SURFACE SUBSIDENCE IN THE NETHERLANDS - THE GRONINGEN GAS-FIELD

In The Netherlands, surface subsidence as a result of hydrocarbon production has become more and more a subject of public interest because of the environmental and political aspects. The most pronounced case of this type of subsidence is demonstrated by the Groningen gas field situated in the north of The Netherlands. Since the start of gas production in 1963, the surface over the centre of the field has subsided by some 18 cm. To monitor reservoir compaction and surface subsidence in Groningen on a regular basis, an extensive monitoring programme was set up by the Nederlandse Aardolie Maatschappij BV, the operator in the Groningen concession. This programme includes yearly levelling surveys, measurements of shallow formation compaction (0 to 400 m below surface) in 14 observation wells and in situ reservoir compaction measurements in 11 deep observation wells drilled specifically for this purpose. Prognoses of gas-production-induced surface subsidence, which are demanded by the State Supervision of Mines, are made using a three-dimensional grid block model to describe the gas-bearing reservoir and the associated aquifer. In the year 2050, when it is planned to abandon the gas field, the maximum subsidence (over the centre of the field) is calculated to be between 33 and 43 cm.