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| Titel |
Online gas monitoring and sampling during drilling of the INFLUINS borehole EF-FB 1/12 into the Thuringian Syncline, Germany |
| VerfasserIn |
Marco Görlitz, Michael Abratis, Thomas Wiersberg |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250100070
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| Publikation (Nr.) |
 EGU/EGU2014-15951.pdf |
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| Zusammenfassung |
| Online monitoring and sampling of drill mud gas (OLGA) was conducted during standard
rotary drilling and core drilling of the INFLUINS borehole EF-FB 1/12 to gain
information on the composition of gases and their distribution at depth within the
Thuringian Syncline (Germany). The method can help to identify areas of enhanced
permeability and/or porosity, open fractures, and other strata associated with gases at
depth.
The gas-loaded drill mud was continuously degassed in a modified gas-water separator,
which was installed in the mud ditch in close distance to the drill mud outlet. The extracted
gas phase was pumped in a nearby field laboratory for continuous on-line analysis.
First information on the gas composition (H2, He, N2, O2, CO2, CH4, Ar, Kr) was
available only few minutes after gas extraction. More than 40 gas samples were
taken from the gas line during drilling and pumping tests for further laboratory
studies.
Enhanced concentration of methane, helium, hydrogen and carbon dioxide were detected in
drill mud when the drill hole encountered gas-rich strata. Down to a depth of 620 m, the drill
mud contained maximum concentration of 55 ppmv He, 1400 ppmv of CH4, 400 ppmv of
hydrogen and 1.1 vol-% of CO2.
The drilling mud gas composition is linked with the drilled strata. Buntsandstein and
Muschelkalk show different formation gas composition and are therefore hydraulically
separated. Except for helium, the overall abundance of formation gases in drilling mud is
relatively low. We therefore consider the INFLUINS borehole to be dry. The correlation
between hydrogen and helium and the relatively high helium abundance rules out any
artificial origin of hydrogen and suggest a radiolytic origin of hydrogen. Values
CH4/(C2H6/C3H8) |
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