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In recent years, multiple exploration breakthroughs have been made in the Third Member of the Leikoupo Formation in the Middle Triassic of Northwest Sichuan Basin. Currently, the overall exploration level is low. The characteristics and formation mechanism of the reservoir are unclear. Techniques such as core observation, pore permeability testing, conventional and cast thin section identification, scanning electron microscopy, mercury intrusion and nuclear magnetic resonance were used to clarify the sedimentary and reservoir characteristics of the 2nd section of the Maokou Formation in the front of the Longmen Mountains in western Sichuan and to explore the main controlling factors of high-quality reservoirs. Research shows that the reservoir rock types are mainly granular dolomite, microbial dolomite and icro-crystalline dolomite. The storage spaces are mainly composed of secondary dissolved pores such as intergranular dissolved pores, microbial “frame” dissolved pores and intercrystalline dissolved pores. The overall physical properties are relatively dense, belonging to medium-low porosity and low permeability reservoirs, with an average porosity of 2. 78% and an average permeability of 0. 76 mD. Sedimentary facies, diagenesis, paleogeomorphology and tectogenesis jointly control the development of the T2 l3 member reservoir in northwestern Sichuan basin. The development of reservoirs is controlled by sedimentary facies, ancient landforms, and diagenesis. The material basis for the development of favorable reservoirs is formed by the deposition of high-energy sand and debris shoals, biogenic debris shoals. The surface dissolution effect of karst slopes in ancient landforms is the best. The quasi contemporaneous dolomitization, recrystallization, and multi-stage karstification are the key factors for reservoir development. Structural fractures and faults are favorable conditions for reservoir improvement. The Zhongba area and the southwestern part of the Shuangyushi area are located at the intersection of high energy beaches and karst slopes with micro ancient landforms. The thickness of the dolomite is large, with developed faults and fractures, strong dissolution, and the development of Class I and II reservoirs. They can be used as key exploration targets for the next step. [ABSTRACT FROM AUTHOR]

The Lower Cretaceous Laiyang Group on Lingshan Island contains typical gas source and clastic reservoir rocks. The densification mechanism of clastic rock and its diagenetic connection have not been systematically studied, which significantly increases the risk associated with hydrocarbon exploration in eastern China. A comprehensive study was conducted on core samples obtained from the Scientific Drilling Borehole LK-1, utilizing core data in conjunction with a range of techniques, including microscopic observation, X-ray diffraction, physical property measurements, and low-temperature nitrogen adsorption. The results indicate that the sandstones are primarily composed of feldspathic litharenite, exhibiting a poorly to moderately sorted texture and a fine-to-medium grain size. The reservoir quality is quite poor, characterized by extremely low porosity and permeability. The reservoir space of tight sandstones is constituted by three main types of pores: residual primary pores, secondary dissolution pores, and intercrystalline pores. Tight sandstone reservoirs experienced notable diagenetic alteration during burial, with calcite, dolomite, quartz, and clay cements identified as the primary diagenetic minerals. Intense compaction and carbonate cementation are the principal mechanisms contributing to the densification of sandstones. Pore-filling clay minerals subdivide macropores into numerous micropores, significantly reducing reservoir permeability. The migration of dissolution products out of the system is a difficult process, which hinders the effectiveness of mineral dissolution in enhancing overall reservoir quality. This study may provide a valuable reference for the effective exploration of Lower Cretaceous clastic reservoirs in eastern Shandong. [ABSTRACT FROM AUTHOR]

The breakthrough of bauxite natural gas in the Taiyuan Formation in the Longdong area of the Ordos Basin makes bauxite natural gas gradually become a new exploration direction. However, the complex sedimentary conditions and diverse developmental strata of the Linxing region present difficulties for the exploration of bauxite gas. In this research, samples of bauxite cores from significant drilling sections in the Linxing area were obtained for comprehensive geochemical, mineralogical, and pore structure analysis. This study investigates the impact of sedimentary environments on the physical properties of bauxite reservoirs within the Benxi Formation, focusing on lithofacies categorization, mineral composition, and pore structure. This study established a lithofacies categorization system that iron minerals, aluminum minerals + titanium minerals, clay minerals as three end‐member components. The study identified four lithofacies types: pure bauxite, clayey bauxite, mixed bauxite, and bauxite mudstone. According to geochemical analysis, the bauxite rock in the study area is deposited in a semi‐enclosed bay with terrestrial freshwater input. The physical properties of bauxite reservoir in the study area are relatively poor, among which the physical properties of bauxite reservoir are the best. Authigenic minerals like pyrite are often filled in dissolution pores. The constraint of sedimentary environment on bauxite reservoir is mainly manifested as the influence on the formation of diaspore mineral framework, and its acidity and alkalinity are very important for the formation of diaspore. Hence, diaspore commonly forms in the shallow lake environments characterized by pure bauxite rock, exhibiting favorable reservoir conditions. This research examines the impact of mineral composition on bauxite reservoirs through the lens of lithofacies and sedimentary environments. The variations in bauxite rock reservoirs across distinct sedimentary environments have been elucidated. It provides a new guidance for the exploration of natural gas in Benxi Formation bauxite in Ordos Basin. [ABSTRACT FROM AUTHOR]

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The editorial discusses the differences in shale oil and gas reservoirs across various sedimentary environments, focusing on theories and applications. It highlights the significance of shale oil and gas as unconventional resources crucial for global energy optimization and carbon neutrality goals. The text explores the development of shale oil and gas in the United States and China, emphasizing technological advancements, resource estimates, and exploration efforts. Additionally, it delves into the characterization of shale pore structure, hydraulic fracturing techniques, and the influence of depositional environments on shale properties, providing valuable insights for future research and development in the field. [Extracted from the article]

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The seventh member of the Triassic Yanchang Formation (Chang 7 Member) in the Xunyi area of the Ordos Basin is a typical tight oil reservoir characterized by low porosity, low permeability, and strong heterogeneity. Elucidating the pore development characteristics and primary controlling factors of the reservoir is beneficial for tight oil exploration and development. Through thin-section analysis, physical property tests, scanning electron microscopy(SEM), X-ray diffraction (XRD) analysis, and mercury intrusion porosimetry, this study investigated the petrological characteristics, reservoir space, and diagenetic evolution of the tight oil reservoir, revealing its main controlling factors. The reservoir depth in Chang 7 Member of the Xunyi area of the Ordos Basin ranged from 500 to 1 250 m. The lithology was primarily composed of lithic arkose sandstone, followed by feldspar lithic sandstone, with the interstitial materials mainly consisting of calcite, dolomite, and mud. The sand bodies in the reservoir were thick, with high compositional maturity. Rigid minerals, such as quartz and feldspar, which are highly resistant to weathering, made up a large portion of the framework grains. The quartz content ranged from 30% to 77%, with an average of 44.97%, while the feldspar content ranged from 4% to 52%, with an average of 31.61%. The pore types were mostly intergranular dissolved pores and intragranular dissolved pores, followed by residual intergranular pores and a few microfractures. The average porosity was 7.3%, and the average permeability was 0.4×10-3 μm2. The reservoir is in the middle diagenetic stage A and has completed tight compaction during the Cretaceous. The primary factors contributing to reservoir densification included its poor resistance to compaction, carbonate cementation, illite/smectite mixed layers, and authigenic quartz. The quartz and feldspar content and early oil and gas charging preserved a significant quantity of primary pores. The ongoing dissolution and fragmentation during the middle diagenetic stage were the primary causes for the development of secondary pores.

The Jurassic Shaximiao Formation in the Sichuan Basin represents a significant tight gas reservoir, exhibiting marked permeability variations between the southern and northern regions of western Sichuan. This study examines the reservoir characteristics of the Shaximiao Formation, with a focus on the evolution of sandstone porosity under bidirectional provenance conditions and the underlying causes of permeability variations. The insights derived from this research are critical for the effective exploration and development of tight sandstone gas reservoirs. Analysis of core samples and thin sections through X-ray diffraction, cathodoluminescence, scanning electron microscopy, and electron probe microanalysis reveals that the southern region predominantly consists of feldspathic and lithic sandstone, whereas the northern region is characterized by feldspathic lithic and lithic feldspathic sandstone. The average porosity and permeability in the southern region are 10.52% and 0.1334 × 10−3 μm2, respectively, while in the northern region, they are 9.74% and 0.5262 × 10−3 μm2. The primary reservoir spaces are intergranular primary pores and intragranular secondary dissolution pores. Compaction significantly reduces porosity, particularly in the northern region (23.94%) compared to the southern region (22.75%), primarily due to the presence of chlorite coatings. Cementation further reduces porosity, whereas dissolution processes enhance it, elucidating the similar porosity values but differing permeabilities between the regions.

The Lower Ordovician Tongzi Formation containing abundant shoal sediments is the most promising stratum for the petroleum exploration in the Sichuan Basin. However, the current studies mainly focus on the central part of the Basin, the systematic analysis of the southeastern part with well-developed shoal facies is lacking. This paper aims to clarify the characteristics and genesis of the Tongzi Formation reservoir in Southeastern Sichuan Basin, following an analysis of sedimentary facies within the sequence stratigraphic framework. The research shows that the main types of reservoir rocks are oolitic, intraclastic and bioclastic dolostones. And the reservoir spaces consist mainly of intergranular (dissolved) pores, intercrystalline (dissolved) pores, intragranular dissolved pores and fractures. Among them, intergranular pores account for the highest proportion, which is followed by intragranular dissolved pores. In addition, most throats are necking and flaky which mainly connect intergranular and intercrystalline pores, respectively. The diagenetic sequence shows that penecontemporaneous karst well improved the porosity of the reservoir in the early-stage although the cementation and compaction reduced parts of pores. The reservoir formation is associated with the tectonic-depositional settings, diageneses and terrigenous contamination. Paleohighlands and submerged uplifts, forming in the early Ordovician amalgamation between Yangtze and Cathaysia blocks, accumulated shoal sediments as the material basis for the reservoir formation. Penecontemporaneous karst forming intragranular dissolved pores and the dolomitization aiding grainstones to resist the pressure solution are the key to increasing porosity and preserving pores. The absence of terrigenous contamination prevented intergranular pores from being strongly cemented, which resulted in the reservoir difference between the central and southeastern Sichuan Basin. The study can be used as a reference for the further exploration of Ordovician petroleum in the Sichuan Basin and other regions owning similar geological settings.

The exploration of the first member of Permian Maokou Formation (Maokou 1) in the Weiyuan area of southern Sichuan Basin has been limited. Previous analyses of cast thin sections and argon ion electron microscopy based on earlier drilling data suggested that talc pores were the primary reservoir spaces, with talc formation significantly contributing to the reservoir. However, the latest drilling data shows substantial differences in the types of reservoir spaces and the genesis of the Maokou 1 marlstone reservoirs compared to earlier understanding. It is necessary to further clarify the main controlling factors for the development of these reservoirs in the Maokou 1 member. Through core observation, thin section identification, physical property analysis, nitrogen adsorption, argon ion polishing scanning electron microscopy, and quantitative pore characterization, the primary reservoir spaces and types of the Maokou 1 marlstone were analyzed from both qualitative and quantitative perspectives. The main controlling factors for the development of these reservoirs were identified by combining total organic carbon (TOC) content determination, rare earth element analysis, and whole rock X-ray diffraction. High-quality reservoirs in the Maokou 1 member of the Weiyuan area are developed in marlstone, characterized by low porosity and permeability fractures and pore-type reservoirs, predominantly Type Ⅲ with some Type Ⅱ reservoirs. The main reservoir spaces include corroded pores, organic matter pores, and talc pores and fractures, with pore development closely related to TOC content. Talc formation, dolomitization, and silicification did not significantly contribute to secondary reservoir spaces, and their contribution to porosity is minimal. The development of marlstone reservoirs is jointly controlled by early dissolution, sedimentary facies, and organic matter abundance. Early dissolution is the key to the formation of corroded pores and fractures, while high primary productivity and high organic matter settling rate of the inner gentle slope shallow water environment provided the material basis for the formation of organic matter pores. This understanding provides theoretical support for the exploration of similar oil and gas reservoirs in the basin.

Based on an elaboration of the resource potential and annual production of tight sandstone gas and shale gas in the United States and China, this paper reviews the researches on the distribution of tight sandstone gas and shale gas reservoirs, and analyzes the distribution characteristics and genetic types of tight sandstone gas reservoirs. In the United States, the proportion of tight sandstone gas in the total gas production declined from 20%–35% in 2008 to about 8% in 2023, and the shale gas production was 8 310×108 m3 in 2023, about 80% of the total gas production, in contrast to the range of 5%–17% during 2000–2008. In China, the proportion of tight sandstone gas in the total gas production increased from 16% in 2010 to 28% or higher in 2023. China began to produce shale gas in 2012, with the production reaching 250×108 m3 in 2023, about 11% of the total gas production of the country. The distribution of shale gas reservoirs is continuous. According to the fault presence, fault displacement and gas layer thickness, the continuous shale gas reservoirs can be divided into two types: continuity and intermittency. Most previous studies believed that both tight sandstone gas reservoirs and shale gas reservoirs are continuous, but this paper holds that the distribution of tight sandstone gas reservoirs is not continuous. According to the trap types, tight sandstone gas reservoirs can be divided into lithologic, anticlinal, and synclinal reservoirs. The tight sandstone gas is coal-derived in typical basins in China and Egypt, but oil-type gas in typical basins in the United States and Oman.

In view of the unclear understanding of reservoir formation conditions such as inside formation structure, reservoir lithology, physical property and distribution law of Carboniferous system of the southern slope of Beisantai Uplift in Junggar Basin, this paper analyzes the inside cycle combination and reservoir characteristics of Carboniferous Bashan Formation from key factors such as lithology, reservoir space and rock based on core, well logging and seismic data. Combined with the distribution of oil source conditions, advantageous reservoir distribution and paleostructural characteristics, the hydrocarbon accumulation rules of inside Carboniferous volcanic reservoir in the south slope of Beisantai Uplift are revealed. The results show that the inside of the Carboniferous Bashan Formation can be divided into three quaternary cycles, which are the first member of the Bashan Formation, the second member of the Bashan Formation and the third member of the Bashan Formation. The dominant lithofacies are concentrated in the third member of Bashan Formation, mainly composed of explosive volcanic breccia, overflow subfacies andesite and basalt. Lithofacies is the basis of determining the development degree of the primary reservoir space of volcanic rock reservoir, and the location of the reservoir from the top of the Carboniferous system determines the intensity of the weathering leaching reform. The southern and eastern craters of the third member of Bashan Formation are the developing areas of high-quality reservoirs. The lithology is mainly lava and volcanic breccia which are relatively developed in solution holes and tectonic fractures respectively. The Bashan Formation reservoir model mainly consists of "backfilling" accumulation of upper and lower reservoirs and lateral accumulation of the reservoir. The paleoup-lift of the third member of Bashan Formation, the inheritable paleo-uplift is well matched with the dominant lithofacies and accumulation period, which is the favorable condition for oil and gas accumulation. The results provide guidance for the exploration and development of Carboniferous insider reservoirs on the south slope of Beisantai Uplift, Junggar Basin. [ABSTRACT FROM AUTHOR]

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Copyright of Journal of Engineering (17264073) is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The geological storage of carbon dioxide (CO2) in offshore saline aquifers stands as a primary option for reducing CO2 emissions in coastal regions. China's coastal regions, particularly Shandong and Jiangsu provinces, face significant challenges in CO2 reduction. Therefore, evaluating the feasibility of CO2 geological storage in the adjacent seas is critical. To assess the suitability of a CO2 storage site, understanding its structural and reservoir characteristics is essential to mitigate injection and storage risks. In this study, we analyzed the structural characteristics and potential traps of the Yantai Depression in the South Yellow Sea Basin based on seismic data interpretation. We further conducted well logging analysis and post-stack seismic inversion to obtain lithological data, including acoustic impedance and sandstone content percentages from the Cenozoic Funing Formation, Dainan–Sanduo Formation, and Yancheng Formation. Our findings highlight that the Yantai Depression in the South Yellow Sea Basin exhibits diverse structural traps and favorable reservoir–caprock combinations, suggesting promising geological conditions for CO2 storage. This area emerges as a suitable candidate for implementing CO2 geological storage initiatives. [ABSTRACT FROM AUTHOR]

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Recent exploration efforts have revealed significant industrial gas flow from the Wujiaping Formation marine shale in the Longmen-Wushankan area of the eastern Sichuan Basin, underscoring its considerable exploration potential. In this study, the reservoir characteristics and exploration potential of the Wujiaping Formation shale gas in this area are further evaluated. On the basis of well rock electrical properties, experimental analyses, and depositional and structural patterns in the eastern region, we characterize the reservoir properties and identify the primary factors controlling shale gas accumulation. The results indicate that the Wujiaping shale is characterized by a high organic matter content, favorable pore types, high porosity, and a high content of brittle minerals, which are conducive to subsequent development and fracturing. A positive correlation is observed between the total organic carbon (TOC) content, porosity, brittle mineral content, and shale gas content. The TOC content is strongly correlated with the gas content (the correlation coefficient is 0.75). The high shale gas yield of the Wujiaping Formation is attributed to a combination of favorable sedimentary environments, pore conditions, roof and floor conditions, and fracturing capabilities. However, compared with the Longmaxi Formation in the Sichuan Basin, the Wujiaping Formation shale is characterized by a lower porosity, thinner shale, and deeper burial, posing challenges for exploration and development. In this study, criteria for evaluating Wujiaping Formation shale gas are established, and four favorable exploration areas are identified. Overall, the Permian Wujiaping Formation marine shale in the Longmen-Wushankan area holds promising exploration and development potential. Further exploration and an enhanced understanding of this formation will provide valuable guidance for future marine shale gas exploration and development in this area. [ABSTRACT FROM AUTHOR]

In order to identify the characteristics of Chang 2 reservoir in Resiwan oil region of the Zichang oilfield in the Ordos Basin, based on the study of sedimentary characteristics, this research uses experimental methods such as mercury intrusion, scanning electron microscopy, and thin section identification to systematically analyze the petrology, physical properties, pore types, structures, and diagenesis of Chang 2 reservoir. The results show that Chang 2 oil layer in Resiwan oil region of Zichang oilfield mainly develops braided river facies sediments, which can be further divided into three sedimentary microfacies: core beach, riverbed retention sediment, and flood plain. The lithology is mainly composed of light gray, gray medium sandy feldspar sandstone, and the significant pores for the reservoir are mainly intergranular dissolution pores and residual intergranular pores. The average porosity and permeability of Chang 2 reservoir in the study area are 11. 7% and 11. 45×10-3μm 2, respectively, indicating a low porosity and low permeability reservoir. The pore structure is divided into four types: Class I large and medium-sized pore type, Class II small and medium-sized pore type, Class III small pore type, and Class IV small microporous type. Among them, Class II and III are the main types of oil and gas reservoir pores in the study area. The favorable diagenesis for reservoir properties is dissolution, while compaction and cementation have destructive effects on reservoir properties. In addition, sedimentary facies are also an important factor affecting the physical properties of reservoirs, among which the core beach microfacies have the best physical properties, followed by the riverbed retention sedimentary microfacies. [ABSTRACT FROM AUTHOR]

As one of the most important future clean energy sources, natural gas hydrate (NGH) is attracting widespread attention due to the vast reserves available and high energy density. How to extract this source in a safe, efficient, and environmentally friendly manner has become the key to the commercial utilization of its resources. This paper reviews the recent advances in the study of the fundamental reservoir properties of offshore NGH, summarizing the methods and technologies for testing the sedimentary properties of reservoirs, analyzing the characteristics in reservoir mechanics, electrics, thermodynamics, and fluid dynamics, and discusses the influence of reservoir fundamental properties on NGH exploitation. The aim is to provide guidance and reference for research on the exploitation of NGH in different target exploitation areas offshore. [ABSTRACT FROM AUTHOR]

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Copyright of Geology & Exploration is the property of Geology & Exploration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Chang 6 reservoir group in the southeastern Wangjiawan area of the Ordos Basin is a tight sandstone reservoir. Reservoir sensitivity evaluation is an important means to study fluid damage to reservoirs and has important guiding significance for later water injection development. Reservoir sensitivity and its influencing factors were studied based on a scanning electron microscope, mercury injection test, and sensitivity test. The results show that the study area is mainly feldspar sandstone with high content of feldspar, quartz and rock debris, and clay minerals are mainly illite, chlorite and illite-montmorillonite mixed layer. The rock is dense, the pore structure is poor, and the pore throat distribution is uneven, which is a low porosity and low permeability reservoir. The sensitivity is characterized by medium-weak velocity sensitivity, medium-weak water sensitivity, medium-strong acid sensitivity, weak-medium-weak alkali sensitivity and medium-weak-weak salt sensitivity. The type and content of clay minerals affect the main factors of reservoir sensitivity. The mixed layer of illite and montmorillonite, illite and chlorite in clay minerals have great influence on salt sensitivity, water sensitivity and acid sensitivity respectively. Therefore, in the process of water injection development, targeted reservoir protection measures should be taken for salt sensitivity, water sensitivity and acid sensitivity. [ABSTRACT FROM AUTHOR]

Based on an elaboration of the resource potential and annual production of tight sandstone gas and shale gas in the United States and China, this paper reviews the researches on the distribution of tight sandstone gas and shale gas reservoirs, and analyzes the distribution characteristics and genetic types of tight sandstone gas reservoirs. In the United States, the proportion of tight sandstone gas in the total gas production declined from 20%--35% in 2008 to about 8% in 2023, and the shale gas production was 8 310x108 m3 in 2023, about 80% of the total gas production, in contrast to the range of 5%--17% during 2000--2008. In China, the proportion of tight sandstone gas in the total gas production increased from 16% in 2010 to 28% or higher in 2023. China began to produce shale gas in 2012, with the production reaching 250x108 m3 in 2023, about 11% of the total gas production of the country. The distribution of shale gas reservoirs is continuous. According to the fault presence, fault displacement and gas layer thickness, the continuous shale gas reservoirs can be divided into two types: continuity and intermittency. Most previous studies believed that both tight sandstone gas reservoirs and shale gas reservoirs are continuous, but this paper holds that the distribution of tight sandstone gas reservoirs is not continuous. According to the trap types, tight sandstone gas reservoirs can be divided into lithologic, anticlinal, and synclinal reservoirs. The tight sandstone gas is coal-derived in typical basins in China and Egypt, but oil-type gas in typical basins in the United States and Oman. [ABSTRACT FROM AUTHOR]

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of China University of Petroleum is the property of China University of Petroleum and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Sedimentologica Sinica is the property of Acta Sedimentologica Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To further study the reservoir characteristics and adsorption capacity of the Taiyuan Formation shale in the South North China Basin (SNCB), the pore structure and adsorption capacity of shale are discussed using various analysis tests, including elemental geochemistry, organic geochemistry, mineral composition, low-temperature nitrogen adsorption (LTNA), and methane adsorption experiments. The results indicate that the Taiyuan Formation shale formed in a poor oxygen and anaerobic sedimentary environment in still water. The average value of total organic carbon (TOC) content is 2.37%. The organic matter type mainly consists of type III kerogen. The vitinite reflectance (Ro) ranges from 3.11% to 3.50%. The clay mineral content varies greatly, averaging at 40.7%, while the quartz content averages at 37.7%. The Taiyuan Formation shale mainly develops interparticle (InterP) pores, followed by organic pores, intraparticle (IntraP) pores, solution pores, and microfractures. BET specific surface area (SSA) is between 9.47 m2/g and 22.14 m2/g, while pore volume (PV) ranges from 0.0098 cm3/g to 0.022 cm3/g, indicating favorable conditions for shale gas storage. According to the results of the CH4 adsorption experiment, Langmuir volume from Taiyuan Formation shales exhibits 1.35~4.30 cm3/g, indicating excellent adsorption capacity. TOC content shows a positive correlation with both Langmuir volume and BET SSA from Taiyuan Formation shales, suggesting that TOC plays a crucial role in controlling microscopic pores and gas adsorption capacity. Organic matter enhances the shale adsorption capacity by providing abundant pore SSA. Due to formation compaction, the pore size of clay minerals decreases, leading to an increase in pore SSA, while kaolinite exhibits weak hydrophilic ability. Consequently, with the increase in clay minerals and kaolinite content, the shale adsorption capacity is enhanced to a certain extent. However, an increase in the carbonate mineral content may result in a decrease in the proportion of clay minerals, therefore reducing the CH4 adsorption capacity of shale. [ABSTRACT FROM AUTHOR]

Due to large burial depths， ultra-deep clastic rock reservoirs have poor physical properties and low oil and gas productivity. However， the newly drilled Well Zheng10 in Shawan Sag， Sinopec exploration area， has encountered high-quality thick reservoirs in the Triassic Karamay Formation at a buried depth of 6 700 m， and conventional tests have obtained high industrial oil and gas flow. To reveal the characteristics of this set of reservoirs and favorable main controlling factors， clarify the direction of ultra-deep clastic rock exploration， and reduce the risk of further oil and gas exploration in this area， this paper comprehensively analyzed the data of core， well logging， cast thin sections， physical properties， scanning electron microscopy， and diagenetic evolution of the reservoirs， and discussed the petrological， physical， and pore characteristics of reservoirs in the Triassic Karamay Formation in this area. The results show that the ultra-deep clastic rocks of the Triassic Karamay Formation in Well Zheng10 area are deposited in the front of the braided river delta. The lithology is dominated by glutenites， gravel-bearing fine sandstones， and fine sandstones， and the rock types are mainly feldspar lithic sandstones with low composition maturity. The remaining primary pores and solution pores dominate the reservoir space. The average porosity of the reservoirs is 9.1%， and the average permeability is 2.85 mD. The reservoir belongs to the ultra-low porosity and ultra-low permeability type and low porosity and low permeability type as a whole. Favorable sedimentary facies zones， constructive diagenesis， and abnormal high-pressure control the development and distribution of favorable reservoirs in this area. Among them， sedimentary microfacies are the basis of favorable reservoir development. The fine sandstones deposited in the underwater distributary channel at the front of the braided river delta are better sorted and rounded. The contents of the muddy matrix are low， and the physical properties of the reservoir are better， which are the dominant phase zones for favorable reservoir development. The sodium feldspar cements generated in the early diagenetic process are dissolved by acids in the later period， which increases the dissolution pores and is an essential constructive diagenesis. The abnormal high-pressures formed by continuous oil and gas charging form early and develop continuously for a long time， playing an important construction role. The research results have a guiding role for the subsequent ultra-deep oil and gas exploration in this area.

The Lower Cambrian Longwangmiao Formation in the Penglai gas area has promising carbonate reservoirs and exhibit strong gas indications, making itself a pivotal exploration zone following the Anyue gas field in the central Sichuan region. However, the lack of clarity regarding reservoir development patterns has constrained exploration deployment. Through comprehensive analysis of the most recent drilling and testing data, this study systematically examines the reservoir characteristics and primary controlling factors of the Longwangmiao Formation in Penglai gas area. Results reveal a mixed sedimentary background of terrigenous debris and carbonate, with reservoirs predominantly situated in the middle and upper strata of the Longwangmiao Formation. The reservoir rock types are predominantly (residual) granular dolomite and crystalline dolomite. Main types of reservoir space include intergranular dissolved pores, intragranular dissolved pores, intercrystalline dissolved pores, and micro-fractures. The reservoir is characterized by low porosity and permeability, with thickness typically ranging between 10-42 m. Reservoir development is controlled by sequence stratigraphy, lithology and diagenesis, particularly evident in the granular dolomite and crystalline dolomite within the middle and upper sections of the progradational parasequence set. Key constructive diagenetic processes include atmospheric freshwater dissolution, oil and gas dissolution and fracture. A comparison with the Moxi-Gaoshiti area in the main area of Anyue gas field suggests similar controlling factors, primarily revolving around granular dolomite, dissolution and fracturing. Nonetheless, the Longwangmiao Formation reservoir in Penglai gas area exhibit distinctive traits such as high ash content, elevated terrigenous clastic content and limited penecontemporaneous exposure. Consequently, identifying high-energy granular dolomite and fine-grained dolomite exposed during the penecontemporaneous period, as well as dolomite modified by supergene karst, emerges as imperative in targeting reservoirs within the Penglai gas area.

In order to identify the exploration prospect of shale gas in Longtan Formation in Zhina area, the mineral composition, organic geochemical characteristics, microscopic pore characteristics, thickness and distribution of bored mud shale and gas content characteristics of Z2 well Longtan Formation were analyzed, and the characteristics of shale gas reservoirs in Longtan Formation were studied and the exploration potential of shale gas was evaluated. The results show that the organic matter type of shale is typeⅡ2 -Ⅲ, and mainlyⅡ2, the total organic carbon content is 1. 34% ~8. 25%, the average is 3. 68%, and the maturity of organic matter is 0. 92% ~3. 24%, with an average of 2. 45%, which belongs to the high-high maturity evolution stage and has good vitality potential. The results of scanning electron microscopy show that the mud shale samples mainly develop four types of microscopic pores, including endogranular science, intergranular pores, organic matter pores and microfractures, and the internal pores are developed, which provid a good storage space for shale gas. The brittle mineral content of mud shale in Z2 well is 24. 40% ~63. 08%, the average is 41. 22%, the total thickness of mud shale is 170. 74 m, accounting for 42%, and five mud shale layers with effective continuous thickness greater than 15 m are developed, and two shale sections can be formed with adjacent wells, which are suitable for fracturing transformation. The shale of Longtan Formation in Zhina area has good vitality conditions, reservoir conditions and fracturability, and has great exploration potential. [ABSTRACT FROM AUTHOR]

This study focuses on the characterization of shale gas reservoirs in the Longmaxi Formation and their controlling factors in the east Sichuan Basin. Detailed mineralogical and reservoir characterization of shale samples in the region was carried out by various methods, including X-ray diffraction analysis and nitrogen adsorption experiments. The results show that the shale is mainly composed of clay minerals (illite content ranges from 34.9% to 55.7%), quartz and calcite. In terms of reservoir characteristics, the shale mesopore morphology is mainly "slit-type", with BET specific surface area ranging from 7.12-25.63 m2/g and BJH pore volume from 0.0095-0.0262 mL/g. These reservoir characteristics show a significant positive correlation with the organic carbon content (1.82-3.87%). correlation. Petrographic analysis further reveals that the brittle mineral content has a significant effect on the brittleness, pore development and fracturing effectiveness of the rocks. In addition, diagenesis (including compaction, cementation, dissolution, and thermal evolution of organic matter) had a significant impact on the formation and characterization of shale pores. These findings provide a key scientific basis for understanding the geological characteristics and development potential of shale gas reservoirs in the Longmaxi Formation in the Sichuan Basin. [ABSTRACT FROM AUTHOR]

The northward subduction of the Neo-Tethys oceanic crust triggered multiple magmatic activities in the West Myanmar Arc, which in turn influenced the deposition of sedimentary pyroclastic rocks from the Cretaceous to Eocene strata in the Central Myanmar Basin (CMB). The pore structure of these lithologic reservoirs is complex and rich in tuffaceous sandstone, which plays an adverse role in reservoir development in this region. To understand the development characteristics and genetic mechanism of the pyroclastic rocks within three sets of reservoirs in this area, a comprehensive analysis was conducted through borehole core observations, thin section identification, scanning electron microscope analysis, and mercury injection tests. The tuffaceous sandstone from the upper Cretaceous to the Eocene is dominated by intermediate-acid volcanic rock debris. The pyroclastic rocks exhibit evident chloritization and ironization, with residual intergranular pores being the principal type accompanied by a smaller amount of intergranular dissolved pores and intragranular dissolved pores. The highest porosity is observed in the Eocene tuffaceous sandstone, ranging from 8% to 12%. The Late Cretaceous to Paleocene sandstones exhibit lower porosity levels of only 4%–6%. These reservoirs are characterized by their low-porosity and low-permeability. Despite the presence of a good source rock in this area, the volcanic debris particles filling the pores, as well as their subsequent devitrification, chloritization, and limonite mineralization, result in pore throat blockage and narrowing. The reservoirs in this area are small in size, exhibit poor reservoir connectivity and lateral continuity, and fail to meet the necessary conditions for commercial-scale hydrocarbon accumulation and migration. [ABSTRACT FROM AUTHOR]

In order to explore the strong heterogeneity of evaporite-carbonate symbolic system, based on core and logging data, this paper clarifies microfacies types of Arab Formation in B Oilfield of Abu Dhabi, and analyzes the reservoir characteristics of various microfacies and the main controlling factors of high-quality reservoirs. Twelve microfacies types (MF1--MF12) can be identified in the Arab Formation. Microfacies types and associations indicate that it is a sedimentary system of Sabha tidal flat-lagoon-barrier beach under the background of limited-evaporation. Microfacies control reservoir quality. MF2 and MF9--MF12 have thicker pore throats, better connectivity, and higher porosity and permeability, making them favorable microfacies types for reservoir development. MF2 and MF10 develop dolomite reservoirs, with the reservoir space mainly composed of intergranular pores, residual intergranular pores and intragranular dissolution pores. Grainstone reservoirs are developed in MF9, MF11 and MF12, with the reservoir space dominated by intergranular (dissolution) pores, mold pores and intragranular dissolution pores. The seismic change of relative sea level causes orderly stacking of sedimentary facies belts in longitudinal direction. The difference of microfacies types and diagenesis between different sedimentary facies belts and within the same sedimentary facies belt is the fundamental reason for the strong heterogeneity of the Arab Formation reservoir. The barrier beach and supratidal are favorable facies belts for the development of high-quality reservoirs. The primary intergranular pores of high-quality reservoirs in the barrier beach facies are well maintained and superimposed with significant early exposure and dissolution, resulting in the generation of secondary pores and the further improvement of pore structure. The development of high-quality reservoirs in the supratidal is controlled by early dolomitization and penecontemporaneous dissolution. Dolomitization improves pore structure, which is conducive to early pore preservation. The early dissolution of dispersed anhydrite produces a large number of secondary pores, significantly improving reservoir physical properties. [ABSTRACT FROM AUTHOR]

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Based on the data of rock coring, thin sections, physical properties and organic texture, the source reservoir characteristics and hydrocarbon generation potential of the Permian Lucaogou Formation migmatite in Malang sag, Santanghu Basin were analyzed by means of microscopic observation, rock pyrolysis analysis and geochemical parameter intersection, and the reservoir forming conditions were discussed. The results show that the reservoir lithology of Lucaogou Formation is divided into mudstone, argillaceous limestone, argillaceous dolomite and tuff. The reservoir space is mainly intergranular pore intergranular pore, intergranular pore, volcanic ash devitrification pore, felsic dissolution pore and dissolution fracture, and the physical properties are low porosity and ultra-low permeability. The dominant lithology of the source rock is dolomitic mudstone and mudstone, with an average total organic carbon (TOC) of 4.41% . The organic matter types are mainly type Ⅰ and type Ⅱ2, and the maturity is mainly low maturity maturity. The source rock is characterized by high organic matter abundance, good organic matter type and hydrocarbon generation evolution in the oil generation stage. The comprehensive analysis shows that the shallow semi deep lacustrine mixed sedimentary rock source reservoir of Lucaogou Formation is integrated, with great hydrocarbon generation potential. It is a set of “ self generation, self storage, high-efficiency accumulation and other source supply” tight dolomitic oil reservoir with favorable reservoir forming conditions of “ good material foundation, sufficient basic conditions and efficient accumulation of oil and gas” . [ABSTRACT FROM AUTHOR]

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Wenchang A oilfield is a recently discovered low-permeability oilfield in the western South China Sea. The exploration target is the Zhuhai Formation, which reservoir lithology changes significantly, and the distribution of favorable reservoirs is unclear. In this study, the reservoir characteristics of the Zhuhai Formation in the Wenchang A oilfield, South China Sea, were analyzed through core identification, thin section identification, physical property testing, prestack geostatistical inversion, and frequency-based AVO inversion. Pre-stack geostatistical inversion is based on geostatistics and combines the seismic inversion algorithm with the stochastic sequential simulation algorithm. While the frequency-varying AVO inversion method is an extension of the conventional AVO inversion method, with its core technology being spectrum decomposition. After frequency division, multiple data sets directly participate in the calculation, which enhances the stability and accuracy of inversion.We also predict the favorable reservoir areas of six small layers in the Zhuhai Formation. The results show that 1) the reservoir lithology of the Zhuhai Formation mainly consists of feldspar quartz sandstone and feldspar quartz sandstone, indicating high compositional maturity. The porosity of the reservoir ranges from 14.0% to 19.0%, with an average value of 16.3%. The permeability of the reservoir ranges from 3.1 mD to 126.1 mD, with an average value of 22.4 mD, indicating a medium porosity and low permeability reservoir. The supporting structure of a sandstone reservoir is particle-supported, with the main contact being the "point-line" contact between particles. The main types of pores in sandstone are primary intergranular pores and secondary intergranular dissolved pores. Some pores are feldspar-dissolved pores, and occasionally there are hetero-based micropore. 2) The diagenesis of the Zhuhai Formation reservoir mainly includes compaction, cementation, and dissolution. Cementation and dissolution have minimal impact on the physical properties of reservoirs. The porosity loss of the reservoir after compaction ranges between 16.0% and 27.9%, and the compaction rate ranges between 40.0% and 69.8%, indicating a medium compaction diagenetic facies. 3) The favorable areas of each layer of the Zhuhai Formation are mainly concentrated in the southwest of the study area. The upper layer of ZH1I, the upper layer of ZH1II and the lower layer of ZH1II exhibit the best physical properties, the thickest favorable sand body, the strongest oil and gas display, the widest range of favorable areas, and the greatest exploration potential. The favorable exploration potential of layer 1 in the lower part of ZH1I and layer 2 in the upper part of ZH1II is moderate. The second layer in the lower part of ZH1II has the poorest properties and lower exploration potential. The main factors affecting the favorable area include physical properties, oil and gas display, sand body thickness, etc. [ABSTRACT FROM AUTHOR]

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