A
borehole is the generalized term for any narrow
shaftShaft mining or shaft sinking refers to the method of excavating a vertical or near-vertical tunnel from the top down, where there is initially no access to the bottom....
boredBoring is drilling a hole, tunnel, or well in the earth.-Earth boring:Boring is used for a wide variety of applications in geology, agriculture, hydrology, civil engineering, and oil and natural gas industries...
in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water or other liquid (such as
petroleumPetroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...
) or gases (such as
natural gasNatural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
), as part of a
geotechnical investigationGeotechnical investigations are performed by geotechnical engineers or engineering geologists to obtain information on the physical properties of soil and rock around a site to design earthworks and foundations for proposed structures and for repair of distress to earthworks and structures caused...
, environmental site assessment,
mineral explorationMineral exploration is the process of finding ore to mine. Mineral exploration is a much more intensive, organized and professional form of mineral prospecting and, though it frequently uses the services of prospecting, the process of mineral exploration on the whole is much more involved.-Stages...
, temperature measurement or as a pilot hole for installing piers or underground utilities.
EngineerEngineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
s and
environmental consultantEnvironmental consulting is often a form of compliance consulting, in which the consultant ensures that the client maintains an appropriate measure of compliance with environmental regulations...
s use the term to collectively describe all of the various types of holes drilled as part of a
geotechnical investigationGeotechnical investigations are performed by geotechnical engineers or engineering geologists to obtain information on the physical properties of soil and rock around a site to design earthworks and foundations for proposed structures and for repair of distress to earthworks and structures caused...
or environmental site assessment (a so-called Phase II ESA). This includes holes advanced to collect soil samples, water samples or rock cores, to advance
in situIn situ is a Latin phrase which translated literally as 'In position'. It is used in many different contexts.-Aerospace:In the aerospace industry, equipment on board aircraft must be tested in situ, or in place, to confirm everything functions properly as a system. Individually, each piece may...
sampling equipment, or to install monitoring wells or
piezometerA piezometer is either a device used to measure static liquid pressure in a system by measuring the height to which a column of the liquid rises against gravity, or a device which measures the pressure of groundwater at a specific point...
s. Samples collected from boreholes are often tested in a laboratory to determine their physical properties, or to assess levels of various chemical constituents or contaminants.
Typically, a borehole used as a
water wellA water well is an excavation or structure created in the ground by digging, driving, boring or drilling to access groundwater in underground aquifers. The well water is drawn by an electric submersible pump, a trash pump, a vertical turbine pump, a handpump or a mechanical pump...
is completed by installing a vertical pipe (casing) and well screen to keep the borehole from caving. This also helps prevent surface contaminants from entering the borehole and protects any installed pump from drawing in sand and sediment.
Oil and natural gas wellsAn oil well is a general term for any boring through the earth's surface that is designed to find and acquire petroleum oil hydrocarbons. Usually some natural gas is produced along with the oil. A well that is designed to produce mainly or only gas may be termed a gas well.-History:The earliest...
are completed in a similar, albeit usually more complex, manner.
The world’s deepest borehole is the
Odoptu OP-11 wellThe Kola Superdeep Borehole is the result of a scientific drilling project of the Soviet Union in Kola Peninsula. The project attempted to drill as deep as possible into the Earth's crust. Drilling began on 24 May 1970 using the Uralmash-4E, and later the Uralmash-15000 series drilling rig. A...
on
SakhalinSakhalin or Saghalien, is a large island in the North Pacific, lying between 45°50' and 54°24' N.It is part of Russia, and is Russia's largest island, and is administered as part of Sakhalin Oblast...
which reached a measured total depth of 12345 m (40,502 ft) and a horizontal displacement of 11475 m (37,647.6 ft).
Exxon Neftegas LimitedExxon Neftegas Limited is a subsidiary of ExxonMobil, an American oil and gas corporation. ENL is the operator of Sakhalin-I Consortium which is involved in exploration and production of oil and gas on Sakhalin Island and offshore, in Chayvo, Odoptu and Arkutun-Dagi fields located in the Sea of...
completed the well in 60 days.
As detailed in proxy (climate), borehole temperature measurements at a series of different depths can be effectively "
inverted" (a mathematical formula to solve a matrix equation) to help estimate historic surface temperatures.
Methodolgy
Drillers may sink a borehole using a
drilling rigA drilling rig is a machine which creates holes or shafts in the ground. 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...
or a hand-operated
rigRig may refer to:* Rig, Something that a dog pulls when Mushing* Rig, a slang term referring to a tractor unit* Drilling rig, a structure housing equipment used to drill or extract oil from underground* Gaming rig, a PC built for high-performance gaming...
. The machinery and techniques to advance a borehole vary considerably according to manufacturer, geological conditions, and the intended purpose.
See also
- Deep borehole disposal
Deep borehole disposal is the concept of disposing of high-level radioactive waste from nuclear reactors in extremely deep boreholes. Deep borehole disposal seeks to place the waste as much as five kilometers beneath the surface of the Earth and relies primarily on the thickness of the natural...
- Drilling rig
A drilling rig is a machine which creates holes or shafts in the ground. 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...
- Hole opener
A hole opener is a device used to enlarge the borehole during a well drilling operation.It can be positioned either above the drill bit or above a pilot run inside the existing borehole....
- Vertical seismic profile
In geophysics, Vertical Seismic Profile is a technique of seismic measurements used for correlation with surface seismic data. The defining characteristic of a VSP is that either the energy source, or the detectors are in a borehole...
External links