20 March 2018
Jointly organised with
TAQA Energy operates Gas Storage Bergermeer, Europe’s largest open-access gas storage. The Bergermeer gas storage is located in the North-Western part of the Netherlands, close to Alkmaar. The reservoir is characterized by excellent Permian sands in the Weissliegend and Rotliegend intervals, with a GIIP of 16.8 BCM (625 BCF). The Bergermeer field was discovered in the late 60’s and taken into production in 1972. Over 15 BCM (558 BCF) of gas has been recovered until 2007. From 2007 the reservoir was being transformed into a gas storage, starting with the injection of cushion gas. In 2012 all permits were in place to start the construction of the gas storage. Fourteen new gas storage and one water injection were drilled and a newly build processing facility is connected to the well site via an 8.5 km long 30” pipeline. In 2015 the Bergermeer Gas Storage became operational, having an injection capacity of 42 million Nm3/d (1.56 BCF/d) and a production capacity of 57 million Nm3/d (2.12 BCF/d). The associated working gas volume is 4.1 BCM (152 BCF).
During the depletion period 1972-2007, seismicity was observed in 1994 (M=3.1) and 2001 (M=3.5) at a pressure below 58 bar. The design of the Bergermeer Gas Storage and the day-to-day operations are based on the reservoir management system to prevent induced seismicity. For safe gas storage operations a permanent down hole micro-seismic array monitoring system has been installed in 2011, to monitor the reservoir. The observed micro-seismic activity is far below the threshold for felt or damaging earthquakes. Subsidence during the depletion phase of the field was measured by five-yearly leveling campaigns and surface heave during the storage cycles is measured continuously using 4 permanent GPS sensors located above the field.
The (micro) seismicity and surface movement will be presented and discussed, providing the basis to understand the geomechanical behavior of the Bergermeer reservoir during the full lifetime of the field comprising depletion, cushion gas injection and storage cycles. Also the theory of fault stability by pore pressure and stress change will be addressed.
Figure 1 The Bergermeer reservoir, intersected by the GWC at 2228 mTVDss. In “red” the old production wells and in “green” the 14 new gas storage wells drilled between 2012 and 2015
Figure 2 Spatial distribution of the microseismic events. The blue lines indicate the location accuracy of the events.