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A Pumpjack pumping oil from an oil well in Texas.
A Pumpjack pumping oil from an oil well in Texas. “Nodding donkey” redirects here For the train see British Rail "Pacer". Texas ( is a state geographically located in the South Central United States and is also known as the Lone Star State.

An oil well is a term for any perforation through the Earth's surface designed to find and release both petroleum oil and gas hydrocarbons. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Petroleum ( L petroleum, from Greek πετρέλαιον, lit Petroleum ( L petroleum, from Greek πετρέλαιον, lit This page is about the physical properties of gas as a state of matter In Organic chemistry, a hydrocarbon is an Organic compound consisting entirely of Hydrogen and Carbon.

Contents

History

An oil well consists of pipe cemented into a drilled hole through which hydrocarbons can be produced.

Some sources claim that from the 9th century, oil fields were exploited in the area around modern Baku, Azerbaijan, to produce naphtha for the petroleum industry. An oil field is a region with an abundance of Oil wells extracting Petroleum (crude oil from below ground Baku (Bakı sometimes known as Baqy, Baky, Baki or Bakü, is the capital the largest city and the largest port of Azerbaijan Azerbaijan ( English; Azərbaycan officially the Republic of Azerbaijan (Azərbaycan Respublikası is the largest and most populous country in the South Naphtha normally refers to a number of different flammable liquid mixtures of hydrocarbons i The petroleum industry includes the global processes of exploration, extraction, refining, transporting (often by Oil tankers and pipelines These fields were described by Marco Polo in the 13th century, who described the output of those oil wells as hundreds of shiploads. Marco Polo ( September 15 1254 – January 9 1324 at earliest but no later than June 1325 was a Venetian trader and explorer When Marco Polo in 1264 visited the Azerbaijani city of Baku, on the shores of the Caspian Sea, he saw oil being collected from seeps. He wrote that "on the confines toward Geirgine there is a fountain from which oil springs in great abundance, inasmuch as a hundred shiploads might be taken from it at one time. "

Shallow pits were dug at the Baku seeps in ancient times to facilitate collecting oil, and hand-dug holes up to 35 meters (115 feet) deep were in use by 1594. These holes were essentially oil wells. Apparently 116 of these wells in 1830 produced 3,840 metric tons (about 28000 barrels) of oil. In 1849, Russian engineer F. N. Semyenov used a cable tool to drill an oil well on the Apsheron Peninsula, ten years before Colonel Drake's famous well in Pennsylvania. Also, offshore drilling started up at Baku at Bibi-Eibat field near the end of the 19th century, about the same time that the "first" offshore oil well was drilled in 1896 at Summerland field on the California Coast.

1904 oil well fire at Bibi-Eibat.
1904 oil well fire at Bibi-Eibat. Oil well fires are Oil gushers that have caught on Fire, and burn uncontrollably

The earliest oil wells were drilled percussively by hammering a cable tool into the earth. For a detailed diagram of a Petroleum drilling rig, See Drilling rig (petroleum A drilling rig is a machine which creates holes (usually called Soon after, cable tools were replaced with rotary drilling, which could drill boreholes to much greater depths and in less time. The record-depth Kola Borehole used non-rotary mud motor drilling to achieve a depth of over 12 000 meters (38,000 feet). The Kola Superdeep Borehole (Кольская сверхглубокая скважина was the result of a Scientific drilling project of the former USSR. Until the 1970s, most oil wells were vertical (although different lithology and mechanical imperfections cause most wells to deviate at least slightly from true vertical). This article is about the Decade 1970-1979 For the Year 1970 see 1970. In Geology, petrology (from Greek πέτρα petra, rock and λόγος logos, knowledge is the study of rocks and the conditions on which However, modern directional drilling technologies allow for strongly deviated wells which can, given sufficient depth and with the proper tools, actually become horizontal. Directional drilling (or slant drilling) is the practice of drilling non-vertical wells It can be broken down into three main groups Oilfield Directional This is of great value as the reservoir rocks which contain hydrocarbons are usually horizontal, or sub-horizontal; a horizontal wellbore placed in a production zone has more surface area in the production zone than a vertical well, resulting in a higher production rate. Petroleum geology refers to the specific set of geological disciplines that are applied to the search for Hydrocarbons ( Oil exploration) The use of deviated and horizontal drilling has also made it possible to reach reservoirs several kilometers or miles away from the drilling location (extended reach drilling), allowing for the production of hydrocarbons located below locations that are either difficult to place a drilling rig on, environmentally sensitive, or populated.

Life of a well

The creation and life of a well can be divided up into five segments:

Drilling

The well is created by drilling a hole 5 to 30 inches (13 – 76 cm) diameter into the earth with an oil platform which rotates a drill bit. Inches redirects here To see the Les Savy Fav album see Inches. An oil platform or oil rig is a large structure used to house workers and machinery needed to drill and/or extract oil and Natural gas through wells Well drilling is the Process of drilling a hole in the ground for the extraction of a natural resource such as Ground water, Natural gas, or Petroleum After the hole is drilled, a steel pipe (casing) slightly smaller than the hole is placed in the hole, and secured with cement. Casing is large diameter pipe that is assembled and inserted into a recently drilled section of a Borehole and typically cemented into place In the most general sense of the word a cement is a binder a substance which sets and hardens independently and can bind other materials together The casing provides structural integrity to the newly drilled wellbore in addition to isolating potentially dangerous high pressure zones from each other and from the surface.

With these zones safely isolated and the formation protected by the casing, the well can be drilled deeper (into potentially more-unstable and violent formations) with a smaller bit, and also cased with a smaller size casing. Modern wells often have 2-5 sets of subsequently smaller hole sizes drilled inside one another, each cemented with casing.

To drill the well,

This process is all facilitated by a drilling rig which contains all necessary equipment to circulate the drilling fluid, hoist and turn the pipe, control downhole pressures, remove cuttings from the drilling fluid, and generate onsite power for these operations. For a detailed diagram of a Petroleum drilling rig, See Drilling rig (petroleum A drilling rig is a machine which creates holes (usually called

Completion

Main article: Completion (oil and gas wells)

After drilling and casing the well, it must be 'completed'. In petroleum production completion is the process of making a well ready for production (or injection Completion is the process in which the well is enabled to produce oil or gas. Petroleum ( L petroleum, from Greek πετρέλαιον, lit This page is about the physical properties of gas as a state of matter

In a cased-hole completion, small holes called perforations are made in the portion of the casing which passed through the production zone, to provide a path for the oil to flow from the surrounding rock into the production tubing. A perforation in the context of Oil wells refers to a hole punched in the casing or liner of an Oil well to connect it to the reservoir Casing is large diameter pipe that is assembled and inserted into a recently drilled section of a Borehole and typically cemented into place In open hole completion, often 'sand screens' or a 'gravel pack' is installed in the last drilled, uncased reservoir section. These maintain structural integrity of the wellbore in the absence of casing, while still allowing flow from the reservoir into the wellbore. Screens also control the migration of formation sands into production tubulars and surface equipment, which can cause washouts and other problems, particularly from unconsolidated sand formations in offshore fields.

After a flow path is made, acids and fracturing fluids are pumped into the well to fracture, clean, or otherwise prepare and stimulate the reservoir rock to optimally produce hydrocarbons into the wellbore. Hydraulic fracturing is a method used to create fractures that extend from a Borehole into Rock formations which are typically maintained by a proppant Finally, the area above the reservoir section of the well is packed off inside the casing, and connected to the surface via a smaller diameter pipe called tubing. This arrangement provides a redundant barrier to leaks of hydrocarbons as well as allowing damaged sections to be replaced. Also, the smaller diameter of the tubing produces hydrocarbons at an increased velocity in order to overcome the hydrostatic effects of heavy fluids such as water.

In many wells, the natural pressure of the subsurface reservoir is high enough for the oil or gas to flow to the surface. However, this is not always the case, especially in depleted fields where the pressures have been lowered by other producing wells, or in low permeability oil reservoirs. Installing a smaller diameter tubing may be enough to help the production, but artificial lift methods may also be needed. Common solutions include downhole pumps, gas lift, or surface pump jacks. “Nodding donkey” redirects here For the train see British Rail "Pacer". The use of artificial lift technology in a field is often termed as "secondary recovery" in the industry. The extraction of petroleum is the process by which usable Petroleum is extracted and removed from the earth Many new systems in the last ten years have been introduced for well completion. Multiple packer systems with frac ports or port collars in an all in one system have cut completion costs and improved production, especially in the case of horizontal wells. A production packer is a standard component of the completion hardware of oil or gas wells used to provide a seal between the outside of the Production tubing and These new systems allow casings to run into the lateral zone with proper packer/frac port placement for optimal hydrocarbon recovery.

Production

The production stage is the most important stage of a well's life, when the oil and gas are produced. By this time, the oil rigs and workover rigs used to drill and complete the well have moved off the wellbore, and the top is usually outfitted with a collection of valves called a wellhead. These valves regulate pressures, control flows, and allow access to the wellbore in case further completion work is needed. From the outlet valve of the wellhead, the flow can be connected to a distribution network of pipelines and tanks to supply the product to refineries, natural gas compressor stations, or oil export terminals.

As long as the pressure in the reservoir remains high enough, the wellhead is all that is required to produce the well. If the pressure depletes and it is considered economically viable, an artificial lift method mentioned in the completions section can be employed.

Workovers are often necessary in older wells, which may need smaller diameter tubing, scale or paraffin removal, acid matrix jobs, or completing new zones of interest in a shallower reservoir. The term workover is used to refer to any kind of Oil well intervention involving invasive techniques such as Wireline, Coiled tubing or Such remedial work can be performed using workover rigs – also known as pulling units to pull and replace tubing, or by the use of a well intervention technique called coiled tubing. A well intervention, or 'well work' is any operation carried out on a oil or gas well during, or at the end of its productive life that alters the state of the well and or Coiled tubing refers to metal piping normally 1" to 2" in diameter used for interventions in oil and gas wells and as production tubing in shallow gas

Enhanced recovery methods such as waterflooding, steam flooding, or CO2 flooding may be used to increase reservoir pressure and provide a "sweep" effect to push hydrocarbons out of the reservoir. Such methods require the use of injection wells (often chosen from old production wells in a carefully determined pattern), and are used when facing problems with reservoir pressure depletion, high oil viscosity, or can even be employed early in a field's life. In certain cases – depending on the reservoir's geomechanics – reservoir engineers may determine that ultimate recoverable oil may be increased by applying a waterflooding strategy early in the field's development rather than later. Such enhanced recovery techniques are often called "tertiary recovery". The extraction of petroleum is the process by which usable Petroleum is extracted and removed from the earth

Abandonment

When the well no longer produces or produces so poorly that it is a liability, it is abandoned. In this process, tubing is removed from the well and sections of well bore are filled with cement to isolate the flow path between gas and water zones from each other, as well as the surface. Completely filling the well bore with cement is costly and unnecessary. The surface around the wellhead is then excavated, and the wellhead and casing are cut off, a cap is welded in place and then buried.

The production from an oil well declines in production. The point at which the well no longer makes a profit and is plugged and abandoned is called the “economic limit. ”

The equation to determine the economic limit contains four factors, namely: (1) taxes, (2) operating cost, (3) oil price, and (4) royalty. When oil taxes are raised, the economic limit is raised. When oil price is increased, the economic limit is lowered.

When the economic limit is raised, the life of the well is decreased. Proven oil reserves are lost when the life of an oil well is decreased. 

       Inversely, when the economic limit is lowered, the life of the well is increased.   Proven oil reserves are increased when the life of the well is increased.

Types of wells

Oil wells come in many varieties. By produced fluid, there can be wells that produce oil, wells that produce oil and natural gas, or wells that only produce natural gas. Natural gas is almost always a byproduct of producing oil, since the small, light gas carbon chains come out of solution as it undergoes pressure reduction from the reservoir to the surface, similar to uncapping a bottle of soda pop where the carbon dioxide effervesces. A petroleum reservoir or an oil and gas reservoir (or system) is a subsurface pool of Hydrocarbons contained in porous Unwanted natural gas can be a disposal problem at the well site. If there is not a market for natural gas near the wellhead it is virtually valueless since it must be piped to the end user. A wellhead is piece of equipment that exists atop (the exposed area above ground of a well Until recently, such unwanted gas was burned off at the wellsite, but due to environmental concerns this practice is becoming less common. Often, unwanted (or 'stranded' gas without a market) gas is pumped back into the reservoir with an 'injection' well for disposal or repressurizing the producing formation. Another solution is to export the natural gas as a liquid. Not to be confused with Natural Gas Liquids (NGL Liquefied natural gas or LNG is Natural gas (primarily Methane, CH4 [1]Gas-to-liquid, (GTL) is a developing technology that converts stranded natural gas into synthetic gasoline, diesel or jet fuel through the Fischer-Tropsche process developed in Word War II Germany. Such fuels can be transported through conventional pipelines and tankers to users. Proponents claim GTL fuels burn cleaner than comparable petroleum fuels. Most major international oil companies are in advanced development stages of GTL production, with a world-scale (140,000 bbl/day) GTL plant in Qatar scheduled to come online before 2010. In locations such as the United States with a high natural gas demand, pipelines are constructed to take the gas from the wellsite to the end consumer. Consumers refers to individuals or households that use goods and services generated within the economy.

Another obvious way to classify oil wells is by land or offshore wells. There is very little difference in the well itself. An offshore well targets a reservoir that happens to be underneath an ocean. Due to logistics, drilling an offshore well is far more costly than an onshore well. By far the most common type is the onshore well. These wells dot the Southern and Central Great Plains, Southwestern United States, and are the most common well in the Middle East.

Another way to classify oil wells is by their purpose in contributing to the development of a resource. They can be characterized as:

At a producing well site, active wells may be further categorised as:

Lahee classification [2]

Cost

The following is a quick comparison of average well costs for the UK Continental Shelf (UKCS). The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located The continental shelf is the extended perimeter of each Continent and associated Coastal plain, which is covered during interglacial periods such These costs exclude testing (e. g. , flow rate testing), and are based on values from March 1998. Year 1998 ( MCMXCVIII) was a Common year starting on Thursday (link will display full 1998 Gregorian calendar) Prices have doubled since then:

Typical well costs for UKCS wells in 1998
Well location Typical cost (in millions of £)
Northern North Sea 8 – 12
West of Shetland 5 – 15
Southern North Sea 7 – 12
Irish Sea 2 – 3

The cost of an offshore well depends strongly on the remoteness of the location being drilled. The Pound Sterling ( symbol £; ISO code: GBP) subdivided into 100 pence (singular penny) is the Currency The North Sea is a marginal, Epeiric sea of the Atlantic Ocean on the European Continental shelf. Shetland (formerly spelled Zetland, from etland; Old Norse non Hjaltland; Sealtainn is an Archipelago off the northeast coast of The Irish Sea ( Irish: Muir Éireann or Muir Meann; Scottish Gaelic: Muir Eireann Welsh: Môr Iwerddon, Hence the Irish Sea (shallow water, close to the coast) is cheap in comparison to the West of Shetland (deep water, far from the coast and other facilities). The 2006 cost of a Central North Sea high pressure, high temperature well is about $35-50 million. Deep water wells in the Gulf of Mexico can cost over $100 million.

Onshore wells can be considerably cheaper, particularly if the field is at a shallow depth, where costs range from less than $1 million to $15 million for deep and difficult wells.

Reefs

Offshore platforms, the well's supporting structure, produce artificial reefs. An artificial reef is a man-made underwater structure typically built for the purpose of promoting marine life in areas of generally featureless bottom

See also

References

External links

Tags

Expandable tubular technology is a system for increasing the Diameter of the casing or liner of an Oil well by up to 20% after it has been run down-hole In Petroleum exploration and development formation evaluation is used to determine the ability of a borehole to produce Petroleum. In the process of drilling a borehole, geosteering is the act of adjusting the borehole position ( Inclination and Azimuth angles on the fly Logging while drilling (LWD is a technique of measuring Geologic formation properties in real-time while drilling an Oil well. Measurement while drilling is a tool that transmits information in real time from the tool located near the drill bit to the surface A mudlogger, or mud logger in the modern oil field positions hydrocarbons with respect to depth Oil reserves are the estimated quantities of Crude oil that are claimed to be recoverable under existing Economic and operating conditions Well logging, also known as borehole logging is the practice of making a detailed record (a well log) of the Geologic formations penetrated by a borehole Spindletop is a Salt dome Oil field located in south Beaumont, Texas (approx Subsea is a general term frequently used to refer to equipment technology and methods employed to explore drill and develop oil and gas fields that exist below the ocean floors

Dictionary

oil well

-noun

  1. A hole drilled into the earth from which petroleum is pumped
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