Different genetic types of meter-scale cyclic sequences in stratigraphic records result from episodic accumulation of strata related to Milankovitch cycles. The distinctive fabric natures of facies succession result f...Different genetic types of meter-scale cyclic sequences in stratigraphic records result from episodic accumulation of strata related to Milankovitch cycles. The distinctive fabric natures of facies succession result from the sedimentation governed by different sediment sources and sedimentary dynamic conditions in different paleogeographical backgrounds, corresponding to high-frequency sea-level changes. Naturally, this is the fundamental criterion for the classification of genetic types of meter-scale cyclic sequences. The widespread development in stratigraphic records and the regular vertical stacking patterns in long-term sequences, the evolution characters of earth history and the genetic types reflected by specific fabric natures of facies successions in different paleogeographical settings, all that show meter-scale cyclic sequences are not only the elementary working units in stratigraphy and sedimentology, but also the replenishment and extension of parasequence of sequence stratigraphy. Two genetic kinds of facies succession for meter-scale cyclic sequence in neritic-facies strata of carbonate and clastic rocks, are normal grading succession mainly formed by tidal sedimentation and inverse grading succession chiefly made by wave sedimentation, and both of them constitute generally shallowing upward succession, the thickness of which ranges from several tens of centimeters to several meters. The classification of genetic types of meter-scale cyclic sequence could be made in terms of the fabric natures of facies succession, and carbonate meter-scale cyclic sequences could be divided into four types: L-M type, deep-water asymmetrical type, subtidal type and peritidal type. Clastic meter-scale cyclic sequences could be grouped into two types: tidal-dynamic type and wave-dynamic type. The boundaries of meter-scale cyclic sequences are marked by instantaneous punctuated surface formed by non-deposition resulting from high-frequency level changes, which include instantaneous exposed punctuated surface, drowned punctuated surface as well as their relative surface. The development of instantaneous punctuated surface used as the boundary of meter-scale cyclic sequence brings about the limitations of Walter's Law on the explanation of facies distribution in time and space, and reaffirm the importance of Sander's Rule on analysis of stratigraphic records. These non-continuous surface could be traced for long distance and some could be correlative within same basin range. The study of meter-scale cyclic sequences and their regularly vertical stacking patterns in long-term sequences indicate that the research into cyclicity of stratigraphic records is a useful way to get more regularity from stratigraphic records that are frequently complex as well as non-integrated.展开更多
One of the key challenges for underground rock reservoirs is ensuring prevention of the unwanted fluid leakage through rock fracture networks during their service life.Microbial-induced calcium carbonate precipitation...One of the key challenges for underground rock reservoirs is ensuring prevention of the unwanted fluid leakage through rock fracture networks during their service life.Microbial-induced calcium carbonate precipitation(MICP)technology has emerged as a promising bio-healing method for rock fractures with small apertures.In this study,a new“three-stage”injection strategy-based MICP(TS-MICP)bio-healing method was proposed,aiming to achieve a“three-high”performance that includes high bridging rate,high mechanical strength,and high homogeneity.A series of meter-scale rock fracture models were prepared to conduct TS-MICP grouting tests.Compared with the traditional injection strategy-based biohealing methods,the TS-MICP method significantly improved the bridging rate(32.1%e89.5%),mechanical properties(0.138e1.023 MPa),and homogeneity of CaCO_(3)precipitation(334.4%).Additionally,it achieved a higher material utilization rate(1.72 times higher),reducing the consumption of cementation solution(CS)by 258.8%,thereby demonstrating greater potential for field applications.The underlying mechanism for achieving high bridging rate and high homogeneity in CaCO_(3)precipitation can be attributed to the synergistic effects of the coupling injection strategy,which optimizes the advantages at each stage.In stage I,under the influence of gravity,the rapid flocculation and hydrogen bonding interactions of organic matter lead to formation of the dense and high-strength CaCO_(3)precipitation at the bottom using a low-concentration bacterial suspension(BS).This process establishes bridging steps along the wall sides for subsequent uniform CaCO_(3)precipitation.In stage II,concentrated BS is utilized to produce looser CaCO_(3)flocculation,which precipitates uniformly on the pre-existing bridging steps.In stage III,a two-step injection strategy was employed to reinforce the loose CaCO_(3)crystals formed in stages I and II,and finally forms a strong bridging effect with“three-high”performance.展开更多
数值天气预报降尺度技术是获取百米级地面风场预报的重要手段。在复杂海湾地形,尽管动力降尺度能较好地表征百米级地面风场,但其对计算资源要求很高且尚未达到业务时效性要求。而统计降尺度的优点是计算效率高,但在实际应用中缺乏统计...数值天气预报降尺度技术是获取百米级地面风场预报的重要手段。在复杂海湾地形,尽管动力降尺度能较好地表征百米级地面风场,但其对计算资源要求很高且尚未达到业务时效性要求。而统计降尺度的优点是计算效率高,但在实际应用中缺乏统计建模所需的百米级实况场。因此,单一的降尺度方法难以满足复杂海湾地面风场的精细化预报需求。本研究选取福建湄洲湾冬季冷空气大风的8次过程为研究对象,基于水平分辨率为0.03°的CMA-GD模式模拟结果进行降尺度,结合动力降尺度和统计降尺度两种方法的优点,探讨复杂海湾百米级地面风场的降尺度技术。首先,利用WRF模式嵌套水平分辨率达111 m的大涡模拟(LES)进行动力降尺度,建立2019~2023年冬季冷空气大风过程的百米级WRF-LES地面风场模拟数据集。其次,基于2019~2022年CMA-GD气象要素模拟数据集和WRF-LES地面风场模拟数据集,采用随机森林算法构建两者之间的分区统计降尺度模型。利用湄洲湾区域气象自动站地面风观测进行对比评估,结果表明,与CMA-GD模拟相比,百米级WRF-LES数据集更能捕捉到近地面风速脉动的时空跳跃性和刻画湍流的脉动特征,与观测风速的均方根误差(RMSE)也更低,而2023年CMA-GD地面风模拟结果经分区随机森林统计模型降尺度至百米级后,空间分布特征与WRF-LES模拟吻合,风速随时间变化趋势也基本一致,且RMSE明显小于CMA-GD地面风模拟的双线性插值降尺度结果,大部分地区的RMSE控制在0~2.5 m s^(-1)范围内。综上所述,联合大涡模拟和机器学习的动力—统计降尺度模型能够有效地将复杂海湾地形的公里级地面风速降尺度至百米级,为复杂海湾地形精细化天气预报提供技术支持。展开更多
基金ThestudyisjointlysupportedbyNationalNaturalScienceFoundationofChina (No .4980 2 0 1 2 )andMinistryofSciencesandTechnology (SSER
文摘Different genetic types of meter-scale cyclic sequences in stratigraphic records result from episodic accumulation of strata related to Milankovitch cycles. The distinctive fabric natures of facies succession result from the sedimentation governed by different sediment sources and sedimentary dynamic conditions in different paleogeographical backgrounds, corresponding to high-frequency sea-level changes. Naturally, this is the fundamental criterion for the classification of genetic types of meter-scale cyclic sequences. The widespread development in stratigraphic records and the regular vertical stacking patterns in long-term sequences, the evolution characters of earth history and the genetic types reflected by specific fabric natures of facies successions in different paleogeographical settings, all that show meter-scale cyclic sequences are not only the elementary working units in stratigraphy and sedimentology, but also the replenishment and extension of parasequence of sequence stratigraphy. Two genetic kinds of facies succession for meter-scale cyclic sequence in neritic-facies strata of carbonate and clastic rocks, are normal grading succession mainly formed by tidal sedimentation and inverse grading succession chiefly made by wave sedimentation, and both of them constitute generally shallowing upward succession, the thickness of which ranges from several tens of centimeters to several meters. The classification of genetic types of meter-scale cyclic sequence could be made in terms of the fabric natures of facies succession, and carbonate meter-scale cyclic sequences could be divided into four types: L-M type, deep-water asymmetrical type, subtidal type and peritidal type. Clastic meter-scale cyclic sequences could be grouped into two types: tidal-dynamic type and wave-dynamic type. The boundaries of meter-scale cyclic sequences are marked by instantaneous punctuated surface formed by non-deposition resulting from high-frequency level changes, which include instantaneous exposed punctuated surface, drowned punctuated surface as well as their relative surface. The development of instantaneous punctuated surface used as the boundary of meter-scale cyclic sequence brings about the limitations of Walter's Law on the explanation of facies distribution in time and space, and reaffirm the importance of Sander's Rule on analysis of stratigraphic records. These non-continuous surface could be traced for long distance and some could be correlative within same basin range. The study of meter-scale cyclic sequences and their regularly vertical stacking patterns in long-term sequences indicate that the research into cyclicity of stratigraphic records is a useful way to get more regularity from stratigraphic records that are frequently complex as well as non-integrated.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFC3007102)the National Natural Science Foundation of China(Grant Nos.42477188 and 41925012).
文摘One of the key challenges for underground rock reservoirs is ensuring prevention of the unwanted fluid leakage through rock fracture networks during their service life.Microbial-induced calcium carbonate precipitation(MICP)technology has emerged as a promising bio-healing method for rock fractures with small apertures.In this study,a new“three-stage”injection strategy-based MICP(TS-MICP)bio-healing method was proposed,aiming to achieve a“three-high”performance that includes high bridging rate,high mechanical strength,and high homogeneity.A series of meter-scale rock fracture models were prepared to conduct TS-MICP grouting tests.Compared with the traditional injection strategy-based biohealing methods,the TS-MICP method significantly improved the bridging rate(32.1%e89.5%),mechanical properties(0.138e1.023 MPa),and homogeneity of CaCO_(3)precipitation(334.4%).Additionally,it achieved a higher material utilization rate(1.72 times higher),reducing the consumption of cementation solution(CS)by 258.8%,thereby demonstrating greater potential for field applications.The underlying mechanism for achieving high bridging rate and high homogeneity in CaCO_(3)precipitation can be attributed to the synergistic effects of the coupling injection strategy,which optimizes the advantages at each stage.In stage I,under the influence of gravity,the rapid flocculation and hydrogen bonding interactions of organic matter lead to formation of the dense and high-strength CaCO_(3)precipitation at the bottom using a low-concentration bacterial suspension(BS).This process establishes bridging steps along the wall sides for subsequent uniform CaCO_(3)precipitation.In stage II,concentrated BS is utilized to produce looser CaCO_(3)flocculation,which precipitates uniformly on the pre-existing bridging steps.In stage III,a two-step injection strategy was employed to reinforce the loose CaCO_(3)crystals formed in stages I and II,and finally forms a strong bridging effect with“three-high”performance.
文摘数值天气预报降尺度技术是获取百米级地面风场预报的重要手段。在复杂海湾地形,尽管动力降尺度能较好地表征百米级地面风场,但其对计算资源要求很高且尚未达到业务时效性要求。而统计降尺度的优点是计算效率高,但在实际应用中缺乏统计建模所需的百米级实况场。因此,单一的降尺度方法难以满足复杂海湾地面风场的精细化预报需求。本研究选取福建湄洲湾冬季冷空气大风的8次过程为研究对象,基于水平分辨率为0.03°的CMA-GD模式模拟结果进行降尺度,结合动力降尺度和统计降尺度两种方法的优点,探讨复杂海湾百米级地面风场的降尺度技术。首先,利用WRF模式嵌套水平分辨率达111 m的大涡模拟(LES)进行动力降尺度,建立2019~2023年冬季冷空气大风过程的百米级WRF-LES地面风场模拟数据集。其次,基于2019~2022年CMA-GD气象要素模拟数据集和WRF-LES地面风场模拟数据集,采用随机森林算法构建两者之间的分区统计降尺度模型。利用湄洲湾区域气象自动站地面风观测进行对比评估,结果表明,与CMA-GD模拟相比,百米级WRF-LES数据集更能捕捉到近地面风速脉动的时空跳跃性和刻画湍流的脉动特征,与观测风速的均方根误差(RMSE)也更低,而2023年CMA-GD地面风模拟结果经分区随机森林统计模型降尺度至百米级后,空间分布特征与WRF-LES模拟吻合,风速随时间变化趋势也基本一致,且RMSE明显小于CMA-GD地面风模拟的双线性插值降尺度结果,大部分地区的RMSE控制在0~2.5 m s^(-1)范围内。综上所述,联合大涡模拟和机器学习的动力—统计降尺度模型能够有效地将复杂海湾地形的公里级地面风速降尺度至百米级,为复杂海湾地形精细化天气预报提供技术支持。
