Effects of CH_(4)/CO_(2) multi-component gas on components and properties of tight oil during CO_(2) utilization and storage: Physical experiment and composition numerical simulation

An essential technology of carbon capture, utilization and storage-enhanced oil recovery (CCUS-EOR) for tight oil reservoirs is CO_(2) huff-puff followed by associated produced gas reinjection. In this paper, the effects of multi-component gas on the properties and components of tight oil are studied. First, the core displacement experiments using the CH_(4)/CO_(2) multi-component gas are conducted to determine the oil displacement efficiency under different CO_(2) and CH_(4) ratios. Then, a viscometer and a liquid density balance are used to investigate the change characteristics of oil viscosity and density after multi-component gas displacement with different CO_(2) and CH_(4) ratios. In addition, a laboratory scale numerical model is established to validate the experimental results. Finally, a composition model of multi-stage fractured horizontal well in tight oil reservoir considering nano-confinement effects is established to investigate the effects of multi-component gas on the components of produced dead oil and formation crude oil. The experimental results show that the oil displacement efficiency of multi-component gas displacement is greater than that of single-component gas displacement. The CH_(4) decreases the viscosity and density of light oil, while CO_(2) decreases the viscosity but increases the density. And the numerical simulation results show that CO_(2) extracts more heavy components from the liquid phase into the vapor phase, while CH_(4) extracts more light components from the liquid phase into the vapor phase during cyclic gas injection. The multi-component gas can extract both the light components and the heavy components from oil, and the balanced production of each component can be achieved by using multi-component gas huff-puff.

Preface to Special Issue: CO_2 capture storage and utilization

Reducing the anthropogenic COemissions from fossil resource combustion and human activities has become one of the major challenges we are facing today.Beyond those practical applications for the utilization of CO,such as the synthesis of salicylic acid,methanol,urea,NaHCO-NaCOchemicals and recently developed polycarbonate synthesis,scientists are still seeking new materials and technologies for efficient capture,

Bipolar membrane electrodialysis integrated with in-situ CO_(2)absorption for simulated seawater concentrate utilization,carbon storage and production of sodium carbonate

In the context of carbon capture,utilization,and storage,the high-value utilization of carbon storage presents a significant challenge.To address this challenge,this study employed the bipolar membrane electrodialysis integrated with carbon utilization technology to prepare Na_(2)CO_(3)products using simulated seawater concentrate,achieving simultaneous saline wastewater utilization,carbon storage and high-value production of Na_(2)CO_(3).The effects of various factors,including concentration of simulated seawater concentrate,current density,CO_(2)aeration rate,and circulating flow rate of alkali chamber,on the quality of Na_(2)CO_(3)product,carbon sequestration rate,and energy consumption were investigated.Under the optimal condition,the CO_(3)^(2-)concentration in the alkaline chamber reached a maximum of 0.817 mol/L with 98 mol%purity.The resulting carbon fixation rate was 70.50%,with energy consumption for carbon sequestration and product production of 5.7 k Whr/m^(3)CO_(2)and1237.8 k Whr/ton Na_(2)CO_(3),respectively.This coupling design provides a triple-win outcome promoting waste reduction and efficient utilization of resources.

Underwater Gas Leakage Flow Detection and Classification Based on Multibeam Forward-Looking Sonar

The risk of gas leakage due to geological flaws in offshore carbon capture, utilization, and storage, as well as leakage from underwater oil or gas pipelines, highlights the need for underwater gas leakage monitoring technology. Remotely operated vehicles(ROVs) and autonomous underwater vehicles(AUVs) are equipped with high-resolution imaging sonar systems that have broad application potential in underwater gas and target detection tasks. However, some bubble clusters are relatively weak scatterers, so detecting and distinguishing them against the seabed reverberation in forward-looking sonar images are challenging. This study uses the dual-tree complex wavelet transform to extract the image features of multibeam forward-looking sonar. Underwater gas leakages with different flows are classified by combining deep learning theory. A pool experiment is designed to simulate gas leakage, where sonar images are obtained for further processing. Results demonstrate that this method can detect and classify underwater gas leakage streams with high classification accuracy. This performance indicates that the method can detect gas leakage from multibeam forward-looking sonar images and has the potential to predict gas leakage flow.

Monitoring Technologies for Marine Carbon Sequestration in Zhanjiang

Marine carbon sequestration is an important component of carbon dioxide capture, utilization and storage(CCUS) technology. It is crucial for achieving carbon peaking and carbon neutralization in China. However, CO_(2) leakage may lead to seabed geological disasters and threaten the safety of marine engineering. Therefore, it is of great significance to study the safety monitoring technology of marine carbon sequestration.Zhanjiang is industrially developed and rich in carbon sources. Owing to the good physical properties and reservoirs and trap characteristics,Zhanjiang has huge storage potential. This paper explores the disaster mechanism associated with CO_(2) leakage in marine carbon sequestration areas. Based on the analysis of the development of Zhanjiang industry and relevant domestic monitoring technologies, several suggestions for safety monitoring of marine carbon sequestration are proposed: application of offshore aquaculture platforms, expansion and application of ocean observation networks, carbon sequestration safety monitoring and sensing system. Intended to build a comprehensive and multi-level safety monitoring system for marine carbon sequestration, the outcome of this study provides assistance for the development of marine carbon sequestration in China's offshore areas.

A review of interaction mechanisms and microscopic simulation methods for CO_(2)-water-rock system

This work systematically reviews the complex mechanisms of CO_(2)-water-rock interactions,microscopic simulations of reactive transport(dissolution,precipitation and precipitate migration)in porous media,and microscopic simulations of CO_(2)-water-rock system.The work points out the key issues in current research and provides suggestions for future research.After injection of CO_(2) into underground reservoirs,not only conventional pressure-driven flow and mass transfer processes occur,but also special physicochemical phenomena like dissolution,precipitation,and precipitate migration.The coupling of these processes causes complex changes in permeability and porosity parameters of the porous media.Pore-scale microscopic flow simulations can provide detailed information within the three-dimensional pore and throat space and explicitly observe changes in the fluid-solid interfaces of porous media during reactions.At present,the research has limitations in the decoupling of complex mechanisms,characterization of differential multi-mineral reactions,precipitation generation mechanisms and characterization(crystal nucleation and mineral detachment),simulation methods for precipitation-fluid interaction,and coupling mechanisms of multiple physicochemical processes.In future studies,it is essential to innovate experimental methods to decouple“dissolution-precipitation-precipitate migration”processes,improve the accuracy of experimental testing of minerals geochemical reaction-related parameters,build reliable characterization of various precipitation types,establish precipitation-fluid interaction simulation methods,coordinate the boundary conditions of different physicochemical processes,and,finally,achieve coupled flow simulation of“dissolution-precipitation-precipitate migration”within CO_(2)-water-rock systems.

CO_(2)storage with enhanced gas recovery(CSEGR):A review of experimental and numerical studies

CO_(2)emission mitigation is one of the most critical research frontiers.As a promising option of carbon capture,utilization and storage(CCUS),CO_(2)storage with enhanced gas recovery(CSEGR)can reduce CO_(2)emission by sequestrating it into gas reservoirs and simultaneously enhance natural gas production.Over the past decades,the displacement behaviour of CO_(2)—natural gas has been extensively studied and demonstrated to play a key role on both CO_(2)geologic storage and gas recovery performance.This work thoroughly and critically reviews the experimental and numerical simulation studies of CO_(2)displacing natural gas,along with both CSEGR research and demonstration projects at various scales.The physical property difference between CO_(2)and natural gas,especially density and viscosity,lays the foundation of CSEGR.Previous experiments on displacement behaviour and dispersion characteristics of CO_(2)/natural gas revealed the fundamental mixing characteristics in porous media,which is one key factor of gas recovery efficiency and warrants further study.Preliminary numerical simulations demonstrated that it is technically and economically feasible to apply CSEGR in depleted gas reservoirs.However,CO_(2)preferential flow pathways are easy to form(due to reservoir heterogeneity)and thus adversely compromise CSEGR performance.This preferential flow can be slowed down by connate or injected water.Additionally,the optimization of CO_(2)injection strategies is essential for improving gas recovery and CO_(2)storage,which needs further study.The successful K12—B pilot project provides insightful field-scale knowledge and experience,which paves a good foundation for commercial application.More experiments,simulations,research and demonstration projects are needed to facilitate the maturation of the CSEGR technology.

International experience of carbon neutrality and prospects of key technologies:Lessons for China

Carbon neutrality(or climate neutrality)has been a global consensus,and international experience exchange is essential.Given the differences in the degree of social development,resource endowment and technological level,each country should build a carbon-neutral plan based on its national conditions.Compared with other major developed countries(e.g.,Germany,the United States and Japan),China's carbon neutrality has much bigger challenges,including a heavy and time-pressured carbon reduction task and the current energy structure that is over-dependent on fossil fuels.Here we provide a comprehensive review of the status and prospects of the key technologies for low-carbon,near-zero carbon,and negative carbon emissions.Technological innovations associated with coal,oil-gas and hydrogen industries and their future potential in reducing carbon emissions are particularly explained and assessed.Based on integrated analysis of international experience from the world's major developed countries,in-depth knowledge of the current and future technologies,and China's energy and ecological resources potential,five lessons for the implementation of China's carbon neutrality are proposed:(1)transformation of energy production pattern from a coal-dominated pattern to a diversified renewable energy pattern;(2)renewable power-to-X and large-scale underground energy storage;(3)integration of green hydrogen production,storage,transport and utilization;(4)construction of clean energy systems based on smart sector coupling(ENSYSCO);(5)improvement of ecosystem carbon sinks both in nationwide forest land and potential desert in Northwest China.This paper provides an international perspective for a better understanding of the challenges and opportunities of carbon neutrality in China,and can serve as a theoretical foundation for medium-long term carbon neutral policy formulation.

Simulation study of supercritical carbon dioxide jet fracturing for carbonate geothermal reservoir based on fluid-thermo-mechanical coupling model

Geothermal energy is a kind of renewable,sustainable and clean energy resource.Geothermal energy is abundant in carbonate reservoirs.However,low matrix permeability limits its exploitation.The super-critical carbon dioxide(SC-CO_(2))jet fracturing is expected to efficiently stimulate the carbonate geothermal reservoirs and achieve the storage of CO_(2) simultaneously.In this paper,we established a transient seepage and fluid-thermo-mechanical coupled model to analyze the impact performance of sc-CO_(2) jet fracturing.The mesh-based parallel code coupling interface was employed to couple the fluid and solid domains by exchanging the data through the mesh interface.The physical properties change of sC-CO_(2) with temperature were considered in the numerical model.Results showed that SC-CO_(2) jet frac-turing is superior to water-jet fracturing with respect to jetting velocity,particle trajectory and pene-trability.Besides,stress distribution on the carbonate rock showed that the tensile and shear failure would more easily occur by SC-CO_(2) jet than that by water jet.Moreover,pressure and temperature control the jet field and seepage field of sC-CO_(2) simultaneously.Increasing the jet temperature can effectively enhance the impingement effect and seepage process by decreasing the viscosity and density of SC-CO_(2).The key findings are expected to provide a theoretical basis and design reference for applying SC-CO_(2) jet fracturing in carbonate geothermal reservoirs.

Advances in subsea carbon dioxide utilization and storage

Decisive steps in innovation and competitiveness are needed to meet global greenhouse gas emissions and climate goals.As an effective method for reducing carbon emissions,carbon dioxide(CO_(2))storage and utilization on the seabed enable the transport of captured CO_(2)via pipelines or ships to permanent storage sites,such as saline aquifers or depleted oil and gas reservoirs in subsea sediments,or by injecting CO_(2)for the replacement and displacement of subsea resources(oil,gas,gas hydrates,etc.).Subsea CO_(2)utilization and storage(SCUS)involves several research hotspots worldwide,including international and local laws and regulations,security,economics,environmental impact,and public acceptance.Its current research and engineering progress are also of great interest.In addition,the vigorous implementation of the energy transition and the rapid development of renewable energy sources globally have resulted in significant advancements in SCUS.This paper provides an overview of carbon dioxide storage and utilization mechanism in the seabed,analyzes key technical and economic issues,and summarizes existing research on safety risks,monitoring technologies,and investment and operating cost control to identify remaining knowledge gaps.This is followed by an overview of global engineering practice to update on current progress.Finally,combined with the actualities of China,the potential and trend of China's seabed carbon storage and utilization are summarized.This review demonstrates the enormous development prospects for seabed carbon storage and utilization,although some risks remain including leakage and contamination,with which innovation in monitoring technologies and the self-sealing effect of gas hydrate,safe subsea utilization and storage of CO_(2)can be achieved.Additionally,considering the development of renewable energy and the demand for large-scale energy storage,hydrogen,ammonia,or other energy carriers and carbon dioxide storage and utilization can be coupled into an industrial chain to form an economically competitive carbon geological storage mode.

Lifecycle carbon footprint and cost assessment for coal-to-liquid coupled with carbon capture,storage,and utilization technology in China

Thecoal-to-liquidcoupledwithcarbon capture,utilization,and storage technology has the potential to reduce CO_(2)emissions,but its carbon footprint and cost assessment are still insufficient.In this paper,coal mining to oil production is taken as a life cycle to evaluate the carbon footprint and levelized costs of direct-coal-toliquid and indirect-coal-to-liquid coupled with the carbon capture utilization and storage technology under three scenarios:non capture,process capture,process and public capture throughout the life cycle.The results show that,first,the coupling carbon capture utilization and storage technology can reduce CO_(2)footprint by 28%-57%from 5.91 t CO_(2)/t:oil of direct-coal-to-liquid and 24%-49%from 7.10 t CO_(2)/t:oil of indirect-coal-to-liquid.Next,the levelized cost of direct-coal-to-liquid is 648-1027$/t of oil,whereas that of indirect-coal-to-liquid is 653-1065$/t of oil.When coupled with the carbon capture utilization and storage technology,the levelized cost of direct-coalto-liquid is 285-1364$/t of oil,compared to 1101-9793/t of oil for indirect-coal-to-liquid.Finally,sensitivity analysis shows that CO_(2)transportation distance has the greatest impact on carbon footprint,while coal price and initial investment cost significantly affect the levelized cost ofcoal-to-liquid.

CO_(2) gas stripped off membranous residual oil from pore surfaces: Effects of temperature, pressure and wettability

The threshold values of CO_(2) gas stripped off membranous residual oil from the pore walls are not clear under different temperatures, pressures and wettability conditions. The extent to which temperature, pressure and wettability influence CO_(2) flooding for enhancing the recovery of residual oil in membranous formations also remains uncertain. Therefore, further quantitative characterization is entailed. In this study, the molecular dynamics method was employed to explore CO_(2) flooding under different temperatures, pressures and wettability conditions, aiming to enhance the production of membranous residual oil. The results reveal that the interaction energy between CO_(2), decane molecules and pore walls exhibits a decrease with increasing temperature and an increase with increasing pressure, respectively, in distinct wettability scenarios. When the temperature was at or below 363 K and the pressure was not lower than 40 MPa, CO_(2) gas could detach the membranous residual oil from the pore walls in the water-wet systems. When the temperature was equal to 363 K and the pressure remained under 40 MPa, or the temperature surpassed 363 K, CO_(2) gas failed to detach the membranous residual oil from the pore walls in the water-wet systems. For the mixed-wet and oil-wet systems, CO_(2) molecules could not detach the membranous residual oil from the pore walls. The hierarchy of influence regarding temperature, pressure and wettability on the competitive adsorption capacity of CO_(2) and decane molecules on the pore walls emerged as follows: wettability > temperature > pressure. The findings of this study offer valuable insights into the application of CO_(2) gas flooding for the exploitation of membranous residual oil on pore walls.

Optimal Operation with Dynamic Partitioning Strategy for Centralized Shared Energy Storage Station with Integration of Large-scale Renewable Energy

As renewable energy continues to be integrated into the grid,energy storage has become a vital technique supporting power system development.To effectively promote the efficiency and economics of energy storage,centralized shared energy storage(SES)station with multiple energy storage batteries is developed to enable energy trading among a group of entities.In this paper,we propose the optimal operation with dynamic partitioning strategy for the centralized SES station,considering the day-ahead demands of large-scale renewable energy power plants.We implement a multi-entity cooperative optimization operation model based on Nash bargaining theory.This model is decomposed into two subproblems:the operation profit maximization problem with energy trading and the leasing payment bargaining problem.The distributed alternating direction multiplier method(ADMM)is employed to address the subproblems separately.Simulations reveal that the optimal operation with a dynamic partitioning strategy improves the tracking of planned output of renewable energy entities,enhances the actual utilization rate of energy storage,and increases the profits of each participating entity.The results confirm the practicality and effectiveness of the strategy.

Clean Coal Technologies in China： Current Status and Future Perspectives

Coal is the dominant primary energy source in China and the major source of greenhouse gases and air pollutants. To facilitate the use of coal in an environmentally satisfactory and economically viable way, clean coal technologies （CCTs） are necessary. This paper presents a review of recent research and development of four kinds of CCTs： coal power generation; coal conversion; pollution control; and carbon capture, utilization, and storage. It also outlines future perspectives on directions for technology re search and development （R＆D）. This review shows that China has made remarkable progress in the R＆D of CCTs, and that a number of CCTs have now entered into the commercialization stage.

Investigation of the role of Ca(OH)2 in the catalytic Alkaline Thermal Treatment of cellulose to produce H2 with integrated carbon capture

The Alkaline Thermal Treatment(ATT)of biomass is one of the few biomass conversion processes that has a potential for BECCS(bio-energy with carbon capture and storage).Combining in-situ carbon capture withcreates a carbon-neutral process that has the potential to be carbon-negative.This study has shown that the conversion of cellulose tosuppressedcan be achieved through the reforming of gaseous intermediates in a fixed bed of 10%Ni/ZrO2.Reforming occurs at low temperatures≤773 K,which could allow for improved sustainability.

An interval-parameter two-stage optimization model for CO_(2) collection,distribution,transportation,utilization,and storage planning

Geological carbon dioxide (CO_(2)) utilization and storage have been widely recognized as one of the important options to deliver greenhouse gas emissions reduction. Reasonable planning is critical to promote CO_(2) utilization and storage. However, CO_(2) emissions gas collection exhibits a stochastic probability distribution, and CO_(2) utilization and storage features fluctuation demands, which have gone beyond current determine planning techniques. To fulfill the current research gap, this study develops an interval-parameter two-stage programming-based CO_(2) collection, distribution, transportation, utilization, and storage optimization model, integrating interval parameter planning and two-stage planning into a general framework. Therefore, the model can address uncertainties expressed as random probabilistic distributions and discrete intervals, tackle dynamic facilities capacity expansion issues, develop optimal predefined CO_(2) distribution policy, and generate recourse schemes to address gas shortage or gas surplus issues. The model is examined by a typical hypnotical case study in China. The results revealed that the model could generate a set of first-stage reasonable CO_(2) distribution and facilities capacity expansion schemes to maximum system benefits and the highest feasibility. Besides, a set of two-stage CO_(2) outsourcing purchases and facilities capacity expansion in reserve storage regions solutions were also generated to address the gas oversupplies and shortage issues. The modeling approach enriches the current CO_(2) utilization and storage distribution research content under multiple uncertainties.

Recent advances,challenges,and perspectives on carbon capture

Carbon capture,utilization and storage(CCUS)technologies play an essential role in achieving Net Zero Emissions targets.Considering the lack of timely reviews on the recent advancements in promising CCUS technologies,it is crucial to provide a prompt review of the CCUS advances to understand the current research gaps pertained to its industrial application.To that end,this review first summarized the developmental history of CCUS technologies and the current large-scale demonstrations.Then,based on a visually bibliometric analysis,the carbon capture remains a hotspot in the CCUS development.Noting that the materials applied in the carbon capture process determines its performance.As a result,the state-of-the-art carbon capture materials and emerging capture technologies were comprehensively summarized and discussed.Gaps between state-of-art carbon capture process and its ideal counterpart are analyzed,and insights into the research needs such as material design,process optimization,environmental impact,and technical and economic assessments are provided.

Theoretical Study About Effects of H20 and Na＋ on Adsorption of CO2 on Kaolinite Surfaces

The density functional theory（DFT） was used to investigate the adsorptions of carbon dioxide（CO2） on kaolinite surfaces and the influences ofNa＋ and HeO on the adsorption. Both cluster and periodic models of kaolinite were considered. The calculated results indicate that stable complexes can be formed between adsorbed CO2 and the surfaces of kaolinite in the presence or absence of sodium cation and water molecule. The Al-O octahedral surface has a larger adsorption affinity for CO2 than the Si-O tetrahedral surface of kaolinite because the hydroxyl groups of kaolinite Al-O surface present more activity than the basal O atoms of the Si-O tetrahedral surface in the intermolecular interactions. The existence of exchangeable sodium cations exerts the significant effect on the adsorption of CO2 with the dramatic increase of the adsorption energy, while the presence of water molecule decreases the adsorption strength insignificantly. The calculated Gibbs free energies of the adsorption reveal that the adsorptions of CO2 on all the investigated kaolinite surfaces are feasible thermodynamically in the gas phase. Surface free energy was calculated to provide the predictions of the surface stability as a function of temperature.

Experimental Investigation on the Performance of[APMIm][NTf_(2)]for Capturing CO_(2)from Flue Gas of the Cement Kiln Tail

Facing the global warming trend,humanity has been paying more and more attention to the Carbon Capture,Utilization and Storage.Large amounts of CO_(2)is emitted with burning fossil fuel as well as by some special industrial processes like the decomposition of calcium carbonate in a cement plant.The cement industry contributes about 7%of the total worldwide CO_(2)emissions and the CO_(2)concentration of flue gas of the cement kiln tail even exceeds 30%.Ionic liquid is considered to be an effective and potential material to capture CO_(2).In order to investigate the performance of ionic liquids for capturing CO_(2)from flue gas of the cement kiln tail,an experiment system was established and an ionic liquid,[APMIm][NTf_(2)](1-aminopropyl-3-imidazolium bis(trifluoromethylsulfonyl)imine),was tested using pure CO_(2)and simulated gas.The results showed that both physical and chemical absorption play roles while physical absorption dominates in the absorption process.Both the absorption capacity and rate decrease with raising the operating temperature.In the experiment with pure CO_(2),the absorption capacity is 0.296molCO_(2)⋅molIL−1 at 30℃ and 0.067molCO_(2)⋅molIL−1 at 70℃.Meanwhile,the ionic liquid can be regenerated for recycling without obvious changes of the absorption capacity.When the ionic liquid is used for flue gas of the cement kiln tail rather than pure CO_(2),a sharp decrease of the absorption capacity and rate was observed obviously.The absorption capacity at 30℃ dropped even to 0.038molCO_(2)⋅mol_(IL)^(−1),12.8%of that for pure CO_(2).Additionally,a natural desorption of CO_(2)from the ionic liquid was observed and affected the experimental results of the absorption capacity and the absorption-desorption rate to some extent.