Fig. 10From: Crystallization of calcium carbonate in a large-scale push–pull heat storage test in the Upper Jurassic carbonate aquiferTypical carbonate crystals during \(T_{\mathrm{Inj}} = 65\), 80, and \(90\,^{\circ }\hbox {C}\): SEM picture (left) and corresponding EDX spectrum (right). Examples for injection at \(80\,^{\circ }\hbox {C}\) (Picture 2) and production at \(45\,^{\circ }\hbox {C}\) (Picture 1, \({T}_{\mathrm{Inj}} = 65\,^{\circ }\hbox {C}\)) and at \(31\,^{\circ }\hbox {C}\) (Picture 3, \({T}_{\mathrm{Inj}} = 80\,^{\circ }\hbox {C}\)). All pictures at these injection temperature indicate irregular calcite crystallization. Still, the morphology suggests rhombohedral calcite crystals. Some of these crystals are magnesium bearing (see Picture 3)Back to article page