Simulation of Large-Scale CO2 Plumes in Deep Saline Aquifer
Abstract/Contents
- Abstract
- The behavior of CO2 plumes in large confined sloping aquifers was simulated. The objective was to reduce the run times required for fine scale simulations, while having reasonable accuracy of the behavior of the CO2 plume under residual and solubility trapping. A reduced-physics numerical model was formulated using immiscible phases: gas and water. A sink term was added in the mass conservation governing equation for the CO2 and this acted as a surrogate for the dissolution of CO2 in the underlying brine. A finite volume of CO2 was initialized at the left down-dip boundary of a two-dimensional gently sloping reservoir representing a saline aquifer. The pre-detachment period begins at initial conditions and ends at the detachment time. The detachment time is when the topmost gridblock at the down-dip boundary reaches the irreducible non-wetting phase saturation. Fine-scale immiscible two-phase simulations were first performed for the pre-detachment period, where solubility trapping was ignored. The saturation profiles at detachment time were converted into a spatially upscaled compositional model, after which the plume evolution was simulated in the post-detachment period. In the post-detachment period, the plume propagates as a gravity current toward the up-dip direction. Both solubility and residual trapping were included in the simulation model. A sensitivity study was done to study the effects of spatial resolution on the position of the tip of the plume and dissolution flux of CO2 into the aqueous phase. The use of coarse models increased the speed of the plume migration and decreased the magnitude of the dissolution flux during the first 200 years of simulation. A sink term was added in the formulation of the purely immiscible two-phase simulation. The modified formulation is referred to as Immiscible Phases with Sink term (IPS). The sink term was applied only to blocks at the CO2-brine interface. The sink term is equivalent to the total flow area and timestep size multiplied by the dissolution flux obtained from compositional simulations. Compared with the immiscible simulations, the IPS formulation shows improved accuracy for the position of the plume and the distribution of CO2 in the mobile and immobile gas phases. Savings of 60-80% in run time were achieved using IPS compared with the compositional simulations. This provides a new method for large scale CO2 simulation during the post-detachment period.
Description
| Type of resource | text |
|---|---|
| Date created | June 2014 |
Creators/Contributors
| Author | Lagasca, Joseph Paul |
|---|---|
| Primary advisor | Tchelepi, Hamdi |
| Degree granting institution | Stanford University, Department of Energy Resources Engineering |
Subjects
| Subject | School of Earth Energy & Environmental Sciences |
|---|---|
| Genre | Thesis |
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Preferred citation
- Preferred Citation
- Lagasca, Joseph Paul. (2014). Simulation of Large-Scale CO2 Plumes in Deep Saline Aquifer. Stanford Digital Repository. Available at: https://purl.stanford.edu/ng540yf2358
Collection
Master's Theses, Doerr School of Sustainability
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