Objectives

1. The thermal effects of sills. Here the focus is on how emplacement of individual sills versus rapid emplacement of sill clusters (complexes) affects the thermal history of the area.
2. Sills (and dykes) as seals for reservoirs. When sills (and dykes) are emplaced, they form chilled selvages (thin, glassy margins) that may have very low permeability. Furthermore, the host rock may become "baked", that is, contact metamorphosed, close to the sill. This sort of contact metamorphism is particularly common during the emplacement of sills in sedimentary or pyroclastic rocks. The baked zone may develop a low permeability, thereby contributing to the sill acting as a seal for a porous sedimentary rock below.
3. Sill (and dyke) contribution to the formation of fractured reservoirs. This contribution follows from two factors. First, there is stress concentration in the vicinity of a sill when it becomes emplaced, in particular at sill-dyke contacts. Second, for layered rocks where the stiffness (Young's modulus) varies abruptly between layers, sill (and dyke) emplacement may induce high stresses in stiff layers far from the sill/dyke. In both cases the intrusion-induced stresses may generate or reactivate fractures, increasing the fracture-related porosity and permeability of the stiff layers, and, thereby make them suitable as potential reservoirs.
4. Items 2-3 will be studied using as following methods and data: (a) Seismic data (images) from the Vøring area, particularly on sills (Fig. 2), but also field data on sills from other areas, such as Iceland. (b) Analytical models (from fracture mechanics, materials science, and rock-and fluid physics). (c) Numerical modelling of sill and dyke emplacement in layered rocks.
5. The thermal effects of sills (Item 1) may cause additional diagenetic alteration of the sediments. This includes quartz cementation in the reservoirs and smectite illitization in the cap rock.
6. The emplacement of sills and dykes will cause heating and boiling of the pore fluids of the host sediments. Additional degassing of the magma may also contribute to the increased pore pressure. This may lead to episodic fluid flow forming hydrothermal vents. The pore pressure and fluid flow related to heating of the pore fluids, as well as degassing, will be studied.
7. Hydrocarbon migration may be affected by magmatic intrusions in different ways. Modelling of hydrocarbon migration through hydrothermal vents will be performed and calibrated to observed hydrocarbon accumulations.