NCS: Lundin preparing extended well test in basementRolvsnes location in PL338C. Source: Lundin

NCS: Lundin preparing extended well test in basement

Lundin Norway received Government approval for sample extraction from the Rolvsnes discovery at the Edvard Grieg field in the North Sea.

The discovery 16/1-12 Rolvsnes was proven in 2009, and subsequently delineated by well 16/1-25S in 2015. The reservoir contains oil in weathered and fractured granitic basement beneath a thin, 20-30 cm Early Cretaceous conglomerate. Rolvsnes is part of PL338 C, where Lundin is the operator with 80% shares and partner OMV  with 20%.

Rolvsnes has a gross estimated resource range of 14 to 78 MMboe. Following the successful appraisal well and production test in 2018, an extended well test (EWT) will be conducted to better understand the long-term reservoir behaviour and performance.

The permit is granted for a duration of 12 months. The extraction will take place with the reuse of an appraisal well which was drilled on the field in 2018. The planned start-up is in the second quarter of 2021.

The EWT will be conducted through a 3 km subsea tie-back of the existing Rolvsnes horizontal well to the Edvard Grieg platform. The produced hydrocarbons will be processed and exported together with oil and gas from the Edvard Grieg and Solveig fields.

Previously, oil accumulations in basement reservoirs have not been considered commercially viable. It is usually not the case for granitic basement. If the granite is sufficiently cracked and it has been subjected to weathering (water flowed through the fracture system and dissolved the minerals) then this reservoir type may be porous enough to accommodate hydrocarbons.  With a high degree of weathering, the granite is dissolved and can have good reservoir properties.

Rolvsnes appraisal well in fractured basement. Source: Lundin

If the test extraction yields good results, it can lead to development at Rolvsnes. In addition, a successful test will open exploration in basement reservoirs in other areas on the Norwegian shelf.

This summer, Lundin is planning an exploration well in Goddo, which is a prospect in fractured weathered bedrock in the vicinity of Rolvsnes.