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The existence of global weak solutions to the Cauchy problem for a generalized Camassa-Holm equation with a dissipative term is investigated in the space C([0,∞) × R)∩L∞([0,∞); H1(R)) provided that its initial value u0(x) belongs to the space H1(R). A one-sided super bound estimate and a space-time higher-norm estimate on the first-order derivatives of the solution with respect to the space variable are derived

A review of sedimentary forward modeling methods for different sedimentary systems of clastic rock series

More and more attention has been paid to the sedimentary forward modeling (SFM) since the study on the sedimentology is targeted toward quantification, process orientation and systematization. This review first stated the main input and output data of the current sedimentary forward modeling and sorted out the determination methods of the input parameters. Then it reviewed the classification methods of the sedimentary forward modeling, and the classification principles included principle of simulation, number of simulation processes, types of simulation results, simulation dimension, simulation scale, data fidelity and source region covering source-sink system. Subsequently, it introduced the sedimentary forward modeling methods for the different sedimentary systems of clastic series, including hillside landform, river and deep-draft waterway, delta, lobe and landslide. It also described some classic simulation programs for the individual series, indicated the sedimentary characteristics of this series to be essentially simulated and their corresponding principles of simulation and covered multiple simulation methods as much as possible to expand the understanding of the sedimentary forward modeling. Finally, it looked into the development of the sedimentary forward modeling believed it would be targeted toward the three-dimension visualization, multi-process integration and multi-discipline integration, proposed to strengthen the training of compound talents in computer, mathematics, mechanics and geosciences; strengthened the experimental study on the sedimentary forward modeling hypothesis to study the sedimentation theory; tried multiple simulation methods and shifted the application foremost to the research and development foremost

Quantitative evaluation of the diagenesis and porosity evolution of tight sandstone reservoirs: A case study of the Yanchang Formation in the southern Ordos basin, China

Evaluation of the pore evolution is key to gaining a better understanding of oil migration and accumulation in tight oil exploration for tight sandstone; to study the diagenesis and porosity evolution of tight sandstone reservoirs, we analysed the 8th member of the Yanchang Formation by core observation, thin section observation, cathodoluminescence, scanning electron microscopy, and logging data analysis. The following conclusions can be drawn (1) In the typical tight sandstone reservoir, numerous secondary pores developed at burial depths in the range of 1300 m to 1400 m, and approximately 1500 m to 1600 m. (2) Compaction was the most influential factor of reservoir density and decreased the average pore size by 24.8%. Carbonate cementation decreased the porosity by 8.2%. The most important diagenetic process for increasing the reservoir porosity was dissolution, which increased the pore size by 5.1%. In addition, chlorite played an active role in inhibiting secondary quartz growth and preserving primary pores. (3) The early gas invasion can inhibit diagenesis, and the organic acids produced by the later oil can increase dissolution, so that the high oil saturation phenomenon becomes more obvious.La evaluación de la evolución de los poros es clave para obtener una mejor comprensión de la migración y acumulación de petróleo en la exploración de petróleo para arenas compactas; Para estudiar la diagénesis y la evolución de la porosidad de los reservorios de arenas compactas, se anlizó el octavo componente de la Formación Yanchang a través de la observación de núcleos, la observación de secciones delgadas, análisis de catodoluminiscencia, microscopía electrónica de barrido y análisis de registro de datos. Del presente studio se pueden extraer las siguientes conclusiones (1) En los reservorios característicos de arenas compactas, se desarrollaron numerosos poros secundarios a profundidades de enterriamiento en el rango de 1300 a 1400 m, y de aproximadamente 1500 m a 1600 m. (2) La compactación fue el factor más influyente en la densidad del yacimiento y disminuyó el tamaño promedio de los poros en un 24.8%. La cementación por carbonato disminuyó la porosidad en un 8,2%. Mientras que el proceso diagenético más importante para aumentar la porosidad del yacimiento fue la disolución, que aumentó el tamaño de los poros en un 5,1%. Además, la clorita desempeñó un papel activo en la inhibición del crecimiento secundario del cuarzo y en la conservación de los poros primarios. (3) La invasión temprana de gas puede inhibir la diagénesis, y los ácidos orgánicos producidos posteriormente por el petróleo pueden aumentar la disolución, por lo que el fenómeno de alta saturación de petróleo se hace más significativo

Research Advances in Mechanical Properties and Applications of Dual Network Hydrogels

Hydrogels with a three-dimensional network structure are particularly outstanding in water absorption and water retention because water exists stably in the interior, making the gel appear elastic and solid. Although traditional hydrogels have good water absorption and high water content, they have poor mechanical properties and are not strong enough to be applied in some scenarios today. The proposal of double-network hydrogels has dramatically improved the toughness and mechanical strength of hydrogels that can adapt to different environments. Based on ensuring the properties of hydrogels, they themselves will not be damaged by excessive pressure and tension. This review introduces preparation methods for double-network hydrogels and ways to improve the mechanical properties of three typical gels. In addition to improving the mechanical properties, the biocompatibility and swelling properties of hydrogels enable them to be applied in the fields of biomedicine, intelligent sensors, and ion adsorption

Quantitative analysis methods of source-to-sink systems in deep-time and their progress

Significane The analysis of source-to-sink system is a comprehensive study of tectonic geology, sedimentology, and sequence stratigraphy. Because of its integral, dynamic, and semiquantitative-quantitative characteristics, it has attracted widespread attention. Progress This review first introduces the key issues of the deep-time source-to-sink systems (pre-Quaternary systems), which include the quantitative characterization of sediment mass balance and the control of the transport process on the sediment. Due to the lack of stratigraphic records and the difficulty in obtaining parameters, the research is still challenging.Second, it reviews the quantitation methods of deep-time source-to-sink systems that can be classified into three categories, namely, geochronology, uniformitarianism, and sedimentology. By obtaining information such as geomorphological parameters, hydraulic parameters, erosion rates, and sediment flux, various methods establish the quantitative relationships between "sources" and "sinks" and then rebuild the sedimentary basin infilling history. This article introduces the principles and related parameters of different methods and then compares the advantages and limitations to provide a reference for future research. It is believed that geochronology is widely used, and the core lies in provenance analysis. The key to uniformitarianism is the analogy of geological background and the selection of geological parameters. The sedimentology is controlled by multiple variables, and the tectonic-climate background and research scale need to be considered comprehensively. Conclusions and Prospects Finally, this review states the development of quantitative analysis of deep-time source-to-sink systems. Under the guidance of the important idea of "the present is the key to the past", the research needs to focus on the provenance systems, sediment routing systems, sediment dispersal, and redistributive process, and coupling relationship between various parameters. Research also needs to pay attention to quantitative analysis at multiple timescales and multidisciplinary dynamic analysis. Compared with continental margin source-to-sink systems, continental lacustrine source-to-sink system patterns and prediction models need to be further improved

Feldspar Dissolution and Its Influence on Reservoirs: A Case Study of the Lower Triassic Baikouquan Formation in the Northwest Margin of the Junggar Basin, China

Feldspar dissolution is a common feature in clastic rock reservoirs of petroliferous basins and has an important influence on reservoir quality. However, the effect of feldspar dissolution on reservoir quality varies under different depositional environments and diagenetic systems. The study area in this paper is located in the Baikouquan Formation in the northwestern margin of the Junggar Basin, which is significantly influenced by feldspar dissolution. Based on the analyses of core and thin section observations, QEMSEM, XRD, SEM, CL, fluorescence, and image analysis software combined with logging and physical property data, this study shows that feldspar dissolution in the subaqueous distributary channel of a fan delta plain, which has good original physical properties and low mud contents, significantly improves the properties of the reservoir. The main reasons for this are as follows: (1) the sedimentary facies with good original properties and low mud content is a relatively open system in the burial stage. The acidic fluids needed for feldspar dissolution are mostly derived from organic acids associated with the source rocks and migrate to the good-permeability area of the reservoir; (2) the by-products of feldspar dissolution, such as authigenic clay minerals and authigenic quartz, are transported by pore water in a relatively open diagenetic system and then precipitated in a relatively closed diagenetic system; and (3) the clay minerals produced by feldspar dissolution in different diagenetic environments and diagenetic stages have different effects on the reservoir. When the kaolinite content is less than 3%, the illite content is less than 4%, and the chlorite content is less than 12%, the clay minerals have a positive effect on the porosity. These clay minerals can reduce porosity and block pore throats when their contents are larger than these values

Types, characteristics and geological significance of event deposits of Chang 9 Member of Triassic Yanchang Formation in southwestern Ordos Basin, NW China

Through core observation, thin section identification, and logging and testing data analysis, the types and characteristics of event deposits in the ninth member of Yanchang Formation of Triassic (Chang 9 Member) in southwestern Ordos Basin, China, are examined. There are 4 types and 9 subtypes of event deposits, i.e. earthquake, gravity flow, volcanic and anoxic deposits, in the Chang 9 Member in the study area. Based on the analysis of the characteristics and distribution of such events deposits, it is proposed that the event deposits are generally symbiotic or associated, with intrinsic genetic relations and distribution laws. Five kinds of sedimentary microfacies with relatively developed event deposits are identified, and the genetic model of event deposits is discussed. Seismites are mainly developed in the lake transgression stage when the basin expands episodically, and commonly affected by liquefaction flow, gravity action and brittle shear deformation. Gravity flow, mainly distributed in the high water level period, sandwiched in the fine-grained sediments of prodelta or semi-deep lake, or creates banded or lobate slump turbidite fan. It is relatively developed above the seismites strata. The volcanic event deposits are only seen in the lower part of the Chang 9 Member, showing abrupt contact at the top and bottom, which reflects the volcanic activity at the same time. Anoxic deposits are mostly formed in the late stage of lake transgression to the highstand stage. Very thick organic-rich shales are developed in the highstand stage of Chang 9 Member, and the event deposits in the depositional period of these shales are conducive to potential reservoirs

The Evolution of Permian Source-to-Sink Systems and Tectonics Implications in the NW Junggar Basin, China: Evidence from Detrital Zircon Geochronology

The basin type of the Junggar Basin changed during the Permian, but the time constraint of the tectonic evolution remains unclear. Besides, the fan deltas developed in the Permian in the Mahu Sag in the northwestern of the oil-rich basin. However, the provenances of the sedimentary systems remain unclear. Based on petrology and detrital zircon U-Pb ages, this study investigates the source-to-sink systems evolution and tectonics implications. Abundant lithic clasts in sandstones with low compositional and textural maturity imply proximal sources. The dating results showed a dominant peak (310–330 Ma) and a secondary peak (400–440 Ma) in the northern Mahu Sag, only one peak at 295–325 Ma in the central Mahu Sag, several peaks at 270–350 Ma in the southern Mahu Sag, and multiple peaks at 370–450 Ma in the Zhongguai Uplift. Thus, the north-western Junggar Basin was divided into four major source-to-sink systems, with adjacent central West Junggar as the main provenance and northern and southern West Junggar as the secondary provenance. The proportion of sediment supply from the southern and northern West Junggar is higher during the Middle-Late Permian. It suggests that the source-to-sink systems show inheritance and evolve from a single provenance into a complex provenance, indicating the uplift of West Junggar. The tectonic inversion may occur early in the Middle Permian and the response to tectonic activity is stronger in the southern West Junggar than in the northern West Junggar

Alkaline-lacustrine deposition and paleoenvironmental evolution in Permian Fengcheng Formation at the Mahu sag, Junggar Basin, NW China

Alkaline-lacustrine deposition and its evolution model in Permian Fengcheng Formation at the Mahu sag, Junggar Basin were investigated through core and thin-section observation, geochemical and elemental analysis, logging response and lithofacies identification. Six lithofacies are developed in the Fengcheng Formation. The Feng 2 Member (P1f2) is dominated by lithofacies with alkaline minerals, while the upper part of the Feng 1 Member (P1f1) and the lower part of the Feng 3 Member (P1f3) are primarily organic-rich mudstones that are interbedded with dolomite and dolomitic rock. Paleoenvironment evolution of Fengcheng Formation can be divided into 5 stages, which was controlled by volcanic activity and paleoclimate. The first stage (the early phase of P1f1) was characterized by intensive volcanic activity and arid climate, developing pyroclastics and sedimentary volcaniclastic rocks. The secondary stage (the later phase of P1f1) had weak volcanic activity and humid climate that contributed to the development of organic-rich mudstone, forming primary source rock in the Fengcheng Formation. The increasing arid climate at the third stage (the early phase of P1f2) resulted in shrinking of lake basin and increasing of salinity, giving rise to dolomite and dolomitic rocks. The continuous aird climate, low lake level and high salinity at the fourth stage (the later phase of P1f2) generated special alkaline minerals, e.g., trona, indicating the formation of alkaline-lacustrine. The humid climate made lake level rise and desalted lake water, therefore, the fifth stage (P1f3) dominated by the deposition of terrigenous clastic rocks and dolomitic rocks. Key words: Junggar Basin, Permian Fengcheng Formation, depositional characteristics, paleoenvironment reconstruction, alkaline-lacustrine deposition, lithofacies, Mahu sa