Diagenesis and reservoir quality of Neoproterozoic dolomitized microbialites following multi-stage diagenetic fluid activity: a case study of the Sinian Dengying Formation, China

Neoproterozoic marine microbialites have been targets for exploration and hydrocarbon reservoir development. The original depositional fabric and diagenesis control the pore systems of microbialites, leading to the complicated origin of microbialite reservoirs. This study aimed to reveal the origin of microbialite reservoirs following multi-stage diagenetic fluid activity in the fourth Member of the Dengying Formation in the central Sichuan Basin in southwestern China. The fourth Member of the Sinian Dengying Formation developed dolomitized microbialites, mainly including stromatolites, laminates, and thrombolites. Based on the background of tectonic movement, petrology and geochemistry examinations were executed to analyze the origin of the microbialite reservoir. Based on the cathodoluminescence and the homogenization temperature of the brine inclusions, it is credible that there were four stages of diagenetic fluid activities in the burial diagenesis. In the first stage, the microbialite reservoir was charged by oil in the Silurian period, with evidence from residual asphalt around the pores. In the second stage, dolomite precipitated to incompletely fill the pore spaces. In the third stage, the silica-rich diagenetic fluid with high temperature resulted in the precipitation of authigenic quartz. In the last stage, the oil charged again during the Triassic period, followed by siliceous filling, with residual asphalt filling the pore spaces. There were two stages of subaerial emergence, which occurred in two episodes of the Sinian-Early Cambrian Tongwan movement. The evidence for the two tectonic events includes two phases of dolomites with meteoric water origin, two cycles of V, Sr, and Na element profiles, two instances of negative excursion δ18O isotope, and two cavity layers. By comparison, the karstification of reservoirs in the Tongwan III episode could generate a higher quality of reservoir than that in the Tongwan II episode. As a result, the quality of the microbialite reservoir from the fourth Member of the Dengying Formation was mainly improved by the subaerial exposure in the Tongwan III episode and then was partly destroyed by the siliceous filling. The identification of multi-staged diagenetic fluid charging can illustrate the evolution of the reservoir quality of Neoproterozoic microbialites

Knowledge mapping concerning applications of nanocomposite hydrogels for drug delivery: A bibliometric and visualized study (2003–2022)

Background: Nanocomposite Hydrogels (NHs) are 3D molecular networks formed by physically or covalently crosslinking polymer with nanoparticles or nanostructures, which are particularly suitable for serving as carriers for drug delivery systems. Many articles pertaining to the applications of Nanocomposite Hydrogels for drug delivery have been published, however, the use of bibliometric and visualized analysis in this area remains unstudied. The purpose of this bibliometric study intended to comprehensively analyze the knowledge domain, research hotspots and frontiers associated with the applications of Nanocomposite Hydrogels for drug delivery.Methods: We identified and retrieved the publications concerning the applications of NHs for drug delivery between 2003 and 2022 from Web of Science Core Collection Bibliometric and visualized analysis was utilized in this investigative study.Results: 631 articles meeting the inclusion criteria were identified and retrieved from WoSCC. Among those, 2,233 authors worldwide contributed in the studies, accompanied by an average annual article increase of 24.67%. The articles were co-authored by 764 institutions from 52 countries/regions, and China published the most, followed by Iran and the United States. Five institutions published more than 40 papers, namely Univ Tabriz (n = 79), Tabriz Univ Med Sci (n = 70), Islamic Azad Univ (n = 49), Payame Noor Univ (n = 42) and Texas A&M Univ (n = 41). The articles were published in 198 journals, among which the International Journal of Biological Macromolecules (n = 53) published the most articles, followed by Carbohydrate Polymers (n = 24) and ACS Applied Materials and Interfaces (n = 22). The top three journals most locally cited were Carbohydrate Polymers, Biomaterials and Advanced materials. The most productive author was Namazi H (29 articles), followed by Bardajee G (15 articles) and Zhang J (11 articles) and the researchers who worked closely with other ones usually published more papers. “Doxorubicin,” “antibacterial” and “responsive hydrogels” represent the current research hotspots in this field and “cancer therapy” was a rising research topic in recent years. “(cancer) therapeutics” and “bioadhesive” represent the current research frontiers.Conclusion: This bibliometric and visualized analysis offered an investigative study and comprehensive understanding of publications regarding the applications of Nanocomposite Hydrogels for drug delivery from 2003 to 2022. The outcome of this study would provide insights for researchers in the field of Nanocomposite Hydrogels applications for drug delivery

The effect of meteoric water on the very fine crystalline dolomite reservoir in the shallow burial zone: A case study of the Ma55 submember of Majiagou Formation in Ordos Basin

The meteoric water has obviously changed the physical properties of dolostone reservoirs in the vertical vadose zone and the horizontal phreatic zone, but its influence on the dolostone reservoirs in the shallow burial zone beneath the phreatic surface is still unclear. This study aims to reveal the effect of meteoric water on the dolostone reservoirs in the shallow burial zone through X-ray diffraction, cathodoluminescence, C, O, and Sr isotope using the sample from Majiagou Formation in the Daniudi gas field, Ordos Basin. The diagenesis and paragenesis of the Ma 55 submember were identified and interpreted through petrological study, combined with data from electron probe, X-ray diffraction analysis, and geochemical parameters of diagenetic minerals. The color of the very fine crystalline dolomite under the cathodeluminescence is dark red and red. The order degree of dolomite ranges from 0.54 to 0.91, showing the origin of early seepage-reflux dolomitization. There are a large number of different calcite cements as fills within the pores and fractures. The color of the calcite cement under the cathodoluminescence is orange-yellow, with a zonal structure. Hydrothermal fluid during late diagenesis could be identified by the authigenic fluorite filling in the fractures. According to the assembly of diagenetic minerals, the very fine crystalline dolostones have experienced the seepage-reflux dolomitization, meteoric water dissolution, shallow burial cementation and late cementation. The void spaces of the very fine crystalline dolostones are intercrystalline pores and microfractures. Although a large number of dissolved pores and caves developed in the period of meteoric water dissolution, these caves and dissolved pores has been mostly filled by multi-stages of cementation. Therefore, the effect of meteoric water on dolostone reservoirs in the shallow burial zone beneath the phreatic surface is not obvious. The main controlling factor for the quality of dolostone reservoir was dolomitization. This study provides a new understanding of the influence of meteoric water on reservoir quality in the shallow burial zone during the paleokarst period

Prediction of Supply Chain Financial Credit Risk Based on PCA-GA-SVM Model

Supply Chain Finance (SCF) is a new type of financing business carried out by commercial banks on the basis of supply chain management, which effectively promotes the healthy development of the supply chain. As the most typical mode of SCF, accounts receivable financing mode can use the part of accounts receivable occupying working capital for financing, which is widely used. In order to effectively manage the credit risk in the Supply Chain Finance and maintain the healthy operation of the supply chain, this paper proposes a supply chain financial credit risk prediction model based on PCA-GA-SVM. First, principal component analysis (PCA) is used to reduce the dimension of the original index system, and then genetic algorithm (GA) is used to optimize the parameters of support vector machine (SVM). Finally, the principal components selected by PCA are input into the GA-SVM model for training, and the final prediction model is established. The running results show that the prediction performance of PCA-GA-SVM model is better than that of SVM and GA-SVM models. It has a good generalization ability, which can be used as a reference for commercial banks to improve the credit risk management ability of Supply Chain Finance and is conducive to the sustainable development of supply chain finance business

Prediction of Supply Chain Financial Credit Risk Based on PCA-GA-SVM Model

Supply Chain Finance (SCF) is a new type of financing business carried out by commercial banks on the basis of supply chain management, which effectively promotes the healthy development of the supply chain. As the most typical mode of SCF, accounts receivable financing mode can use the part of accounts receivable occupying working capital for financing, which is widely used. In order to effectively manage the credit risk in the Supply Chain Finance and maintain the healthy operation of the supply chain, this paper proposes a supply chain financial credit risk prediction model based on PCA-GA-SVM. First, principal component analysis (PCA) is used to reduce the dimension of the original index system, and then genetic algorithm (GA) is used to optimize the parameters of support vector machine (SVM). Finally, the principal components selected by PCA are input into the GA-SVM model for training, and the final prediction model is established. The running results show that the prediction performance of PCA-GA-SVM model is better than that of SVM and GA-SVM models. It has a good generalization ability, which can be used as a reference for commercial banks to improve the credit risk management ability of Supply Chain Finance and is conducive to the sustainable development of supply chain finance business

Classification of Void Space Types in Fractured-Vuggy Carbonate Reservoir Using Geophysical Logging: A Case Study on the Sinian Dengying Formation of the Sichuan Basin, Southwest China

The fractured-vuggy carbonate reservoirs display strong heterogeneity and need to be classified into different types for specific characterization. In this study, a total of 134 cores from six drilled wells and six outcrops of the Deng #2 and Deng #4 members of the Dengying Formation (Sichuan Basin, Southwest China) were selected to investigate the petrographic characteristics of void spaces in the fractured-vuggy carbonate reservoirs. Four void space types (VSTs) were observed, namely the solution-filling type (SFT), cement-reducing type (CRT), solution-filling breccia type (SFBT) and solution-enlarging fractures and vugs type (SEFVT). The CRT void spaces presented the largest porosity and permeability, followed by the SEFVT, SFBT and SFT. The VSTs presented various logging responses and values, and based on these, an identification method of VSTs using Bayes discriminant analysis (BDA) was proposed. Two test wells were employed for the validation of the identification method, and the results show that there is good agreement between the identification results and core description. The vertical distribution of VSTs indicates that the SFT and SEFVT are well distributed in both the Deng #2 and Deng #4 members. The CRT is mainly found in the Deng #2 member, and the SFBT occurs in the top and middle of the Deng #4 member

The Effect of Single Sandstone Stacking Pattern on the Sandstone Reservoir Physical Properties—A Case Study from the Shanxi Formation in the Daniudi Area, Northeastern Ordos Basin

The role of the single sandstone stacking pattern in controlling the physical properties of the sandstones deposited in the distribution channels of the deltaic plain is unclear. This study aims to reveal the effect of the single sandstone packing patterns on the reservoir qualities of sandstones from the Shanxi Formation in the Daniudi gas field of Ordos Basin. Based on the core observation, 2D-image analysis, and thin section identification, the lithofacies were identified, the stacking patterns of the single sandbody were divided, and the differences in minerals composition and diagenesis of different sandstone stacking patterns were analyzed. According to the sedimentary facies analysis, 10 types of lithofacies have been identified in the Shanxi Formation in the study area. The single sandstone stacking patterns include mixed stacking patterns of coarse to medium-grained sandstone, fining upwards stacking patterns of coarse- to medium-grained sandstone, and coarsening upwards stacking patterns of fine- to coarse-grained sandstone. Among these single sandstone stacking patterns, there is a greater percentage of lithofacies with high reservoir quality in the fining upwards stacking patterns of coarse- to medium-grained sandstone. Through a comparative study of the differences in minerals composition, the degree of compaction, and dissolution of sandstones, it is suggested that the high porosities and permeabilities of the coarse- to medium-grained sandstone lithofacies in the fining upwards stacking patterns are caused by the low content of the matrix in sandstone, relatively weak compaction, relatively high amounts of primary pores, and strong dissolution. The relatively high content of rigid clastic particles with coarser-grained size was favorable for the preservation of primary pores. The relatively high primary porosity could provide favorable passages for the late diagenetic fluid, leading to the development of dissolved pores. The study can provide an important basis for the exploration of high-quality sandstone reservoirs in the distributary channels of the delta plain

Investigation on left ventricular multi-directional deformation in patients of hypertension with different LVEF

Abstract Background This study is aimed at investigating myocardial multi-directional systolic deformation in hypertensive with different left ventricular ejection fraction (LVEF), and exploring its contribution to LVEF. Methods One hundred and twenty-three patients with primary hypertension (HT) were divided into group A (LVEF ≥ 55%), group B (45% ≤ LVEF < 50%, or 50% ≤ LVEF < 55% + LVEDVI ≥ 97 ml/m2), and group C (LVEF < 45%). Two-dimensional strain echocardiography (2DSE) including LV longitudinal strain (SL), radial strain (SR) and circumferential strain (SC) were measured. Results SL decreased gradually from group A, B to C (all p < 0.05) while SR and SC were reduced only in group B and C (all p < 0.05). All strain measurements correlated to LVEF, with the strongest correlation in SC (r = −0.82, p < 0.01) and the second in SL (r = −0.76). The diastolic E/e increased from group A, B to C. Conclusions Left ventricular multi-directional deformation correlated well to LVEF in hypertension and particularly SC, indicating that it was SC, not SL or SR, that makes the prominent contribution to left ventricular pump function

The Diagenetic Alteration of the Carbonate Rocks from the Permian Qixia Formation as Response to Two Periods of Hydrothermal Fluids Charging in the Central Uplift of Sichuan Basin, SW China

The hydrothermal fluid–carbonate rock reaction is frequently regarded to occur in deep-burial diagenesis, and the hydrothermal dissolution is usually distributed and takes place along the faults. Previous studies have suggested that there was hydrothermal fluid activity locally in the Permian Qixia Formation in Sichuan Basin, likely related to the Emeishan basalt eruption. However, the effect of hydrothermal fluids on the carbonate rocks of the Qixia Formation in the central uplift of Sichuan Basin is still unclear. Based on the characteristics and geochemical parameters of the diagenetic minerals, this study aims to reveal the diagenetic alteration related to the hydrothermal fluid–rock reaction in the Qixia Formation and reestablish the diagenetic evolution by using the timing of diagenetic mineral precipitation. The methods include petrographic observation; trace and rare earth element (REE) analysis; C, O and Sr isotope measurement; fluid inclusion temperature measurement and cathodoluminescence analysis. According to the petrographic characteristics, the dolostones are mainly of crystalline structure, namely fine-medium crystalline dolostone, meso-coarse crystalline dolostone, and coarse crystalline dolostone, with the cathodoluminescence color becoming brighter in that order. The limestones from the Qixia Formation are of the bioclastic limestone type, with no cathodoluminescence color. Compared with dolostones, limestones have higher Sr content, lower Mn content, and heavier oxygen isotopes. With the crystalline size of dolostone becoming coarser, the oxygen isotopes of dolostones tend to become lighter. The meso-coarse crystalline dolostone has the highest Mn content and negative carbon isotope. Both limestones and dolostones have an obvious positive Eu anomaly in the Qixia Formation. However, the REE patterns of fine-medium crystalline dolostones are very different from those of meso-coarse crystalline dolostones. It is credible that there were two periods of hydrothermal fluid charging, with different chemical compositions. The first period of hydrothermal fluids could laterally migrate along the sequence boundary. Fine-medium crystalline dolostones were almost completely distributed below the sequence boundary and were dolomitized during the shallow burial period. As products of the hydrothermal fluid–dolostone reaction, the saddle-shaped dolomites in the meso-coarse crystalline dolostones were the evidence of the second period of hydrothermal fluids. As a result, the dolomitization model was established according to the timing of diagenetic mineral precipitation, which can improve that the geological understanding of the effect of hydrothermal fluid activities on the carbonate rocks in the Qixia Formation

The Nonuniform Distribution of Stylolite in Bioclastic Limestones and Its Influence on Reservoir Petro-Physical Properties—A Case Study of the Mishrif Formation from the Ah Oilfield

The effect of stylolite caused by the pressure dissolution process on the reservoir petro-physical properties is still controversial. This study aims to reveal the effect of stylolite on the porosity and permeability of packstone and wackestone in the Mishrif Formation from the Ah oilfield in the Middle East. Based on the observation of thin sections and cores, X-ray diffraction analysis and porosity and permeability measurement, the lithofacies, diagenesis and patterns of stylolites have been investigated. There are six lithofacies in the Mi4 member, including bivalve green algae packstone, green algae packstone, pelletoid green algae packstone, echinoderm packstone, rudist packstone, planktonic foraminifera wackestone and bioclastic wackestone. The mechanical compaction and pressure dissolution could be observed in these lithofacies, with the development of dissolution seams and stylolites. The density of stylolite has a relationship with the lithofacies and early cementation. The boundary between the echinoderm packstone and the green algae packstone mostly developed as stylolites. There are four types of stylolite on the cores. Type A is the wave-like stylolite developed at the boundary between the echinoderm packstones and green algae packstones. Type B is the zigzag stylolite with high amplitude in the green algae packstones. Type C is the stylolites with low amplitude in the bioclastic wackestones. Type D is the high-angle stylolite, which is oblique to the bedding plane. The permeability of reservoir rocks could be improved by dissolution along the type B stylolite, while the type A and type C stylolite have little effect on permeability. The permeability of green algae packstone and echinoderm packstone will decrease with the development of stylolites. The porosity and permeability of bivalve green algae packstone will decrease after stylolitization, resulting from the relatively high density of stylolite. The physical properties of bioclastic wackestone could be improved by the bioturbation and formation of stylolite. According to the analysis of production performance in the same lithofacies, the occurrence of stylolites could result in the development of oil baffles. This study could be extended to evaluate the effect of stylolite in carbonate reservoir rocks