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Gravity changes and natural gas extraction in Groningen
Author(s) -
Van Gelderen Martin,
Haagmans Roger,
Bilker Mirjam
Publication year - 1999
Publication title -
geophysical prospecting
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.735
H-Index - 79
eISSN - 1365-2478
pISSN - 0016-8025
DOI - 10.1046/j.1365-2478.1999.00159.x
Subject(s) - gemology , extraction (chemistry) , geology , data set , environmental geology , geodesy , hydrogeology , telmatology , statistics , engineering geology , mathematics , geotechnical engineering , seismology , chemistry , tectonics , chromatography , volcanism
Gravity observations made over the Groningen gasfield from 1978 onwards are available. The existing gravity data were reanalysed and a new survey was carried out. The observed gravity changes obtained during four surveys, spanning an 18‐year period, were compared with the gravity effect due to natural gas extraction computed from the reservoir model and the production data. The random error in the gravity values is small enough to detect the effect of gas extraction after a few years (up to 2 μgal/year). The trends obtained from observed and calculated gravity changes agree well within their expected error margins after statistical data snooping. Due to the inadequate measurement set‐up of the previous surveys, systematic errors present in the gravity data hampered the use of this data for refinement of the reservoir and the production models. However, with improved gravity monitoring, in particular a very systematic network set‐up and well‐calibrated instruments, this should now be feasible. By using the network analysis from the 1996 measurements for the planning of a network in space and time, most of the current problems can be avoided.