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

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand ...

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 (at about under the oceans and about under the continents) and ends at the top of the lower mantle at . Temperatures range from appr ...

. 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 ro ...

and of the subsurface

biosphere The biosphere (from Greek βίος ''bíos'' "life" and σφαῖρα ''sphaira'' "sphere"), also known as the ecosphere (from Greek οἶκος ''oîkos'' "environment" and σφαῖρα), is the worldwide sum of all ecosystems. It can also ...

, mostly

microbial life A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...

, 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 s ...

(ICDP) and at sea by the

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

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

s and

ice sheet In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are in Antarctica and Greenland; during the Last Glacial Period at La ...

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. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ...

s is related but will not be described further here. Like probes sent into

outer space Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near-perfect vacuum containing a low density of particles, pred ...

, 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 breakaway region of Georgia. At 2,212 meters (7,257 ft) deep, it is the deepest-known cave on Earth. Its entrance is 2,285 metres (7,497 ft) above sea level. The entrance ...

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

Caucasus mountains The Caucasus Mountains, : pronounced * hy, Կովկասյան լեռներ, : pronounced * az, Qafqaz dağları, pronounced * rus, Кавка́зские го́ры, Kavkázskiye góry, kɐfˈkasːkʲɪje ˈɡorɨ * tr, Kafkas Dağla ...

of the country of

Georgia Georgia most commonly refers to: * Georgia (country), a country in the Caucasus region of Eurasia * Georgia (U.S. state), a state in the Southeast United States Georgia may also refer to: Places Historical states and entities * Related to the ...

. Gold miners in

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...

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 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 earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, fro ...

and

volcanic A volcano is a rupture 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 found where tectonic plat ...

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 crater-forming body, or to one that explodes in the atmosphere. It can be a ...

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 change in the diversity and abundance of multicellular organisms. I ...

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 hydrophobic, and their odors are usually weak or ...

maturation, ore deposition and

evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...

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 consi ...

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 subsiden ...

s and

fossil fuel A fossil fuel is a hydrocarbon-containing material formed naturally in the Earth's crust from the remains of dead plants and animals that is extracted and burned as a fuel. The main fossil fuels are coal, oil, and natural gas. Fossil fuels ma ...

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

plate tectonics Plate tectonics (from the la, label= Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of larg ...

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 physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term ''geophysics'' some ...

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

Deepest drillings

The

Kola Superdeep Borehole The Kola Superdeep Borehole (russian: Кольская сверхглубокая скважина, translit=Kol'skaya sverkhglubokaya skvazhina) SG-3 is the result of a scientific drilling project of the Soviet Union in the Pechengsky District ...

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, sedimentary, and metamorphic 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 '' sial'' be ...

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 ultramafic ...

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 295px, Drillship ''JOIDES Resolution'' in 1988 The riserless research vessel ''JOIDES Resolution'' (Joint Oceanographic Institutions for Deep Earth Sampling), often referred to as the JR, is one of the scientific drilling ships used by the Intern ...

, 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, not "bop") is a specialized valve or similar mechanical device, used to seal, control and monitor oil and gas wells to prevent blowouts, the uncontrolled release of crude oil or natural gas from a w ...

(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 and for drilling into thick sediments where oil and gas might reside.

References

{{reflist

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