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Preliminary geochemical investigation of a possible CO 2 injection in the Ungaran geothermal field, Indonesia: equilibrium and kinetic modeling
Author(s) -
Utomo Gagas Pambudi,
Güleç Nilgün
Publication year - 2021
Publication title -
greenhouse gases: science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.45
H-Index - 32
ISSN - 2152-3878
DOI - 10.1002/ghg.2037
Subject(s) - calcite , geochemical modeling , geothermal gradient , brine , solubility , dissolution , carbon dioxide , mineralogy , geology , geochemistry , petroleum engineering , chemistry , organic chemistry , geophysics
Carbon capture and storage (CCS) is considered to be an effective method to mitigate anthropogenic carbon emissions that have been the major cause of global warming. One of the possible sites to store CO 2 is in geothermal reservoirs. In this study, an attempt to simulate CO 2 –brine reservoir rock interaction inside a geothermal reservoir is carried out using the PHREEQC program. The study utilizes published rock mineralogy of the assumed reservoir lithology and chemistry of the hot water in the Ungaran geothermal field, Java, Indonesia. The simulation is based on equilibrium and kinetic modeling and assumes a single stage CO 2 injection kept at a constant temperature and pressure. The amount of injected CO 2 is determined by solubility modeling of CO 2 in hot water under estimated reservoir conditions. The modeling predicted (i) the effect of solubility trapping at early stages of CO 2 –brine rock interaction, (ii) dissolution of Ca‐bearing silicates (plagioclases) coupled with calcite precipitation as a potential chemical processes relevant to a possible CO 2 mineralization, (iii) progressive transition from solubility to mineral trapping becoming significant after 30 days following injection, (iv) minor porosity increase (∼0.5%), and (v) achievement of equilibrium between CO 2 –brine‐rock in 10 years after injection. Sensitivity analysis associated with the uncertainties for altering mineral proportion and rock porosity reveal no significant change in the ability of the modeled reservoir to trap injected CO 2 into mineral phases. Concerning the CCS studies so far carried out in geothermal fields in volcanic reservoirs, this modeling comprises one of the first performed for fields with intermediate volcanics. The result from this study can be utilized as foreknowledge for possible future CCS operations in Indonesian geothermal fields. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.