ResNet and CWT Fusion: A New Paradigm for Optimized Heterogeneous Thin Reservoir Evaluation.

The endeavor to explore and characterize oil and gas reservoirs presents significant challenges due to the inherent heterogeneities that are further compounded by the existence of thin sand layers encapsulated in shale strata. This complexity is intensified by limited and low-resolution seismic data, missing critical well-log information, and inaccessible angle stack data. Conventional reservoir classification approaches have struggled to address these issues, primarily due to their limitations in handling missing data effectively and, hence, precise estimations. This study focuses on the characterization of thin, heterogeneous potential sands of the B-interval within the Lower Goru Formation, a proven gas reservoir in the Badin area. The reservoir sands with varying thicknesses are assessed in detail for their optimized description and field productions by handling challenges, including low seismic resolutions, heterogeneities, and missing data sets. An innovative solution is developed based on the integration of continuous wavelet transform (CWT) and machine learning (ML) techniques for the approximation of missing data sets, i.e., S-wave (DTS), along with enhanced elastic and petrophysical properties. The improved properties are augmented by the high resolution attained by CWT and captured variability more profoundly through the implication of residual neural networks (ResNet). The limitations of conventional approaches are harnessed by ML solutions that operate with limited input data and deliver significantly improved results in characterizing enigmatic thin sand reservoirs. The high-frequency petroelastic properties reliably determined the thin heterogeneous potential sand bodies and illuminated a channelized play fairway that can be tested for additional wells with low-risk involvement.

A comprehensive analysis of Holocene extraordinary flood events in the Langxian gorge of the Yarlung Tsangpo River valley.

Increasing extreme temperature, precipitation and rapid meltwater events have added stress to the Himalaya's hydrological sensitivity and major flood risks, however, current extreme hydrological dataset and their genesis are insufficient to assess future flood discharge extremes in High Asian' rivers. Here, Holocene extreme floods in the Yarlung Tsangpo River valley were reconstructed by using physic-chemical analysis, optically stimulated luminescence dating and palaeohydraulic techniques. Palaeoflood slackwater deposits (SWDs) were identified by means of palaeohydrological criteria and comparison with SWDs from large flood that occurred in 2018. Palaeoflood SWDs consist of well-sorted silt and sand with a consistent geochemical composition, implying a similar sedimentary source. Such results suggest that these SWDs were transported in suspension over long distances during flood events. The chronological analysis indicates that there are three palaeoflood events, dated to 5.7, 3.9 and 2.9-1.2 ka, during the mid-late Holocene. Palaeoflood peak discharges in the bedrock reach and meandering channel were estimated to be 27,600-35,000 m3/s using one-dimensional and two-dimensional hydrodynamic modelling. The simulation results clearly show the potential palaeoflood depositional range in the lower-velocity and eddy backwater environments between Jiacha and Langxian gorge. The palaeoflood magnitudes redefine the regional largest flood discharge, and fit well with global maximum flood curves. And mid-late Holocene extreme flood magnitudes were generally 2.5-3.5 times larger than the current maximum gauged flood, but lower than the Jiedexiu glacial lake outburst floods. Comprehensive analysis highlights the three extraordinary floods were possibly induced by monsoon rains and glacial meltwater. Site-specific palaeoflood information advances our knowledge of rare and extraordinary floods in the highest and largest river in the southern Tibetan Plateau.

Consideration of high-quality development strategies for soil and water conservation on the loess plateau.

The construction of check dams is an important measure to prevent soil erosion on the Loess Plateau and reduce the amount of sediment entering the Yellow River. Based on an analysis of the current situation of soil and water conservation on the Loess Plateau and the three major problems faced by the traditional homogeneous soil check dam construction, the study of anti-scouring materials, hydrological calculation methods, dam design and construction technology and soil and water conservation monitoring are carried out in this paper. The results showed that the current soil and water conservation measures on the Loess Plateau have achieved remarkable outcomes. The new design and application concept of check dams with anti-burst and multi-sand interceptions is innovatively proposed in this paper. The new materials of solidified loess have good durability and anti-scouring characteristics and could meet the overflow and anti-scouring requirements of the new check dam. The small watershed high sand content of hydrological calculation can establish the upper limit of the flood sediment boundary for the anti-scouring protection layer of the check dam. The new technology of dam design and construction can achieve no collapse or slow collapse when encountering floods exceeding the standard. Intelligent monitoring systems can realize real-time dynamic monitoring for soil and water conservation on the Loess Plateau. The results will eventually contribute to the national strategy of the Ecological Protection and High Quality Development in the Yellow River basin.

Combined effects of climate, restoration measures and slope position in change in soil chemical properties and nutrient loss across lands affected by the Wenchuan Earthquake in China.

The MS 8.0Wenchuan Earthquake in 2008 caused huge damage to land cover in the northwest of China's Sichuan province. In order to determine the nutrient loss and short term characteristics of change in soil chemical properties, we established an experiment with three treatments ('undestroyed', 'destroyed and treated', and 'destroyed and untreated'), two climate types (semi-arid hot climate and subtropical monsoon climate), and three slope positions (upslope, mid-slope, and bottom-slope) in 2011. Ten soil properties-including pH, organic carbon, total nitrogen, total phosphorus, total potassium, Ca2+, Mg2+, alkaline hydrolysable nitrogen, available phosphorus, and available potassium-were measured in surface soil samples in December 2014. Analyses were performed to compare the characteristics of 3-year change in soil chemical properties in two climate zones. This study revealed that soil organic carbon, total nitrogen, Ca2+ content, alkaline hydrolysable nitrogen, available phosphorus, and available potassium were significantly higher in subtropical monsoon climate zones than in semi-arid hot climate zones. However, subtropical monsoon climate zones had a higher decrease in soil organic carbon, total nitrogen, total phosphorus, total potassium, and alkaline hydrolysable nitrogen in 'destroyed and untreated' sites than in semi-arid hot climate zones. Most soil chemical properties exhibited significant interactions, indicating that they may degrade or develop concomitantly. 'Destroyed and treated' sites in both climate types had lower C:P and N:P ratios than 'destroyed and untreated' sites. Principal component analysis (PCA) showed that the first, second, and third principal components explained 76.53% of the variation and might be interpreted as structural integrity, nutrient supply availability, and efficiency of soil; the difference of soil parent material; as well as weathering and leaching effects. Our study indicated that the characteristics of short term change in soil properties were affected by climate types and treatments, but not slope positions. Our results provide useful information for the selection of restoration countermeasures in different climate types to facilitate ecological restoration and reconstruction strategies in earthquake-affected areas.