Abstract

In the current study, a novel methodology is introduced based on classical conservation model equations of mass, momentum and heat transfer in porous media sediments. Set of model equations have been used in discrete form to investigate liquefied high pressure CO2 transformation into solid hydrates. During this numerical analysis, CO2 phase transition, effect of hydrate nucleation on temperature variations by exothermic heat release and effect of injected CO2 pressure and temperature on hydrate growth speed have been studied.

The results of numerical simulation show that at 0.01 Darcy intrinsic permeability of formation, a significant pressure delay is witnessed during CO2injection in hydrate formation. At 18 MPa injection pressure, the pressure hardly becomes stable during 4 weeks of hydrate growth process. Due to slow pressure distribution, it also affects temperature distribution and hydrate covered length during hydrate growth process. Low formation absolute permeability decreases the speed of injected CO2 and it is also unable to reduce the temperature of formation. Thus, the temperature near the injection point continuously increases at initial stage of hydrate growth process(during 1stweek) and finally, exceeds the formation initial local temperature. From 2nd week, the exothermic effect diminishes and temperature starts decreasing near the wellbore region but in the far zones it exceeds from initial temperature and temperature boundary moves towards extended formation. The partially saturated hydrate covered length during this time is 585 m with 315 m fully saturated hydrate region length. When the injection pressure is increased to 19 MPa, both regions extend to 617 m and 325 m respectively. The 5 K decrease in injected CO2 temperature doesn't give any appreciable results. But if dual-injection method is used, the hydrate storage capacity can be enhanced significantly using less injection pressure.

This content is only available via PDF.
You can access this article if you purchase or spend a download.