Yandy Scientific Press
Not a member yet
641 research outputs found
Sort by
Mechanical properties of nodular natural gas hydrate-bearing sediment
Get PDFNatural gas hydrate is a relatively realistic alternative energy source to conventional fossil fuels with considerable reserves. Natural gas hydrate sediments are widely distributed in marine sediment on continental margins. In this study, a numerical modeling method for sediment containing nodular gas hydrates is developed using the two-dimensional discrete element simulation software. The effects of saturation, confining pressure, and nodule radius on the mechanical properties of heterogeneous nodular gas-hydrate-bearing sediment were analyzed using the stress-strain, fracture development, and partial body strain curves, as well as force chain distribution. The results indicated that the mechanical strength of sediment containing round nodular gas hydrates was proportional to the gas hydrate saturation and simulated confining pressure. When hydrate saturation was low, the failure strength of the gas-hydrate-bearing sediment diminished as the nodule radius increased. The simulations showed that variations in sediment porosity influenced the development and evolution of the shear band, resulting in higher porosity around the shear band. These results were analyzed from the perspectives of saturation and confining pressure to determine the failure and deformation law of simple nodular gas hydrate-bearing sediment and provide theoretical support for the subsequent study of the exploitation method of shallow buried deep gas hydrates.Document Type: Original articleCited as: Jiang, Y., Zhang, R., Ye, R., Zhou, K., Gong, B., Golsanami, N. Mechanical properties of nodular natural gas hydrate-bearing sediment. Advances in Geo-Energy Research, 2024, 11(1): 41-53. https://doi.org/10.46690/ager.2024.01.0
Impact of stress dependence of elastic moduli and poroelastic constants on earth surface uplift due to injection
Get PDFHydromechanical models have typically assumed constant stress-independent elastic moduli to estimate, forecast, and history-match earth surface uplift. The effect of stress-dependent elastic moduli and poroelastic constant (i.e., Biot coefficient) on Earth surface uplift during injection is investigated in this study. Experimental data gathered for different rock types shows that Biot coefficient and bulk modulus vary in response to Terzaghi effective stress. Stress-dependent elastic modulus was imported to the numerical model representing Berea sandstone. Hydromechanical simulations were performed to model CO2 injection into the Berea reservoir by incorporating elastic moduli stress dependency. Hydromechanical modeling results show that using stress-independent elastic moduli causes under-estimation of Earth surface uplift due to injection. A decrease in Young’s modulus and an increase in Biot coefficient because of injection can contribute to a higher estimated uplift. Neglecting the stress dependency effect could cause an erroneous estimate of potential surface uplift due to injection. The impact of geological properties of Berea and injecting brine instead of CO2 on surface uplift trend were also investigated.Document Type: Original articleCited as: Raziperchikolaee, S. Impact of stress dependence of elastic moduli and poroelastic constants on earth surface uplift due to injection. Advances in Geo-Energy Research, 2023, 10(1): 56-64. https://doi.org/10.46690/ager.2023.10.0
Spontaneous imbibition behavior in porous media with various hydraulic fracture propagations: A pore-scale perspective
Get PDFHydraulic fracturing technology can improve the geologic structure of unconventional oil and gas reservoirs, yielding a complex fracture network resulting from the synergistic action of hydraulic and natural fractures. However, the impact of spontaneous imbibition associated with hydraulic fracture propagation on the reservoir matrix remains poorly understood. In this study, combining the Cahn-Hilliard phase field method with the Navier-Stokes equations, pore-scale modeling was employed to capture the evolution of the oil-water interface during dynamic spontaneous imbibition for hydraulic fracture propagation in a two-end open mode. This pore-scale modeling approach can effectively circumvent the challenges of conducting spontaneous imbibition experiments on specimens partitioned by hydraulic fractures. A direct correlation was established between the pressure difference curve and the morphology of discharged oil phase in the primary hydraulic fracture, providing valuable insights into the distribution of oil phase in spontaneous imbibition. Furthermore, it was shown that secondary hydraulic fracture propagation expands the longitudinal swept area and enhances the utilization of natural fractures in the transverse swept area during spontaneous imbibition. When secondary hydraulic fracture propagation results in the interconnection of upper and lower primary hydraulic fractures, competitive imbibition occurs in the matrix, leading to reduced oil recovery compared to the unconnected models. Our results shed light upon the spontaneous imbibition mechanism in porous media with hydraulic fracture propagation, contributing to the refinement and application of hydraulic fracturing techniques.Document Type: Original articleCited as: Zhou, Y., Guan, W., Zhao, C., Zou, X., He, Z., Zhao, H. Spontaneous imbibition behavior in porous media with various hydraulic fracture propagations: A pore-scale perspective. Advances in Geo-Energy Research, 2023, 9(3): 185-197. https://doi.org/10.46690/ager.2023.09.0
Feasibility analysis of storing solar energy in heterogeneous deep aquifer by hot water circulation: Insights from coupled hydro-thermo modeling
Get PDFStoring solar energy in the subsurface as heat is a promising way for energy storage and conversion, which has a great potential to address the temporal and spatial mismatch between energy demand and supply. Thermal energy storage in deep aquifers can convert intermittent solar energy into stable high temperature geothermal energy. In this study, a new solar energy storage and conversion system is proposed where solar energy is firstly converted into heat using parabolic troughs and then stored in deep aquifers by high temperature hot water circulation. The geostatistical modelling and hydro-thermo coupling simulations are adopted to investigate the feasibility and efficiency of solar energy storage in deep aquifers. Specifically, how rock permeability heterogeneity (in terms of autocorrelation length and global permeability heterogeneity) impacts the temporal and spatial evolution of temperature distribution and storage efficiency is examined. The simulation results indicate that increased horizontal autocorrelation length and global heterogeneity may accelerate thermal breakthrough, deteriorating storage efficiency. High permeability heterogeneity may also lead to high injection pressure. Deep aquifers with small horizontal autocorrelation lengths and low global heterogeneity tend to have higher storage efficiency. These findings may improve our understanding of solar energy storage mechanism in deep aquifers and guide field applications.Document Type: Original articleCited as: Wang, Y., Zhong, K., Gao, Y., Sun, Z., Dong, R., Wang, X. Feasibility analysis of storing solar energy in heterogeneous deep aquifer by hot water circulation: Insights from coupled hydro-thermo modeling. Advances in Geo-Energy Research, 2023, 10(3): 159-173. https://doi.org/10.46690/ager.2023.12.0
Construction of multi-mineral digital rocks for upscaling the numerical simulation of tight rock physical properties
Get PDFTight sandstone reservoirs are characterized by multi-scale pore space and high clay content, resulting in intricate rock physical responses. In this work, multi-scale imaging techniques, including computed tomography and stitched scanning electron microscopy, are applied to identify the large intergranular pores and micropores within major minerals. The pore structure of tight sandstones is quantitatively investigated using multi-scale images. Besides, multi-mineral digital rocks are constructed by performing registration and segmentation processing on the images obtained from microcomputed tomography and energy-dispersive scanning electron microscopy. These digital rocks are treated as composite materials consisting of different mineral types and micro-porosities, which enables the upscaling of the numerical simulation of rock physics properties. The results reveal that residual intergranular pores are interconnected through micropores within clay minerals, which significantly influences the electrical conductivities and permeabilities of tight sandstones. The proposed upscaling method can effectively couple the contribution of formation brine in multi-scale pores and clay minerals to bulk rock physics properties. This approach is suitable for the numerical simulation of diverse rock physical properties and can be applied to various tight reservoirs.Document Type: PerspectiveCited as: Hu, J., Xiao, Z., Ni, H., Liu, X. Construction of multi-mineral digital rocks for upscaling the numerical simulation of tight rock physical properties. Advances in Geo-Energy Research, 2023, 9(1): 68-70. https://doi.org/10.46690/ager.2023.07.0
Advances in mining safety theory, technology, and equipment
Get PDFMineral resources are an important pillar of human social development. With the gradual depletion of shallow resources, deep mining is an inevitable choice for ensuring energy security in various countries in the future. The complex and harsh environment in deep mining areas has led to frequent occurrences of hazardous events such as rockburst, coal and gas outburst, and mine fires. Mining safety science and engineering issues are receiving increasing attention. In August 2023, the 6th International Symposium on Mine Safety Science and Engineering was held in Harbin to promote innovative development of mining safety, and foster international collaborations among scholars in the field of mining safety. It served as a platform for the exchange of the most recent advancements in mining safety scientific theories, technologies, and equipment by bringing together global talent. Over 400 delegates representing 9 countries, including Australia, Russia, United State, Kazakhstan, and Canada, engaged in academic discussions and knowledge sharing on new theories, technologies, equipment, and methods in mining safety science and engineering. The latest research results are of great significance in enhancing the practices of preventing mine disaster and ensuring the safety of mining operations.Document Type: EditorialCited as: He, S., He, X., Mitri, H., Meng, S., Wu, Q., Ren, T., Liu, S. Advances in mining safety theory, technology, and equipment. Advances in Geo-Energy Research, 2023, 10(2): 71-76. https://doi.org/10.46690/ager.2023.11.0
Current methods for measuring three-phase relative permeability and its influencing factors
Get PDFThree-phase fluid flow in reservoirs is present in the entire process of oil field development, and three-phase relative permeability data are crucial for reservoir engineering and numerical simulation. At the same time, carbon dioxide flooding and storage have garnered significant attention recently. The calculation of dynamic storage volumes and an in-depth understanding of three-phase flow within formations are inextricably linked to three-phase relative permeability. This review is centered around the available experimental measurements, theoretical models that predict three-phase relative permeability using two-phase data, and four Lattice Boltzmann method models. By analyzing the strengths, weaknesses and limitations of each method and assessing the impact of factors like saturation history, interfacial tension, rock properties, and fluid characteristics on three-phase relative permeability, this paper seeks to offer a comprehensive understanding of the topic. In summary, we provide a concise overview of the prospects and challenges in advancing three-phase relative permeability, serving as a valuable reference for the field of carbon dioxide flooding and storage.Document Type: Invited reviewCited as: Mei, Y., Lv, W., Zhou, X., Huang, J., Jia, N., Wang, G. Current methods for measuring three-phase relative permeability and its influencing factors. Advances in Geo-Energy Research, 2023, 10(1): 21-38. https://doi.org/10.46690/ager.2023.10.0
The impact of wettability and fluid saturations on multiphase representative elementary volume estimations of micro-porous media
Get PDFThe occurrence of multi-phase flows in porous media is a complex phenomenon that involves multiple scales, ranging from individual pores to larger continuum scales. Upscaling frameworks have emerged as a response to the need for addressing the disparity between micro-scale processes and macroscopic modelling. Determination of the representative elementary volume is important for understanding fluid dynamics in micro-porous materials. The size of the representative elementary volume for multiphase flow in porous media is significantly affected by wettability and fluid saturations. Previous studies have overlooked this aspect by conducting simulations under conditions of constant medium wettability and fluid saturations. This study uses finite volume simulations with a volume of fluid approach for two distinct asymptotic homogenization methods, namely hydrodynamic bounds of relative permeability and thermodynamic bounds of entropy production. Strong wetting conditions with high wetting phase saturation were found to require a smaller sample size to establish representative elementary volume, while mixed-wettability scenarios necessitate the largest sample sizes. These findings improve our understanding of multiphase fluid flow behaviour in micro-porous materials and aid in enhancing techniques for scaling up observations and predictive modelling in engineering and environmental fields.Document Type: Short communicationCited as: Hussain, S. T., Regenauer-Lieb, K., Zhuravljov, A., Hussain, F., Rahman, S. S. The impact of wettability and fluid saturations on multiphase representative elementary volume estimations of micro-porous media. Capillarity, 2023, 9(1): 1-8. https://doi.org/10.46690/capi.2023.10.0
Research progress and scientific challenges in the depressurization exploitation mechanism of clayey-silt natural gas hydrates in the northern South China Sea
Get PDFNatural gas hydrate reservoirs in the northern South China Sea primarily comprise clayey silt, making exploitation more challenging relative to sandy reservoirs in other countries and regions. This paper provides an overview of the latest research developments in the exploitation mechanism covering the past five years, focusing on hydrate phase transition, multiphase flow in the decomposition zone, the seepage regulation of reservoir stimulation zone, and production capacity simulation, all of which are relevant to the previously conducted two rounds of hydrate trial production in offshore areas of China. The results indicate that the phase transition of clayey-silt hydrate remains in a dynamic equilibrium, with the decomposition efficiency mainly controlled by the coupling of heat and flow and high heat consumption during decomposition. The decomposition zone exhibits strong hydrophilicity, easy adsorption, and sudden permeability changes. A temperature drop is present that is concentrated near the wellbore, and once a water lock has formed, the gas-phase flow capacity significantly decreases, leading to potential secondary hydrate formation. To enhance permeability and increase production, it is imperative to implement reservoir and temperature field reconstruction based on initial formation alterations, which will further optimize and improve the transport capacity of the reservoir.Document Type: Current minireviewCited as: Lu, C., Qin, X., Sun, J., Wang, R., Cai, J. Research progress and scientific challenges in the depressurization exploitation mechanism of clayey-silt natural gas hydrates in the northern South China Sea. Advances in Geo-Energy Research, 2023, 10(1): 14-20. https://doi.org/10.46690/ager.2023.10.0
The influence of heterogeneous structure on salt precipitation during CO2 geological storage
Get PDFThe presence of rock heterogeneity and fractures may cause abrupt spatial changes in capillary action and flow characteristics, which eventually change the precipitation behavior during CO2 geological storage. Therefore, the salt precipitation mechanism of the heterogeneous structure needs to be studied. In this paper, the salt precipitation behavior in different heterogeneous structures was studied through pore-scale experiments at room temperature and atmospheric conditions. In the up-down heterogeneous structure, the salt precipitation has little effect on the injectivity regardless of the CO2 injection rate. When the CO2 injection rate is low, the salt tends to precipitate in situ in the small pore structure to form a crystal structure. When the CO2 injection rate is high, the salt tends to precipitate in the large pore structure to form a cluster structure. In the left-right heterogeneous structure, regardless of the CO2 injection rate, the precipitated salt is mainly in the cluster structure, and the salt is more dispersed in distribution, the impact on injectivity is small. The injection well can be selected in the formation with strong heterogeneity, to alleviate the blockage caused by salt precipitation. When CO2 leaks in the fractures, salt tends to grow until the fracture is plugged, which is of great significance for the self-healing of the fracture for the caprock.Document Type: Original articleCited as: He, D., Jiang, P., Xu, R. The influence of heterogeneous structure on salt precipitation during CO2 geological storage. Advances in Geo-Energy Research, 2023, 7(3): 189-198. https://doi.org/10.46690/ager.2023.03.0