Subaqueous distributary channel sandbodies within delta fronts are crucial reservoirs in continental petroliferous basins. Understanding the spatiotemporal transition of river patterns in these channels is essential for accurate evaluation and prediction of oil and gas reservoirs, as well as for providing direct evidence of basin evolution. In the Yabus Formation of the Sag A of Melut Basin, a comprehensive analysis involving sequence division, sedimentary characteristics, seismic facies, high-resolution reservoir inversion, and sand body distribution revealed significant insights. During the Yabus Formation deposition, three intermediate base-level cycles were identified, each showing transition phenomena in the river patterns of subaqueous distributary channels within the delta front. Clear identification criteria for different river patterns were established. Braided subaqueous distributary channels exhibited dominant vertical accretion, high sand content, significant sandstone thickness, and continuous-strong amplitude seismic reflections. While the braided-meandering transition pattern showed a combination of vertical and lateral accretion, medium sand content, moderate sandstone thickness, and medium continuous-medium strong amplitude seismic reflections. Meandering subaqueous distributary channels were characterized by lateral accretion, low sand content, minimal sandstone thickness, weak continuous-weak amplitude seismic reflections, and mud-rich inversion features. The primary control factor influencing the transition of river patterns in these channels was identified as the long-term base-level cycle, shaped by paleotopography and sediment supply. Braided subaqueous distributary channels emerged as the main exploration interval for structural prospects, serving as lateral high-speed migration pathways. Dendritic braided and meandering transition intervals were deemed favorable for both structure-lithologic prospects and the expansion of new exploration fields and layers.

The characteristics and formation mechanism of clastic reservoirs have a significant impact on petroleum accumulation in the deep-seated strata of sedimentary basins. Newly drill data indicate that the tight reservoirs in the lower slop of Fukang Sag in the Junggar Basin produce a lot of oil despite being buried extremely deep and with low porosity. By using lithological and geochemical studies, we investigated the formation of these deep-seated reservoirs through the comparison between upper and lower slopes. The results suggest that the reservoir of lower slop is highly compacted and has weaker dissolution than the reservoir in the upper slope. Dissolution and micro fractures are the key factors in determining the formation of deep-seated reservoirs. The fluids that caused the dissolution of reservoir can be divided into three stages and sourced from the mixture of deep and basin fluids. A model of reservoir formation and evolution has been set up. Our research could provide an insight for the formation of deep-seated reservoirs in similar geological conditions worldwide.

In the Baikouquan Formation of the Shawan Depression, there exist thin, high-quality conglomerate reservoirs with low porosity and low permeability. Only the underwater gray-green conglomerate with medium porosity is considered a high-quality reservoir. Due to the overlapping wave impedance between these thin high-quality reservoirs and tight layers, traditional post-stack inversion and pre-stack simultaneous inversion methods are ineffective in predicting such thin reservoirs. Pre-stack geostatistical inversion, which combines the advantages of simultaneous inversion and geostatistical inversion, has proven to be effective in this context. This study integrates core, logging, and test data to construct petrophysical charts using P-impedance and V_p/V_s ratios, idengtify key reservoir parameters, and apply pre-stack geostatistical inversion to predict thin high-quality conglomerate reservoirs. The results show that pre-stack geostatistical inversion can accurately identify thin high-quality reservoirs, providing a reliable basis for further exploration and development.

With continued exploration and the increased need for energy resources, deep reservoirs have gradually become the main target of oil and gas exploration in recent years. The Lower Wuerhe Formation on the northern slope of the Central Depression of the Junggar Basin has a high-quality, deep, glutenite (coarse-grained clastic) reservoir at depths greater than 4500 m. However, its genetic mechanism remains unclear. Here, we improve our understanding of the origin of this deep reservoir by performing comprehensive investigations via thin section analysis, field emission scanning electron microscopy, electron probe analysis, X-ray diffraction analysis, and whole-rock carbon and oxygen isotope analysis. The results reveal that the deep reservoir lithology within the study area comprises primarily gray-white gravelly gritstone and conglomerate. Zeolite cement is predominant, and secondary dissolution pores are the primary type of reservoir space in deep reservoirs. The Lower Wuerhe Formation has experienced significant compaction in the study area. Debris flow microfacies serve as the prevailing sedimentary microfacies containing substantial amounts of laumontite. The effect of dissolution of organic acids on laumontite is pivotal in the formation of high-quality deep reservoirs in the study area. These findings serve as valuable references for the genesis of deep zeolite-rich reservoirs in the Central Depression of the Junggar Basin and other areas worldwide.

There are some high-quality reservoirs of internal dolomite within the Ordovician Majiagou Formation in the Ordos Basin, located in western China. However, influenced by sedimentary environments and differential diagenetic processes, these high-quality dolomite reservoirs exhibit thin sedimentary thickness and relatively small differences in elastic parameters compared to the surrounding rocks. Identifying these reservoirs using seismic data presents a significant challenge. In the study area, systematic sampling was conducted, and the physical and elastic properties of dolomite, limestone, and anhydrite were tested in the laboratory. Through various analyses, including physical property tests, thin-section observations, and CT scans, researchers discovered that the carbonate rocks in the study area underwent complex diagenetic evolution. The primary constructive diagenetic processes include dolomitization and dissolution; while the main destructive diagenetic processes involve compaction and cementation. Dolomitization leads to abundant intercrystalline pores, increasing rock porosity. The pore aspect ratio is relatively large, with predominantly near-circular pores. Additionally, because the longitudinal wave velocity of dolomite minerals exceeds that of calcite, dolomitization enhances the rock’s elastic parameters. Dissolution primarily alters pore shape, increasing rock porosity while reducing the aspect ratio of pores (mainly flattened pores). Consequently, this decreases the rock’s elastic parameters. Different diagenetic processes significantly impact the elastic parameters of the rocks. By analyzing the differences in elastic parameters before and after various diagenetic processes, researchers can clearly define the elastic parameter characteristics of high-quality dolomite reservoirs, providing a foundation for reservoir prediction in the study area.

Bathymetric mapping using quantitative remote sensing techniques is a crucial research domain for accurately retrieving oceanic depths. This study uses GF5-AHSI hyperspectral remote sensing data to evaluate the accuracy of three semi-empirical models for shallow water depth retrieval: single-band, multi-band, and band-ratio models. The methodology involved parameter extraction, optimal band selection, and combining bands to create the models. A Pearson correlation analysis was conducted to assess parameter sensitivity, optimizing the models for water depth retrieval. The models’ precision was evaluated by comparing their outputs with actual underwater topography measurements from Meizhou Bay, Fujian Province. Error margins in estimated water depths ranged from 10% to 50% across the three models, with accuracy generally improving at greater depths. Among the models, the band-ratio model showed the highest reliability, followed by the multi-band model, and the single-band model was the least reliable. However, in depths greater than 30 m, the single-band model’s error margin could be reduced to within 10%, surpassing the performance of the multi-band and band-ratio models. A spectral reflectance sensitivity test revealed variations in reflectance across different water depths, with a slight increase in the near-infrared band due to water turbidity. To further improve model accuracy, strategies must be implemented to mitigate the interference of suspended sediments and reduce noise, thereby enhancing the reliability of water depth retrieval.

The alteration pathways of volcanic ashes depend on the physicochemical conditions of the watermass in which they are deposited. Different conditions in terrestrial, paralic, and marine facies may impart recognizable chemical signatures on altered ash beds (i.e., K-bentonites) that are potentially useful for distinguishing depositional facies in ancient ash-bearing stratigraphic successions. Western Guizhou Province in South China contains widespread Permian-Triassic transition strata from terrestrial lacustrine to shallow-marine shelf facies. In this study, factors influencing the mineralogy and geochemistry of K-bentonites accumulating across a spectrum of freshwater facies in Permian-Triassic transition strata of south-western China were comparatively investigated using mineralogical and geochemical data. Our results show that K-bentonites preserve diagnostic information regarding their depositional environment. The clay mineral assemblages of these K-bentonites are facies-dependent, with dominance of mixed-layer illite/smectite (I/S) clays in freshwater lacustrine facies, kaolinite and I/S in lagoonal facies, mixed-layer kaolinite/smectite (K/S) in mixed marine-terrestrial facies, and smectite and I/S in littoral-neritic facies. The lagoonal Chinahe (CNH) K-bentonites exhibit clay mineral compositions dominated by kaolinite (both highly and poorly crystalline forms) and R1 and R3 I/S clays; the CNH-16 K-bentonite additionally contains minor chlorite. The abundance of kaolinite and absence of smectite in the CNH K-bentonites resulted from strong chemical weathering in an organic acid-rich and oxidizing environment characterized by low porewater pH. The littoral Langdai (LD) K-bentonites contain mainly R1 and R3 mixed-layer illite/smectite (I/S) and smectite, with minor poorly crystalline kaolinite, suggesting a higher pH in seawater-derived pore fluids. The littoral LD K-bentonites and their host sediments have Sr/Ba ratios of 0.34−0.49, consistent with deposition in brackish coastal facies, whereas the higher Sr/Ba ratios of the CNH K-bentonites (0.67−1.07) indicate deposition in a marine to slightly hypersaline lagoonal facies linked to warm, arid climate conditions.

Assemblages of limestone and shale have been proven favorable shale oil-producing layers in North American and Chinese basins. However, the Jurassic Da’anzhai Formation in the Sichuan Basin did not meet these expectations. The relationship between the lithofacies assemblages and shale oil enrichment was investigated based on FE-SEM, XRD, N₂ adsorption, HPMI, NMR, and rock pyrolysis experiments. The results showed that ten main lithofacies developed in the Da’anzhai Formation. The undeveloped dissolution pores in the shell limestone led to clay intergranular pores and microfractures constituted the main oil reservoir space. With increased shale content, the physical properties and oil content gradually improved. These special geological conditions indicate that the breakthrough of shale oil in the Da’anzhai Formation depends only on the developed fracture system. A favorable exploration target was the layered lithofacies with developed veined calcite and bedding fractures. The results obtained in this study are significant for shale oil exploration of the same type of lithological assemblage worldwide.

In the context of global warming, winter temperature variability exhibits marked regional differences and has become a central focus in climate research. This study reconstructs winter minimum temperatures (WMT) since AD 1879 using a tree-ring width index chronology of Taxus baccata L., sampled at 1500–1600 m elevation in the south-western Caspian Sea region. It also offers preliminary insights into the mechanisms driving winter temperature variability. The results show that tree radial growth is significantly and positively correlated with both late spring to early summer precipitation and winter temperatures, with the strongest association observed with WMT. The reconstructed WMT series reveals distinct interannual and decadal fluctuations over the past century. Prolonged warm periods (lasting five or more consecutive years) occurred during 1886–1890, 1914–1918, 1921–1925, 1933–1939, 1961–1965, 1975–1980, and 1997–2005. Despite a warming trend since the 1980s, a cooling signal has emerged in the early 21st century, and reconstructed temperatures remain within the range of historical variability. Spatial correlation analysis indicates that the reconstruction captures winter temperature variability across westerly-dominated regions of Central and Western Asia. Wavelet analyses further reveal a phase-dependent relationship with the North Atlantic Oscillation (NAO) in the 6–12-year band, and significant coherence with Niño 3.4 sea surface temperatures (SST) in the 4–8-year band during specific periods. Overall, WMT variability appears to be modulated by the combined influence of NAO and ENSO at multiple scales, although other regional processes may also contribute.

Storm surges pose serious threats to densely populated coastlines and demand accurate forecasting. This study develops a fully coupled wind–wave–circulation forecasting system for Hong Kong coastal waters within the Earth System Modeling Framework (ESMF). The system integrates the Weather Research and Forecasting (WRF) model for atmospheric forcing, the Simulating Waves Nearshore (SWAN) model for wave dynamics, and the Finite-Volume Community Ocean Model (FVCOM) for ocean circulation. Validation against tide-gauge records for five typhoons, Hato (2017), Mangkhut (2018), Higos (2020), Kompasu (2021), and Saola (2023), shows that the coupled system consistently outperforms both an uncoupled ocean model and a wave–current coupled model. It achieves domain-averaged root-mean-square errors (RMSEs) of about 0.10 m, reduces errors by 31%–61% across events, and maintains high correlation coefficients (CCs). Peak surge timing generally follows north-westward storm tracks but displays irregular inter-station lags, reflecting complex local hydrodynamics. The largest improvements occur in semi-enclosed bays such as Tolo Harbour, where RMSE reductions of 0.10–0.16 m underscore the importance of wave setup, sea-state-dependent wind stress, and current–wave feedbacks. Overall, the findings confirm that full coupling is essential for reliable surge prediction in complex coastal environments, and the achieved accuracy supports near-term operational application. Remaining challenges include sensitivity to atmospheric forcing and computational demands, though advances in high-performance computing and hybrid physics–AI approaches offer promising solutions.