Boring (earth)
Encyclopedia
Boring is drilling a hole, tunnel, or well in the earth.
, agriculture
, hydrology
, civil engineering
, and oil
and natural gas
industries. Today, most earth drilling is done in order to do one of the following things:
Unlike drilling in other materials where the aim is to create a hole for some purpose, often the case of drilling or coring is to get an understanding of the ground/lithology. This may be done for prospecting to identify and quantify an ore body for mining, or to determining the type of foundations needed for a building or raised structure, or for underground structures, including tunnels and deep basements where an understanding of the ground is vital to determining how to excavate and the support philosophy. Drilling is also used in vertical and inclined shaft construction.
When drilling in stone, one must pay particular attention to the type of material. There are three different classifications of drill bits used for drilling into stone: soft, medium, and hard. Soft formation rock bits are used in unconsolidated sands, clays, and soft limestones, etc. Medium formation bits are used in dolomites
, limestones, and shale
, while hard formation bits are used in hard shale, mudstones, granite
, limestones and other hard and/or abrasive formations.
Soft ground drilling can be undertaken using a rotary auger or wash boring techniques, while rock drilling often use methods such as NMLC which allow for recovery of a core of material which can be examined to determine the strength, degree of weathering, understanding of any how intact the rock is (RQD) and identify any discontinuities or other planes of weakness.
Testing of the material in borehole
s is also possible. In soft ground standard penetration test
can be used to determine the strength of the material. In rock in-situ stress testing using hydrofracturing or overcoring, Acoustic Televiewer can be used to map discontinuities to determine their orientation. It is also possible once a borehole is complete it is possible to measure the permeability. Samples of water and material are also taken examination and lab testing.
, to sample the Mohorovicic Discontinuity
. The deepest hole ever drilled failed not because of lack of money or time, but because of the physics
of rocks within the crust. The hole achieved approximately 12,000 metres depth, a depth at which rock begins to act more like a plastic
solid than a rigid solid. The rock also approached temperatures of several hundred degrees Celsius
, requiring that the drilling fluid be refrigerated
before being sent to the cutting face of the drill. As the drill bits burnt out and were removed for replacement, the hole simply flowed closed, and the rock had to be re-drilled. Due to the temperature, the drill bits burnt out before achieving any headway. The hole was scrapped.
Further attempts at super-deep drillholes are planned by American
consortia and further Russia
n attempts in Finland
.
and Antarctic Muon And Neutrino Detector Array
projects to drill as deep as 2,450 meters.
Earth boring
Boring is used for a wide variety of applications in geologyGeology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
, agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
, hydrology
Hydrology
Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...
, civil engineering
Civil engineering
Civil engineering is a professional engineering discipline that deals with the design, construction, and maintenance of the physical and naturally built environment, including works like roads, bridges, canals, dams, and buildings...
, and oil
Petroleum
Petroleum 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...
and natural gas
Natural gas
Natural 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...
industries. Today, most earth drilling is done in order to do one of the following things:
- return samples of the rockRock (geology)In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
through which the drill passes - access rocks from which material can be extracted
- access rocks which can then be measured
- provide access to rock for purposes of providing engineering support
Unlike drilling in other materials where the aim is to create a hole for some purpose, often the case of drilling or coring is to get an understanding of the ground/lithology. This may be done for prospecting to identify and quantify an ore body for mining, or to determining the type of foundations needed for a building or raised structure, or for underground structures, including tunnels and deep basements where an understanding of the ground is vital to determining how to excavate and the support philosophy. Drilling is also used in vertical and inclined shaft construction.
When drilling in stone, one must pay particular attention to the type of material. There are three different classifications of drill bits used for drilling into stone: soft, medium, and hard. Soft formation rock bits are used in unconsolidated sands, clays, and soft limestones, etc. Medium formation bits are used in dolomites
Dolomites
The Dolomites are a mountain range located in north-eastern Italy. It is a part of Southern Limestone Alps and extends from the River Adige in the west to the Piave Valley in the east. The northern and southern borders are defined by the Puster Valley and the Sugana Valley...
, limestones, and shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
, while hard formation bits are used in hard shale, mudstones, granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...
, limestones and other hard and/or abrasive formations.
Soft ground drilling can be undertaken using a rotary auger or wash boring techniques, while rock drilling often use methods such as NMLC which allow for recovery of a core of material which can be examined to determine the strength, degree of weathering, understanding of any how intact the rock is (RQD) and identify any discontinuities or other planes of weakness.
Testing of the material in borehole
Borehole
A borehole is the generalized term for any narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water or other liquid or gases , as part of a geotechnical investigation, environmental site...
s is also possible. In soft ground standard penetration test
Standard Penetration Test
The standard penetration test is an in-situ dynamic penetration test designed to provide information on the geotechnical engineering properties of soil...
can be used to determine the strength of the material. In rock in-situ stress testing using hydrofracturing or overcoring, Acoustic Televiewer can be used to map discontinuities to determine their orientation. It is also possible once a borehole is complete it is possible to measure the permeability. Samples of water and material are also taken examination and lab testing.
The Kola Superdeep Borehole
In the 1970s and early 1980s the USSR attempted to drill a hole through the crustCrust (geology)
In geology, the crust is the outermost solid shell of a rocky planet or natural satellite, which is chemically distinct from the underlying mantle...
, to sample the Mohorovicic Discontinuity
Mohorovicic discontinuity
The Mohorovičić discontinuity , usually referred to as the Moho, is the boundary between the Earth's crust and the mantle. Named after the pioneering Croatian seismologist Andrija Mohorovičić, the Moho separates both the oceanic crust and continental crust from underlying mantle...
. The deepest hole ever drilled failed not because of lack of money or time, but because of the physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
of rocks within the crust. The hole achieved approximately 12,000 metres depth, a depth at which rock begins to act more like a plastic
Plasticity (physics)
In physics and materials science, plasticity describes the deformation of a material undergoing non-reversible changes of shape in response to applied forces. For example, a solid piece of metal being bent or pounded into a new shape displays plasticity as permanent changes occur within the...
solid than a rigid solid. The rock also approached temperatures of several hundred degrees Celsius
Celsius
Celsius is a scale and unit of measurement for temperature. It is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...
, requiring that the drilling fluid be refrigerated
Refrigeration
Refrigeration is a process in which work is done to move heat from one location to another. This work is traditionally done by mechanical work, but can also be done by magnetism, laser or other means...
before being sent to the cutting face of the drill. As the drill bits burnt out and were removed for replacement, the hole simply flowed closed, and the rock had to be re-drilled. Due to the temperature, the drill bits burnt out before achieving any headway. The hole was scrapped.
Further attempts at super-deep drillholes are planned by American
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
consortia and further Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
n attempts in Finland
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
.
Ice boring
Ice cores are drilled by hollow bits, in much the same way that sediment cores are drilled. When all that is needed is the hole, hot water drill technology may be used to melt holes in ice or snow for both Arctic and Antarctic research purposes. It is also lightweight when drilling deep holes, compared to traditional drilling equipment. Hot water drilling have been used successfully in the IceCube Neutrino DetectorIceCube Neutrino Detector
The IceCube Neutrino Observatory is a neutrino telescope constructed at the Amundsen-Scott South Pole Station in Antarctica...
and Antarctic Muon And Neutrino Detector Array
Antarctic Muon And Neutrino Detector Array
The Antarctic Muon And Neutrino Detector Array is a neutrino telescope located beneath the Amundsen-Scott South Pole Station. In 2005, after nine years of operation, AMANDA officially became part of its successor project, the IceCube Neutrino Observatory.AMANDA consists of optical modules, each...
projects to drill as deep as 2,450 meters.