**7. Conclusions**

Detailed study of seismic data from our study area revealed a complex development of salt structures since early Triassic time, involving both the extensional and compressional phases.

Our detailed modeling has recreated the salt evolution and shown that the presence of salt structures have a substantial e ffect on temperature and maturation, both close to the salt itself, and in a larger distance around and below salt structures.

The results show that basin areas at least 3–5 km to the sides of the salt structures are a ffected by lowered temperatures and maturation. The conductivity e ffect of salt increases toward the surface and thus salt structures near or at the surface are more e fficient at draining heat out of the basin.

Temperatures increase in the sediments above the salt structures, but this has very little impact on maturation, because the heated sediments are too shallow and the temperature increase too small to increase maturation potential. The cooling of the sediments around salt structures may play a larger role as it a ffect larger areas and in deeper units. Cooling of the sediments due to presence of salt may be a very important factor in hydrocarbon exploration in regions with salt structures.

The geometry of the present day salt and its history of development are very important. A vertical columnar salt diapir will have a symmetrical temperature anomaly around the salt. If an irregular salt geometry develops with a shallow overhanging salt volume, an increased temperature anomaly would occur below the salt overhang, possibly preserving maturation in the position of stratigraphic traps. A larger area above the salt is also a ffected by heating than for a narrow columnar structure. Our modeling software allows modeling of complex development of such overhanging salt structures.

A simple salt anticline or a vertical salt column still connected to the initial salt layer has the largest salt volumes at depth where the conductivity-contrast to the surrounding sediments is the least. A detached allochtonous salt volume [2] or a canopy or mushroom-shaped salt structures have most of its salt volume at shallower depths where they can more e ffectively drain the heat from sediments below.

In our modeling, the e ffects on maturation occur at depths below 2 km, and at depths of more than 3.5–4 km the maturation levels are lowered as much as 500 m in pod-basins between vertical diapirs and as much as 1–1.5 km below and overhanging mushroom-shaped salt structure. This shows that the e ffect is substantial enough that it should be considered when exploring for hydrocarbons in salt regions.

**Author Contributions:** Conceptualization, I.G. and A.M.; methodology, I.G.; software, I.G.; validation, I.G. and A.M; investigation, I.G.; writing—original draft preparation, I.G. and A.M.; writing—review and editing, I.G. and A.M.; project administration, I.G.; funding acquisition, I.G.

**Funding:** This research received no external funding.

**Acknowledgments:** First we have to thank LOTOS Exploration and Production Norge AS (LEPN), the operator of PL 498/B, for letting us publish results based on their data, for their valuable input and help with expertise and data. Also thanks to the partners in PL 498/B; Skagen 44, Edison, North and Lime. Thanks to Willy Fjeldskaar, Ingrid F. Løtveit and two anonymous reviewers for constructive comments and suggestions.

**Conflicts of Interest:** The authors declare no conflict of interest.
