Scientific drilling into the Earth is a way for scientists to probe the Earth's

sediment Sediment is a solid material that is transported to a new location where it is deposited. It occurs naturally and, through the processes of weathering and erosion, is broken down and subsequently sediment transport, transported by the action of ...

s, crust, and

upper mantle The upper mantle of Earth is a very thick layer of rock inside the planet, which begins just beneath the crust (geology), crust (at about under the oceans and about under the continents) and ends at the top of the lower mantle (Earth), lower man ...

. In addition to rock samples, drilling technology can unearth samples of

connate fluids In geology and sedimentology, connate fluids are liquids that were trapped in the pores of sedimentary rocks as they were deposited. These liquids are largely composed of water, but also contain many mineral components as ions in solution. As r ...

and of the subsurface

biosphere The biosphere (), also called the ecosphere (), is the worldwide sum of all ecosystems. It can also be termed the zone of life on the Earth. The biosphere (which is technically a spherical shell) is virtually a closed system with regard to mat ...

, mostly

microbial life A microorganism, or microbe, is an organism of microscopic scale, microscopic size, which may exist in its unicellular organism, single-celled form or as a Colony (biology)#Microbial colonies, colony of cells. The possible existence of unseen ...

, preserved in drilled samples. Scientific drilling is carried out on land by the

International Continental Scientific Drilling Program The International Continental Scientific Drilling Program is a multinational program to further and fund geosciences in the field of continental scientific drilling. Scientific drilling is a critical tool in understanding of Earth processes and ...

(ICDP) and at sea by the

Integrated Ocean Drilling Program The Integrated Ocean Drilling Program (IODP) was an international marine research program, running from 2003 to 2013. The program used heavy drilling equipment mounted aboard ships to monitor and sample sub-seafloor environments. With this rese ...

(IODP). Scientific drilling on the continents includes drilling down into solid ground as well as drilling from small boats on lakes. Sampling thick

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

s and

ice sheet In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacier, glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are the Antarctic ice sheet and the Greenland ice sheet. Ice s ...

s to obtain

ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier ...

s is related but will not be described further here. Like probes sent into outer space, scientific drilling is a technology used to obtain samples from places that people cannot reach. Human beings have descended as deep as 2,212 m (7,257 ft) in

Veryovkina Cave Veryovkina Cave (also spelled Verëvkina Cave, , ) is a cave in Abkhazia, a disputed region of Georgia_(country), Georgia. At deep, it is the deepest-known cave on Earth. Veryovkina is in the Arabika Massif, in the Gagra Range, Gagra mountain ra ...

, the world's deepest known cave, located in the

Caucasus Mountains The Caucasus Mountains * * Azerbaijani: , * * * * * * * * * * * is a mountain range at the intersection of Asia and Europe. Stretching between the Black Sea and the Caspian Sea, they are surrounded by the Caucasus region ...

of the country of

Georgia Georgia most commonly refers to: * Georgia (country), a country in the South Caucasus * Georgia (U.S. state), a state in the southeastern United States Georgia may also refer to: People and fictional characters * Georgia (name), a list of pe ...

. Gold miners in

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

regularly go deeper than 3,400 m, but no human has ever descended to greater depths than this below the Earth's solid surface. As depth increases into the Earth, temperature and pressure rise. Temperatures in the crust increase about 15 °C per kilometer, making it impossible for humans to exist at depths greater than several kilometers, even if it was somehow possible to keep shafts open in spite of the tremendous pressure. Scientific drilling is interdisciplinary and international in scope. Individual scientists cannot generally undertake scientific drilling projects alone. Teamwork between scientists, engineers, and administrators is often required for success in planning and in carrying out a drilling project, analyzing the samples, and interpreting and publishing the results in scientific journals.

Purposes

Scientific drilling is used to address a wide range of problems, which cannot be addressed using rocks exposed on the surface or the seafloor. The

has a broad set of research objectives, which can be divided into three principal themes: #The nature of the

deep biosphere The deep biosphere is the part of the biosphere that resides below the first few meters of the ocean's surface. It extends below the continental surface and below the sea surface, at temperatures that may reach beyond which is comparable to s ...

and the oceanic sub-seafloor #Understanding environmental change, processes and effects #Cycles and geodynamics of the solid Earth ICDP focuses on scientific drilling to address the following questions about the history, chemistry, and physics of Earth and the biosphere: #What are the physical and chemical processes responsible for

earthquakes An earthquakealso called a quake, tremor, or tembloris the shaking of the Earth's surface resulting from a sudden release of energy in the lithosphere that creates seismic waves. Earthquakes can range in intensity, from those so weak they c ...

and

volcanic A volcano is commonly defined as a vent or fissure in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often fo ...

eruptions, and what are the best ways to minimize their effects? #How has Earth's climate changed in the recent past and what are the reasons for such changes? #What have been the effects of meteorite impacts (

bolide A bolide is normally taken to mean an exceptionally bright meteor, but the term is subject to more than one definition, according to context. It may refer to any large Impact crater, crater-forming body, or to one that explodes in the atmosphere. ...

s) on climate and

mass extinction An extinction event (also known as a mass extinction or biotic crisis) is a widespread and rapid decrease in the biodiversity on Earth. Such an event is identified by a sharp fall in the diversity and abundance of multicellular organisms. It occ ...

s of life? #What is the nature of the deep biosphere and its relation to geologic processes such as

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and Hydrophobe, hydrophobic; their odor is usually fain ...

maturation,

ore Ore is natural rock or sediment that contains one or more valuable minerals, typically including metals, concentrated above background levels, and that is economically viable to mine and process. The grade of ore refers to the concentration ...

deposition and

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

of life on Earth? #What are the ways to safely dispose of

radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

and other

toxic waste Toxic waste is any unwanted material in all forms that can cause harm (e.g. by being inhaled, swallowed, or absorbed through the skin). Mostly generated by industry, consumer products like televisions, computers, and phones contain toxic chemi ...

materials? #How do

sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock They form when long-term subsidence ...

s and

fossil fuel A fossil fuel is a flammable carbon compound- or hydrocarbon-containing material formed naturally in the Earth's crust from the buried remains of prehistoric organisms (animals, plants or microplanktons), a process that occurs within geolog ...

resources originate and evolve? #How do mineral, and metal ore deposits form? #What are the fundamental physics of

plate tectonics Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...

and heat, mass, and fluid transfer through Earth's crust? #How can people better interpret

geophysical Geophysics () is a subject of natural science concerned with the physical processes and properties of Earth and its surrounding space environment, and the use of quantitative methods for their analysis. Geophysicists conduct investigations acros ...

data used to determine the structure and properties of Earth's crust?

Deepest drillings

The

Kola Superdeep Borehole The Kola Superdeep Borehole SG-3 () is the deepest human-made hole on Earth (since 1979), which attained maximum true vertical depth of in 1989. It is the result of a scientific drilling effort to penetrate as deeply as possible into the ...

on the Kola peninsula of Russia reached and is the deepest penetration of the Earth's solid surface. The German Continental Deep Drilling Program at has shown the earth crust to be mostly porous. Drillings as deep as into the seafloor were achieved at DSDP/ ODP/ IODP Hole 504B. Because the

continental crust Continental crust is the layer of igneous, metamorphic, and sedimentary rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as '' continental shelves''. This layer is sometimes called '' si ...

is about 45 km thick on average, whereas

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramaf ...

is 6–7 km thick, deep drillings have penetrated only the upper 25-30% of both crusts. Riserless and mudlift drilling

Ocean drilling

The

drillship A drillship is a merchant vessel designed for use in exploratory offshore drilling of new oil and gas wells or for scientific drilling purposes. In recent years the vessels have been used in deepwater and ultra-deepwater applications, equipped ...

that has been used for the past 20 and more years, the JOIDES Resolution, drills without a riser. Riser-less drilling uses seawater as its primary drilling fluid, which is pumped down through the drill pipe. This cleans and cools the drill bit and lifts cuttings out of the hole, piling them in a cone around the hole. Japan's new drillship, the Chikyu, uses a riser for drilling. The riser system includes an outer casing that surrounds the drill pipe, to provide return-circulation of drilling fluid for maintaining pressure balance within the borehole. A

blowout preventer A blowout preventer (BOP) (pronounced B-O-P) is a specialized valve or similar mechanical device, used to seal, control and monitor oil well, oil and gas wells to prevent Blowout (well drilling), blowouts, the uncontrolled release of crude oil ...

(BOP) protects the vessel and the environment from any unexpected release of gas and oil. This technology is necessary for drilling several thousand meters into the Earth.

References

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External links

Integrated Ocean Drilling Program official websiteInternational Continental Scientific Drilling ProgramUSA initiative DOSECC (Drilling, Observation, and Sampling of the Earth's Continental Crust)
Geophysics