Numerical Simulation of Effects of Microbial Action on CO 2 Geological Storage in Deep Saline Aquifers
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Original Paper
Numerical Simulation of Effects of Microbial Action on CO2 Geological Storage in Deep Saline Aquifers Xiaofang Shen,1,3 Weihong Dong,1,3 Yuyu Wan,2,4,5 Fengjun Zhang,2,4 Zhijiang Yuan,1,3 and Qichen Zhang1,3 Received 31 July 2020; accepted 3 November 2020
CO2 geological storage (CGS) is a crucial strategy for meeting CO2 emission reduction targets. However, the effect of microbial action on CGS in deep saline aquifer is unclear. In this paper, numerical simulations based on previous experimental data were conducted to investigate CO2 solubility-trapping and mineral-trapping by microbial-mediated process in CGS demonstration base in Ordos, north of China. The simulation results reveal that the presence of a microbial community has a positive influence on CGS, mainly in terms of the amount of CO2 that can be injected and the manner by which it is stored. With the effect of microbial action, the amount of injected CO2 was increased by 23.33% and the CO2 mineral sequestration increased from 1.12 to 2.05%. In addition, microbial action plays different roles at different stages of CGS. In the initial stage of CO2 injection, the microbial action promotes dissolution of calcite, oligoclase and clay minerals such as chlorite and kaolinite, providing a favorable condition (more K+, Ca2+, Na+, Mg2+, Fe2+ and HCO3) for CO2 mineral-trapping. In the following stage of CGS, microbial action accelerates the precipitation of carbon-fixing minerals such as calcite and siderite, enhancing the CO2 storage security in deep saline aquifer. As such, secondary minerals such as ferroan dolomite and dawsonite were observed in advance in microbially mediated CO2–saline–sandstone interactions, further indicating that microbes play a positive role in CO2 mineral-trapping. Consequently, the microbial action can promote mineral capture of CO2 and increase the CO2 storage security in deep saline aquifer. These conclusions can provide a reference and basis for the suitability assessment of CGS in such deep saline aquifer like Erdos, China. KEY WORDS: CO2 geological storage (CGS), Microbial action, Numerical model, Precipitation and dissolution of minerals.
INTRODUCTION 1
College of Construction Engineering, Jilin University, Changchun 130021, Jilin, China. 2 Key Laboratory of Groundwater Resources and Environments, Ministry of Education, Jilin University, Changchun 130021, Jilin, China. 3 Institute of Water Resources and Environment, Jilin University, Changchun 130021, Jilin, China. 4 Jilin Provincial Key Laboratory of Water Resources and Environment, Jilin University, Changchun 130021, Jilin, China. 5 To whom correspondence should be addressed; e-mail: [email protected]
CO2 emissions from fossil fuels into the atmosphere have become the main gas contributing to the greenhouse effect (Boot-Handford et al. 2013; Sanna et al. 2015). The greenhouse effect creates a series of ecological problems, such as sea-level rise and increase frequency of extreme weather events globally (Huntingford and Mercado 2016). Hence, dealing with CO
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