Open AccessFirst measurements of the methane concentration in the North Sea with a new in-situ device
Author(s) -
G. Werneck,
G Floser,
S. Korn,
C. Weitkamp,
W. Michaelis
Publication year - 1994
Publication title -
bulletin of the geological society of denmark
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.674
H-Index - 28
eISSN - 2245-7070
pISSN - 0011-6297
DOI - 10.37570/bgsd-1995-41-01
Subject(s) - wellhead , methane , fjord , natural gas , seawater , detection limit , methane gas , environmental science , in situ , absorption (acoustics) , geology , analytical chemistry (journal) , hydrology (agriculture) , oceanography , materials science , chemistry , environmental chemistry , petroleum engineering , chromatography , geotechnical engineering , organic chemistry , composite material
A device is briefly described for the continuous in-situ measurement of methane gas dissolved insea water. The device extracts dissolved gas from a continuous flow of water and quantitativelydetermines the methane partial pressure in the gas phase by laser absorption spectrometry. Alower detection limit of 30 ppt (parts per trillion, 30 pg of methane per g of water) is achieved,and the dynamic range exceeds six orders of magnitude. Thus, the natural background concentration of the open ocean (35 ppt) can be measured. First measurements with the device have beentaken in the North Sea. Depth profiles at Statpipe, in the Bømla Fjord and at the location of aseepage in the Gullfaks area are shown. Horizontal profiles across a natural seepage show thedistribution of the methane around the source. Measurements at a gas injection wellhead maygive a hint of a microleakage of the structure.