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Pyrolysis behavior and pyrolysate characteristics of Huadian oil shale kerogen catalyzed by nickel-modified montmorillonite
Get PDFGiven the abundance of clay minerals in oil shales, the in-situ cracking of oil shale is preferably enhanced by catalysis, such as by modifying reservoir clays with soluble catalytically active materials. In this work, nickel-modified montmorillonite was synthesized via a simple method, and the feasibility of in-situ catalytic cracking of oil shales to facilitate engineering implementation was investigated. Thermogravimetric analysis was performed to assess the impact of the catalyst on the pyrolysis behavior of kerogen. The results demonstrated that nickel-modified montmorillonite effectively reduces the initial cracking temperature of kerogen and enhances the hydrocarbon generation rate. The results of thermogravimetric-Fourier transform infrared spectrum and thermogravimetric mass spectrometry analysis revealed a significant boost in the production of smaller molecules and non-condensable gases, including hydrogen, methane, ethane, and benzene. Concurrently, there was a notable reduction in carbon dioxide and sulfur dioxide emissions. Pyrolysis experiments were conducted to provide additional evidence of the effectiveness of nickel-modified montmorillonite, confirmed by a decrease in semi-coke production and a notable 11.25% increase in oil yield. Furthermore, the composition analysis of shale oil indicated an increased production of alkenes and aromatic hydrocarbons. These findings suggest that the addition of nickel-modified montmorillonite effectively enhances the depolymerization, deoxygenation and aromatization reaction, resulting in the formation of valuable products during the pyrolysis of oil shale kerogen. This study offers a promising avenue of cost-effective and efficient in-situ oil shale exploitation.Document Type: Original articleCited as: Gu, J., Deng, S., Sun, Y., Guo, W., Chen, H., Shi, B. Pyrolysis behavior and pyrolysate characteristics of Huadian oil shale kerogen catalyzed by nickel-modified montmorillonite. Advances in Geo-Energy Research, 2024, 11(3): 168-180. https://doi.org/10.46690/ager.2024.03.0
Pore-scale mechanism of coupled pressure-driven flow and spontaneous imbibition in porous media during high-pressure water injection processes
Get PDFDuring the development of low-permeability oil fields, high-pressure water injection is employed as a means of increasing reservoir pressure and enhancing oil recovery. This process features an interplay between pressure-driven flow and spontaneous imbibition, which exerts a pivotal influence on the distribution of oil and water. To describe the dynamics of this interplay, pore-scale visualization experiments and core flooding online nuclear magnetic resonance experiments were conducted in the present work. The results demonstrate that after water flooding, residual oil predominantly exists in clustered forms. Initially, during high-pressure water injection and the early stages of well shut-in, crude oil movement is driven primarily by pressure. As the process continues, however, a spontaneous imbibition mechanism driven by capillary forces becomes the predominant force, which results in the transformation of clustered residual oil into various mobilizable forms. This reorganization of residual oil is a migration pattern from smaller to larger pores, facilitated by spontaneous imbibition.Document Type: Original articleCited as: Kong, D., Peng, Y., Zhou, Z., Peng, H., Chen, Z. Pore-scale mechanism of coupled pressure-driven flow and spontaneous imbibition in porous media during high-pressure water injection processes. Capillarity, 2024, 13(2): 29-36. https://doi.org/10.46690/capi.2024.11.0
Research progress and prospects of utilizing carbon-based nanomaterials in enhanced oil recovery
Get PDFCarbon-based nanomaterials have received heightened global interest by petroleum researchers because of their abundant stocks of necessary raw materials, ease of size control, readiness for modification, and high stability. In light of the practical demand for oil development, this study reviews the recent progress in the research of enhancing oil recovery using carbon-based nanomaterials of various dimensions, including carbon dots, carbon nanotubes, carbon nanofibers, and graphene and its derivatives. Moreover, the study elaborates on the application of these materials in high-efficiency oil displacement, profile control and water shutoff, as well as the fracturing process. The related challenges and solutions in practical oil exploration and development are analyzed, and the application prospects of these materials in future oil reservoirs and oilfields are predicted. This review provides valuable theoretical and experimental references for the large-scale application of carbon-based nanomaterials.Document Type: Invited reviewCited as: Shen, M., Zhang, C., Yan, X., Wang, L., Wu, Y., Jin, X. Research progress and prospects of utilizing carbon-based nanomaterials in enhanced oil recovery. Advances in Geo-Energy Research, 2024, 14(3): 201-214. https://doi.org/10.46690/ager.2024.12.0
Advances in global natural hydrogen research and exploration
Get PDFThe development of natural hydrogen confronts numerous challenges. This paper sum marizes the status of research and exploration in the natural hydrogen field and outlines future directions and trends. The accumulation of natural hydrogen is a dynamic process, and current research on its origins, migration pathways, reservoir and cap rocks, chemical and biological consumption and final occurrence state is still at the exploratory stage. This lack of comprehensive understanding hinders the exploration and commercial development of natural hydrogen. Due to the unique characteristics of natural hydrogen, there is currently a shortage of effective exploration technologies and commercial development cases for natural hydrogen. The dynamic enrichment process of natural hydrogen and the consumption reaction mechanisms during this process will be the main aspects of future theoretical research on natural hydrogen. Additionally, the exploration of natural hydrogen needs to be combined with more practical applications of theory to enrich experience. It is necessary to establish and standardize work processes for different geological environments to achieve commercial development of natural hydrogen.Document Type: PerspectiveCited as: Han, S., Huang, J., Prinzhofer, A., Wang, C. Advances in global natural hydrogen research and exploration. Advances in Geo-Energy Research, 2025, 15(2): 91-94. https://doi.org/10.46690/ager.2025.02.0
Natural hydrogen resource exploitation must confront the issue that certain gas compositions are undesirable in terms of environmental sustainability
Get PDFExploration for natural hydrogen subsurface accumulations (“white” hydrogen) is justified based on supply requirements for expanded hydrogen-based energy systems. However, there are some key issues that require more detailed assessment before the exploitation of such resources can be justified from resource availability, environmental and sustainability perspectives. Three key issues of concern are: lack of large porous and permeable reservoirs containing hydrogen found to date; avoiding leakage of hydrogen from surface and subsurface production facilities; and finding sub-surface hydrogen reservoirs not substantially contaminated with methane or carbon dioxide but ideally almost pure hydrogen accompanied by commercial volumes of helium. The perspective presented explains why these issues are important and why the energy industry, academia and governments need to focus more on them if expanded hydrogen-based energy systems are to be developed to contribute to net-zero global emissions from the energy sector by 2050.Document Type: PerspectiveCited as: Wood, D. A. Natural hydrogen resource exploitation must confront the issue that certain gas compositions are undesirable in terms of environmental sustainability. Advances in Geo-Energy Research, 2025, 15(3): 185-189. https://doi.org/10.46690/ager.2025.03.0
Novel method for the rapid evaluation of pressure depletion in tight oil reservoirs
Get PDFTight oil reservoirs hold immense development potential but are characterized by challenging reservoir properties, severe heterogeneity, and extremely low permeability and porosity. Massive hydraulic fracturing of horizontal wells is applied to achieve sustainable production in these reservoirs. The swift assessment of pressure depletion in tight reservoirs is essential for their successful and cost-effective development. Traditional pressure testing methods necessitate well shutdown, impacting subsequent production, while numerical simulation methods demand significant computational resources and expertise from technical personnel. To identify the sensitivity parameters influencing the reservoir pressure drop, this study uses a Plackett-Burman design and variance analysis. Using numerical simulations, variance analysis and multi-linear regression, we formulate evaluation indices and surrogate models for individual well depletion. The method’s reliability is validated through multiple experiments along with testing data. Our rapid evaluation method accurately assesses pressure depletion in typical well groups, with a fitting rate exceeding 85%. In regions where the pressure maintenance is below 80%, indicating severe reservoir depletion, enhanced oil recovery treatments, e.g., gas or water injection, are applied based on the evaluation results. The proposed method for evaluating individual well pressure depletions provides crucial guidance for realizing the efficient development of tight oil reservoirs.Document Type: Short communicationCited as: Ding, C., Chen, J., Yang, G., Bao, R., Dou, Y., Song, K. Novel method for the rapid evaluation of pressure depletion in tight oil reservoirs. Advances in Geo-Energy Research, 2024, 11(1): 74-80. https://doi.org/10.46690/ager.2024.01.0
Efforts to untie the multicollinearity knot and identify factors controlling macropore structures in shale oil reservoirs
Get PDFTraditional correlation analyses based on whole-rock data have limitations in discerning pore development determinants in shale oil reservoir, given the complex lithology of shale formations and intricate interdependencies (multicollinearity) among geological variables. In this study, mercury injection capillary pressure and digital analysis of scanning electron microscopy were employed to examine the macropore structures of both whole rocks and their constituent lithologies for the Upper Triassic Chang-7 shale of the Ordos Basin. Variations were observed among clay shale (shale primarily consisting of clay-sized mineral grains), massive siltstone and silty laminae within the Chang-7 shale. Through the combination of correlation analysis and scanning electron microscope digital technique, it was demonstrated that total organic carbon content primarily controls the level of macropore development, while lithology primarily governs macropore types and structures. Although quartz and pyrite exhibit correlations with macropore volume, they do not emerge as primary factors; instead, they appear interconnected to total organic carbon. Due to detrital mineral framework preservation during compaction, larger macropores are more developed in massive siltstones and silty laminae than in clay shale. Additionally, silty laminae, situated closer to the source rock and influenced by organic acids, exhibit a higher abundance of larger dissolution pores, potentially favoring shale oil development. This study overcomes traditional method constraints, disentangling multi-correlations, and providing new insights into shale macropore development mechanisms, potentially advancing shale oil exploration and production.Document Type: Original articleCited as: Wang, Z., Dong, L., Jin, Z., Zou, S., Fu, J., Zhu, R. Efforts to untie the multicollinearity knot and identify factors controlling macropore structures in shale oil reservoirs. Advances in Geo-Energy Research, 2024, 11(3): 194-207. https://doi.org/10.46690/ager.2024.03.0
Prediction of displacement patterns in porous media using the probability of pore-scale filling events
Get PDFMultiphase flow in porous media is a common process in numerous engineering applications. While numerous studies have been conducted to investigate the impact of flow conditions, fluid properties, and wettability, the influence of flow geometry on the flow process remains poorly understood. Here, a theoretical model is proposed to directly forecast the displacement patterns across a wide range of porosity and disorder. This model is built upon the revelation that the overlap event stabilizes the invasion front, allowing us to predict displacement patterns by computing the probability of the overlap event. A value of 1 indicates a stable invasion process, resulting in compact displacement. Conversely, a value of 0 signifies an unstable invasion process, leading to capillary fingering. In the intermediate range between 0 and 1, a crossover zone is observed. The predicted phase diagram is evaluated using pore-network simulations and experiments in the literature, confirming that this model can reasonably predict displacement patterns under varying porosity and disorder. This contribution extends classical phase diagrams and holds practical significance for engineering applications.Document Type: Original articleCited as: Lan, T., Hu, R. Prediction of displacement patterns in porous media using the probability of pore-scale filling events. Capillarity, 2024, 11(1): 22-30. https://doi.org/10.46690/capi.2024.04.0
Determination of CO2 convective mixing flux in saline aquifers based on the optimality
Get PDFWhen carbon dioxide is sequestrated in a saline aquifer, the dissolution of carbon dioxide plume results in density difference between the brine with dissolved carbon dioxide and the ambient brine. This causes fingering flow and transport, or convective mixing, that is the dominant mechanism for the carbon dioxide solubility trapping. This work presents the first theoretical relationship for the carbon dioxide convective mixing flux from the plume that is critical for evaluating the long-term safety of carbon dioxide storage in a saline aquifer. This new development is based on the optimality: the density-difference driven fingering flow and transport are self-organized in such a way that the downward mass transport rate of dissolved carbon dioxide is maximized. The optimality has a root in non-equilibrium thermodynamics and been successfully applied to modeling the gravitational fingering flow for soil water in the vadose zone. Our theoretical relationship is shown to be able to accurately predict the experimental results of the convective mixing flux in three-dimensional porous media that were reported by the two different research groups. The average relative error between the theoretical flux values and experimental observations is about 10% or less, while uncertainties exist in the test observations. The flux for Sleipner carbon dioxide injection site (22 kg/m2 /yr), estimated using our new relationship, is also consistent with the previous estimates in the literature, in a range between 0 and 30 kg/m2 /yr with the most likely value of 15 kg/m2 /yr, that were obtained using a complex model to analyze the field data. These comparisons support the usefulness and validity of our relationship that does not need the knowledge of individual fingers associated with the convective mixing and is easy to use in practice.Document Type: Short communicationCite as: Liu, H., Chen, J., Jin, G., AlYousef, Z. Determination of CO2 convective mixing flux in saline aquifers based on the optimality. Advances in Geo-Energy Research, 2024, 13(2): 89-95. https://doi.org/10.46690/ager.2024.08.0
Application prospects of deep in-situ condition-preserved coring and testing systems
Get PDFShallow resources are becoming increasingly depleted, deep resource exploration has become a global strategy. The design and testing of deep in-situ core samples are prerequisites for exploring deep resources; however, no in-situ condition-preserved coring and testing techniques and tools have been reported yet. Here, the first deep in-situ condition-preserved coring system (with the preservation of pressure, temperature, substance, light, and moisture) was developed that considers the effects of high water pressure and formation dynamic loads, along with an in-situ condition-preserved testing system. A pressure-preserved controller was designed, achieving the ultimate capacity of 140 MPa and 150 ◦C. A temperature-preserved coring system combining active heating and passive insulation was constructed, realizing temperature preservation from room temperature to 150 ◦C. Three generations of film-formation principles and methods were designed, achieving an excellent quality preserved rate, moisture preserved rate, and visible light barrier rate. Moreover, a deep in-situ condition-preserved coring system, and a simulated coring platform for large cores under in-situ environments was fabricated. A non-contact testing system was derived to cut and prepare specimens under in-situ environment and to perform non-contact non-destructive testing and true triaxial testing. The research findings can be successfully applied to deep coal and gas development, deep oil and gas resources assessment, and deep-sea sediment prospecting, achieving excellent application outcomes. This study provides important theoretical, technical and hardware support for deep in-situ rock physics and mechanics research and deep resource exploitation.Document Type: Original articleCited as: Xie, H., Gao, M., Zhang, R., Zhou, H., Gao, F., Chen, L., Peng, X., Li, X., Ju, Y. Application prospects of deep in-situ condition-preserved coring and testing systems. Advances in Geo-Energy Research, 2024, 14(1): 12-24. https://doi.org/10.46690/ager.2024.10.0