Scientific drilling

Scientific drilling

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Scientific drilling is a way to probe down into the Earth, allowing scientists and students to obtain samples of sediments, crust, and upper mantle. In addition to rock samples, drilling technology allows humans to obtain samples of connate fluids
Connate fluids
The term connate fluids in the context of geology, and of sedimentology in particular, refers to the 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...

 and of the subsurface biosphere
Biosphere
The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth, a closed and self-regulating system...

, mostly microbial life, preserved in drilled samples. Most of the technology used for drilling results from advances in the oil and gas industry. Scientific drilling is carried out on land by the International Continental Scientific Drilling Program
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 structure. It provides direct insight into Earth...

 (ICDP) and at sea by the Integrated Ocean Drilling Program
Integrated Ocean Drilling Program
The Integrated Ocean Drilling Program is an international marine research program. The program uses heavy drilling equipment mounted aboard ships to monitor and sample sub-seafloor environments...

 (IODP).

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 2,080 m (6,822 ft) in Voronya Cave
Voronya Cave
The Krubera Cave is the deepest known cave on Earth. It is located in the Arabika Massif of the Gagrinsky Range of the Western Caucasus, in the Gagra district of Abkhazia, Georgia’s breakaway republic.The difference in the altitude of the cave's entrance and its deepest explored point is...

, the world's deepest known cave, located in the Caucasus mountains of Georgia. Gold miners in South Africa 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. The Kola Superdeep Borehole
Kola Superdeep Borehole
The 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 the Kola peninsula of Russia reached 12.262 km (~7.62 mi) and is the deepest penetration of the Earth's solid surface. Humans have drilled down 2.1 km (~1.3 mi) into the seafloor at DSDP
Deep Sea Drilling Program
The Deep Sea Drilling Project was an ocean drilling project operated from 1968 to 1983. The program was considered to be successful as evidenced by the data and publications that have resulted from it and is now supported by Texas A&M University, although for the years of its operations these were...

/ODP
Ocean Drilling Program
The Ocean Drilling Program was an international cooperative effort to explore and study the composition and structure of the Earth's ocean basins. ODP, which began in 1985, was the direct successor to the highly successful Deep Sea Drilling Project initiated in 1968 by the United States...

/IODP
Integrated Ocean Drilling Program
The Integrated Ocean Drilling Program is an international marine research program. The program uses heavy drilling equipment mounted aboard ships to monitor and sample sub-seafloor environments...

 Hole 504B. Because the continental crust
Continental crust
The continental crust is the layer of igneous, sedimentary, and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called sial due to more felsic, or granitic, bulk composition, which lies in...

 is about 45 km thick on average, whereas oceanic crust
Oceanic crust
Oceanic crust is the part of Earth's lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium...

 is 6-7 km thick, humans have penetrated only the upper 25-30% of both crusts.

Scientific drilling on the continents includes drilling down into solid ground as well as drilling from small boats on lakes. Sampling thick glaciers and ice sheets to obtain ice core
Ice core
An ice core is a core sample that is typically removed from an ice sheet, most commonly from the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere. As the ice forms from the incremental build up of annual layers of snow, lower layers are older than upper, and an ice...

s is related but will not be described further here.

Scientific drilling is used to address a wide range of problem, which cannot be addressed using rocks exposed on the surface or on the seafloor. The Integrated Ocean Drilling Program
Integrated Ocean Drilling Program
The Integrated Ocean Drilling Program is an international marine research program. The program uses heavy drilling equipment mounted aboard ships to monitor and sample sub-seafloor environments...

 has a broad set of research objectives, which can be divided into three principal themes:
  1. The nature of the deep biosphere
    Biosphere
    The biosphere is the global sum of all ecosystems. It can also be called the zone of life on Earth, a closed and self-regulating system...

     and the oceanic sub-seafloor
  2. Understanding environmental change, processes and effects
  3. 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:
  1. What are the physical and chemical processes responsible for earthquakes and volcanic eruptions, and what are the best ways minimize their effects?
  2. How has Earth's climate change
    Climate change
    Climate change is a significant and lasting change in the statistical distribution of weather patterns over periods ranging from decades to millions of years. It may be a change in average weather conditions or the distribution of events around that average...

    d in the recent past and what are the reasons for such changes?
  3. What have been the effects of meteorite impacts (bolides) on climate and mass extinctions of life?
  4. What is the nature of the deep biosphere and its relation to geologic processes such as hydrocarbon
    Hydrocarbon
    In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

     maturation, ore
    Ore
    An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....

     deposition and evolution
    Evolution
    Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

     of life on Earth
    Life on Earth
    Life on Earth: A Natural History by David Attenborough is a television natural history series made by the BBC in association with Warner Bros. and Reiner Moritz Productions...

    ?
  5. What are ways to safely dispose of radioactive
    Radioactive waste
    Radioactive wastes are wastes that contain radioactive material. Radioactive wastes are usually by-products of nuclear power generation and other applications of nuclear fission or nuclear technology, such as research and medicine...

     and other toxic waste
    Toxic waste
    Toxic waste is waste material that can cause death or injury to living creatures. It spreads quite easily and can contaminate lakes and rivers. The term is often used interchangeably with “hazardous waste”, or discarded material that can pose a long-term risk to health or environment.Toxic waste...

     materials?
  6. How do sedimentary basin
    Sedimentary basin
    The term sedimentary basin is used to refer to any geographical feature exhibiting subsidence and consequent infilling by sedimentation. As the sediments are buried, they are subjected to increasing pressure and begin the process of lithification...

    s and fossil fuel
    Fossil fuel
    Fossil fuels are fuels formed by natural processes such as anaerobic decomposition of buried dead organisms. The age of the organisms and their resulting fossil fuels is typically millions of years, and sometimes exceeds 650 million years...

     resources originate and evolve?
  7. How do mineral and metal ore
    Ore
    An ore is a type of rock that contains minerals with important elements including metals. The ores are extracted through mining; these are then refined to extract the valuable element....

     deposits form?
  8. What are the fundamental physics of plate tectonics
    Plate tectonics
    Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...

     and heat, mass and fluid transfer through Earth's crust?
  9. How can people better interpret geophysical
    Geophysics
    Geophysics is the physics of the Earth and its environment in space; also the study of the Earth using quantitative physical methods. The term geophysics sometimes refers only to the geological applications: Earth's shape; its gravitational and magnetic fields; its internal structure and...

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

Scientific ocean drilling is about to go through a revolution in technology. The drillship
Drillship
A drillship is a maritime vessel that has been fitted with drilling apparatus. It is most often used for exploratory offshore drilling of new oil or gas wells in deep water or for scientific drilling. The drillship can also be used as a platform to carry out well maintenance or completion work such...

 that has been used for the past 20 and more years, the JOIDES Resolution
JOIDES Resolution
thumb|right|295px|Drillship JOIDES Resolution in 1988JOIDES Resolution is a scientific drilling ship once used by the Ocean Drilling Program, then by its successor, the Integrated Ocean Drilling Program. It is the successor of the Glomar Challenger.The ship was launched as Sedco/BP 471, an oil...

, 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 (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.

Scientific drilling is very interdisciplinary and international in scope. Individual scientists or students cannot undertake scientific drilling projects alone. Teamwork between scientists, engineers, and administrators is required for success in planning and in carrying out a drilling project, analyzing the samples, and interpreting and publishing the results in scientific journals.

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