Study on displacement units for water flooded low-permeability oil reservoirs.

Understanding the reservoir feature changes is essential for optimizing oil exploitation throughout the development lifecycle. This paper proposed an analytical displacement unit method to character the features of water-flooded, low-permeability oil reservoirs. The method hinges the ratio of fluid flux to area and average water saturation, providing a fine description of reservoir dynamics. It has been implemented in a case study of a five-spot waterflooding scheme. The reservoir can be categorized into sixteen distinct unit types, each with specific attributes. This paper delves into the evolution of these displacement units and the key factors that influence their behavior. The findings provide insights into the degree of waterflooding and oil distribution following continuous waterflooding. Furthermore, the proposed method offers a valuable framework for analyzing the development of dominant water flow channels and exploiting the residual oil.

Multi-Label Adversarial Attack With New Measures and Self-Paced Constraint Weighting.

An adversarial attack is typically implemented by solving a constrained optimization problem. In top-k adversarial attacks implementation for multi-label learning, the attack failure degree (AFD) and attack cost (AC) of a possible attack are major concerns. According to our experimental and theoretical analysis, existing methods are negatively impacted by the coarse measures for AFD/AC and the indiscriminate treatment for all constraints, particularly when there is no ideal solution. Hence, this study first develops a refined measure based on the Jaccard index appropriate for AFD and AC, distinguishing the failure degrees/costs of two possible attacks better than the existing indicator function-based scheme. Furthermore, we formulate novel optimization problems with the least constraint violation via new measures for AFD and AC, and theoretically demonstrate the effectiveness of weighting slack variables for constraints. Finally, a self-paced weighting strategy is proposed to assign different priorities to various constraints during optimization, resulting in larger attack gains compared to previous indiscriminate schemes. Meanwhile, our method avoids fluctuations during optimization, especially in the presence of highly conflicting constraints. Extensive experiments on four benchmark datasets validate the effectiveness of our method across different evaluation metrics.

Prognostic value and drug sensitivity of F­box and leucine­rich repeat protein 6 in glioma.

Gliomas are highly malignant and invasive tumors lacking clear boundaries. Previous bioinformatics and experimental analyses have indicated that F-box and leucine-rich repeat protein 6 (FBXL6), a protein crucial for the cell cycle and tumorigenesis, is highly expressed in certain types of tumors. The high expression level of FBXL6 is reported to promote tumor growth and adversely affect patient survival. However, the molecular mechanism, prognostic value and drug sensitivity of FBXL6 in glioma remain unclear. To address this, the present study analyzed FBXL6 expression in gliomas, utilizing data from The Cancer Genome Atlas and Chinese Glioma Genome Atlas databases. Analysis of FBXL6 mRNA expression levels, combined with patient factors such as age, sex and tumor grade using Kaplan-Meier plots and nomograms, demonstrated a strong correlation between FBXL6 expression and glioma progression. Co-expression networks provided further insights into the biological function of FBXL6. Additionally, using CIBERSORT and TISDB tools, the correlation between FBXL6 expression correlation tumor-infiltrating immune cells and immune genes was demonstrated to be statistically significant. These findings were validated by examining FBXL6 mRNA and protein levels in glioma tissues using various techniques, including western blot, reverse transcription-quantitative PCR and immunohistochemistry. These assays demonstrated the role of FBXL6 in glioma progression. Furthermore, drug sensitivity analysis demonstrated a strong correlation between FBXL6 expression and various drugs, which indicated that FBXL6 may potentially act as a future promising therapeutic target in glioma treatment. Therefore, the present study identified FBXL6 as a diagnostic and prognostic marker in patients with gliomas and highlighted its potential role in glioma progression.

Unravelling the Flotation Performance of 1-Hydroxy-2-naphthyl hydroxamic Acid and Styrene Phosphonic Acid Collectors on Monazite Using Experiments and DFT Calculations.

The atomic-level structure and electronic properties of monazite were investigated using a first-principles method based on density functional theory (DFT). First, the geometric structure of monazite was optimized, followed by calculations of its Mulliken population, electron density, and density of states, which were subsequently analyzed. The findings of this analysis suggest that monazite is highly susceptible to cleavage along the {100} plane during crushing and grinding. When SPA was utilized as the collector, the recovery rate of monazite was higher than that when LF-P8 was used. The zeta potential and adsorption energy results indicated that the zeta potential after SPA adsorption tended towards negativity, and the adsorption energy was smaller, indicating that SPA exhibited stronger adsorption performance. LF-P8 was stably adsorbed on the monazite (100) surface via mononuclear double coordination. SPA was stably adsorbed on the surface of monazite (100) via binuclear double coordination. The results of this study provide valuable insights into the adsorption of monazite by commonly used flotation collectors. These findings are of substantial importance for future endeavors in designing flotation collectors capable of achieving selective monazite flotation.

Investigation of Fracturing Fluid Flowback in Hydraulically Fractured Formations Based on Microscopic Visualization Experiments.

Fracturing fluids are widely applied in the hydraulic fracturing of shale gas reservoirs, but the fracturing fluid flowback efficiency is typically less than 50%, severely limiting the shale gas recovery. Additionally, the mechanism and main influencing factors of fracturing fluid flowback are unclear. In this study, microscopic experiments are conducted to simulate the fracturing fluid flowback progress in shale gas reservoirs. The mechanism and factors affecting fracturing fluid flowback/retention in the fracture zone were analyzed and clarified. Results show that the ultimate flowback efficiency of fracturing fluid is positively correlated with the fracturing fluid concentration and the gas driving pressure difference. There are four kinds of mechanisms responsible for fracturing fluid retention in the pore network: viscous resistance, the Jamin effect, the gas blockage effect and the dead end of the pore. Additionally, the ultimate flowback efficiency of the fracturing fluid increases linearly with increasing capillary number. These insights will advance the fundamental understanding of fracturing fluid flowback in shale gas reservoirs and provide useful guidance for shale gas reservoirs development.

Study on Pressure Propagation in Tight Oil Reservoirs with Stimulated Reservoir Volume Development.

The stimulated reservoir volume fracturing development in tight oil reservoirs is characterized by multiscale flow of the reservoir matrix, fracture network, and hydraulic fracture. Therefore, the flow field structure is extremely complex. Multiscale flow characteristics have been revealed through the systematical experiments including the threshold pressure gradient and the stress sensitivity. Based on the theory of elliptical flow, a comprehensive and practical mathematical model of multiregion coupling flow is established to characterize the multiscale flow, and the pressure distribution equation is derived. The calculation method of moving boundary is established to simulate the dynamic supply boundary and the dynamic pressure distribution by using the steady-state sequential replacement method. The characteristics of multiscale flow, multistage development state, and stress sensitivity are considered, especially the different stress sensitivity characteristics in different regions. Finally, the pressure propagation in tight reservoirs is clarified and the influence of matrix permeability, stress sensitivity characteristics, and drawdown pressure on the distance at the dynamic supply boundary are revealed. The research results provide theoretical basis for the development effect evaluation.

Pseudomonas eucalypticola sp. nov., a producer of antifungal agents isolated from Eucalyptus dunnii leaves.

Pseudomonas are ubiquitously occurring microorganisms and are known for their ability to produce antimicrobials. An endophytic bacterial strain NP-1 T, isolated from Eucalyptus dunnii leaves, exhibits antifungal properties against five tested phytopathogenic fungi. The strain is a Gram-negative rod-shaped bacterium containing a single polar flagellum. It is strictly aerobic, grows at 4-37 °C, 2-5% NaCl, and pH 3-7. The 16S rRNA sequence analysis showed that NP-1 T belongs to the Pseudomonas genus. Phylogenetic analysis based on four concatenated partial genes (16S rDNA, gyrB, rpoB and rpoD) and the phylogenomic tree indicated that NP-1 T belongs to Pseudomonas fluorescens lineage but is distinct from any known Pseudomonas species. The G + C mol % of NP-1 T genome is 63.96, and the differences between NP-1 T and related species are larger than 1. The digital DNA-DNA hybridization and tetranucleotide signatures are 23.8 and 0.97, which clearly separates strain NP-1 T from its closest neighbours, Pseudomonas coleopterorum and Pseudomonas rhizosphaerae. Its phenotypic and chemotaxonomic features confirmed its differentiation from related taxa. The results from this polyphasic approach support the classification of NP-1 T as a novel species of Pseudomonas, and the name of Pseudomonas eucalypticola is thus proposed for this strain, whose type is NP-1 T (= CCTCC M2018494T = JCM 33572 T).

The complete chloroplast genome of an ornamental orchid, Vanda coerulescens (Orchidaceae).

Though the chloroplast genomes of several Vanda species have been sequenced, there is little information about the complete chloroplast (cp) genome of Vanda coerulescens. Herein, we established the cp genome of V. coerulescens. The chloroplast genome circle was 149,410 bp in length, with the structure of an 85,954 bp large single-copy (LSC) region and a 11,526 bp small single-copy (SSC) region, which separated by two inverted repeat (IRs) regions of 25,965 bp. It encoded 130 genes, including 74 protein-coding genes, 38 tRNA genes and 8 rRNA genes. The overall GC-content of the whole plastome is 36.7%, whereas the corresponding values of the LSC, SSC, and IR regions ranged from 28.2% to 43.1%. In addition, the phylogenetic analysis base on 20 chloroplast genomes of Orchidaceae indicates that V. brunnea is closely related to V. coerulescens. This announcement of the complete V. coerulescens cp genome sequence could provide valuable information for further genetic modification and phylogenetic study in Vanda genus.

Experimental study on flow characteristics of gas transport in micro- and nanoscale pores.

Gas flow behavior in porous media with micro- and nanoscale pores has always been attracted great attention. Gas transport mechanism in such pores is a complex problem, which includes continuous flow, slip flow and transition flow. In this study, the microtubes of quartz microcapillary and nanopores alumina membrane were used, and the gas flow measurements through the microtubes and nanopores with the diameters ranging from 6.42 µm to 12.5 nm were conducted. The experimental results show that the gas flow characteristics are in rough agreement with the Hagen-Poiseuille (H-P) equation in microscale. However, the flux of gas flow through the nanopores is larger than the H-P equation by more than an order of magnitude, and thus the H-P equation considerably underestimates gas flux. The Knudsen diffusion and slip flow coexist in the nanoscale pores and their contributions to the gas flux increase as the diameter decreases. The slip flow increases with the decrease in diameter, and the slip length decreases with the increase in driving pressure. Furthermore, the experimental gas flow resistance is less than the theoretical value in the nanopores and the flow resistance decreases along with the decrease in diameter, which explains the phenomenon of flux increase and the occurrence of a considerable slip length in nanoscale. These results can provide insights into a better understanding of gas flow in micro- and nanoscale pores and enable us to exactly predict and actively control gas slip.

The complete chloroplast genome of Liparis nervosa (Orchidaceae).

Liparis nervosa, a terrestrial orchid was widely used as a traditional medicinal plant in China. In this study, we assembled the complete chloroplast genome of L. nervosa using Illumina sequencing data. The whole genome is 158,716 bp, contains a large single-copy region (LSC 86,010 bp), a small single-copy region (SSC 18,276 bp), and a pair of inverted repeats (IR 27,215 bp). The complete genome has 132 genes, including 77 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. In addition, a maximum-likelihood phylogenetic analysis demonstrated that L. nervosa was most closely related to Oberonia japonica. This work provides a theoretical basis for the development of conservation strategies of L. nervosa.

Chloroplast characterizations and phylogenetic position of an endangered orchid, Vanda coerulea (Orchidaceae).

Vanda coerulea possess a high ornamental value and medical effect against glaucoma and cataract. The whole complete chloroplast (cp) genome of V. coerulea and the phylogenetic position based on the cp sequences remain unclear. Herein, we report the complete chloroplast genome of V. coerulea. The chloroplast genome was 149,376 bp in length, including a large single-copy (LSC) region of 86,100 bp, a small single-copy (SSC) region of 11,702 bp, and two inverted repeat (IRs) regions of 25,787 bp. A total of 129 genes were characterized, including 74 protein-coding genes, 36 tRNA genes, and 8 rRNA genes. The overall GC content was 36.6%, and GC percentages range from 27.9% to 43.2% throughout LSC, IRs, and SSC regions. Phylogenetic analysis based on 20 chloroplast genomes of Orchidaceae indicated that V. coerulea is closely related to V. brunnea. Our study provides a valuable resource for the identification and distinction of Vanda genus, and will lay a foundation for further research and conservation measures of V. coerulea.

Study on distribution of reservoir endogenous microbe and oil displacement mechanism.

In order to research oil displacement mechanism by indigenous microbial communities under reservoir conditions, indigenous microbial flooding experiments using the endogenous mixed bacterium from Shengli Oilfield were carried out. Through microscopic simulation visual model, observation and analysis of distribution and flow of the remaining oil in the process of water flooding and microbial oil displacement were conducted under high temperature and high pressure conditions. Research has shown that compared with atmospheric conditions, the growth of the microorganism metabolism and attenuation is slowly under high pressure conditions, and the existence of the porous medium for microbial provides good adhesion, also makes its growth cycle extension. The microbial activities can effectively launch all kinds of residual oil, and can together with metabolites, enter the blind holes off which water flooding, polymer flooding and gas flooding can't sweep, then swap out remaining oil, increase liquidity of the crude oil and remarkably improve oil displacement effect.

Dynamic investigation of nutrient consumption and injection strategy in microbial enhanced oil recovery (MEOR) by means of large-scale experiments.

Microbial enhanced oil recovery (MEOR) depends on the in situ microbial activity to release trapped oil in reservoirs. In practice, undesired consumption is a universal phenomenon but cannot be observed effectively in small-scale physical simulations due to the scale effect. The present paper investigates the dynamics of oil recovery, biomass and nutrient consumption in a series of flooding experiments in a dedicated large-scale sand-pack column. First, control experiments of nutrient transportation with and without microbial consumption were conducted, which characterized the nutrient loss during transportation. Then, a standard microbial flooding experiment was performed recovering additional oil (4.9 % Original Oil in Place, OOIP), during which microbial activity mostly occurred upstream, where oil saturation declined earlier and steeper than downstream in the column. Subsequently, more oil remained downstream due to nutrient shortage. Finally, further research was conducted to enhance the ultimate recovery by optimizing the injection strategy. An extra 3.5 % OOIP was recovered when the nutrients were injected in the middle of the column, and another additional 11.9 % OOIP were recovered by altering the timing of nutrient injection.

Morphological Variation and Recovery Mechanism of Residual Crude Oil by Biosurfactant from Indigenous Bacteria: Macro- and Pore-Scale Experimental Investigations.

Microbial enhanced oil recovery (MEOR) is being used more widely, and the biological contributions involved in MEOR need to be identified and quantified for the improvement of field applications. Owing to the excellent interfacial activity and the wide distribution of producing strains in oil reservoirs, lipopeptides have proved to be an essential part of the complex mechanisms in MEOR. In this study, crude lipopeptides were produced by a strain isolated from an indigenous community in an oil reservoir. It was found that crude lipopeptides can effectively reduce the IFT (interfacial tension) to 10(-1)~10(-2) mN/m under high salinity without forming stable emulsions, and the wettability of natural sandstone can be enhanced (Amott index, from 0.36 to 0.48). The results of core flooding experiments indicate that an additional 5.2% of original oil in place can be recovered with a 9.5% reduction of injection pressure. After the shut-in period, the wettability of the core, the reduction of injection pressure, and the oil recovery can be improved to 0.63, 16.2% and 9.6%, respectively. In the microscopic flooding experiments, the crude oil in membrane, cluster, and throat states contribute nearly 90% in total of the additional oil recovery, and the recovery of membranestate oil was significantly enhanced by 93.3% after shut in. Based on the results in macro and pore scale, the IFT reduction and the wettability alteration are considered primary contributors to oil recovery, while the latter was more dominant after one shut-in period.

[Formation mechanism of by-product PCBs in the p-DCB production].

A typical p-DCB production process was selected in this study. A series of p-DCB product samples, 1 Japanese sample and 1 chlorobenzene sample were collected and analyzed for by-product polychlorinated biphenyls (PCBs). It is a common phenomenon that byproduct PCBs exists in the p-DCB production process. The PCBs levels in the p-DCB samples were 62-781 ng/g and the highest WHO-TEQ in the process was 0.24 ng/g, while the PCBs level in the Japanese sample reached 881 ng/g. PCB31 was the dominate PCB congener in all the p-DCB samples with the maximum 98.5% of the total PCBs. Maximum content of PCBs was TrCBs in the p-DCB samples with the next TeCBs, DiCBs and PeCBs, while MoCBs were the highest in the chlorobenzene sample. Furthermore, a formation mechanism of PCBs in the production process was proposed and proved by the analysis result. It suggested that the formation of PCBs form the condensation of polychlorobenzenes had a relation with the concentration of polychlorobenzenes and the chlorine position in the benzene ring.