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The Mittelplate Oil Field

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journal contribution
posted on 30.04.2020 by M. DOEHLER
The Mittelplate Oil Field with its 950 MMBOIP is Germany's largest oil field and lays offshore Germany in the coastal tidal flats about 100 km northwest of Hamburg at the mouth of the river Elbe estuary and some 25 km northeast of Cuxhaven. It is located in the West Holstein Jura Trough with its flanking salt walls Oldensworth and Heide. The discovery well Mittelplate-1 was drilled in 1980 by the consortium RWE Dea AG and Wintershall AG. The prospects targeted by the Mittelplate-1 well were stacked Middle Jurassic Dogger sandstone reservoirs. At the time only 2D data was available to the group and only few seismic lines defined the play. The discovery well encountered two separate oil columns within the Middle Jurassic 'Mittelplate' sands and when tested flowed low gravity oil from four sandstone reservoir horizons at a depth between 2134-2743 mTVD. In 1981 three appraisal wells were drilled confirming the structure with today's proven recoverable reserves to be at around 220 MMBO. The distance of the field towards the coast is between seven and thirteen kilometres and its NS extension of more than 10 km is straddling along the western flank of the Büsum salt dome. After building an artificial drilling and production island in 1985, 15 wells have been drilled since 1986 from the Mittelplate-A platform draining the central part of the field. Along with acquiring of new 3D seismic in 1997 in the area between the appraisal wells Mittelplate-2 and Mittelplate-3, a pilot project was initiated to develop the field through extended reach wells from onshore. Three wells were drilled from the Mittelplate island to the salt dome to verify geology and drilling requirements. At the same time one well, the Dieksand-1 was drilled from the shore to investigate the situation from the onshore side. After only half a year of engineering time the first extended reach well, Dieksand-2 was spudded, drilled more than 3600 m horizontally through the Büsum salt dome and was successfully completed at a TD of 7727 m in 1998. Since then a further six ERD wells have been drilled from onshore reaching a maximum length of 9275 m MD. Since nearly 17 years of undisturbed and accident free operation, the Mittelplate group is now at the planning stage to investigate the development of the southern and northern part of the field with horizontal wells of more than 8 km to develop and drain the remaining 350 MMBO of proven and probable reserves.