Impure CO2 Research Articles

Determination of minimum near miscible pressure region during CO2 and associated gas injection for tight oil reservoir in Ordos Basin, China

CO2 flooding is believed as an effective and promising method to enhance oil recovery. However, for tight oil reservoirs of Long Dong (LD) region in Ordos Basin, CO2 flooding cannot achieve miscible condition since reservoir pressure is lower than minimum miscibility pressure (MMP). Meanwhile, this region has abundant associated gas production. Impure CO2 with associated gas re-injection at the near-miscible condition is a promising enhanced oil recovery (EOR) method which may solve the problem above. This study aims to investigate the oil recovery potential of this method by conducting experiments and simulations. Firstly, based on the reservoir condition (64 ℃), slim-tube experiments and simulations were performed to acquire correlations of pressure, interfacial tension (IFT) and oil recovery of pure CO2 flooding. Then the MMP, the minimum near-miscible pressure (MNMP), and near-miscible region were determined. The pressure interval of the near-miscible region ranges from 17.82 MPa to 22.75 MPa. Secondly, the minimum CO2 concentration for conducting impure CO2 with associated gas re-injection at the near-miscible condition was investiaged, which is 73.3% for the target formation. Furthermore, by studying the composition of injected gas, it is found that the presence of methane and nitrogen impedes oil and gas to achieve the miscible or near-miscible phase. With the decrease of CO2 concentration of injected gas by 10% or the concentration of impurities in the injected gas increases by 7% each time, MMP and NMMP increase by 1.08 MPa and 0.89 MPa, respectively. This study explores the feasible application of using impure CO2 with associated gas re-injection to improve oil recovery for tight oil reservoirs.

Unlocking the impurity-induced pipeline corrosion based on phase behavior of impure CO2 streams

This study explored the phase behavior of impure CO2 streams and further unmasked its effects on pipeline corrosion by combing thermodynamic calculation and corrosion test. Thermodynamically, H2S impurity promotes water precipitation via reducing the H2O solubility in CO2. H2S-induced phase distribution changes point to the root cause of H2S-enhanced corrosion. To mitigate the above effects from impure CO2 streams on pipeline steel, we prepared an amorphous Ni–P coating on steel and found that the formation of protective film endows the coating with good corrosion resistance. Hence, more than 80 % of corrosion effects and the localized corrosion are effectively prevented.

Understanding gas-phase breakout with high H2 content in CCS pipeline gathering networks

An accurate understanding of the behaviour of impure carbon dioxide (CO2) during pipeline transport stage is required for commercial scale deployment of Carbon Capture and Storage (CCS) networks. Impurities in the CO2 stream modify phase behaviour and change the thermophysical and transport properties of the stream. CO2 streams containing hydrogen (H2) are a particular challenge due to the unique physical properties of H2. In a CCS gathering network where CO2 is sourced from processes such as pre-combustion capture or hydrogen production, H2 with a concentration of 2% mol can be expected to be present in the mixture.This paper describes foreseeable operating scenarios where gas breakout in single-phase CCS gathering networks might occur, leading to pockets of gas with high H2 concentration. Multiphase flow modelling of a CCS gathering network with impure CO2 containing H2 has been performed, demonstrating these operating scenarios and providing a basis for design. The H2 content of the gas breakout is shown to be >20% mol when the conditions are close to bubble point.High concentrations of H2 due to gas breakout must be considered as part of a single-phase CCS gathering network design, whenever H2 is present. This paper provides practical guidelines for understanding, quantifying and, managing the worst design cases for H2 exposure due to gas breakout. Specific recommendations for what must be included in the project design basis are presented. Potential mitigating factors and engineering measures that can be taken to manage high H2 concentration in a CCS system are also discussed.

Factorial two-stage analyses of parameters affecting the oil–gas interface and miscibility in bulk phase and nanopores

In this paper, a factorial analysis approach is applied to characterize the potential single and interactive factors as well as their effects on the interface and miscibility of three light oil–CO2 systems under 32 different conditions. First, a modified Peng–Robinson equation of state coupled with the parachor model is applied to calculate the vapour–liquid equilibrium and interfacial tensions (IFTs) at a variation of pore radii and different pressures, based on which the MMPs are determined from the diminishing interface method. Second, by means of the factorial-analysis approach and calculated IFTs and minimum miscibility pressures (MMPs), the following five factors are specifically studied to evaluate their main and interactive effects on the IFTs and MMPs: temperature, initial oil and gas compositions, feed gas to oil ratio (feed GOR), and pore radius. It is found that the main and interactive effects of the five factors on the IFTs are inconsistent at different pressures. The effects of the five factors on the MMPs are evaluated quantitatively, which contribute to screen out significant factors, analyze interactions, and identify schemes for the miscible CO2 enhanced oil recovery. The most positive significant main and interactive effects on the MMPs are Factors C (gas composition) and AB (temperature and oil composition), whereas the most negative results are Factors E (pore radius) and AC (temperature and gas compositions). A three-factor analysis indicates that the MMP is substantially reduced in small pores by controlling the percentage of the CH4-dominated gas in the impure CO2 sample and lowering the feed GOR.

(Invited) Polymer Electrolyte Fuel Cell Catalysis - Older Goodies and New Concepts

Polymer Electrolyte Fuel Cell (PEFC) Research has been performed over the more than 30 years now with the results that both stationary and automotive systems are commercially available. Two prominent examples are the Enefram stationary systems in Japan with more than 250 000 installed systems, and several commercial and pre-commercial fuel cell cars from e.g. Toyota, Hyundai and Honda. Catalysis in PEFC has been mainly dominated by research on the oxygen reduction reaction over the last 20 years; however specifically for the stationary system, anode catalysis using impure CO containing hydrogen streams from reforming reactions are still quite important but less prominent nowadays. In this contribution, a subjective selection of important new PEFC catalysis concepts as well as still important elder goodies from the last 20 years will be given and an attempt is made to connect this summary to Shimshon Gottesfeld's work.

Insights into the Interfacial Process in Electroless Ni-P Coating on Supercritical CO2 Transport Pipeline as Relevant to Carbon Capture and Storage.

To reduce the amount of greenhouse gas emissions and remedy related environmental damage, the research on carbon capture and storage (CCS) is gaining momentum and so is the search for a more effective way to control corrosion of pipeline steel used to transport impure supercritical (SC) CO2. Herein, we prepared an electroless high-phosphorus Ni-P coating and, for the first time, systematically explored the underlying mechanism of the interfacial process in applying Ni-P coating to protect pipeline steel that transports impure SC CO2. It is found that, benefiting from the formation of a protective surface film, Ni-P coating significantly mitigates the corrosion effects from SC CO2 and impurities (e.g., O2 and NO2), especially the synergistic effect of impurities. Concurrently, it effectively avoids the localized corrosion resulting from nonuniform adsorption of the aqueous phase. Although O2 and NO2 can degrade the coating through boosting water precipitation, deteriorating the water chemistry, and reducing the surface film protectiveness, the corrosion inhibition efficiency of Ni-P coating is invariably higher than 80%, independent of the varying causticity of SC CO2 streams, demonstrating that the coating has a superior stability toward corrosion attack. The as-prepared Ni-P coating undoubtedly holds great potential as an alternative for corrosion control of CO2 transport pipeline in the CCS industry. This work provides a new, feasible method to ensure the safe and efficient operation of CCS.

Modeling the Saturation Pressure of Systems Containing Crude Oils and CO2 Using the SRK Equation of State

This work investigates the saturation pressure of crude oil–CO2 mixtures and how the oil plus-fraction characterization methods affect it. Different distribution functions were tested to split the plus-fraction as well as correlations to calculate the critical parameters and the acentric factor. The Soave–Redlich–Kwong (SRK) equation of state was used to calculate the saturation pressure of the crude oil and its mixtures with pure and impure CO2. The results were compared with experimental data and reveal that the effect of the characterization methods on the modeling of the saturation pressure of reservoir fluids is strong mainly for CO2 molar fraction values higher than 50%.

Role of residual 2-amino-2-methyl-1-propanol and piperazine in the corrosion of X80 steel within an impure supercritical CO2 environment as relevant to CCUS

The corrosion of steels in the supercritical CO2 environment with impurities in a carbon capture, utilization and storage system has attracted great interests in recent years. In this work, corrosion inhibition mechanisms of the residual 2-amino-2-methyl-1-propanol and piperazine from the CO2 capture process on X80 steel within an impure supercritical CO2 environment were investigated by weight-loss method and surface analysis techniques. The results showed that a small amount of 2-amino-2-methyl-1-propanol had marginal effect on the corrosion of steel. Corrosion rate was decreased as the 2-amino-2-methyl-1-propanol concentration increased further. When 100 ppm 2-amino-2-methyl-1-propanol + 50 ppm piperazine was added, a lowest corrosion rate was observed, reaching 0.41mm/a. Meanwhile, pitting corrosion was observed under all conditions. The combination of 2-amino-2-methyl-1-propanol and piperazine cannot inhibit pitting corrosion efficiently, while flow accelerated the propagation of pits in the presence of 2-amino-2-methyl-1-propanol. FeSO4 was confirmed as the corrosion product for all conditions. RNH3+, PZH+, Fe2O3 and Fe3O4 were detected in the corrosion products depending on the test conditions. The results indicated that the inhibition mechanism of piperazine and 2-amino-2-methyl-1-propanol was attributed to both the neutralization and adsorption effects on the steel surface. A non-uniform adsorption inhibition mechanism is proposed based on these test results.

New empirical correlations for predicting Minimum Miscibility Pressure (MMP) during CO2injection; implementing the Group Method of Data Handling (GMDH) algorithm and Pitzer’s acentric factor

Miscible injection of carbon dioxide (CO2) with ability to increase oil displacement as well as to reduce greenhouse effect has become one of the pioneering methods in Enhanced Oil Recovery (EOR). Minimum Miscibility Pressure (MMP) is known as a key indicator to ensure complete miscibility of two phases and maximum efficiency of injection process. There are various experimental and computational methods to calculate this key parameter. Experimental methods provide the most accurate and valid results. However, such methods are time consuming and expensive leading researchers to use mathematical methods. Among computational methods, empirical correlations are the most straight-forward and simple tools to precisely estimate MMP, especially for gases with impurities.Furthermore, in predicting the miscibility state of oil–gas system, phase behavior is a vital issue which should be taken into account to achieve reliable results. In this regard, equations of state have an indisputable role in predicting the phase behavior of reservoir fluids. Remarkable improvements have been introduced to elevate performance of equations of state, based on Pitzer’s acentric factor. Hereupon, this study aims to enumerate acentric factor of injected gas (impure CO2) as a correlating parameter alongside conventional parameters including reservoir temperature, oil constituents (molecular weight of C5+, ratio of volatiles to intermediates) and critical properties of injected gas (pseudo-critical pressure & temperature).Thus, in this study an effective empirical correlation is created, implementing the Group Method of Data Handling (GMDH) algorithm along with including the acentric factor of injected gas, which eventuated to precise predictions of MMP for impure CO2injection. The GMDH is one of the most robust mathematical modeling methods for predicting physical parameters using linear equations.A comparison with well-known correlations, demonstrated at least 2% improvement in average absolute error with enumerating the acentric factor and the final error was equal to 12.89%.

Suppressing the formation of NOx and N2O in CO2/N2 dielectric barrier discharge plasma by adding CH4: scavenger chemistry at work

Significantly suppressing the in situ NOx formation during plasma based conversion of low-cost impure CO2 feeds, by adding chemical scavengers.

An improved correlation to determine minimum miscibility pressure of CO2–oil system

An accurate and reliable estimation of minimum miscibility pressure (MMP) of CO2–oil system is a critical task for the design and implementation of CO2 miscible displacement process. In this study, an improved CO2–oil MMP correlation was developed to predict the MMP values for both pure and impure CO2 injection cases based on ten influential factors, i.e. reservoir temperature (TR), molecular weight of C7+ oil components (MWC7+), mole fraction of volatile oil components (xvol), mole fraction of C2C4 oil components (xC2-C4), mole fraction of C5C6 oil components (xC5-C6), and the gas stream mole fractions of CO2 (yCO2), H2S (yH2S), C1 (yC1), hydrocarbons (yHC) and N2 (yN2). The accuracy of the improved correlation was evaluated against experimental data reported in literature concurrently with those estimated by several renowned correlations. It was found that the improved correlation provided higher prediction accuracy and consistency with literature experimental data than other literature correlations. In addition, the predictive capability of the improved correlation was further validated by predicting an experimentally measured CO2–oil MMP data, and it showed an accurate result with the absolute deviation of 4.15%. Besides, the differential analysis of the improved correlation was analyzed to estimate the impact of parameters uncertainty in the original MMP data on the calculated results. Also, sensitivity analysis was performed to analyze the influence of each parameter on MMP qualitatively and quantitatively. The results revealed that the increase of xC2-C4, xC5-C6 and yH2S lead to the decrease of MMP, while the increase of TR, MWC7+, xvol, yCO2, yC1, yHC and yN2 tend to increase the MMP. Overall, the relevance of each parameter with MMP follows the order of TR > xC5-C6 > MWC7+ >xvol > yH2S > yHC > yCO2 >yC1 >yN2 >xC2-C4.

Onset of convection controlled by N2 impurity during CO2 storage in saline aquifers

This paper presents experimental and theoretical studies of the onset of natural convection induced by the dissolution of carbon dioxide- nitrogen (CO2-N2) mixtures into brine. Using a high- pressure Hele-Shaw cell, we conducted four sets of experiments under high-pressure conditions (with initial pressure range of 3375 to 3691 kPa) where 0%, 10%, 20% and 100% (molar base) N2 at different brine salinities and permeability (Rayleigh number of 3120 to 4840) were conducted to obtain quantitative and qualitative data from pressure decay and image analysis respectively. Furthermore, we performed Linear Stability Analysis (LSA) based on the quasi-steady-state approximation and Direct Numerical Simulation (DNS) to theoretically examine the effect of N2 on the onset of convection. We calculated effective diffusion coefficients from experimental data, and then used them in the LSA and DNS analyses. The experimental results confirmed by theoretical analysis revealed that the onset of convection occurred earlier in 10% N2 - 90% CO2 cases than in the pure CO2 cases. On the other hand, the onset of convection for an impure CO2 mixture with 20% N2 was close to that of the pure CO2 system. These findings suggest that, depending on the mole fraction of N2, the presence of N2 as an impurity may impede or promote the onset of natural convection. Since both the solubility and diffusion of CO2 in brine are nonlinear functions of N2 concentration, increasing N2 concentration reduces the solubility and diffusion coefficient, which have opposing impacts on the stability of the diffusive boundary layer.

Molecular dynamics simulation to estimate minimum miscibility pressure for oil with pure and impure CO2

CO2 enhanced oil recovery (CO2-EOR) has gained great attention worldwide for increasing oil production and reducing greenhouse emissions. In CO2-EOR project, the minimum miscibility pressure (MMP) is the key factor to determine the possibility of CO2 miscible-phase displacement. In this study, we used molecular dynamics (MD) simulation to estimate the MMP of pure and impure CO2 with oil by obtaining interfacial tensions (IFTs) based on the vanishing interfacial tension technique. To get accurate IFTs, modified Lorentz-Berthelot rules were developed for all simulations. Then, we performed MD simulations for CO2 + n-hexane binary system, CO2 + n-hexane + n-decane ternary system and complex CO2 + crude oil system to calculate the MMPs. Firstly, MMPs predicted by MD simulation show good agreement with previous experimental data. Secondly, the effects of injected gas components, oil components and reservoir temperature on the MMP are investigated. The results demonstrate that methane and N2 will increase the MMP of CO2-oil system significantly; the effects of a certain oil component on the MMP depend on the properties of crude oil, generally speaking, heavy oil components will increase the MMP while light oil components decrease it; temperature will increase the MMP of CO2-oil system, while it will decrease the MMP of N2-oil system, which is due to their different solubility in oil. Thirdly, sensitivity analysis is conducted to evaluate the effects of those influence parameters on the MMP of CO2-oil system, finding that N2 concentration in CO2 and reservoir temperature have more significant impacts on the MMP.

A comprehensive study of the effect of chemical impurities on selection and sizing of centrifugal machines for supercritical carbon dioxide transport pipelines

Compressors and booster pumps constitute the “heart” of the supercritical carbon dioxide transport pipeline network because they consume most of the required energy input. In other words, most of the operating expenditure for the transport pipeline goes to the running of compressors and pumps. The long-term economic feasibility of running such pipeline networks is achievable only if operating costs linked to the energy consumption of both machines can be kept as low as possible. Energy consumption can be kept as low as possible by sizing compressors and booster pumps optimally to ensure that power losses in both machines are minimized.In this study, a quasi-dimensional model based on the laws of conservation was developed, validated with available experimental data and then used for a detailed investigation of the effect of various impurities on the performance of a centrifugal machine handling supercritical carbon dioxide of varying purity. Results of the study show that discharge pressure, power requirement and efficiency of a centrifugal machine are strongly dependent on certain key parameters; namely, the size and speed of its impeller rotor as well as the composition of the impure CO2 stream. More importantly, this study also demonstrates that the quasi-dimensional model can be used as a tool for appropriate selection and sizing of centrifugal compressors and booster pumps installed on a supercritical carbon dioxide transport pipeline.

Effects of N2 and H2S binary impurities on CO2 geological storage in stratified formation – A sensitivity study

Impurities are unavoidable during CO2 geological storage, and they would potentially affect the plume spread as well as storage capacity and/or efficiency of CO2. The current study numerically investigated the effects of binary impurities comprising typical components N2 and H2S on CO2 geological storage in stratified formations. For a fixed total content of the binary impurities, increasing ratio of N2/H2S resulted in larger plume spread which meant a higher dissolution trapping efficiency. Because of the backflow of formation brine during the post-injection period, the residual trapping efficiency decreased while the dissolution trapping efficiency increased. This tendency was reinforced with increasing ratio of N2/H2S. Besides, this work examined the effects of the ratio of vertical permeability (kv) to horizontal permeability (kh) and the addition of an injection point in the stratified formation. It was found that lower kv/kh shrunk the plume spread and intensified the maximum pressure build-up. However, in the case of two injection points, the plume in the vertical direction was elongated and the maximum pressure build-up was lessened. The results should be taken into consideration to determine the types and concentrations of impurities allowed in the injected CO2 stream as well as the site selection and injection design for impure CO2 geological storage in stratified formation.

Experimental Determination of Impure CO2 Alteration of Calcite Cemented Cap-Rock, and Long Term Predictions of Cap-Rock Reactivity

Cap-rock integrity is an important consideration for geological storage of CO2. While CO2 bearing fluids are known to have reactivity to certain rock forming minerals, impurities including acid gases such as SOx, NOx, H2S or O2 may be present in injected industrial CO2 streams at varying concentrations, and may induce higher reactivity to cap-rock than pure CO2. Dissolution or precipitation of minerals may modify the porosity or permeability of cap-rocks and compromise or improve the seal. A calcite cemented cap-rock drill core sample (Evergreen Formation, Surat Basin) was experimentally reacted with formation water and CO2 containing SO2 and O2 at 60 °C and 120 bar. Solution pH was quickly buffered by dissolution of calcite cement, with dissolved ions including Ca, Mn, Mg, Sr, Ba, Fe and Si released to solution. Dissolved concentrations of several elements including Ca, Ba, Si and S had a decreasing trend after 200 h. Extensive calcite cement dissolution with growth of gypsum in the formed pore space, and barite precipitation on mineral surfaces were observed after reaction via SEM-EDS. A silica and aluminium rich precipitate was also observed coating grains. Kinetic geochemical modelling of the experimental data predicted mainly calcite and chlorite dissolution, with gypsum, kaolinite, goethite, smectite and barite precipitation and a slight net increase in mineral volume (decrease in porosity). To better approximate the experimental water chemistry it required the reactive surface areas of: (1) calcite cement decreased to 1 cm2/g; and, (2) chlorite increased to 7000 cm2/g. Models were then up-scaled and run for 30 or 100 years to compare the reactivity of calcite cemented, mudstone, siderite cemented or shale cap-rock sections of the Evergreen Formation in the Surat Basin, Queensland, Australia, a proposed target for future large scale CO2 storage. Calcite, siderite, chlorite and plagioclase were the main minerals dissolving. Smectite, siderite, ankerite, hematite and kaolinite were predicted to precipitate, with SO2 sequestered as anhydrite, alunite, and pyrite. Predicted net changes in porosity after reaction with CO2, CO2-SO2 or CO2-SO2-O2 were however minimal, which is favourable for cap-rock integrity. Mineral trapping of CO2 as siderite and ankerite however was only predicted in the CO2 or CO2-SO2 simulations. This indicates a limit on the injected O2 content may be needed to optimise mineral trapping of CO2, the most secure form of CO2 storage. Smectites were predicted to form in all simulations, they have relatively high CO2 sorption capacities and provide additional storage.

Simulation Study of Different Modes of Miscible Carbon Dioxide Flooding

Carbon dioxide flooding has been applied worldwide as a successful enhanced oil recovery. Carbon dioxide flooding may be applied as a continuous injection or as water-alternating-gas (WAG) process. Optimization of the injection mode of carbon dioxide is important for economical field application. This paper focuses on using a fully compositional simulation model for “AEB-3C” sandstone oil reservoir of one of the Western Desert oil fields in Egypt to predict the impact of CO2 miscible flooding on the reservoir oil recovery and net present value (NPV), to define the best mode of operation that is straight CO2 injection or water alternating gas (WAG) processes and to show the difference between pure and impure CO2. Moreover, several sensitivity runs were done on the oil price to show minimum profitable value of oil price when applying such a tertiary method in the subject field.The reservoir under study has been producing under a successful water flooding project since May-2010. The recovery factor by the end of water flooding project is predicted as 32%. CO2 flooding processes have started by the end of water flooding. A significant increase in the oil recovery factor was noticed due to applying this method; it reached up to 57%. Comparisons between different modes of operations were shown which showed better results when applying WAG process than that with straight CO2 injection. Moreover; sensitivities were done on the cycle periods in WAG processes and showed increase in the recovery factor with shortening the cycle periods. In addition to a comparison between pure and impure CO2 which showed very close results.

Understanding the pitting corrosion mechanism of pipeline steel in an impure supercritical CO2 environment

This work was undertaken to investigate the pitting corrosion mechanism of pipeline steel in an impure supercritical CO2 environment by executing experiments with different exposure times and varied rotation speeds. The results revealed that in a water-saturated supercritical CO2-SO2-NO2-O2 environment, the average maximum pitting depth stabilized after three days, which indicated that pits were unstable and cannot rapidly propagate with time while also implying that a local acidification process might not exist. The product accumulation in the pit cavities can eventually prevent the diffusion of the corrosive media and water from the product surface to the metal substrate. The effect of flow on the propagation of pits was marginal, revealing the weak influence of flow on the mass transfer of species through the product scales. The formation of spherical products was possibly attributed to the influence of NO2 on the contact angle of water droplets on the steel surface.

Cross impact of CO2 phase and impurities on the corrosion behavior for stainless steel and carbon steel in water-containing dense CO2 environments

A series of study was conducted to investigate the corrosion behavior of 2Cr13 stainless steel and X65 carbon steel exposed to water-saturated and water-unsaturated dense CO2 environments with SO2 and O2 impurities in the conditions of 25 °C and 50 °C, 8 MPa. Each test lasted for 48 h. The cross impacts of CO2 phase (liquid phase and supercritical phase), water contents and steel types on the corrosion behavior were elaborately discussed. In water-saturated impure dense CO2 with SO2, SO2/O2 systems, the impacts of single impurity of SO2 and multiple impurities of SO2 and O2 on accelerating general corrosion for both 2Cr13 and X65 steels was much stronger in the supercritical CO2 system than in the liquid CO2 system. At water-unsaturated conditions, 2Cr13 stainless steel exhibited better resistance to the general corrosion attack in liquid and supercritical CO2 with SO2 in comparison with X65 carbon steel, but suffered high risk of localized corrosion in liquid CO2 mixtures. The 2Cr13 and X65 steels could bear higher amounts of water in supercritical CO2 with SO2 systems (∼1300 ppm H2O) than in the liquid CO2 with SO2 systems (<300 ppm H2O).

Effects of SO2 contamination on rising CO2 drops under high pressure

Although the flow dynamics of pure liquid drops in other liquids has been well researched, little attention has been paid to the impacts of impurities. Hence, most of research is not directly applicable to the real world. To address this gap, we conducted numerical experiments simulating the rise of pure and contaminated drops. It was selected to study liquid CO2 drops contaminated with SO2 under high pressure because such mixtures mimic potential scenarios in which drops may leak from carbon capture and storage (CCS) facilities or pipelines. First, numerical simulation experiments were performed to validate our method by comparing our results with previous research on pure drops. Second, the validated numerical approach was applied to simulations of contaminated drops to investigate how contaminants affect rising drops. The results show that the SO2 contamination caused changes in deformation, breakup phenomena, rising velocities, surrounding flow fields and drag coefficients. Most importantly, the contamination resulted in the formation of smaller “child drops”; such breakup is not observed in pure CO2 drops. The formation of child drops in turn affects the streamlines, patterns and areas of wakes behind the contaminated drops. The addition of contaminants also enhances the dissolution rate, which is affected by the contaminant concentration and by the flow dynamics of the rising drop. Our results would improve understanding the rise of impure CO2 drops, such as drops potentially leaked by future CCS operations.