Characterization and Properties of Reaction Majnoon Field Rock Stone with Carbon Dioxide

Abstract

Under simulated in-situ settings (T = 60°C, P = 74bar, 87-day batch tests), representative Majnoon rock stone samples from the Majnoon Field (Iraq) were analyzed to study geo-chemical responses arising from CO2 exposure. Albite, calcite, quartz, feldspars, clinochlore, dolomite, kaolinite, muscovite, orthoclase, and ankerite were among the mineral phases found by XRD examination. Because of the dissolution of minerals, the CO2 interaction caused the brine to become acidic and enriched in cations. Elements including silicon, oxygen, sodium, calcium, chlorine, carbon, fluorine, magnesium, and aluminum were verified by SEM and EDX. Prior to the reaction, kaolinite had the lowest phase abundance (~0.77 wt%) and calcite the greatest (~67 wt%). After the reaction, orthoclase dramatically dropped (~0.41 wt%), but calcite remained dominant (~69.67 wt%).. The highest reaction percentages were recorded for albite (~82%) and orthoclase (~84%), while kaolinite and quartz showed the lowest (~14% and ~24%, respectively). CO₂ addition caused a pH drop and led to calcium concentrations reaching ~1009 mg/L within five days. The study comes to the conclusion that carbonate dissolution, phyllosilicate (clinochlore/muscovite) hydrolysis, and montmorillonite precipitation are all involved in the CO2–Majnoon rock stone interaction.