Pore-Scale Numerical Simulation of CO2 Hydrate Formation

Fuji, Tatsuya (University of Tokyo OTPE) | Sato, Toru (University of Tokyo OTPE) | Oyama, Hiroyuki (University of Tokyo OTPE)

OnePetro 

ABSTRACT

Carbon Capture Storage method is expected to be counterpart for global warming but it holds also a risk of CO2 leaking in the sea. CO2 hydrate formation has the potential of solving the problem. The aim of this work is to build CO2 hydrate formation model based on previous studies. In order to determine hydrate growth rate, matching with temperature rise of experimental result, interface mobility parameter was decided.

After several numerical calculations, the order of interface mobility parameter was identified.

INTRODUCTION

As one of the methods to suppress the global warming, Carbon Capture and Storage(CCS) attracts much attention over the world.

CCS method is gathering CO2 gases from big emission source such as factory or thermal power plant and accumulating them under the seafloor.

By the method, it can be expected to reduce the concentration of CO2 in the atmosphere. In the other hand, CCS method holds also the risk of CO2 defluxion in the sea. If stored CO2 leak into the sea, it may make impacts to ecological system in the sea and CO2 concentration in atmosphere.

To prevent the CO2 defluxion from the seabed CO2 hydrate technology is taken into account. CO2 hydrate has cage structures that trap CO2 molecules in water molecules. Hydrate is stable under high temperature and low temperature condition. Though the areas in which CO2 is stored are unstable for hydrate structure, if accumulated CO2 gases arrived seafloor in which temperature become lowest, it makes hydrate structure. Then generated CO2 hydrates reduce the width of CO2 gases flow to the sea (Fig. 1).

To estimate how much CO2 hydrate can block the CO2 gases flow, it is necessary to calculate change of permeability under the sea floor by the CO2 hydrate generation.

As previous work, (Fukumoto 2013) used the Phase-Field Model (PFM), which simulates the growth of CH4 hydrate and calculated permeability change in porous media.

The objective of this research is to develop a PFM for the growth of CO2 hydrate, based on the model of Fukumoto (2013) in order to evaluate how CO2 hydrate formation prevents the gas leakage.