The review summarizes the microbial metabolism, chemical transformations, soil structure, and colloidal stability with reference to the reduction process in waterlogged soils. Ammonia and nitrate, ferrous ion, sulfide, various gases and organic acids are sequentially formed, corresponding to the activities of aerobic and facultatively anaerobic bacteria, sulfate reducing bacteria, and methane producing bacteria with the development of reduction reactions. The increase of water soluble cations leads to the flocculation of soil suspensions in the earlier period of waterlogging. The formation of ferrous precipitates in the later period of waterlogging causes the decrease in the concentration of divalent water soluble cations and the dispersion of soil colloidal suspensions. The changes of soil colloidal stability under reduction conditions have been demonstrated to be the electro kinetic mechanism.
Abstract Background Recent studies have proposed that the serine protease inhibitor E2 ( SERPINE2 ) was a novel susceptibility gene for chronic obstructive pulmonary disease (COPD) in Caucasians. However, this issue still remained controversial. Additional evidences from populations with different environments and/or genetic backgrounds, such as East Asian, would be helpful to elucidate the issue. Methods In this study, five proposed causal SNPs in SERPINE2 were genotyped in 327 COPD patients and 349 controls, all of which belonged to the Han population sampled from Southwest China. The frequency of each SNP was compared both individually and in combination between patients and controls. The potential relationship between these SNPs and severity of COPD was also investigated. Results Three SNPs (rs3795877, rs6747096, and rs3795879) showed complete linkage disequilibrium (r 2 = 1), and the minor allele frequencies were 13.0% and 12.9% in case and control cohorts, respectively, with no significant difference observed ( P = 0.96). We also failed to observe any significant correlation between these SNPs and COPD severity ( P = 0.67). The other two SNPs (rs7579646 and rs840088) also presented a similar pattern. Moreover, four major haplotypes were observed in our sample but none showed a significant difference between case and control groups ( P > 0.1). Conclusion Our results failed to obtain the evidence that these SNPs in SERPINE2 contributed to the COPD susceptibility in the Han Chinese population.
There are strong heterogeneous characteristics of reservoir property between the core and limbs of the Kela-2 anticline, although they are in the same structure. The reservoir heterogeneity mode of "small-scale and east-west" cannot be explained by the distribution mode of compressional stress "large-scale and south-north" proposed by previous scholars. Statistical result of petrographic composition and diagenetic characteristics shows that the differentiation of reservoir compaction between the core and limbs of the Kela-2 anticline is clear. The differentiation is controlled by the difference of tensile stress suffered by strata above the neutral plane during folding deformation. The tensile stress suffered by strata in the anticlinal core is stronger than that in the anticlinal limbs. In the Kela-2 anticline, the difference of tensile stress between the anticlinal core (Kela-201) and limbs (Kela-203 & Kela-204) is obvious. The tensile stress offsets the compaction effect caused by vertical and lateral (south-north) stress, and it is constructive to reservoir quality. It is the major factor controlling the differentiation of reservoir compaction.
A historical review on developments of international sedimentology shows that the role of diagenesis in sedimentology evidently has changed since 1990s,and the diagenesis research community basically has been forming in the world.The authors synoptically suggest the knowledge system of diagenesis from four aspects:petrological types,geographical-climatic types,diagenetic phases and basin types,and further indicates a key scientific problem of diagenesis research in the oil-gas-bearing basins,that is, fluid-rock interaction systems and their spatio-temporal evolutional mechanisms controlled by basin geodynamic process.Subsequently, combined with focus themes in the Special Issue,this paper presents and discusses main frontiers of sedimentary diagenesis research in oil-gas-bearing basins,including basin geodynamic setting of diagenesis,fluid-rock interaction mechanisms and distribution,diagenetic traps and pool-forming condition,diagenetic application in oil-gas exploration and development.Finally some important but unsubstantial research fields are indicated in allusion to current diagenetic development in China.
Abstract Detrital composition and major element geochemistry of Jurassic sandstones in the south Hefei Basin, central China, show their provenance to be the Dabie Mountains, whose tectonic attributes are closely related to continent–island arc complexes. It was found that a provenance change, from recycled orogen signatures and mixed orogenic sandstones to arc orogen, occurs from the lower Middle Jurassic to the Upper Jurassic (the Zhougongshan Formation). Dissected magmatic arc sources were gradually exposed in the Dabie Mountains due to intensive exhumation during the Late Jurassic, particularly after the Fenghuangtai depositional phase. Furthermore, it can be infered that the magmatic arc was initially present in both the Early Paleozoic and the Triassic, according to isotopic dating studies in previously published reports. δ 13 C–δ 18 O tracing between existing marbles of different strata in the Dabie block and marble gravels of the Fenghuangtai Formation in the Hefei Basin indicate that partial lithostratigraphic units for the Jurassic provenances have entirely disappeared from the Dabie block; therefore, it is impossible to reconstruct integral orogenic processes from studies on the remaining Dabie block alone. These findings, together with basin‐fill sequences, also suggest that the Hefei Basin was mainly subjected to compressive mechanical regimes rather than extensional regimes in the Jurassic, which resulted in reverse‐grading clastic depositional sequences, and is probably related to the northward intracontinental deep subduction of the Yangtze Plate. Regional exhumation properties and a tectonic model of the Late Mesozoic Dabie orogenesis are discussed in this paper.
Abstract The Cretaceous Bashijiqike Formation is the main gas‐bearing strata in the northern structural deformation zone of Kuqa subbasin. The acidic dissolution of this formation arose at 5–4Ma, which corresponds to the late burial stage of the Bashijiqike Formation. Variability of interlayer due to rock composition is negligible. Differentiation of acidic dissolution in sandstones was controlled by difference in amount of exogenous acid fluid from underlying strata. For the absence of sedimentary and structural carrier system between the isolated sandstone reservoirs, most fluid‐rock systems show relative sealing feature during later burial stage by sealing feature of formation pressure, geochemical characteristics of formation water and content of diagenetic products in sandstones. Variation of sealing effects for different fluid‐rock systems is obvious. The pressure coefficient is inversely proportional to acidic dissolved porosity of sandstone reservoirs, indicating that the variation of sealing effects for fluid‐rock system mainly controls the differentiation of acidic dissolution.
The oil-gas reservoirs in igneous rocks have notably differences at the petrologic and fluids properties from the traditionally normal reservirs of classic rocks.The original pores in the igneous rocks didn't undergo strong compaction during cooling down.The formation and evolution of the secondary pores are very important to the development of the igneous reservoirs.Water-rock interaction is one of the major driving forces in the formation and evolution of the secondary pores.Researches on this issue are important for understanding and predicting the igneous reservoirs.However,previous studies on the igneous reservoirs mainly focused on descriptions of surface characters and the geological surroundings,few of details about the water-rock interactions within the igneous rock reservoirs.To better understand formation and evolution of secondary pores in the reservoir of igneous rocks,new conceptions and techniques are much needed in comprehensive water-rock interaction studies on the igneous rock reservoirs.
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