineering that applies scientific principles to the fluid flow through a porous medium during the development and production of oil and gas reservoirs so as to obtain a high economic recovery. The working tools of the reservoir engineer are subsurface geology, applied mathematics, and the basic laws of physics and chemistry governing the behavior of liquid and vapor phases of crude oil, natural gas, and water in reservoir rock. Of particular interest to reservoir engineers is generating accurate reserves estimates for use in financial reporting to the SEC and other regulatory bodies. Other job responsibilities include numerical reservoir modeling, production forecasting, well testing, well drilling and workover planning, economic modeling, and PVT analysis of reservoir fluids. Reservoir engineers also play a central role in field development planning, recommending appropriate and cost-effective reservoir depletion schemes such as waterflooding or gas injection to maximize hydrocarbon recovery. Due to legislative changes in many hydrocarbon-producing countries, they are also involved in the design and implementation of carbon sequestration projects in order to minimise the emission of greenhouse gases.
Carbon dioxide (CO2) flooding is a process in which carbon dioxide is injected into an oil reservoir to increase the output when extracting oil. This is most often used in reservoirs where production rates have declined due to depletion.
Steam injection is an increasingly common method of extracting heavy crude oil. Used commercially since the 1960s, it is considered an enhanced oil recovery (EOR) method and is the main type of thermal stimulation of oil reservoirs. There are several different forms of the technology, with the two main ones being Cyclic Steam Stimulation and Steam Flooding. Both are most commonly applied to oil reservoirs, which are relatively shallow and which contain crude oils which are very viscous at the temperature of the native underground formation. Steam injection is widely used in the San Joaquin Valley of California (US), the Lake Maracaibo area of Venezuela, and the oil sands of northern Alberta, Canada.
B3 is a major oil and gas field in the Baltic Sea. The field is located 80 km north of the Polish coastal town Rozewie. The crude oil is also referred to as Rozewie crude. Processing, drilling and accommodation is based on the jack up rig Baltic Beta located in the field. Most of the oil is shipped by tanker to the Gdańsk refinery as a part of the refinery feedstock. The associated gas is transmitted by pipeline to the combined heat and power (CHP) plant in Wladyslawowo.
Heavy oil production is a developing technology for extracting heavy oil in industrial quantities. Estimated reserves of heavy oil are over 6 trillion barrels, three times that of conventional oil and gas.
The Weyburn-Midale Carbon Dioxide Project was, as of 2008, the world's largest carbon capture and storage project. It has since been overtaken in terms of carbon capture capacity by projects such as the Shute Creek project and the Century Plant. It is located in Midale, Saskatchewan, Canada.
Unconventional reservoirs, or unconventional resources are accumulations where oil and gas phases are tightly bound to the rock fabric by strong capillary forces, requiring specialized measures for evaluation and extraction.
