CO2 Convective Dissolution in Oil-Saturated Unconsolidated Porous Media at Reservoir Conditions

Widuramina Amarasinghe,Nils Giske,Ingebret Fjelde,Ying Guo

doi:10.3390/en14010233

Widuramina Amarasinghe, Nils Giske + Show 2 more

Open Access

https://doi.org/10.3390/en14010233

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Abstract

During CO2 storage, CO2 plume mixes with the water and oil present at the reservoir, initiated by diffusion followed by a density gradient that leads to a convective flow. Studies are available where CO2 convective mixing have been studied in water phase but limited in oil phase. This study was conducted to reach this gap, and experiments were conducted in a vertically packed 3-dimensional column with oil-saturated unconsolidated porous media at 100 bar and 50 °C (representative of reservoir pressure and temperature conditions). N-Decane and crude oil were used as oils, and glass beads as porous media. A bromothymol blue water solution-filled sapphire cell connected at the bottom of the column was used to monitor the CO2 breakthrough. With the increase of the Rayleigh number, the CO2 transport rate in n-decane was found to increase as a function of a second order polynomial. Ra number vs. dimensionless time τ had a power relationship in the form of Ra = c×τ−n. The overall pressure decay was faster in n-decane compared to crude oil for similar permeability (4 D), and the crude oil had a breakthrough time three times slower than in n-decane. The results were compared with similar experiments that have been carried out using water.

Highlights

CO2 storage is a commonly considered topic when it comes to climate change mitigation
We experimentally investigated CO2 convective mixing inside an oil-saturated porous media at realistic reservoir pressure and temperature conditions (100 bar and 50 °C)
CO2 breakthrough time was quantitatively measured with porous media of different permeabilities

Summary

Introduction

CO2 storage is a commonly considered topic when it comes to climate change mitigation. When CO2 is injected into the oil fields, a CO2 plume will usually develop above the fluid phases inside the porous media due to the low density of CO2 compared to the density of the reservoir fluids, as shown in Figure 1 [8]. This CO2 plume mixes with the oil and water phases present in the reservoir mainly due to diffusion. It is essential to know the behavior of the CO2 plume in the reservoir along with how CO2 will dissolve convectively into the oil phase This helps to understand how CO2 will be transported during long-term storage after injection for storage and EOR.

Experimental Setup

Set of Experiments

Conclusions