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Deep coalbed methane (CBM) has become one of the most significant potential sources of natural gas in China. However, the exploration and development of deep CBM in China is still in an initial stage, and its accumulation-forming characteristics require further study. Therefore, taking the No. 8 deep coal seam in the central-eastern region of Ordos Basin as an example, this study investigated the geologic characteristics of CBM accumulations to establish a numerical model. The evolution of the burial and accumulation of CBM in the area was reconstructed. The modeling results suggest that the No. 8 coal seam experienced continuous subsidence from the Late Cretaceous to the Triassic, alternating subsidence and uplift during the Jurassic, rapid burial throughout the Early Cretaceous, and continuous uplift since the Late Cretaceous. The coal reached its maximum maturity at the end of the Early Cretaceous. Furthermore, CBM generation in the region was divided into four stages of thermal events—biogenic and early thermogenic gas, cracking of light oil into gas, cracking of the remaining kerogen into gas, and hydrocarbon generation ceasing—which accelerated coal maturity and generation. The adsorption capacity presented an overall declining trend prior to the end of the Cretaceous, followed by a rapid increase since the Late Cretaceous. As for adsorption mass evolution, the CBM successively underwent unsaturated minor adsorption, unsaturated rapid-rising adsorption, saturated decreasing adsorption, and saturated rising adsorption. The in-situ gas mass was found to be controlled by a combination of generation, adsorption, and expulsion of hydrocarbons, with its present-day value being 9–29 × 104 t/km2 and the corresponding gas volume per ton of coal being 12–28 m3/t. Moreover, free gas evolution initially showed an increasing trend, followed by a decline, ultimately accounting for 11%–28% of the total gas content.

Abstract Background There are numerous methods available for predicting sepsis following Percutaneous Nephrolithotomy. This study aims to compare the predictive value of Quick Sequential Organ Failure Assessment (qSOFA), Systemic Inflammatory Response Syndrome (SISR), National Early Warning Score (NEWS), interleukin-6 (IL-6), and procalcitonin (PCT) for septicemia. Methods Patients who underwent percutaneous nephrolithotomy were included in the study and divided into a control group and a septic shock group. The effectiveness of qSOFA, SIRS, NEWS, Interleukin-6, and Procalcitonin was assessed, with Receiver Operating Characteristic curves and Area Under the Curve used to compare the predictive accuracy of these four indicators. Results Among the 401 patients, 16 cases (3.99%) developed septic shock. Females, elderly individuals, and patients with positive urine culture and positive nitrite in urine were found to be more susceptible to septic shock. PCT, IL-6, SIRS, NEWS, qSOFA, and surgical time were identified as independent risk factors for septic shock. The cutoff values are as follows: qSOFA score > 0.50, SIRS score > 2.50, NEWS score > 2.50, and IL-6 > 264.00 pg/ml. Among the 29 patients identified by IL-6 as having sepsis, 16 were confirmed to have developed sepsis. The qSOFA identified 63 septicemia cases, with 16 confirmed to have developed septicemia; NEWS identified 122 septicemia cases, of which 14 cases actually developed septicemia; SIRS identified 128 septicemia patients, with 16 confirmed to have developed septicemia. In terms of predictive ability, IL-6 (AUC 0.993, 95% CI 0.985 ~ 1) demonstrated a higher predictive accuracy compared to qSOFA (AUC 0.952, 95% CI 0.928 ~ 0.977), NEWS (AUC 0.824, 95% CI 0.720 ~ 0.929) and SIRS (AUC 0.928, 95% CI 0.888 ~ 0.969). Conclusions IL-6 has higher accuracy in predicting septic shock after PCNL compared to qSOFA, SIRS, and NEWS.

A well-connected network formed by multi-scale fractures is a key factor in the formation of high-quality reservoirs and the achievement of high and stable oil and gas production in tight sandstones. Taking the Upper Paleozoic of the Qingshimao gas field in the Ordos Basin, China, as an example, based on data from image logs, cores, and thin sections, fine quantitative characterization of multi-scale natural fractures in tight sandstone reservoirs was carried out. We also established a method for dividing network patterns of multi-scale fractures and discussed the effect of each fracture network pattern on the gas enrichment and production capacity. Results indicate regular changes in the length, density, aperture, porosity, permeability, and connectivity of natural fractures at different scales. Based on the spatial combination patterns and connectivity of fractures of different scales, four types of fracture network patterns were established: multi-scale fracture network with high density and multi-orientations, multi-scale fracture network with moderate-high density and dual orientations, small-scale fracture network with moderate density and dual orientations, small-scale fracture network with low density and single orientation. The first fracture network pattern can destroy the integrity of the cap layer, causing natural gas leakage. The second fracture network pattern is a favorable area for natural gas enrichment. The third fracture network pattern requires the use of hydraulic fracturing to obtain commercial airflow. The fourth fracture network pattern has little effect on reservoir control and storage. The study of natural fractures in tight sandstone reservoirs is usually based on a single-scale perspective. Understanding the development characteristics of multi-scale fractures and their controlling effects on the reservoir helps to comprehensively understand the spatial configuration relationship of multi-scale fracture network structure patterns and promotes the development of multi-scale fractures in tight reservoir research.

In this paper, the limestone reservoir of the Upper Permian Taiyuan Formation in the Ordos Basin is taken as the research object. Through various analysis and testing methods, the characterization and classification evaluation of pore structure were carried out. The core porosity and pore structure characteristics were analyzed using nuclear magnetic resonance, gas measurement, and CT scanning. Based on the characteristics of the limestone reservoir, the optimal parameters of NMR testing were calibrated, the NMR testing method of limestone reservoir properties was established, and the NMR porosity of limestone was calculated. Using the core gray map obtained using CT scanning imaging technology, the three-dimensional digital core model of limestone was constructed, its pore space was extracted, and the porosity, pore fractal dimension, and tortuosity were calculated. The results show that with the thermodynamic experiment, the porosity of the sample will remain basically unchanged after 180 min, and the pressure in the sample was measured after 4 h and no air leakage was found. The T2 spectrum of saturated marlite is in the form of three peaks, two peaks, and one peak. On the whole, the p1 peak of the T2 spectrum of limestone corresponds to micropores, and most of the p2 and p3 peaks correspond to mesopores–macropores. The pore size of high porosity samples is 150–350 nm, and the micropores are well developed; the pore size of medium porosity samples is 80–150 nm, and some samples are well developed; the pore size of low porosity samples is mostly bimodal, with two peaks >> 300 nm and <

To conquer the trade-off dilemma of the nanofiltration membranes for both high permeability for water and high rejection for pollutants has long been highly concerned. In this work, TiO2 and Bi2S3 nanoparticles were evenly dispersed successively into the interlayers of Ti3C2Tx nanosheets, and then filtered onto cellulose acetate support membranes. The as-obtained composite membranes exhibited a maximum water flux of 374.4 L m−2 h−1 bar−1, and a high rejection ratio for RhB, GR, MB and BSA at 97.8–100%, apparently higher than those of the Ti3C2Tx and the related membranes in literature. Such a high separation capacity was found quite stable for various dye-containing aqueous solutions, even in a high salinity environment of 5 wt% NaCl. Interestingly, 25% NaCl salt was also rejected accompanying the almost complete rejection of dye pollutants. After the filtering process, the membrane fouling of fouled Ti3C2Tx/TiO2/Bi2S3 membranes was verified quite lower than that of fouled Ti3C2Tx/TiO2 and Ti3C2Tx membranes. Furthermore, the flux recovery rate of the fouled composite membrane could reach 92.1% after washing under visible light, which could be ascribed to the composition of heterojunction causing the red shift of diffuse reflectance UV–vis spectra and the narrowing of the band gap. This study provides a new idea for the preparation of highly permeable and rejective nanofiltration membranes, and lays a foundation for its high-capacity dye removal applications.

To address the issue of non-unique interpretation of dolomite reservoir diagenetic and porosity evolution in the previous qualitative or semi-quantitative studies, we investigate two dolomite reservoir types, i.e. weathering-crust karstic reservoirs and mound-beach reservoirs, in the Ordovician Majiagou Formation, Ordos Basin by using in-situ laser ablation U-Pb dating as well as carbon and oxygen isotopic composition analysis. The results show that: (1) According to the dating of 8 reservoir samples, the Majiagou Formation experienced 5 diagenetic stages (Stage 1: deposition of matrix dolomite or penecontemporaneous dolomitization, in 444.0–494.0 Ma; Stage 2: dogtooth- or blade-shaped dolomite cementation, in 440.0–467.0 Ma; Stage 3: dolomitic silt filling, in 316.5–381.0 Ma; Stage 4: crystalline dolomite filling, in 354.0 Ma; Stage 5: crystalline calcite filling, in 292.7–319.0 Ma). (2) Supra-salt weathering-crust karstic dolomite reservoirs went through several diagenetic processes including penecontemporaneous dolomitization, compaction, weathering-crust karstification, packing, and rupturing in succession. Gypsum mold pores formed in the phase of hypergenic karstification and were filled with such minerals as dolomitic silts and calcites, and thus the porosity decreased from 10%–40% to 3%–8%. (3) Sub-salt mound-beach dolomite reservoirs went through the diagenetic processes including penecontemporaneous dolomitization, compaction, subsea cementation, penecontemporaneous corrosion, infiltration backflow dolomitization, packing, and rupturing. The porosity of reservoirs was originally 10%–30%, decreased to 0–6% due to seawater cementation, rose back to 5%–15% owing to penecontemporaneous corrosion, and finally declined to 2%–6% as a result of crystalline dolomites and calcites packing. The above methodology for the restoration of dolomitization and porosity evolution may be helpful for the restoration of porosity evolution in other basins or series of strata.

The relationship between paleogeographic pattern and sedimentary differentiation of evaporite-carbonate symbiotic system is examined based on logging, core and thin section data, by taking the sixth sub-member of fifth member of Ordovician Majiagou Formation (M56) in the central-eastern Ordos Basin as an example. (1) Seven sub-geomorphic units (Taolimiao west low, Taolimiao underwater high, Taolimiao east low, Hengshan high, East salt low, North slope and Southwest slope) developed in the study area. (2) The “three lows” from west to east developed dolomitic restricted lagoon, evaporite evaporative lagoon and salt evaporative lagoon sedimentary facies respectively, the “two highs” developed high-energy grain beach and microbial mound, and the north and south slopes developed dolomitic flats around land. (3) The paleogeographic pattern caused natural differentiation of replenishment seawater from the northwest Qilian sea, leading to the eccentric sedimentary differentiation of dolomite, evaporite and salt rock symbiotic system from west to east, which is different from the classic “bull's eye” and “tear drop” distribution patterns. (4) As the Middle Qilian block subducted and collided into the North China Plate, the far-end compression stress transferred, giving rise to the alternate highland and lowland in near north to south direction during the sedimentary period of M56 sub-member. (5) Taolimiao underwater high and Hengshan high developed favorable zones of microbial mounds and grain shoals in south to north strike in M56 sub-member, making them favorable exploration areas with great exploration potential in the future.

Abstract Karstification in carbonate successions has an important influence on hydrocarbon accumulation. Taking the Ordos Basin, currently the largest petroliferous basin in China, as an example, this study examines the large‐scale, long‐term (~120 Myr) paleokarst at the top of the Ordovician. The objectives of the study are to characterize the karst paleogeomorphology of this area, to explain the inconsistency between existing understandings of karst paleogeomorphology and exploration in the eastern Ordos Basin, and to reveal the control of paleokarst on natural gas accumulation and its paleogeographic significance. A total of 860 exploration wells were used for detailed stratigraphic correlation and analysis, along with core observations, well‐logging analyses, physical property characterization, and isotope analyses. Results of residual thickness and moldic thickness reconstruction reveal variation in karst paleogeomorphology between north and south in the eastern Ordos Basin, differing from the traditionally recognized E‐W variation. Two geomorphic units are classified as follows: the karst highland and the karst slope from north to south, with the karst slope being subdivided into northern and southern slope areas. The karst highland area has negligible reservoir capacity and hydrocarbon accumulation owing to the enhanced denudation that occurred there. In contrast, the northern karst slope shows favorable reservoir properties and has abundant gas wells according to well‐logging interpretations, whereas the southern karst slope is of poor reservoir quality and hosts mainly water wells. Differences in dissolution‐filling effects controlled by the surface paleodrainage system are suggested to be the main contributor to differential reservoir space preservation, which, together with the variable width and depth of source rocks in the grooves (thereby variably exposing source rock), further promoted differential gas accumulation. The Ordos Basin and its periphery in the southwestern North China Craton (NCC) show inheritance of sedimentary‐tectonic patterns from the Middle Ordovician to the Late Carboniferous. These results should provide a reference for hydrocarbon exploration in the Ordovician of other basins in the NCC in which karst occurs and karst basins worldwide, and deepens understanding of the paleogeographic framework in the context of regional uplift of the North China Platform.

Abstract Background Internalins are surface proteins that are utilized by Listeria monocytogenes to facilitate its invasion into human intestinal epithelial cells. The expression of a full-length InlA is one of essential virulence factors for L. monocytogenes to cross the intestinal barrier in order to invade epithelial cells. Results In this study, the gene sequences of inlA in 120 L. monocytogenes isolates from food (n = 107) and humans (n = 13) were analyzed. Premature stop codon (PMSC) mutations in inlA were identified in 51 isolates (50 from food and 1 from human). Six mutation types of PMSCs were identified. Among the 51 isolates with PMSCs in inlA, there were 44 serogroup 1/2c, 3c isolates from food, of which seven belonged to serogroups 1/2a, 3a. A total of 153,382 SNPs in 2247 core genes from 42 genomes were identified and used to construct a phylogenetic tree. Serotype 1/2c isolates with inlA PMSC mutations were grouped together. Cell culture studies on 21 isolates showed that the invasion to Caco-2 cells was significantly reduced among isolates with inlA PMSC mutations compared to those without PMSC mutations (P

Adding organic compounds to wastewater can improve the carbon/nitrogen ratio and benefit microalgae growth. We studied microalgal growth, nutrient removal and lipid accumulation of Chlorella pyrenoidosa cultured in a mixture of swine wastewater (SW) and furfural wastewater (FW). The mix ratio of SW:DFW (diluted furfural wastewater) had a significant effect on microalgae growth. As the mix ratio of SW:DFW decreased from 1:0.5 to 1:19, the maximum microalgal biomass increased, while the specific growth rate initially increased and then decreased. The efficiency of nutrient removal also depended on the mix ratio of wastewater. The highest chemical oxygen demand (COD) removal efficiency (57.30%) occurred at the mix ratio of SW:DFW = 1:3. The highest removal efficiencies of total phosphorous (TP) reached 61.93% when the mix ratio of SW:DFW was 1:9. Wastewater at the mix ratio of SW:DFW = 1:19 had a maximum lipid productivity of 49.48 mg L−1 d−1, which was 4.9 times higher than that at a mix ratio of SW:DFW = 1:0.5. These results showed that C. pyrenoidosa can be used to remove nutrients from mixed wastewater sources and simultaneously produce algal lipids.

Gas reservoir development of the Ordovician weathering crust in the Ordos Basin is closely controlled by the pre-Carboniferous paleogeomorphy. Previous studies show that the paleogeomorphy is high in the west and low in the east, and the karst highland, karst slope and karst basin are developed from west to east. With further exploration in recent years, many karst breccia that represent strong karstification, are found in the east area which previously is considered to be the Ordovician karst basin. Thus, it is necessary to revaluate controlling factors of karst paleogeomorphy development from a viewpoint of the dynamic paleogeomorphy evolution, to investigate the paleogeomorphy evolution of the Ordovician weathering crust in geological history and guide further research and prediction of development law of reservoir spaces. In order to reconstruct the paleogeomorphy of the weathering crust in the top of Ordovician in the east Ordos Basin, paleogeography, thickness of residual strata and paleokarst characteristics are well studied. The result shows that a wide range of paleokarst highland occurred in the central to east part of Ordos Basin in the early period, and the karst reservoir spaces were formed; but in the late period, the east part of the basin gradually evolved into the paleokarst basin, the current pre-Carboniferous paleogeomorphy was thus formed, and the dissolution reservoir spaces formed in the early period were mostly filled, accordingly the reservoirs were tight. However fracture networks formed by cave collapse connect intercrystalline pores of dolomite, therefore, the reservoirs can still be well preserved locally and are worthy targets for hydrocarbon exploration. Keywords: The Ordovician weathering crust, Paleogeomorphy, Karst highland, Karst slope, Karst basin, Karst reservoir, Majiagou Formation, The eastern Ordos Basin

On the basis of comprehensive analysis of drilling, gas testing, laboratory analysis and testing data, the characteristics and genesis of tight carbonate reservoirs in Ma51+2 Member of Ordovician Majiagou Formation, eastern Yi-Shan slope, Ordos Basin were examined, and the potential of natural gas exploration and development were analyzed. The tight carbonate reservoir is defined as the reservoir with a porosity of less than 2% and permeability of less than 0.1×10−3 μm2. The Ma51+2 reservoirs are dominantly gypsum mud dolomite, muddy dolomite and Karst-breccia dolomite and has strong heterogeneity, pore types being mainly composed of fracture-dissolution pores and fracture-intercrystalline pores, and thin reservoir layers are distributed in a large area. The unconformity structure adjustment at the top of the Ordovician caused pore creation and pore filling effects, and the joint effect of dissolution pore increase and pore reduction by filling is the major reason for extensive reservoir densification. The thin tight dolomite reservoirs and the overlying adjacent coal source rock in the Upper Paleozoic formed extensive tight carbonate gas with shallow depth (1900−2500 m) and formed a three-dimensional gas containing pattern combined with the Upper Paleozoic tight sandstone gas. The eastern Yi-shan slope in the Ordos Basin has great exploration and development potential. Key words: Ordos Basin, eastern Yi-Shan slope, tight carbonate reservoir, tight gas, exploration potential

The Middle Ordovician Majiagou Formation in the eastern Ordos Basin, central China, is an important area in the exploration for tight carbonate gas, especially within weathering crust layers in the first and second submembers of the fifth member of the formation (herein referred to as Ma 5 1 + 2 ). However, karstification prevents a clear understanding of the petrological characteristics and facies distribution of these layers, which hinders exploration. Based on cores, thin sections, and cathodoluminescence analysis, we investigate the petrological characteristics of Ma 5 1 + 2 , determine the nature of lateral lithological variations in the eastern and central parts of the Ordos Basin, and constrain facies distribution in the region. In addition to karst breccias with unrecognizable parent rocks, Ma 5 1 + 2 comprises four lithologies: gypsum/halite mold-bearing micritic dolomite, micritic dolomite, grain dolomite, and microbial dolomite. We recognize three main sedimentary subfacies: restricted lagoon, grain shoal, and mound–shoal complex. Ma 5 1 + 2 records a complete transgression–regression cycle. The Ma 5 2 2 layer was deposited during a transgression associated with enhanced water circulation and abundant mound–shoal complexes, for which their frequency is positively correlated with the thickness of the unit. The Ma 5 1 2 layer and overlying deposits correspond to a regression cycle, and the abundance of mound–shoal complexes in these units is negatively correlated with layer thickness. The Ma 5 1 3 period represents the timing of maximum regression, when a gypsum-bearing dolomitic lagoon was dominant, associated with a restricted water body. The overall facies distribution is one of a restricted evaporite lagoon environment, similar to the central basin. Therefore, reservoir tightness is unlikely to be related to the sedimentary facies. The next phase of exploration should focus on “sweet spots” resulting from differential diagenesis or hydrocarbon accumulation. Our results provide guidance for research on tight carbonate reservoirs and hydrocarbon accumulation in other regions that experienced similar geological conditions.

Staphyloxanthin (STX), a golden carotenoid pigment produced by Staphylococcus aureus, is suggested to act as an important virulence factor due to its antioxidant properties. Restraining biosynthesis of STX was considered as an indicator of virulence decline in pigmented S. aureus isolates. However, it is not clear whether natural non-pigmented S. aureus isolates have less virulence than pigmented ones. In this study, it is aimed to compare the pigmented and non-pigmented S. aureus isolates to clarify the genetic and virulent differences between the two groups. Here, 132 S. aureus isolates were divided into two phenotype groups depending on the absorbance (OD450) of the extracted carotenoids. Then, all isolates were subjected to spa typing and multilocus sequence typing (MLST), and then the detection of presence of 30 virulence factors and the gene integrity of crtN and crtM. Furthermore, 24 typical S. aureus isolates and 4 S. argenteus strains were selected for the murine infection assay of in vivo virulence, in which the histological observation and enumeration of CFUs were carried out. These isolates were distributed in 26 sequence types (STs) and 49 spa types. The pigmented isolates were scattered in 25 STs, while the non-pigmented isolates were more centralized, which mainly belonged to ST20 (59%) and ST25 (13%). Among the 54 non-pigmented isolates, about 20% carried intact crtN and crtM genes. The in vivo assay suggested that comparing with pigmented S. aureus, non-pigmented S. aureus and S. argenteus strains did not show a reduced virulence in murine sepsis models. Therefore, it suggested that there were no significant genetic and virulent differences between pigmented and non-pigmented S. aureus.