Well 6507/4-2S, operated by Wintershall Dea and partnered by Petoro (35%) and Edison (10%), was spudded less than two weeks ago in an attempt to firm up gas in the Dvalin North prospect.
Situated in PL211, the well lies on trend with the Dvalin East and West fields further to the south and given that the same Middle Jurassic Garn and Ile formations are being targeted, it seems that these fields form a good analogue of what is anticipated to be found in 6507/4-2S.
Dvalin field – an interesting history
Estimated to contain 18 BCM or 18 MMboe at production start, the Dvalin East and West fields were put on production late November last year after four development wells were drilled from a subsea template. Wintershall also operates the Dvalin field.
In the light of the two ConocoPhillips discoveries announced last year – Slagugle in the east and Warka in the west – the exploration history behind the discovery of Dvalin is quite interesting. Namely, the first well testing the Dvalin structure was a Conoco operated well, 6507/7-1, drilled in 1984. As nicely outlined in this story (in Norwegian), Conoco drilled the well based on 2D seismic data and in hindsight hit the reservoir just outside the closure. Although the well was tested at the time, only traces of gas were produced from a poor Middle Jurassic reservoir. As a consequence, the area was written off for about 20 years until RWE DEA came along and challenged the concept as to why the well was dry.
Based on 3D seismic data that was now available, and the realisation that reservoir pressures were not high enough to have caused seal failure, a slightly smaller closure was now mapped and successfully drilled through 6507/7-14S in 2010. Reservoir quality was also found to be much better than in the 6507/7-1 well, caused by early oil charge and a subsequent arrest of pore cementation.
In that light, the Dvalin discovery was a great example of challenging old ideas in conjunction with the availability of better seismic data, something that ConocoPhillips no doubt applied when they drilled the Warka and Slagugle wells last year. For now it is hoped that the Dvalin North prospect is going to deliver for Wintershall Dea as well.
HENK KOMBRINK
