Petroleum Science最新文献

{"title":"Organic petrographic investigation for artificially matured marine shale: Insights from anhydrous pyrolysis of Upper Ordovician shale from the Baltic Basin, Lithuania","authors":"Ye Wang ,&nbsp;Zhong-Liang Ma ,&nbsp;Nan-Sheng Qiu ,&nbsp;Bao-Jian Shen ,&nbsp;Xiao-Min Xie ,&nbsp;Tenger Borjigin ,&nbsp;Lun-Ju Zheng ,&nbsp;Zhao-Xi Zuo ,&nbsp;An-Yang Pan","doi":"10.1016/j.petsci.2025.03.028","DOIUrl":"10.1016/j.petsci.2025.03.028","url":null,"abstract":"<div><div>The absence of humic vitrinite complicates the determination of thermal maturity in pre-Devonian sediments. Lower Paleozoic shales contain structured zooclasts, solid bitumen, and vitrinite-like materials, and their reflectances have been found to be valid maturity proxies. Yet there remains much controversy as to the degree of evolution of reflectances. The current work aims to investigate the reflectance of dispersed organic matter (DOM), as well as their transformation degree and organic pore development. To this end, this study evaluated an Upper Ordovician zooclasts-bearing shale and a Middle Jurassic coal sample via anhydrous-pyrolysis to compare differences in the maturation pathways between marine-derived DOM and terrigenous vitrinite. These two original samples were cut into small blocks and placed in an identical vacuum stainless vessel simultaneously. The pyrolysis was carried out at isothermal temperatures ranging from 250 to 550 °C for 48 h. The morphologic and reflectance changes of DOM in pyrolysis residues were studied and compared with previous pyrolysis results.</div><div>Adopting the combined use of optical reflectance and scanning electron microscope (SEM) techniques, the study shows that DOM in the shale components consists of solid bitumen (SB), bituminite, chitinozoans, a few graptolites, vitrinite-like particles (VLP), alginate and liptodetrinite. The reflectance sequence, from high to low, is zooclasts, VLP and SB. Their reflectances gradually increases as the pyrolysis temperature rises, although the rate of growth is slower than that of co-heating coal vitrinite. Notably, zooclasts yield significantly higher reflectance values than those of VLP and SB at each pyrolysis temperature. However, the VLP undergoes two distinct phases in reflectance development, despite gradual morphology changes similar to vitrinite. Based on evidence of the optical texture and organic pore evolution, we argue that a fair amount of VLP in studied Upper Ordovician shale does not consist of graptolite-type fragments. Consequently, the VLPR_o serves as a reliable indicator for assessing organic matter maturity in Ordovician shales with a reflectance value of less than 2.0%. This investigation enhances scholarly understandings of marine-derived DOM evolution issues, providing clearer correlations among reflectances of different DOM and reducing uncertainties in thermal maturity determination.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 7","pages":"Pages 2677-2698"},"PeriodicalIF":6.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144757588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Corrigendum to “Evolution of multi-cluster fracturing in high-density layered shale considering the effect of injection scheme” [Pet. Sci. 22 (2025) 2109–2122]","authors":"Xiao Yan ,&nbsp;Haitao Yu ,&nbsp;Peng Zhang","doi":"10.1016/j.petsci.2025.07.016","DOIUrl":"10.1016/j.petsci.2025.07.016","url":null,"abstract":"","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 7","pages":"Page 3068"},"PeriodicalIF":6.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144758091","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-temperature and high-salinity resistance hydrophobic association zwitterionic filtrate loss reducer for water-based drilling fluids","authors":"Tai-Feng Zhang ,&nbsp;Jin-Sheng Sun ,&nbsp;Jing-Ping Liu ,&nbsp;Kai-He Lv ,&nbsp;Yuan-Wei Sun ,&nbsp;Zhe Xu ,&nbsp;Ning Huang ,&nbsp;Han Yan","doi":"10.1016/j.petsci.2025.05.016","DOIUrl":"10.1016/j.petsci.2025.05.016","url":null,"abstract":"<div><div>As the global exploration and development of oil and gas resources advances into deep formations, the harsh conditions of high temperature and high salinity present significant challenges for drilling fluids. In order to address the technical difficulties associated with the failure of filtrate loss reducers under high-temperature and high-salinity conditions. In this study, a hydrophobic zwitterionic filtrate loss reducer (PDA) was synthesized based on N,N-dimethylacrylamide (DMAA), 2-acrylamido-2-methylpropane sulfonic acid (AMPS), diallyl dimethyl ammonium chloride (DMDAAC), styrene (ST) and a specialty vinyl monomer (A₁). When the concentration of PDA was 3%, the FL_API of PDA-WBDF was 9.8 mL and the FL_HTHP (180 °C, 3.5 MPa) was 37.8 mL after aging at 240 °C for 16 h. In the saturated NaCl environment, the FL_API of PDA-SWBDF was 4.0 mL and the FL_HTHP (180 °C, 3.5 MPa) was 32.0 mL after aging at 220 °C for 16 h. Under high-temperature and high-salinity conditions, the combined effect of anti-polyelectrolyte and hydrophobic association allowed PDA to adsorb on the bentonite surface tightly. The sulfonic acid groups of PDA increased the negative electronegativity and the hydration film thickness on bentonite surface, which enhanced the colloidal stability, maintained the flattened lamellar structure of bentonite and formed an appropriate particle size distribution, resulting in the formation of dense mud cakes and reducing the filtration loss effectively.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 7","pages":"Pages 2851-2867"},"PeriodicalIF":6.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144757537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel method for predicting formation pore pressure ahead of the drill bit by embedding petrophysical theory into machine learning based on seismic and logging-while-drilling data","authors":"Xu-Yue Chen ,&nbsp;Cheng-Kai Weng ,&nbsp;Lin Tao ,&nbsp;Jin Yang ,&nbsp;De-Li Gao ,&nbsp;Jun Li","doi":"10.1016/j.petsci.2025.04.012","DOIUrl":"10.1016/j.petsci.2025.04.012","url":null,"abstract":"<div><div>Formation pore pressure is the foundation of well plan, and it is related to the safety and efficiency of drilling operations in oil and gas development. However, the traditional method for predicting formation pore pressure involves applying post-drilling measurement data from nearby wells to the target well, which may not accurately reflect the formation pore pressure of the target well. In this paper, a novel method for predicting formation pore pressure ahead of the drill bit by embedding petrophysical theory into machine learning based on seismic and logging-while-drilling (LWD) data was proposed. Gated recurrent unit (GRU) and long short-term memory (LSTM) models were developed and validated using data from three wells in the Bohai Oilfield, and the Shapley additive explanations (SHAP) were utilized to visualize and interpret the models proposed in this study, thereby providing valuable insights into the relative importance and impact of input features. The results show that among the eight models trained in this study, almost all model prediction errors converge to 0.05 g/cm³, with the largest root mean square error (RMSE) being 0.03072 and the smallest RMSE being 0.008964. Moreover, continuously updating the model with the increasing training data during drilling operations can further improve accuracy. Compared to other approaches, this study accurately and precisely depicts formation pore pressure, while SHAP analysis guides effective model refinement and feature engineering strategies. This work underscores the potential of integrating advanced machine learning techniques with domain-specific knowledge to enhance predictive accuracy for petroleum engineering applications.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 7","pages":"Pages 2868-2883"},"PeriodicalIF":6.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144757539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental study of acid fracturing behavior in carbonate reservoirs with different fracture-cavity development","authors":"Song-Cai Han ,&nbsp;Li-Le Li ,&nbsp;Sen Hu ,&nbsp;Chu-Hao Jing ,&nbsp;Xu-Di Wu ,&nbsp;Jun-Chao Yang ,&nbsp;Tao Liu ,&nbsp;Cai-Yun Xiao","doi":"10.1016/j.petsci.2025.04.022","DOIUrl":"10.1016/j.petsci.2025.04.022","url":null,"abstract":"<div><div>Heterogeneity in carbonate formations due to discontinuities (e.g., fractures and cavities) will bring about distinctive acid stimulation effects. However, the differences in fracturing behavior between homogeneous and heterogeneous carbonate formations remain unclear, complicating the optimization of acid fracturing strategies. In this paper, full-diameter carbonate rock samples with different degrees of discontinuity development are selected to investigate the fracturing behavior under different fluid types and injection schemes. Advanced techniques, including 3D CT scanning and 3D laser scanning, are employed to analyze fracture morphology and etching characteristics, respectively. Experimental results show that the coupled hydraulic-chemical effects play different roles in fracture induction between fracture-cavity developed and undeveloped carbonate rocks. Acid-fracturing stimulation consistently induces multiple types of complex fractures in fracture-cavity carbonate rocks, whereas it results in a single artificial fracture in less fracture-cavity carbonate rocks. Furthermore, localized etching patterns are prevalent in most fracture-cavity carbonate rocks, whereas homogeneous carbonate rocks exhibit regional or global etching characteristics. In both carbonate rocks, the stimulation effect of guar fluid is inferior to that of gelled acid but comparable to self-generating acid. Further findings are that alternating fracturing with guar and acid fluids in fracture-cavity carbonate rocks can sustain or even increase the injection pressure, facilitating the formation of new or depth-penetrating fractures. This phenomenon, however, is not observed in fracture-cavity undeveloped carbonate rocks. Potential interaction modes between induced fracture and natural fractures/cavities under different injection conditions are also identified. Finally, preferred fracturing schemes applicable to different carbonate formations are recommended based on the area, number and roughness of the induced fractures.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 7","pages":"Pages 2937-2949"},"PeriodicalIF":6.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144757543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of CO2–brine–kerogen wettability on CO2 sequestration in shale: Implications from molecular dynamics simulation","authors":"Kan-Yuan Shi ,&nbsp;Jun-Qing Chen ,&nbsp;Xiong-Qi Pang ,&nbsp;Sha-Sha Hui ,&nbsp;Zhang-Xin Chen ,&nbsp;Ben-Jie-Ming Liu ,&nbsp;Yu-Jie Jin ,&nbsp;Si-Jia Zhang","doi":"10.1016/j.petsci.2025.03.040","DOIUrl":"10.1016/j.petsci.2025.03.040","url":null,"abstract":"<div><div>As the main factor influencing the flow and preservation of underground fluids, wettability has a profound impact on CO₂ sequestration (CS). However, the influencing factors and internal interaction mechanisms of shale kerogen wettability remain unclear. In this study, we used molecular dynamics to simulate the influence of temperature, pressure, and salinity on wettability. Furthermore, the results were validated through various methods such as mean square displacement, interaction energy, electrostatic potential energy, hydrogen bonding, van der Waals forces, and electrostatic forces, thereby confirming the reliability of our findings. As temperature increases, water wettability on the surface of kerogen increases. At CO₂ pressures of 10 and 20 MPa, as the temperature increases, the kerogen wettability changes from CO₂ wetting to neutral wetting. As the CO₂ pressure increases, the water wettability on the surface of kerogen weakens. When the pressure is below 7.375 MPa and the temperature is 298 or 313 K, kerogen undergoes a wettability reversal from neutral wetting to CO₂ wetting. As salinity increases, water wettability weakens. Divalent cations (Mg²⁺ and Ca²⁺) have a greater impact on wettability than monovalent cations (Na⁺). Water preferentially adsorbs on N atom positions in kerogen. CO₂ is more likely to form hydrogen bonds and adsorb on the surface of kerogen than H₂O. As the temperature increases, the number of hydrogen bonds between H₂O and kerogen gradually increases, while the increase in pressure reduces the number of hydrogen bonds. Although high pressure helps to increase an amount of CS, it increases the permeability of a cap rock, which is not conducive to CS. Therefore, when determining CO₂ pressure, not only a storage amount but also the storage safety should be considered. This research method and results help optimize the design of CS technology, and have important significance for achieving sustainable development.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 7","pages":"Pages 2747-2759"},"PeriodicalIF":6.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144757591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanisms of organic matter accumulation in marine clear water conditions: The Upper Permian Dalong Formation, Sichuan Basin, China","authors":"Guo-Dong Xia ,&nbsp;Yue-Hao Ye ,&nbsp;Shu-Gen Liu ,&nbsp;Hua Wang ,&nbsp;Kun Jiao ,&nbsp;Jin-Min Song ,&nbsp;Zhi-Wu Li ,&nbsp;Wei Chen ,&nbsp;Ying Ming ,&nbsp;Xiao-Gang Ma ,&nbsp;Heng Wang ,&nbsp;Chun-Qiao Yan ,&nbsp;Yun Zeng","doi":"10.1016/j.petsci.2025.03.029","DOIUrl":"10.1016/j.petsci.2025.03.029","url":null,"abstract":"<div><div>The Late Permian to Early Triassic marked a pivotal phase in paleoenvironmental and tectonic shifts. The Kaijiang-Liangping intracratonic sag, a tectonic geomorphology formed by Emei taphrogenesis in the Sichuan Basin, is situated within a clear water carbonate platform. Under these conditions, the black shales of the Dalong Formation in the sag have ultrahigh organic matter content. However, the mechanism by which these conditions control the accumulation of such organic matter remains unclear. Petrological and geochemical analyses of well DY-1H revealed four distinct units within the Dalong Formation: A, B, C, and D, with average total organic carbon contents of 3.00%, 9.59%, 4.57%, and 0.27%, respectively. The kerogen maceral, carbon isotope, and pyrolysis results show that the organic matter mainly comprises Type Ⅱ₂ kerogen. Benthic plants growing in clear water may be the primary source of this kerogen. Shallow water, suboxic conditions, strong volcanism, and high productivity characterize Unit A. Unit B features restricted ocean circulation, anoxic conditions, weak upwelling, moderate volcanism, and high productivity. Unit C is characterized by anoxic conditions, strong upwelling, weak volcanism, and moderate productivity. Oxic conditions and low productivity define Unit D. These findings challenge traditional models that struggle to explain the accumulation of ultrahigh organic matter in Unit A under suboxic conditions, Unit C under moderate productivity, and Unit B with abnormally high organic matter content. The flourishing of benthic plants, a considerable source of Type II₂ kerogen that resists decomposition and favors preservation, is the dominant factor controlling the ultrahigh organic matter accumulation of black shales in Units A, B, and C under clear water conditions. Oxidized bottom waters and decreased benthic plant growth were crucial to the sharp decline in organic matter.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 7","pages":"Pages 2699-2718"},"PeriodicalIF":6.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144757589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiscale investigation into EOR mechanisms and influencing factors for CO2-WAG injection in heterogeneous sandy conglomerate reservoirs using NMR technology","authors":"Jun-Rong Liu ,&nbsp;Deng-Feng Zhang ,&nbsp;Shu-Yang Liu ,&nbsp;Run-Dong Gong ,&nbsp;Li Wang","doi":"10.1016/j.petsci.2025.04.004","DOIUrl":"10.1016/j.petsci.2025.04.004","url":null,"abstract":"<div><div>The sandy conglomerate reservoir is tight and exhibits strong heterogeneity, rendering conventional water flooding and gas drive methods inefficient and challenging for the effective development. CO₂ water alternating gas (CO₂-WAG) injection as an effective enhanced oil recovery (EOR) method has been applied in heterogeneous reservoirs. Simultaneously, it facilitates carbon sequestration, contributing to the green and low-carbon transformation of energy. However, the EOR mechanisms and influencing factors are still unclear for the development of heterogeneous sandy conglomerate reservoirs. In this paper, we conducted core flooding experiments combined nuclear magnetic resonance (NMR) technology to investigate EOR mechanisms of the CO₂-WAG injection on the multiscale (reservoir, layer, and pore). The study compared multiscale oil recovery in sandy conglomerate reservoirs under both miscible and immiscible conditions, while also analyzing the effects of water–gas ratio and injection rate. In the immiscible state, the CO₂-WAG displacement achieves an oil recovery of approximately 22.95%, representing a 7.82% increase compared to CO₂ flooding. This method effectively inhibits CO₂ breakthrough in high-permeability layers while enhancing the oil recovery in medium- and low-permeability layers. Furthermore, CO₂-WAG displacement improves the microscopic oil displacement efficiency within mesopores and micropores. As the water–gas ratio increases, the total oil recovery rises, with enhanced oil recovery in low-permeability layers and micropores. Moreover, a gradual increase in injection rate leads to a decrease in total oil recovery, but it leads to an increase in oil recovery from low-permeability sandy conglomerate layers and micropores. In the miscible state, the displacement efficiency of CO₂-WAG is significantly enhanced, the total oil recovery three times higher than that in the immiscible state. In particular, the oil recovery from low permeability layers and micropores has further improved. Additionally, experimental results indicate that parameters such as water–gas ratio and injection rate do not significantly affect the oil recovery of CO₂-WAG miscible displacement. Therefore, maintaining the reservoir pressure above the minimum miscible pressure is the key to maximizing ultimate recovery factor in these reservoirs.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 7","pages":"Pages 2977-2991"},"PeriodicalIF":6.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144758084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Measurement while drilling of downhole engineering parameters by application of a newly designed micro-measurer","authors":"Yu-Xi Wang ,&nbsp;Mu Li ,&nbsp;Mao-Lin Liao ,&nbsp;Wei Liu ,&nbsp;Ting-Rui Li ,&nbsp;Joseph Páez Chávez ,&nbsp;Gong-Hui Liu ,&nbsp;Jun Li ,&nbsp;Sheng-Lian Yao","doi":"10.1016/j.petsci.2025.04.025","DOIUrl":"10.1016/j.petsci.2025.04.025","url":null,"abstract":"<div><div>As the well drilling depth has broken through the 10,000 m in China, accurate measurements of downhole engineering parameters, such as annulus temperature and pressure for the whole wellbore, are significant in controlling potential downhole complexities. In this present work, a new micro-measurer is developed by integrating measurements of downhole temperature, pressure, magnetic field strength, and its own dynamic signals. The micro-measurer can flow with drilling fluid from the drillstring to the bottomhole and then float up back to the ground via the wellbore annulus. Compared with other downhole measurement tools that are fixedly connected to the drill string, its “measure-and-move-on” approach reduces the residence time in the high-temperature and high-pressure zone at the bottomhole; moreover, both the pressure and temperature at different well depth can be measured, thereby the temperature and pressure profiles of the whole wellbore can be constructed. In addition, the bluetooth low energy (BLE) technique is applied to offer the micro-measurer with the capability of wireless information transmission; while hydrodynamic optimization of the micro-measurer is carried out to design the structure of the micro-measurer, which can promote its recovery rate from downhole. In addition, an intelligent joint for releasing micro-measurers from the wellbore annulus is also proposed, aiming to overcome the limitation imposed by the nozzle on the size of the micro-measurer. Both the indoor experiments and the field tests have verified the feasibility of the newly designed micro-measurer, which is a key step for establishing a complete downhole internet of things (IoT) system to serve the intelligent drilling in the future.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 7","pages":"Pages 2905-2919"},"PeriodicalIF":6.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144757541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study on the effect of clay minerals on phase transition of methane hydrate in sand sediments: Kinetic behavior and microstructural observation","authors":"Xinxu Wang ,&nbsp;Yuan Yuan ,&nbsp;Zhongming Du ,&nbsp;Bo Liu ,&nbsp;Chenlu Xu ,&nbsp;Jijin Yang","doi":"10.1016/j.petsci.2025.03.047","DOIUrl":"10.1016/j.petsci.2025.03.047","url":null,"abstract":"<div><div>Natural gas hydrates widely accumulate in submarine sediments composed of clay minerals. However, due to the complex physiochemistry and micron-sized particles of clay minerals, their effects on methane hydrate (MH) formation and dissociation are still in controversy. In this study, montmorillonite and illite were separately mixed with quartz sand to investigate their effects on MH formation and dissociation. The microstructure of synthesized samples was observed by cryo-SEM innovatively to understand the effects of montmorillonite and illite on MH phase transition in micron scale. Results show that montmorillonite and illite both show the inhibition on MH formation kinetics and water-to-hydrate conversion, and illite shows a stronger inhibition. The 10 wt% montmorillonite addition significantly retards MH formation rate, and the 20 wt% montmorillonite has a less inhibition on the rate. The increase of illite mass ratio (0–20 wt%) retards the rate of MH formation. As the content of clay minerals increase, the water-to-hydrate conversion decreases. Cryo-SEM images presented that montmorillonite aggregates separate as individual clusters while illite particles pack as face-to-face configuration under the interaction with water. The surface-overlapped illite aggregates would make sediments pack tightly, hinder the contact between gas and water, and result in the more significant inhibition on MH formation kinetics. Under the depressurization method, the addition of clay minerals facilitates MH dissociation rate. Physicochemical properties of clay minerals and MH distribution in the pore space lead to the faster dissociation rate in clay-containing sediments. The results of this study would provide beneficial guides on geological investigations and optimizing strategies of natural gas production in marine hydrate-bearing sediments.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"22 7","pages":"Pages 3029-3041"},"PeriodicalIF":6.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144758087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}