The oil-generating potential of the Upper Paleozoic coal-bearing strata in the Ordos Basin has long been underestimated. To clarify its genetic mechanisms and resource potential, this study conducted a systematic investigation of the coal-derived oil in the Benxi Formation from the Linxing and adjacent areas by integrating coal petrology, organic geochemistry, and fluid inclusion analysis. The results show that: (1) Liquid hydrocarbons in the Benxi Formation coals occur in two states: free and adsorbed. Free oil predominantly accumulates in tectonic microfractures and pores of ferroan carbonate minerals, which have very low capillary entry pressures, forming dominant storage and migration spaces. Adsorbed oil is hosted in the nano-scale intercrystalline pores of authigenic kaolinite aggregates, where its strong water-wetness causes significant capillary blocking and surface adsorption effects. (2) The genetic type of the coal-derived oil is identified as a primary high-maturity condensate-wet gas system, rather than a secondary cracked residual oil. (3) Oil-source correlation confirms that the crude oil is mainly derived from the Benxi Formation coals themselves. The hydrocarbon-generating precursors consist of hydrogen-rich aquatic algae-plankton input under a marine transgression background and terrestrial liptinite macerals (sporinite and cutinite). (4) The coal-derived hydrocarbons follow a sequential generation-evolution pathway, evolving from an early biogas stage, through a low-maturity oil window and a peak condensate-generation stage, to an oil-associated gas stage, and ultimately to a dry gas stage. (5) Rock-Eval and chloroform bitumen "A" data indicate that the coals in the study area are currently in the condensate oil-gas generation stage. It is suggested that the exploration and development strategy should shift from pure coalbed methane production towards integrated "coalbed methane-condensate oil" co-production. Priority should be given to fairways with vitrinite reflectance (Ro) between 0.7 and 1.3%, and pressure-controlled production should be adopted to delay the onset of retrograde condensation, thereby ensuring effective resource recovery.

The Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation are important target strata for shale gas exploration in the Sichuan Basin, China. In this paper, the sedimentary facies and palaeogeography of the two formations in Chongqing area have been analyzed, and total organic carbon (TOC) contents are correlated with the sedimentary facies to prospect the favorable areas for shale gas exploration. According to the lithological characteristics and sedimentary structures, five sedimentary facies are identified, i.e., siliceous deep-water shelf, muddy deep-water shelf, calcareous shallow-water shelf, muddy shallow-water shelf, and silty-muddy shallow-water shelf facies, respectively. The palaeogeography reconstruction is based on the lithological distribution in the study area. The lower part of Wufeng Formation was developed with the muddy deep-water shelf, siliceous deep-water shelf, and calcareous shallow-water shelf facies. The Guanyinqiao Member, representing the upper part of Wufeng Formation, was developed with the transition from siliceous deep-water shelf and muddy deep-water shelf facies to a domination of muddy shallow-water shelf and calcareous shallow-water shelf facies, which was deposited during the glacial-induced global regression. The Lower Member of Longmaxi Formation was characterized by the expansion of siliceous deep-water shelf facies and contraction of muddy shallow-water shelf and calcareous shallow-water shelf facies, signifying a rapid sea level rise associated with global warming. The Upper Member of Longmaxi Formation was developed with muddy shallow-water shelf facies, with the expansion of calcareous shallow-water shelf and silty-muddy shallow-water shelf facies. The shales with higher TOC content tend to be developed in the siliceous deep-water shelf and muddy deep-water shelf facies that were distributed in the Nanchuan, Shizhu, Yongchuan, and Wuxi areas. The results of lithofacies palaeogeography reconstruction have a certain significance to predict shale-gas target areas in Wufeng and Longmaxi formations of Chongqing.

Gas content and its occurrence characteristics are two key factors affecting the evaluation of shale gas reservoirs' exploration and development potential. Conventional analysis methods, however, are often costly and generate only discrete data. To address this, this study highlights the Qiongzhusi Formation shale in the Sichuan Basin, developing logging-based prediction models targeting adsorbed and free gas content by integrating well logging data with results from 30 methane isothermal adsorption tests and 3 variable-temperature adsorption experiments. These models were used to characterize the formation's gas content. According to the results, the model-predicted total gas content deviates slightly from measurements via preserved core testing, with an average error rate of 11.89%. Logging interpretation indicates the Qiongzhusi Formation shale has a gas content of 1.56 to 18.55 cm(3)/g, dominated by free gas. The ratio of free to adsorbed gas varies from 0.001 to 8.55, averaging 3.78. By layer, gas content ranks as: (5) > (4) > (7) > (3) > (6) > (1) > (2) > (8) . Notably, layer (4) has the highest free-to-adsorbed gas ratio, suggesting exploration should not be limited to layers (5) and (6) -layers (4) , (7), and (3) , especially layer (4) , also have significant potential.

With the recent breakthroughs in deep coalbed methane exploration in the Ordos Basin, Upper Paleozoic coals are widely recognized as strongly gas-prone, whereas their oil-generating capacity has long been underestimated. However, abundant light oil has been repeatedly observed in flowback fluids from Benxi Formation coalbed methane wells in the Linxing and adjacent areas, indicating these coals can act as both effective source rocks and oil reservoirs. Integrating coal petrography, organic geochemistry, and fluid inclusion microthermometry, this study re-evaluates the condensate potential of these marine-continental transitional coals. Crucially, we demonstrate that the Benxi coals host a high-maturity, strongly self-sourced primary condensate-wet-gas system, fundamentally challenging the traditional view that they contain only severely cracked residual oil. Liquid hydrocarbons occur primarily in two modes: free oil within structural microfractures (providing the dominant migration pathways) and adsorbed oil immobilized by capillary blocking within kaolinite aggregates. More importantly, we reveal a distinctive oil-generation mechanism unique to marine-continental transitional facies. Unlike strictly continental coals dominated by higher plants, the principal oil-prone parent materials here are significantly enhanced by marine transgressions. The incorporation of transgression-derived aquatic algal-planktonic organic matter, alongside terrestrial hydrogen-rich liptinite, provides highly efficient, aliphatic-rich, and high-H/C precursors. This synergistic dual-source mechanism significantly boosts condensate generation, offering a new perspective on the hydrocarbon systems of transitional coals and broadening the exploration targets for coal-derived liquids.

Gas-bearing shales have become a major source of future natural gas production worldwide. It has become increasingly urgent to develop a reliable prediction model and corresponding workflow for identifying shale gas sweet spots. The formation of gas-bearing shales is closely linked to relative sea-level changes, providing an important approach to predicting sweet spots in the Wufeng-Longmaxi shale in the southern Sichuan Basin, China. Three types of marine shale gas sweet spots are identified in the shale based on their formation stages combined with relative sea-level changes: early, middle, and late transgression types. This study develops a prediction model and workflow for identifying shale gas sweet spots by analyzing relative sea-level changes and facies sequences. Predicting shale gas sweet spots in an explored block using this model and workflow can provide a valuable guide for well design and hydraulic fracturing, significantly enhancing the efficiency of shale gas exploration and development. Notably, the new prediction model and workflow can be utilized for the rapid evaluation of the potential for shale gas development in new shale gas blocks or those with low exploratory maturity.

In recent years, extensive low-resistivity shale reservoirs have been discovered in the Sichuan Basin, especially in the Lower Cambrian Qzs Fm (Qiongzhusi Formation). However, significant variations in gas production from these low-resistivity reservoirs across different regions have posed challenges in selecting and predicting sweet spots for the exploration and development of shale gas. Therefore, the shale samples were subjected to the analysis of a series of experiments, including core resistivity measurements, thermal simulations, and Raman spectroscopy, in order to explore the genesis mechanisms behind low-resistivity shale reservoirs and analyze their response characteristics to pore structure. The results show that HMG-OM (highly mature graphitized organic matter) and formation water stored in pores and fractures provide more conductive pathways, which are the primary mechanisms driving the low-resistivity characteristics of shale within the study area. As graphitization increases, shale resistivity significantly decreases, while maturity increases. Additionally, there are notable changes in the shale mineral composition and pore structure, including quartz breakage, clay minerals transforming into quartz, feldspar, and other minerals, and the dissolution of calcite and pyrite, which leads to a significant increase in inorganic pores. Meanwhile, the graphitization of OM causes the continuous deformation, shrinkage, and collapse of OM pores, resulting in poor development of OM pores. In this study, we integrate theoretical analysis and the experimental results and identify the Weiyuan-Ziyang area in southwestern Sichuan as a key area for future shale development in the Qzs Fm, with the aim of providing theoretical guidance for the exploration and development of shale gas in the Sichuan Basin.

The formation and distribution of sedimentary facies of the Wufeng Formation reflect the evolution of Guangxi Movement and significantly impact shale reservoir quality in southern Sichuan Basin, China. This study characterizes the sedimentary facies and their evolution of Ordovician-Silurian transition shale based on detailed core descriptions, full-scale imaging of large slabs, and field emission scanning electron microscopy of argon-ion polished sections. There only exist fine-grained turbidite deposits, hemipelagic deposits, and shallow shoal deposits for the Wufeng shale. Fine-grained turbidite deposits consist primarily of clastic quartz and clay minerals and can be divided into nine subdivisions. Hemipelagic deposits are mainly composed of quartz, detrital carbonate, and clay minerals. Shallow shoal deposits are dominated by clay minerals, dolomite, and calcite, with carbonates primarily of autochthonous origin. The fine-grained turbidite deposits predominantly occur within the Dicellograptus complanatus and D. complexus graptolite biozones, while hemipelagic deposits are confined to the Paraorthograptus pacificus biozone, and shallow shoal deposits are restricted to the Metabolograptus extraordinarius biozone. Formation and distribution of the three sedimentary facies are closely related to the Guangxi Movement. During the strong tectonic compression stage, sufficient sediment supply and intensive volcanic eruption favored the formation of the fine-grained turbidite deposits. Along with waning tectonic activity and reduced terrestrial input, hemipelagic deposits formed and then shallow shoal deposits. Sedimentary facies exert first-order controls on shale reservoir quality, with hemipelagic deposits exhibiting optimal reservoir characteristics. Laboratory analyses reveal that hemipelagic facies possess the highest porosity (3.34–4.15%) and TOC content (2.91–4.10%) due to biogenic quartz enrichment and minimal allochthonous dilution, whereas fine-grained turbidites show degraded properties (porosity: 1.58–3.81%; TOC: 0.15–2.6%) from high-energy siliciclastic influx. Shallow shoal deposits display intermediate values (porosity: 3.92%; TOC: 3.25%), constrained by carbonate cementation.

ObjectiveShales in the Lower Cambrian Qiongzhusi Formation within the Upper Yangtze region preserve critical information about primitive oceans. Furthermore, these shales serve as vital source rocks and reservoirs, having demonstrated considerable potential for shale gas exploration. Methods Using seismic, borehole, and outcrop data, this study investigated the shale strata and their distribution in the Qiongzhusi Formation through comparative analysis. Accordingly, the sweet-spot interval was determined. Results and conclusions The results indicate that the Lower Cambrian Qiongzhusi Formation in the Upper Yangtze region can be divided into the first and second members (also referred to as the Qiong 1 and 2 members, respectively), with the former consisting of Q1-1 to Q1-4 sub-members and the latter comprising Q2-1 to Q2-4 sub-members. The Maidiping Formation and the Qiong 1 Member predominantly occur within the Deyang-Anyue intracratonic rift, while the Qiong 2 Member is extensively distributed both inside and outside the rift. Within the rift, the west and east sides of the Maidiping Formation - Qiong 1 Member terminates at the limestone of the Dengying Formation, with the west side gradually thinning while the east side pinching out rapidly. In the north-south direction, the Qiong 1 Member thins southward, while the Qiong 2 Member is thin in the central part but thick in the northern and southern parts. Outside the rift, the Qiong 2 Member is distributed throughout the region, with the Q2-1 sub-member directly overlapping either the Qiong 1 Member or the limestone of the Dengying Formation. Shales in the Q2-1 sub-member enjoy superior hydrocarbon generation and reservoir conditions, as well as vertical/lateral sealing performance, emerging as a shale gas enrichment interval. For instance, in the northern part of the intracratonic rift, shales in the Q2-1 sub-member in well Tianxing-1 contain well-developed micropores and microfractures, with logging-derived porosity ranging from 4.93% to 6.57% (average: 5.08%). In the central part of the Deyang-Anyue intracratonic rift trough, shales in the Q2-1 sub-member in well Weiye-1 well exhibit organic matter-hosted pores, with logging-derived porosity ranging from 4.20% to 4.70% (average: 4.51%). In the Qujing area, Yunnan Province, within the southern part of the rift, black shales in the Qiongzhusi Formation in wells Qudi-1 and Quye-1 reveal well-developed black shales with high-pressure mercury injection-derived porosity spanning 1.59% to 11.33% (average: 5.0%). Although shales in the Qiong 1 Member exhibit favorable source-reservoir properties, the shale gas generated is prone to escape along karst zones or faults, unconducive to in-situ accumulation. For instance, in the northern part of the intracratonic rift, the Q1-3 submember in well Chuanshen-1 exhibits a thickness of about 40 m, logging-derived average TOC of 3.5%, and logging-derived porosity of 6.4%, suggesting high-quality source rocks and reservoirs but unfavorable conditions for in-situ accumulation. Overall, shales in the Q2-1 sub-member are identified as a sweet-spot interval for shale gas exploration due to their high porosity and great sealing performance. This study can serve as a critical basis and guide for future shale gas exploration in the Upper Yangtze region.

The hydrodynamics and their evolution on the Upper Yangtze Block during the Ordovician-Silurian transition period remain unclear.The present study is an assessment of how regional and global events may have influenced the hydrodynamic evolution based on a planar lamination investigation of the shales from the Upper Yangtze Block.Analyses of large thin sections and argon-ion polished thin sections using field emission-scanning electron microscopy(FE-SEM)showed that there are four types of planar lami-nation,namely,silty graded planar lamination(SGPL),silt-clay graded planar lamination(SCGPL),silt-clay interlaminated planar lamination(SCIPL),and paper-like planar lamination(PPL).SGPL is formed by turbidity current with a flow speed less than 15 cm/s.SCGPL is formed by turbidity currents with a flow speed less than 15 cm/s for normal grading type and 15-25 cm/s for alternating grading type.SCIPL has a continuum of sparsely spaced type,closely spaced type,and alternating type,which is formed by bottom current with an increasing flow speed from 15 to 25 cm/s to above 25 cm/s.PPL can be divided into normal grading and composite grading types.The former is formed by vertical settling,while the latter is formed by bottom current with a flow speed of 5-15 cm/s.Vertically,types of planar lamination varied from SGPL to PPL and then SCIPL manifesting the waxing and waning of flow speed with a positive excursion at graptolite biozone Metabolograptus extraordinarius(WF4)and a negative excursion at graptolite biozone Persculptograptus persculptus(LM1).The sudden decrease in flow speed across Linxiang and graptolite biozone Paraorthograptus pacificus(WF3)and the subsequent progressive increase from graptolite biozone Akidograptus ascensus(LM2)to graptolite biozone Demirastrites triangulatus(LM6)and to graptolite biozone Stimulograptus sedgwickii(LM8)during deposition of the Ordovician-Silurian transition succession on the Upper Yangtze Block were linked to the bulge uplift,the rapid subsidence,and the relaxation controlled by the Kwangsian orogeny.In contrast,the positive excursion at WF4 and the negative excursion at LM1 were strongly controlled by the Hirnantian Glaciation and global warming,respectively.

The usage of heterogeneous resources provisioned by edge nodes can be co-optimized through re-scheduling microservices. Current (re-)scheduling approaches typically treat the task of co-optimization as a single-objective optimization problem, which cannot address the issue of imbalanced usage of heterogeneous resources (e.g., CPU, memory, bandwidth) on a single edge node. More importantly, these approaches are inadequate in handling: (i) the adaptive co-optimization of heterogeneous resources, (ii) the fine-grained construction of microservice dependencies, and (iii) multi-step online microservice re-scheduling. To address these challenges, this article proposes a Dependency-aware Online Microservice re-Scheduling (DOMS) approach. DOMS formulates microservice re-scheduling as a multi-knapsack optimization problem and solves it using a Double Dueling Deep Q-Network (D3QN) with prioritized experience replay. Specifically, an adaptive heterogeneous resources balancing detection algorithm is developed, incorporating a dynamic detection threshold mechanism. A fine-grained microservice performance metrics dependency graph is constructed by capturing causal relationships to represent sequential execution dependency. Based on this graph, a microservice multi-step scheduling partition algorithm is devised. Extensive experiments are conducted upon publicly-available datasets, and evaluation results demonstrate that DOMS outperforms the state-of-the-art techniques with improvements of at least 1.85%, 6.45%, 0.56%, and 3.18% in terms of latency, energy consumption, balance degree, and throughput. These results highlight the effectiveness and superiority of DOMS in maintaining a balanced usage of heterogeneous resources and improving network throughput, while satisfying latency and energy consumption constraints.

The big data system has been developed to optimally combine numerical-model predictions with actual measurements from the gas shale play to create the best estimates of current shale gas conditions and their uncertainties, improving our ability to forecast and understand the shale gas production variations. However, considering the hydraulic fracturing fluid flowback in predicting shale gas production introduces new challenges. For example, complexities in the flow of gas-water two-phase fluid defy traditional numerical simulation, while flowback are complicated by strong environmental disruptions, and shale gas production encounters substantial noise interference. Here, we developed CNN-Transformer, a production and fluid flowback predicted system using deep learning, by integrating a convolutional neural network (CNN) and a Transformer network. CNN's receptive field focus irregular observational data on the local region correlation of the sequence, while Transformer network extracts the state information of historical production and flowback volumes from previous time frames, and predicts future time states, aiming to capture temporal patterns. We contrast the performance of CNN-Transformer, CNN-LSTM, CNN-GRU-AM models in predicting shale gas production, flowback volume and the relationship between the two. We show that the CNN-Transformer outperforms the other models, with R²=0.644 and RMSE = 0.1424, compared to CNN-GRU-AM (R²=0.6068, RMSE = 0.1513) and CNN-LSTM (R²=0.5727, RMSE = 0.1618) in predicting flowback volume. We conclude that CNN-Transformer (R2 = 0.72, RMSE = 0.3824) markedly reduces analysis error of the shale gas production, outperforming both CNN-LSTM (R2 = 0.4911, RMSE = 0.44912) and CNN-GRU-AM (R2 = 0.5705, RMSE = 0.4249). We deem our results to lay a foundation for further debates on striking a balance between fracturing fluid flowback volume and prediction of shale gas production.

Laumontite is a calcium-rich zeolite that typically occurs as an authigenic mineral in sedimentary rocks. Due to its specific formation conditions and its high instability in acidic environments, laumontite provides a key geological indicator for analysing sedimentary-diagenetic system and identifying high-quality reservoirs in middle-deep strata. This study offers a comprehensive review of the distribution, occurrence, chemical composition, genesis, controlling factors, and the impacts on hydrocarbon reservoirs of laumontite in the sedimentary rocks of typical non-marine basins in China, such as the Junggar Basin, the Ordos Basin, and the Sichuan Basin. Previous research indicates that laumontite commonly develops as a continuous or patchy cement, fracture filling, and replacement product within vertically stacked deltaic subaqueous distributary channels. Sandstones enriched in plagioclase or volcanic material are considered ideal host rocks for laumontite formation. During eodiagenesis (<85 °C), laumontite extensively fills intergranular pores, with individual crystals typically exhibiting a long prismatic habit, and commonly occurring in association with clay minerals, quartz, and heulandite. During mesodiagenesis (85–175 °C), laumontite occurs as patchy intergranular fillings, with individual crystals progressively developing a short prismatic morphology, and is mainly associated with calcite, illite, quartz, and albite. Laumontite in sedimentary rocks is typically characterised by a low Si/Al ratio (2.00–2.20), and its chemical composition shows no systematic variation with temperature or occurrence. Formation mechanisms of laumontite include the albitisation of plagioclase, transformation of volcanic material, and alteration of early-formed zeolites. Incomplete transformation of plagioclase may result in a higher Si/Al ratio in laumontite. Fluid inclusion homogenisation temperature data indicates laumontite in sedimentary rocks primarily forms within a temperature range of 60–140 °C. The transformation of plagioclase and volcanic material to laumontite can proceed throughout this interval, while alteration of heulandite to laumontite generally requires temperatures above 90 °C. High pH, low pCO2 and Ca-rich pore fluids are key factors controlling laumontite formation, while the presence of Na+ lowers the equilibrium temperature of laumontite-forming reactions. Although early-formed laumontite occupies primary pores, it also contributes to compaction resistance. Owing to its well-developed cleavage and large internal pore volume, laumontite dissolves more readily in acidic fluids than K-feldspar, albite, or other aluminosilicates. Its dissolution zone provides a favourable environment for hydrocarbon accumulation. Additionally, the internal cavities within laumontite crystals possess a large specific surface area, which enables strong physical adsorption of methane molecules.

Organic matter exhibits significant heterogeneity and complexity, with varying pore structures across different types influenced by multiple interacting factors. This paper introduces a “two categories, six subcategories” classification scheme based on morphological observations using a combination of argon ion polishing and scanning electron microscopy (SEM). Organic matter is classified into two main categories: depositional organic matter and migrated organic matter, based on whether migration has occurred. Depositional organic matter is further subdivided into three types based on microscopic characteristics: bioclasts, compacted kerogen, and in situ remnants from post-hydrocarbon generation. Migrated organic matter is categorized into three types: organic matter in intragranular pores, organic matter in intergranular pores, and bitumen in microfractures. Bioclasts can be further classified into alginite, zooclasts, acritarchs, and encapsulated organic matter based on maceral type. Zooclasts, acritarchs, encapsulated organic matter, and compacted kerogen—types of depositional organic matter—have few or no pores. This is primarily related to the nature of the hydrocarbon-generating precursor materials, with compacted kerogen being influenced by low thermal maturity and diagenetic compaction. In contrast, pores are more developed in alginite, in situ remnants from post-hydrocarbon generation, and all forms of migrated organic matter, largely due to the expulsion of gaseous hydrocarbons during thermal evolution. The pores in alginite reflect both the original structural properties of the hydrocarbon-generating precursor materials and the thermal evolution process. Depositional organic matter exhibits a stronger oil-generating potential and a higher gas-generating potential, while migrated organic matter primarily possesses a stronger gas-generating capability. Specifically, organic matter enriched in alginite, in situ remnants from post-hydrocarbon generation, as well as migrated organic matter in intragranular pore and intergranular pore, exhibit a higher hydrocarbon-generation potential.

The characteristics and formation of maximum flooding (MF) black shales are important aspects in defining the geology of fine-grained reservoirs. The MF black shales are located at the bottom of the Longmaxi Formation on the Upper Yangtze Platform, corresponding to graptolite zone LM1. Seismic interpretation, X-ray diffraction entire rock analysis, total organic carbon (TOC) tests, and field emission scanning electron microscopy analysis indicate that the MF black shales have an average content of 49.3% quartz (85% clay size), 10.5% calcite, 8.4% dolomite, and 23.4% clay minerals. The quartz content increases basinward, whereas the clay mineral content decreases. The shale has developed during rapid sea level rise, with a thickness of 0.5–2.8 m that gradually thickens basinward. The TOC content, averaging 5.4%, gradually decreases basinward, with four distinct stacking patterns. The mineral composition and thickness of the Longmaxi shale are related closely to rapid transgression, biology, and volcanism during the period of sedimentation. Rapid transgression has led to a decrease in terrestrial input and shale thickness. In addition, biological activity and volcanism have caused the prevalence of microcrystalline quartz. Shales with high TOC content are related to anoxic conditions, along with low sedimentation rates and high primary productivity. The combination of an anoxic water column, weak dilution, and enhanced organic matter (OM) supply have enhanced the preservation of the OM. The four TOC stacking patterns are related to the water depth. The supply of clay minerals decreases with increasing water depth, whereas the degradation and recycling of OM decrease the TOC content. The sediment accommodation increases with increasing water depth, resulting in four TOC stacking patterns.

SEM images on ion-polished shale samples can visualize organic pores and can be used to analyze the organic pore structures quantitatively. Compared to the routine fluid intrusion methods (e.g., helium porosity, N2 adsorption, mercury intrusion, etc.), the SEM image-based organic pore structure analysis has many unique benefits. However, image resolution can significantly influence the analysis results. This should be investigated carefully. The image resolution effects on the analysis of organic pore structures was confirmed and estimated through (1) imaging organic matters and their organic pores at different resolutions (0.7–29.2 nm/pixel), and (2) comparing the differences of 2D organic porosity, pore size distribution (PSD), and organic pore geometry calculated at different image resolutions. The two ways of image resolution effect on organic pore analysis was revealed. First, organic pores with a wall close to the sample surface were more challenging to recognize at low image resolution. Any incorrect recognition of these organic pores can significantly affect the calculated 2D organic porosity and the sectional area-based PSD. Second, the small size organic pores were also difficult to recognize at low image resolution, considerably affecting the estimation of pore amount-based PSD but only slightly affecting the calculated organic porosity and sectional area-based PSD due to their small pore size. When SEM image resolution is less than 10nm/pixel, organic porosity will be significantly underestimated, and the estimated PSD and geometry usually have high uncertainty. Therefore, SEM images with 5nm/pixel or higher resolution are recommended to assess organic pore structures.

In the deep Longmaxi Formation shale gas reservoirs of the southern Sichuan Basin, strong overpressure is universally developed to varying degrees. However, there is currently a lack of in-depth research on the formation mechanisms, evolutionary patterns, and the controlling effects on reservoir pore characteristics of strong overpressure. This limitation significantly restricts the evaluation of deep shale gas reservoirs. This study selected typical overpressured shale gas wells in Yongchuan, Luzhou, and Dazu areas as research subjects. Through comprehensive methods such as log analysis, fluid inclusion analysis, and numerical simulation, the dominant mechanisms of strong overpressure formation were determined, and the pressure evolution from early burial to late strong uplift was characterized. Additionally, the impact of varying degrees of overpressure on reservoir pore characteristics was studied using techniques such as scanning electron microscopy, gas adsorption-mercury intrusion, and helium porosity testing. The research findings indicate that hydrocarbon generation expansion is the primary mechanism for strong overpressure formation. The pressure evolution in the early burial phase is controlled by the processes of kerogen oil generation and residual oil cracking into gas. The reservoir experienced three stages: normal pressure (Ordovician to Early Triassic), overpressure (Early Triassic to Early Jurassic), and strong overpressure (Early Jurassic to Late Cretaceous), with pressure coefficients of approximately 1.08, 1.56, and 2.09, respectively. During the late strong uplift phase, the adjustment of early overpressure occurred due to temperature decrease and gas escape, leading to a decrease in formation pressure from 140.55 MPa to 81.63 MPa, while still maintaining a state of strong overpressure. Different degrees of strong overpressure exert a significant control on the physical properties of shale reservoirs and the composition of organic matter pores. Variations exist in the organic matter pore morphology, structure, and connectivity within the deep Wufeng-Longmaxi shale. Higher overpressure favors the preservation of organic large pores and reservoir porosity. Under conditions of strong overpressure development, deep siliceous shales and organically rich clay shales exhibit favorable reservoir properties. By determining the dominant mechanisms of strong overpressure in the Wufeng-Longmaxi Formation and studying pore characteristics, this research not only deepens the understanding of the geological features of deep shale gas reservoirs but also provides a new perspective for understanding the overpressure mechanisms and reservoir properties of deep shale gas reservoirs. Moreover, it is of significant importance for guiding the exploration and development of deep Longmaxi shale and provides valuable references for further research in related fields.

Empowered by edge computing, resources and computation capabilities provided by edge devices can be encapsulated as containerized services, and domain applications can be achieved through service compositions. When burst requests are coming to be satisfied, there may exist edge devices which are overloaded, since requests are mostly spatially and temporally constrained, and edge devices are resource-scarceness and capacity-limited. In this setting, overloaded devices should be relieved through optimally migrating one or more activated services to contiguous edge devices. Besides, sensory data gathered by original edge devices should be periodically transmitted to migrated devices for data analysis purpose. To mitigate this issue, this paper proposes an Energy-efficient Online Service Migration (EOSM) mechanism to conduct the migration of multiple services simultaneously. Specifically, a light service sharing strategy is developed to only transmit the top container layer, and a modified NSGA-II algorithm is adopted to generate one or multiple paths for the container layer and time-series sensory data migration of each migrated service. Extensive experimental results show that our EOSM strategy outperforms the state of arts techniques in mitigating overloading devices in terms of access latency, energy consumption, and request success rate.

Empowered by edge computing, resources and computation capabilities provided by edge devices can be encapsulated as containerized services. When burst requests are coming, there may have edge devices which are overloaded, since most requests are spatially and temporally constrained, and edge devices are resource-scarceness and capacity-limited. Overloaded devices should be relieved through optimally migrating one or more activated services to contiguous edge devices. Besides, sensory data gathered by original edge devices should be periodically transmitted to migrated devices for data analysis purpose. To mitigate this issue, this paper proposes an Energy-efficient Online Service Migration (EOSM) mechanism to conduct the migration of multiple services simultaneously. Extensive experimental results show that our EOSM mechanism outperforms the state of arts techniques in mitigating overloaded services in terms of access latency, energy consumption, and request success rate.

Shale has horizontal bedding of diverse origins in differential permeability.An integrated analysis of core data,full-diameter images of enlarged thin section and scanning electron microscope(SEM)images of argon-ion-milled samples,shows that the gas-bearing Wufeng-Longmaxi shale in southern Sichuan Basin develops four types of horizontal bedding,that is,grading type composed of claystone,grading type composed of siltstone and claystone,alternating siltstone and claystone type,and page type.The grading type of claystone constitutes the multi-layer superimposed siltstones in parallel,with siltstone and claystone depositing in graded bedding.The grading type composed of siltstone and claystone is composed of parallelly alternating silty and clayey beds,where the silty beds mainly in clast-supported texture,has abrupt boundary at the bottom and gradual contact with the clayey bed on top,featuring normal grading as a whole.The alternating siltstone and claystone type features abrupt contact between both beds and lamina with no grading.The page type constitutes parallel bedding of very thin clayey lamina with weakly normal grading.The four types of horizontal bedding are of different genesis.The grading type of claystone and grading type of siltstone and claystone are of relatively low-energy turbidite origin,with the former derived from even weaker hydrodynamic conditions;the alternating siltstone and claystone is of contourite origin such as shelf facies;and the page type is of pelagic origin from suspended sediment deposition.The horizontal bedding serves to directly affect shale permeability.The page type is characterized by the abundance of organic matter and organic pores,ranking top in permeability;the alternating siltstone and claystone type takes the second place in permeability with better sorting;while the two grading types come at last in permeability with poor sorting and low organic matter content.