3.3.4 K12-B

Various monitoring tools are used for monitoring the K12-B storage complex, located in the Dutch sector of the North Sea. The storage demonstration project started in 2004 when a part of the CO2 separated from the natural gas extracted from the K12-B was re-injected into the same reservoir containing the gas deposit via injection well K12-B8. In 2005 the injection started in another well, K12-B6. The reservoir top is at 3,800 m depth below sea level and its cap rock is represented by rock salts alternating with clay intervals. Since 2004 a total of 60,000 tonnes of CO2 has been injected.

A very important part of the monitoring programme has been related to a continuous well integrity assessment in relation to the specific down-hole conditions induced by the CO2 injection and storage. For this purpose, several monitoring tools were deployed, as multi-finger imaging tools (surveys in 2005 and 2006), cement bond logging, downhole video logging (2007), electromagnetic imaging tool, gamma ray logging (Fig. 3-5; Vandeweijer et al., 2011).

Gaining a better understanding of the behaviour of the CO2 in the injection wells and the migration of the CO2 in the reservoir were also important goals of the monitoring programme. In order to achieve this goal, multiple reservoir models were built over the years using 3D seismic data, well logs, production logs, etc. Additional measurements and analysis were used in order to refine these models, such as well head production and injection measurements, production and injection analysis, down-hole pressure and temperature measurements, chemical tracer analysis and dynamic flow modelling (Vandeweijer et al., 2011).

Fig 3 5 K12 B ProjectFig 3 5 K12 B Project MAP_V

Fig. 3-5: Location, 3D visualisation and overview of relevant wells and compartments of the K12-B gas field (from Vandeweijer et al., 2011).