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Tight carbonate reservoirs in the Western Qaidam Basin have complex lithologies and pore structures. The oil–water mobility law in reservoirs has not yet been completely determined, restricting the formulation of rational reservoir development methods. To bridge this gap, in this study, we used several test methods, such as casting thin sections, mercury intrusion, and nuclear magnetic resonance, to obtain the pore structure and oil–water displacement characteristics of tight carbonate reservoirs in the Western Qaidam Basin. The pore structures of the reservoirs could be categorized into three types: microfractures + dissolved pores + micropores (MFD), microfractures + micropores (MF), and matrix (M). The characteristics of single‐phase oil seepage and water flooding in reservoirs with various pore structures differed evidently. For the MF‐ and M‐types, the water‐locking effect caused by the strong capillary force affected oil charging in the micropores. The effect of the pressure drop on the MFD‐type algal limestone was less than that on the MF‐type limestone (dolomite) because of the occurrence of a non‐Darcy flow. The MFD‐type, which contained microfractures, had preferential seepage channels, resulting in obvious fluid channeling and low water displacement efficiency. Oil−water displacement mainly occurred in the dissolved pores and microfractures, suggesting that starting oil accumulation in the micropores was crucial. This study will assist in efficient development of tight carbonate reservoirs in the Western Qaidam Basin. [ABSTRACT FROM AUTHOR]

The reservoir evaluation and classification are restrained by the progress of research on the pore structure and fluid occurrence in dolomite intercrystalline pores of the Paleogene lacustrine carbonate rock in the western Qaidam Basin. The experimental method adopted to investigate the fluid occurrence of the lacustrine carbonate rock in the study area can be used as a reference for studying tight reservoirs. By integrating technical approaches such as the thin-section petrographic analysis, SEM, electron probe, mercury injection test, and NMR test, this research studies the petrology, pore type and distribution, and pore structure of the reservoir. Moreover, the pore fluid distribution and threshold pore throat radius for the distribution of movable fluids are investigated by integrating the centrifuging treatment and NMR characterization. Results show that pores of samples in the study area are dolomite intercrystalline pores, intercrystalline dissolved pores, framework dissolved pores of algal limestone (dolostone), dissolved pores of saline minerals, and interlayer fractures, among which dolomite intercrystalline pores and intercrystalline dissolved pores are found with the highest proportions (60%). The dolomite intercrystalline pores and intercrystalline dissolved pores are nano-micropore throats with a narrow distribution. Their capillary pressure curve is characterized by a high plateau and negative skewness, while the NMR relaxation time spectrum is left-skewed and presents higher bond water saturation (over 65%). For intercrystalline pores and intercrystalline dissolved pores, the main storage space for movable fluids is provided by small and medium pores (corresponding to the NMR relaxation time of 1–10 ms and 10–100 ms, respectively), and the experimentally determined threshold pore throat radius for movable fluids is 47 nm. The reservoir is hydrophilic and therefore movable fluids mainly occur in the centers of pores. The samples with higher proportions of coarse pores and pore connectivity are associated with higher proportions of movable fluids. Our analysis shows the dolomite intercrystalline pore has a certain storage capacity and yet inferior connectivity; the proportion of movable fluids that can effectively flow is key to evaluating the effectiveness of reservoirs with dolomite intercrystalline pores. [ABSTRACT FROM AUTHOR]

Many of the exploration and development theories derived for conventional clastic rock reservoirs are not applicable to pore-fracture lacustrine carbonate reservoirs. The fluid flow mechanisms under reservoir conditions are still unclear. Therefore, in this study, the rock samples were characterized using X-ray diffraction (XRD), porosity-permeability analysis, scanning electron microscopy (SEM), plain thin sections, and casting thin sections. The core samples were classified into two types (fractures and matrix pores) based on their reservoir spaces. The core flow experiments were performed under reservoir conditions using reservoir core plugs. The experimental results demonstrate that the cores, especially the fractured cores, have a strong stress sensitivity. The oil phase flow in the core has the characteristics of non-Darcy flow, and the threshold pressure gradient is 0.01–0.003 MPa/m. Additionally, for the oil-water two-phase flow in the fractured core, the water phase relative permeability of the residual oil is high. In contrast, the water phase relative permeability of the matrix core is less than 0.2. The nuclear magnetic resonance (NMR) transverse relaxation time ( T 2 ) spectra were used to analyze the differences between the water flooding characteristics of the two pore structures. The experimental results show that the peaks of the T 2 spectra after water flooding are lower than those before water flooding, and the matrix cores have a better oil displacement effect. The relaxation time of 0.1–10 ms makes the greatest contribution to the water flooding efficiency. The micropores smaller than 10 μm in diameter play an important role in the water flooding of the matrix core. These results will provide theoretical basis for solving the difficult problems of developing deep lacustrine carbonate reservoirs. [ABSTRACT FROM AUTHOR]

The Paleogene upper Xiaganchaigou Formation (E32) is the most important source rock and reservoir in the Qaidam Basin. However, there are few studies on the processes of hydrocarbon accumulation in this formation; therefore, its hydrocarbon resource potential has not been estimated reasonably. This paper evaluates the hydrocarbon generation properties in light of an improved hydrocarbon generation and expulsion potential model. According to the geochemical characteristics of source rocks and the petrological features of reservoirs, the potentials of different resource types, including conventional oil, tight oil and shale oil, are quantified by combining the buoyancy-driven hydrocarbon accumulation depth (BHAD) and the lower limit for movable resource abundance. The results show that the source rocks are characterized by a large thickness (more than 1000 m), moderate organic matter content, high marginal maturity and a high conversion rate (50% hydrocarbons have been discharged before Ro = 1%), which provide sufficient oil sources for reservoir formation. Moreover, the reservoirs in the Qaidam Basin consist mainly of low-porosity and low-permeability tight carbonates (porosity of 4.7% and permeability less than 1 mD). The maximum hydrocarbon generation, expulsion, retention and movable retention intensities at present are 350 × 104 t/km2, 250 × 104 t/km2, 130 × 104 t/km2 and 125 × 104 t/km2, respectively. The thresholds of hydrocarbon generation, expulsion and BHAD were 0.46% Ro, 0.67% Ro and 0.7% Ro, respectively. Moreover, the dynamic evolution process of hydrocarbon accumulation was divided into three evolution stages, namely, (a) initial hydrocarbon accumulation, (b) conventional hydrocarbon reservoir and shale oil accumulation and (c) unconventional tight oil accumulation. The conventional oil, tight oil and movable shale oil resource potentials were 10.44 × 108 t, 51.9 × 108 t and 390 × 108 t, respectively. This study demonstrates the good resource prospects of E32 in the Qaidam Basin. A comprehensive workflow for unconventional petroleum resource potential evaluation is provided, and it has certain reference significance for other petroliferous basins, especially those in the early unconventional hydrocarbon exploration stage. [ABSTRACT FROM AUTHOR]

Objective: To explore the pathogenosis and prognostic markers for non-smoking female lung cancer patients with bioinformatics analysis and functional prediction of potential lung cancer associated genes in female non-smokers. Methods: Data for nonsmoking female patients with lung cancer were downloaded from the Gene Expression Omnibus (GEO) database and the differentially expressed genes (DEGs) were identified using GEO2R. DAVID online data base was used to perform gene ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG), and STRING online software was used to perform protein-protein interaction (PPI) analysis; then the plug-in (M-CODE) was used to screen the key DEGs; finally, GEPIA and Kaplan-Meier plotter were used to perform function prediction and prognosis analysis of key DEGs. Results: A total of 160 DEGs were screened, including 54 up-regulated and 106 down-regulated genes; GO enrichment analysis showed that these DEGs were mainly related to neovascularization, single cell adhesion, positive regulation of GTPase activity and signal transduction (all P<0.05). KEGG pathway analysis revealed that DEGs were mainly involved in cell adhesion molecules (CAMs), leukocyte transendothelial migration, tight junction and endocytosis (all P<0.05); PPI network analysis revealed 8 key DEGs, including TIE1, PECAM1, CLDN5, VEGFD, ICAM2, ESAM, EMCN and ROBO4. Conclusion: TIE1, CLDN5, ICAM2, ESAM, VEGFD and ROBO4 may be the research targets of the pathogenesis of non-smoking female lung cancer patients. PECAM1 and EMCN may be the new bio-markers to predict the progression and prognosis of nonsmoking female lung cancer patients. [ABSTRACT FROM AUTHOR]

It has been reported that rapa could selectively expand the murine naturally occurring CD4+CD25+Foxp3+ Treg cells in vitro. However, the in vivo effect of rapa on the inducible CD4+CD25+Foxp3+ Treg cell population (iTregs) need to be elucidated. The aim of this study was to investigate the effect of rapa on activities of iTregs. The results indicated that rapa administration in vivo(14 consecutive days) significantly prolonged the allograft survival (13.2±1.5d to 22.8±2.1d). CD4+ T cells from tolerance mice treated with rapa in vitro result in obviously increase of iTreg, the higher expression of Foxp3 and IL-10 secretion. Adoptive transfer of those CD4+ T cells obviously prolonged the allograft survival in allo-transplanted SCID mice. This study indicated that rapa can expand the ratio of iTreg in vivo and in vitro in allografted model mice, and the expanded iTreg cells keep their inhibitory activities in vivo. [ABSTRACT FROM AUTHOR]