Evaluation of CO₂-Fluid-Rock Interaction in Enhanced Geothermal Systems: Field-Scale Geochemical Simulations

Table 3

Chemical composition and initial volume fractions of primary and secondary minerals for geochemical simulations of the St. John’s CO₂ field site.

Mineral	Chemical composition	Initial volume fraction of minerals
Primary
Quartz	SiO2	0.475
Oligoclase	Na0.77Ca0.23Al1.23Si2.77O8	0.280
K-Feldspar	KAlSi3O8	0.200
	KFe3AlSi3O10(OH)2	0.0075
	KAlMg3Si3O10(OH)2	0.0075
Muscovite	KAl3Si3O10(OH)2	0.025
Secondary
Calcite	CaCO3	0.0
Magnesite	MgCO3	0.0
Illite	(K,H3O)(Al,Mg,Fe)2(Si,Al)4O10[(OH)2,(H2O)]	0.0
Smectite	K0.04Ca0.5(Al2.8Fe0.53Mg0.7)(Si7.65Al0.35)O20(OH)4	0.0
Kaolinite	Al2Si2O5(OH)4	0.0
Chlorite	Mg2.5Fe2.5Al2Si3O10(OH)8	0.0
Albite	NaAlSi3O8	0.0
Hematite	Fe2O3	0.0
Dolomite	CaMg(CO3)2	0.0
Ankerite	CaMg0.3Fe0.7(CO3)2	0.0
Dawsonite	NaAlCO3(OH)2	0.0
Siderite	FeCO3	0.0

Biotite is assumed as 50% of Annite and 50% of Phlogopite.