Test drilling

Gazprom test drilling for a planned natural gas storage facility near Hinrichshagen

In the geosciences and deposit research, a vertical borehole from a few meters to a hectometer deep is referred to as test boreholes (test boreholes ) that either

1. serves to investigate the subsoil for the construction of a structure or tunnel ,
2. preparing a deep borehole ,
3. preparing a wellbore for oil or natural gas,
4. or the predominantly scientific study of the earth's crust .

In construction projects, test bores serve to explore the subsurface near the surface or, in the case of deeper bores, a maximum of the first kilometer depth, as far as this is considered sensible or promising after a geophysical preliminary investigation. Such previous explorations are initially carried out with gravimetry , then mostly with reflection seismics .

A mobile drilling rig is usually sufficient for depths of up to a few tens of meters .

Above all, important data to be collected are

• Conditions of the subsoil (up to a few meters depth), water flow , load-bearing capacity, etc.
• approximate regional geological conditions:
  • Stratigraphy , appearance of crevices
  • Type and storage of the rock (solid, loose rock )
  • Faults and geological fault lines
• Exploration of potential deposits :
  • Groundwater and soil water
  • Porosity of the possible storage rocks for crude oil or natural gas
  • Borehole geophysics and escaping gases
  • Coal , ores , salt , etc.

For projects with economic objectives, the cost-risk question for the design of the borehole is decisive, since by no means all test boreholes bring the hoped-for success. If so, the knowledge gained is implemented in economically usable or at least hopeful projects - raw material extraction or actual production wells , studies for a tunnel construction, etc.

Purely scientific information acquisition is the exception, since drilling is much more expensive than most geophysical exploration. Larger projects with scientific objectives are e.g. B. in southern Germany the continental deep drilling or in the alpine countries the civil engineering of the Eastern Alps .

If exploratory or test wells are used to prepare deeper wells, then it is usually about later production wells

• for the extraction of crude oil and natural gas or the creation of better production conditions
• or vice versa for filling underground natural gas storage facilities
• Extraction of geothermal water
• Ground water or mineral water .

Individual evidence

1. ^ Heinrich Otto Buja: Handbook of deep, shallow, geothermal and horizontal drilling technology . Vieweg & Teubner, 2011, ISBN 978-3834812780 , pp. 86ff.
2. ^ Author collective: Lexicon of Geosciences, Volume I, Spectrum Academic Publishing House, Heidelberg, Berlin 2000, ISBN 3-8274-0299-9 , pp. 297f

literature

• German Bohrmeisterschule: Bohrtechnisches Handbuch (loose-leaf collection of the German Bohrmeisterschule), Celle 1981
• Paul Heinz Düring: Geological drilling , 2 volumes, German publishing house for basic industry, Leipzig 1983
• Peter Hatzsch: Tiefbohrtechnik , 3rd edition, Enke 1991, ISBN 3-432-99511-3 , 119 pp.
• Erich Bieske, Wilhelm Rubbert and Christoph Treskatis: artesian , 8th edition, Oldenbourg, Munich, Vienna 1998. ISBN 3-486-26388-9 , 455 S.