Abstract
Microbially induced calcite precipitation (MICP) is a new and sustainable technology which utilizes biochemical processes to create barriers by calcium carbonate cementation; therefore, this technology has a potential to be used for sealing leakage zones in geological formations. The complexity of current MICP models and present computer power limit the size of numerical simulations. We describe a mathematical model for MICP suitable for field-scale studies. The main mechanisms in the conceptual model are as follow: suspended microbes attach themselves to the pore walls to form biofilm, growth solution is added to stimulate the biofilm development, the biofilm uses cementation solution for production of calcite, and the calcite reduces the pore space which in turn decreases the rock permeability. We apply the model to study the MICP technology in two sets of reservoir properties including a well-established field-scale benchmark system for CO2 leakage. A two-phase flow model for CO2 and water is used to assess the leakage prior to and with MICP treatment. Based on the numerical results, this study confirms the potential for this technology to seal leakage paths in reservoir-caprock systems.
Highlights
Negative emissions technologies and carbon storage must be implemented to avoid dangerous climate changes (Haszeldine et al, 2018; Tong et al, 2019)
We summarize the main assumptions that we have adopted to build the simplified Microbially induced calcite precipitation (MICP) model: only one fluid phase and three solid phases are presented, there are only three rate-limiting components dissolved in the fluid phase, the amount of urease is only related to the amount of biofilm, and the calcite formation only depends on urea and biofilm
Since the flow velocities near the injection side are higher in radial flow (e.g., 2D flow horizontal circular system (2Dfhcs)) than in plug flow (e.g., 1D flow horizontal system (1Dfhs)), in the former the Damkoler numbers are lower in this region which effects the MICP process [see e.g., Zambare et al (2019)]
Summary
Negative emissions technologies and carbon storage must be implemented to avoid dangerous climate changes (Haszeldine et al, 2018; Tong et al, 2019). Carbon capture and storage (CCS) is one of the promising scalable technologies for storing huge amounts of CO2. Caprocks in reservoirs provide the main trapping mechanism for CO2 sequestration (Bentham and Kirby, 2005). The existence of faults, fractures, and abandoned wells in the primary sealing caprock of a CO2 storage reservoir can create pathways for CO2 to migrate back to the surface (Fang et al, 2010).
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