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Fig. 2 SW-NE trending seismic profile southwest of Margretheholm (left). Theprofile illustrates the importance of identifying faults, which reduce the lateralreservoir continuity. The map (right) displaying the depth to the top of theBunter reservoir shows the location of the seismic lines and illustrates thesouthwards shallowing of the reservoir top, the disappearance of thereservoir (southern white area) and the faults cutting the reservoir (greytone). Red dot: Margretheholm and the wells MAH-1 and MAH-2.Porosity and permeabilityPorosity and permeability decrease with increasing burial depth due tomechanical compaction and formation of diagenetic minerals that reducepore volume (porosity) and pore connections (permeability) (Figs 3 & 4; 5).The amount of diagenetic alteration is related to petrography of the sedimentsource areas, sorting and grain sizes of the material supplied to the basins,burial depth and temperature, and chemistry of the formation water. Thus thevarious depositional processes, mineralogy of the reservoir rocks and theirsubsequent burial history determine their qualities as geothermal reservoirs.6Risø International Energy Conference 2011 Proceedings Page 132