Petroleum Science最新文献

{"title":"Fluid inclusion analysis and carbonate U–Pb dating reveal shale oil accumulation processes in the Qingshankou Formation, Songliao Basin, NE China","authors":"Yue Huang,&nbsp;Qing-Chun Jiang,&nbsp;Jian Chang,&nbsp;Nan-Sheng Qiu,&nbsp;Yong-Shui Zhou,&nbsp;Hua Kang,&nbsp;Meng-Fei Zhang","doi":"10.1016/j.petsci.2026.06.054","DOIUrl":"10.1016/j.petsci.2026.06.054","url":null,"abstract":"<div><div>Direct constraints on the absolute timing of shale oil accumulation and microscale migration within shale systems remain limited. Here we investigate ostracod limestone interbeds, calcite veins, and barite veins from the Qingshankou Formation in the Songliao Basin, integrating fluid inclusion petrography, diagenetic phase analysis of host minerals, and in situ U–Pb dating to reconstruct the timing and evolution of shale oil accumulation in Member 1 of the Qingshankou Formation. Hydrocarbon inclusions within the veins are dominated by yellow-green, blue-white, and predominantly blue fluorescence assemblages. Blue-fluorescing inclusions are characterized by fluorescence <em>λ</em>_max below 485 nm and CIE chromaticity coordinates (<em>X</em>, <em>Y</em>) lower than 0.3, indicating a relatively high level of thermal maturity. Homogenization temperatures of hydrocarbon inclusions and their coexisting aqueous inclusions show good correspondence with the diagenetic stages of host minerals, reflecting multiple episodes of fluid trapping. Trapping ages of hydrocarbon inclusions inferred from burial–thermal history reconstruction are broadly consistent with in situ U–Pb ages of calcite veins (65.3 ± 4.8 Ma and 58.2 ± 5.2 Ma), indicating that vein formation and hydrocarbon-bearing fluid activity were essentially synchronous at the study area scale. Image-based analysis of the hydrocarbon inclusion abundance index (IHI-AI) shows that blue-fluorescing inclusions are relatively enriched in the central Gulong Sag, and their spatial distribution closely matches the occurrence of high-maturity, light shale oil. Integrated interpretation of fluorescence spectral parameters, equivalent hydrocarbon inclusion reflectance derived from the image-based fluorescence CIE chromaticity (IF–CIE) method (EqHI<em>R</em>_o), homogenization temperature data, diagenetic evolution, and in situ U–Pb dating indicates that, after the Qingshankou Formation reached a high level of thermal maturity near the end of the Cretaceous, shale oil retained within the source rock continued to undergo intrasource microscale migration and redistribution from the middle to late Paleogene through the Neogene. Distinct fluorescence–chromaticity signatures of hydrocarbon inclusions indicate that shale oil accumulation was closely associated with continuous hydrocarbon generation and sustained intrasource micromigration. This study provides an integrated framework for constraining the timing and evolutionary pathways of shale oil accumulation in lacustrine shale systems.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"23 10","pages":"Pages 6053-6069"},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149095407","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence factors of long-term stability of silica-enriched Portland cement under ultrahigh temperatures","authors":"Yang Li,&nbsp;Xue-Yu Pang,&nbsp;Yong-Jin Yu,&nbsp;Sheng-Lai Guo,&nbsp;Jia-Pei Du,&nbsp;Hai-Ge Wang,&nbsp;Kai-He Lv,&nbsp;Jin-Sheng Sun","doi":"10.1016/j.petsci.2026.05.046","DOIUrl":"10.1016/j.petsci.2026.05.046","url":null,"abstract":"<div><div>Downhole high-temperature and high-pressure (HTHP) conditions can cause significant deteriorations of well cement, posing a major risk to wellbore integrity. A comprehensive experimental program is designed to investigate the long-term physical and mechanical property stability of silica-enriched Portland cement (SEPC) systems and various influencing factors. Formulations representing three different densities and two silica dosages are designed for two different curing regimes commonly adopted in the literature: 1) direct high-temperature curing at 240 °C and 2) 80 °C low-temperature pre-curing followed by high temperature curing at 240 °C. Under the direct-curing regime, SEPC systems containing 70% silica undergoes progressive microstructural coarsening and strength retrogression over time. The gradual transformation of tobermorite into xonotlite and other crystal phases, as well as potential structural changes in amorphous C–S–H, both causing reductions in bound water content in hydration products, are the principal factors driving strength retrogression. In contrast, under the pre-curing regime, the tobermorite and bound water contents remain stable or increase progressively with curing time, which lead to significant improvements in their physico-mechanical properties during long term curing. Compared to SEPC systems containing 70% silica, the SEPC systems with 40% silica exhibit improved strength stability and comparable long-term strength but lower initial strength, higher porosity and permeability, due to the generation of large amounts of xonotlite as the main hydration product. Decreasing cement slurry density by increasing water to solid ratio promotes the formation of more crystalline phases, which leads to significantly higher porosity and permeability as well as lower strengths with similar long-term retrogression behavior.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"23 10","pages":"Pages 6341-6353"},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149095474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Laboratory testing of clayey-silty hydrate reservoir exploitation: Considering the permeability-stress coupling effect","authors":"Jia-Qi Liu,&nbsp;Ya-Peng Zhao,&nbsp;Xin-Rui Wang,&nbsp;Liang Kong,&nbsp;Song-Kui Sang,&nbsp;Zhi-Yuan Wang,&nbsp;Xue-Wei Wu,&nbsp;Gao-Wei Hu","doi":"10.1016/j.petsci.2026.03.026","DOIUrl":"10.1016/j.petsci.2026.03.026","url":null,"abstract":"<div><div>Elucidating the multi-field, multi-phase coupling mechanisms in submarine hydrate reservoirs is essential for releasing their energy potential. Current research gaps remain in understanding the permeability-stress coupling characteristics of hydrate reservoirs. This study conducted permeability-stress coupling tests on hydrate-bearing clayey-silty sediments (HBCS). The seepage characteristics and mechanical response of HBCS under seepage-stress coupling effects were investigated. The results indicate that under stress conditions, the seepage flow of HBCS follows a logarithmic relationship with axial strain, with its rate of increase decelerating as axial strain grows. Apparent permeability decreases rapidly at first and then more gradually with increasing axial strain. Hydrate saturation (<em>S</em>_h) and seepage pressure difference (<em>P</em>_S) exhibit a coupling effect on apparent permeability. At low-<em>S</em>_h levels, particle migration induced by seepage reduces permeability. At high-<em>S</em>_h levels, permeability is affected by two competing mechanisms (pore expansion and particle migration) driven by seepage forces. Unlike triaxial tests for HBCS, under seepage conditions, the plastic deformation capacity of HBCS is enhanced. The stress-strain curve exhibits strain hardening and plastic flow, and lacks obvious strain softening. Shear strength decreases with increasing <em>S</em>_h and <em>P</em>_S, while the secant modulus <em>E</em>₅₀ rises with both parameters. During hydrate exploitation, production efficiency correlates with <em>S</em>_h. In low-<em>S</em>_h reservoirs, a “slow and steady” production strategy is recommended to prevent sand production and wellbore blockage. In high-<em>S</em>_h reservoirs, increasing <em>P</em>_S can promote pore expansion and fracture propagation, thereby enhancing production efficiency. This study provides a reference for engineers to understand the multi-field and multi-phase coupling characteristics during the exploitation of hydrate reservoirs.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"23 10","pages":"Pages 6903-6928"},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149095787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Progress and perspectives on ZSM-22-based catalysts for long-chain n-alkane hydroisomerization","authors":"Qiang Wang,&nbsp;Ley Boon Sim,&nbsp;Ping Wang,&nbsp;Qiang Wang,&nbsp;Bing-Hui Chen","doi":"10.1016/j.petsci.2026.04.019","DOIUrl":"10.1016/j.petsci.2026.04.019","url":null,"abstract":"<div><div>Hydroisomerization of long-chain <em>n</em>-alkanes holds significant value in pour point reduction and quality enhancement of fuels, the development of premium lubricants, and the industrial advancement of biofuels. Among various catalysts, ZSM-22 zeolite has emerged as an ideal support due to its unique pore structure and tunable acidity. This review summarizes the latest research progress on ZSM-22-based bifunctional catalysts. Studies have shown that two main strategies are commonly employed to enhance isomerization performance: optimizing the hydrogenation/dehydrogenation functionality of metal sites and tailoring the physicochemical properties of the zeolite. High-quality metal function contributes to an ideal bifunctional catalytic mechanism, which can be achieved by precisely controlling the dispersion, location, and exposed crystal facets of noble metals (e.g., Pt, Pd). While non-noble metals (e.g., Ni) can show hydroisomerization performance rivaling noble metals, their development relies on constructing bimetallic sites and carefully balanced metal-support interactions. In terms of ZSM-22 functional modification, reducing crystal size and constructing hierarchical pore structures are effective in mitigating the diffusion limitations imposed by its micropores on alkanes and olefinic intermediates. Meanwhile, acidity modulation can be achieved via framework heteroatom incorporation, ion exchange, surface acid site passivation, and partial pore blockage. Additionally, co-crystallization and composite zeolite strategies offer promising pathways for further enhancing the isomerization performance of ZSM-22-based catalysts. This review aims to provide both theoretical insights and technical guidance for the development of efficient catalysts for long-chain <em>n</em>-alkane hydroisomerization, offering value to researchers new to this field.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"23 10","pages":"Pages 6832-6851"},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149095789","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Glucose derived carbon spheres grafted with an oil-absorbing polymer as a composite plugging agent for oil-based drilling fluids","authors":"Jia-Ning He,&nbsp;Yang Bai,&nbsp;Tuo-Ming Zhang,&nbsp;Deng Gu,&nbsp;Rui-Fang Wang","doi":"10.1016/j.petsci.2026.07.011","DOIUrl":"10.1016/j.petsci.2026.07.011","url":null,"abstract":"<div><div>A composite plugging agent, glucose-derived carbon spheres grafted with poly (methyl methacrylate-co-octadecyl methacrylate-co-styrene) (GCS-g-PMOS), was synthesized by grafting an oil-absorbing polymer onto glucose-derived carbon spheres through suspension polymerization for application in oil-based drilling fluids. This material was designed to overcome the limited adaptability of conventional rigid plugging agents by integrating the structural support of carbon spheres with the swelling and filling capabilities of the polymer phase. Response surface methodology was used to optimize the preparation parameters, and the optimum formulation was determined to be 0.75 wt% glucose-derived carbon spheres, 1.5 wt% <em>N</em>,<em>N</em>′-methylenebisacrylamide, and 2.0 wt% benzoyl peroxide. Under these conditions, the oil absorption capacity reached 9.02 g/g. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and wettability analyses confirmed successful grafting of the polymer phase and showed that the composite possessed good thermal stability and strong oil affinity. After aging at 160 °C, the addition of 6 wt% GCS-g-PMOS reduced the American Petroleum Institute (API) filtrate loss from 4.4 to 2.4 mL and decreased the filter cake thickness from 2.0 to 0.9 mm. The material also exhibited effective plugging performance in media of different scales and reduced the permeability of the filter cake, with a maximum permeability reduction rate of 63.53%. These results demonstrate that the integration of rigid carbon spheres and an oil-absorbing polymer is beneficial for forming a dense sealing structure and enhancing fluid-loss control in oil-based drilling fluids under high temperature conditions.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"23 10","pages":"Pages 6610-6623"},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149095920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An advanced comprehensive statistical physical model revealing the effect of slickwater on methane adsorption in shale","authors":"Shuo Duan,&nbsp;Yong-Jian Zhang,&nbsp;Xiang-Yang Ling,&nbsp;Peng-Fei Shen,&nbsp;Ling-Zao Zeng,&nbsp;Ze-Yu Li","doi":"10.1016/j.petsci.2026.06.009","DOIUrl":"10.1016/j.petsci.2026.06.009","url":null,"abstract":"<div><div>The impact of slickwater on methane adsorption in shale reservoirs is a critical factor in hydraulic fracturing design and production prediction, but its quantitative evaluation is a common problem facing current research. In this work, an advanced integrated model was established to combine multi-scale shale characterization with statistical physics modeling to reveal its underlying mechanisms. Two typical shale samples from the Bohai Bay Basin were taken in situ and treated with different concentrations of slickwater. The evolution of elemental and mineral composition, surface chemistry, and pore structure of shale samples before and after processing was compared using multi-scale characterization techniques. An advanced statistical physical adsorption model was established to analyze the CH₄ adsorption characteristics of raw and treated shale. The results indicated that shale treated with slickwater reduced the clay mineral content, specific surface area, and micropore volume, but increased the average pore size. The methane adsorption capacity of shale treated with slickwater was significantly reduced, and CH₄ molecules were adsorbed on the shale surface in a mixed parallel or vertical manner. In addition, in the shale samples treated with slippery water, the spontaneous decrease in CH₄ adsorption and the increase in disorder resulted in a reduction in the number of low-energy and high-energy sites available for CH₄ adsorption on the shale surface. These findings establish a quantitative, mechanistic framework for evaluating slickwater–shale interactions, providing critical theoretical support for enhancing shale gas recovery strategies.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"23 10","pages":"Pages 6411-6442"},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149095841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-objective optimization of oilfield water injection operations under dynamic electricity prices: For equivalent reduction of carbon emissions","authors":"Shuang-Qing Chen,&nbsp;Chao Chen,&nbsp;Yu-Chun Li,&nbsp;Lan Meng,&nbsp;Li-Xin Wei,&nbsp;Bing Guan","doi":"10.1016/j.petsci.2026.08.003","DOIUrl":"10.1016/j.petsci.2026.08.003","url":null,"abstract":"<div><div>Low-carbon oilfield requires the water injection system with huge electricity consumption to reduce carbon emissions, and there is an urgent need to establish an operation optimization method with low-carbon goals. This paper constructs a multi-objective optimization model of time-segmented water injection in oilfield water injection systems considering time-of-use electricity pricing that minimizes carbon emissions and electricity cost under time-of-use electricity pricing. The model comprehensively considers local head losses, pipeline network hydraulic balance, water balance constraint, pressure constraint of water injection well, pump flow rate constraint, water injection volume constraint, and time period priority constraint. Traditional solvers are prone to falling into local optima when solving the water injection optimization model. This paper proposes the innovative algorithm named Quantum Leader-Follower Formation Optimization Algorithm (QLFFOA). Compared with 10 classical algorithms, QLFFOA exhibits better solution performance. Finally, the proposed method was applied to a real oilfield water injection system containing 131 water injection wells and 2 water injection stations, and time-segmented water injection optimization was performed for 4 injection pumps over 13 independent time periods throughout the day under the time-of-use (TOU) electricity pricing mechanism. Under the premise of satisfying the core constraints of the water injection system, the optimized schedule decreased system energy consumption by about 7.3%, saved electricity costs by 10.8%, decreased carbon emissions by 7.2%, decreased unit energy consumption by 0.4 kWh/m³, and raised the system average pump efficiency by 1.84%. The optimized scheme avoided night-time peak periods, effectively reduced electrical energy consumption and correspondingly decreased CO₂ emissions. The results indicate that this model and algorithm can scientifically guide the time-segmented operation management of oilfield water injection systems, thereby reducing harmful gas emissions from the electricity demand side.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"23 10","pages":"Pages 6723-6748"},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149095844","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental research on failure mechanism and evolution characteristics of thermal-treated granites under action of impact load with PDC cutter","authors":"Hao-Yu Wang,&nbsp;Yan Xi,&nbsp;Wei Lian,&nbsp;Jun Li,&nbsp;Hai-Long Jiang,&nbsp;Yu-Mei Li","doi":"10.1016/j.petsci.2026.05.034","DOIUrl":"10.1016/j.petsci.2026.05.034","url":null,"abstract":"<div><div>High rock temperatures and complex engineering environments are the most significant problems in enhancing the rate of penetration (ROP) and drilling tool efficiency for hot dry rocks (HDR). Studying the failure characteristics of different thermal-treated granites by PDC cutters during percussive drilling has profound significance in enhancing the compatibility between drilling teeth and rock during HDR mining and optimizing the drilling toolʼs efficiency in breaking rocks. Through drillability tests and SHPB tests, the present study explored the relationship between drillability and the dynamic behavior of granites. In addition, granites with different heating temperatures and cooling methods were subjected to dynamic rock-breaking tests by the SHPB system installed with the PDC cutter. Furthermore, the impact crater was quantified by 3D contour scanning technology, and the fractal theory was utilized to analyze the fragments. Then, the equations for the dynamic magnification factor of intrusion, fractal dimension, and specific rock-breaking energy of granite upon impact loading are discussed. According to the results, the impact crater size is closely associated with the heating temperature of the rock. Heating and rapid cooling treatments will affect the thermal shock damage and strength of rock, and then change the penetration depth, damage volume, and area of impact craters generated from the PDC cutter. The granite at 600 °C exhibits about 45% smaller fragment size than that at room temperature, while the damage degree of the liquid nitrogen-cooled specimen will be greater. According to the variation of dynamic magnification factor, fractal dimension, and specific rock-breaking energy of rock with thermal shock damage, it can be found that with the temperature increasing, the problems drilling tools need to solve gradually shift from increasing ROP to improving cleaning efficiency. The experimental results are expectedly to lay the ground for high compatibility between drilling tools and formation in HDR.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"23 10","pages":"Pages 6294-6318"},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149095409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Volcanically-induced sedimentary evolution of fine-grained rocks and environmental responses: A case study of the Chang 73 submember in Ordos Basin, NW China","authors":"Jing-Jing Shen,&nbsp;Wen-Zhi Zhao,&nbsp;Wei Liu,&nbsp;Cong-Sheng Bian,&nbsp;Yong-Xin Li,&nbsp;Jin Dong,&nbsp;Zhi-Qian Gao","doi":"10.1016/j.petsci.2026.07.058","DOIUrl":"10.1016/j.petsci.2026.07.058","url":null,"abstract":"<div><div>Volcanism is an important controlling factor for organic matter enrichment and sedimentary evolution in proximal continental lakes. Numerous studies have focused on revealing the intrinsic mechanisms of high organic carbon burial regulated by volcanism, while the understanding of the dynamic evolutionary processes of volcanically induced lacustrine depositional systems remains unclear. We integrated core, logging, and geochemical data from more than 20 fully cored wells spanning all sedimentary facies belts of the Chang 7₃, to reconstruct the paleoenvironment and establish sedimentary models during volcanism. By combining sequence stratigraphy, carbon isotope chemostratigraphy, zircon U–Pb dating and astronomical cycle techniques, we established a high-precision isochronous stratigraphic framework, spanning ∼241.36 Ma to ∼239.7 Ma. This study presented the first detailed record of sedimentary evolution in response to volcanism in the Ordos Basin: Early volcanism led to a transient, relatively dry-cold climate and low weathering intensity; volcanic ash supplied nutrients to the lake, and the accumulation of loose pyroclastics induced overloading and instability of the delta front, triggering slump-type gravity flows. These factors jointly promoted the formation of tuffaceous shale; and sustained volcanism induced a greenhouse effect, resulting in an extremely humid climate and enhanced weathering, thus inducing hyperpycnal flows and appropriate-intensity hyperpycnal flows facilitate felsic shale formation. Furthermore, the climatic background modulated by astronomical cycles amplifies the sedimentary evolutionary responses to volcanism. Multistage siltstone–muddy siltstone assemblages with good reservoir properties, which act as favorable shale oil “sweet intervals”. This study provides new perspectives for understanding the controlling factors of continental lacustrine basin depositional systems and offers guidance for the spatial prediction of shale oil “sweet spots” in the Chang 7₃.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"23 10","pages":"Pages 6118-6136"},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149095468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multi-task ensemble learning for real-time efficiency prediction and condition diagnosis in beam-pumping well systems","authors":"Biao Ma,&nbsp;Shi-Min Dong","doi":"10.1016/j.petsci.2026.06.051","DOIUrl":"10.1016/j.petsci.2026.06.051","url":null,"abstract":"<div><div>Currently, real-time efficiency prediction and condition diagnosis for beam-pumping well systems predominantly rely on single-task models. However, conventional single-task approaches typically require constructing two separate models, resulting in doubled computational resource demands and an inability to effectively exploit the coupling relationships between prediction and diagnosis tasks. To address these limitations, this paper proposes a series of multi-task learning-based models for real-time efficiency prediction and condition diagnosis of beam-pumping well systems. First, we propose a multi-task learning model based on multimodal dual-path fusion, which enables effective feature sharing between efficiency prediction and condition diagnosis tasks using a dual-path network architecture. Second, we introduce a multimodal cross-scale fusion multi-task learning model designed to effectively capture the coupling relationships among multimodal features across different scales. Finally, to further improve the prediction accuracy of system efficiency and enhance the precision of condition diagnosis, we develop a meta-learning-based dynamic voting ensemble multi-task learning model, which dynamically integrates predictions from multiple tasks. To verify the effectiveness of the proposed methods, comprehensive experiments and ablation studies are conducted on a dataset consisting of 3938 actual beam-pumping wells. Experimental results demonstrate that, compared with the baseline networks, the proposed method achieves significant performance improvements: relative to the comparison networks, it reduces RMSE by 18.91%–44.73%, increases <em>R</em>² by 13.03%–101.13%, and enhances Accuracy and F1-score by 2.20%–32.84% and 2.16%–34.31%, respectively. Compared with the multimodal cross-scale multi-task learning network, it decreases RMSE by 6.86%–32.69%, raises <em>R</em>² by 3.66%∼38.61%, and improves Accuracy and F1-score by 2.30%–173.35% and 2.31%–293.73%, respectively. Relative to the multi-task learning-based on meta-learning dynamic voting ensemble, it reduces RMSE by 17.30%–36.80%, increases <em>R</em>² by 5.40%–20.00%, and boosts Accuracy and F1-score by 1.77%–5.92% and 1.76%–6.17%, respectively. When compared with the ablation networks, the baseline network achieves RMSE reductions of 6.05%–27.78%, <em>R</em>² improvements of 3.05%–25.51%, and Accuracy and F1-score enhancements of 4.59%–53.73% and 7.76%–65.18%, respectively. Furthermore, the network exhibits significant sensitivity to hyperparameters, with notable performance fluctuations observed under different hyperparameter configurations.</div></div>","PeriodicalId":19938,"journal":{"name":"Petroleum Science","volume":"23 10","pages":"Pages 6796-6818"},"PeriodicalIF":6.4,"publicationDate":"2026-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149095782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}