Impact of effective stress on permeability for carbonate fractured-vuggy rocks

To gain insight into the flow mechanisms and stress sensitivity for fractured-vuggy reservoirs,several core models with different structural characteristics were designed and fabricated to investigate the impact of effective stress on permeability for carbonate fractured-vuggy rocks(CFVR).It shows that the permeability performance curves under different pore and confining pressures(i.e.altered stress conditions)for the fractured core models and the vuggy core models have similar change patterns.The ranges of permeability variation are significantly wider at high pore pressures,indicating that permeability reduction is the most significant during the early stage of development for fractured-vuggy reservoirs.Since each obtained effective stress coefficient for permeability(ESCP)varies with the changes in confining pressure and pore pressure,the effective stresses for permeability of four representative CFVR show obvious nonlinear characteristics,and the variation ranges of ESCP are all between 0 and 1.Meanwhile,a comprehensive ESCP mathematical model considering triple media,including matrix pores,fractures,and dissolved vugs,was proposed.It is proved theoretically that the ESCP of CFVR generally varies between 0 and 1.Additionally,the regression results showed that the power model ranked highest among the four empirical models mainly applied in stress sensitivity characterization,followed by the logarithmic model,exponential model,and binomial model.The concept of“permeability decline rate”was introduced to better evaluate the stress sensitivity performance for CFVR,in which the one-fracture rock is the strongest,followed by the fracture-vug rock and two-horizontalfracture rock;the through-hole rock is the weakest.In general,this study provides a theoretical basis to guide the design of development and adjustment programs for carbonate fractured-vuggy reservoirs.

A novel box-counting method for quantitative fractal analysis of threedimensional pore characteristics in sandstone

Fractal theory offers a powerful tool for the precise description and quantification of the complex pore structures in reservoir rocks,crucial for understanding the storage and migration characteristics of media within these rocks.Faced with the challenge of calculating the three-dimensional fractal dimensions of rock porosity,this study proposes an innovative computational process that directly calculates the three-dimensional fractal dimensions from a geometric perspective.By employing a composite denoising approach that integrates Fourier transform(FT)and wavelet transform(WT),coupled with multimodal pore extraction techniques such as threshold segmentation,top-hat transformation,and membrane enhancement,we successfully crafted accurate digital rock models.The improved box-counting method was then applied to analyze the voxel data of these digital rocks,accurately calculating the fractal dimensions of the rock pore distribution.Further numerical simulations of permeability experiments were conducted to explore the physical correlations between the rock pore fractal dimensions,porosity,and absolute permeability.The results reveal that rocks with higher fractal dimensions exhibit more complex pore connectivity pathways and a wider,more uneven pore distribution,suggesting that the ideal rock samples should possess lower fractal dimensions and higher effective porosity rates to achieve optimal fluid transmission properties.The methodology and conclusions of this study provide new tools and insights for the quantitative analysis of complex pores in rocks and contribute to the exploration of the fractal transport properties of media within rocks.

Identification of In-intro Antagonistic Activity of HAS1 Protein against Sporisorium scitanminea

Sugarcane smut greatly influences yield and quality of sugarcane.HAS1 gene in biocontrol strain HAS antagonistic to Sporisorium scitanminea was selected for prokaryotic expression vector construction and inducible expression,and the antagonistic effect of HAS1 protein was detected in vitro.The results showed that the expression product of antifungal HAS1 gene obtained through prokaryotic expression vector construction and inducible expression had better antagonistic effect against S.scitanminea.This study provides an experimental basis for further utilization of this protein.

Vaginal Delivery and Breastfeeding Benefit Infant Immune Response to Hepatitis B Vaccine:A Prospective Cohort Study

Background and Aims:Natural vaginal delivery and breastfeeding favor the development of a strong immune system in infants,and the immune response of infants to vaccines is closely related to their immune system.This large prospective cohort study aimed to explore the effects of delivery and feeding mode on infant’s immune response to hepatitis B vaccine(HepB).Methods:A total of 1,254 infants who completed the whole course of HepB immunization and whose parents were both HBsAg negative were enrolled from infants born in Jinchang City during 2018-2019 by cluster sampling method.Results:Twenty(1.59%)of the 1,254 infants were nonresponders to HepB.Among the other 1,234 infants,10.05%(124/1,234),81.69%(1,008/1,234)and 8.27%(102/1,234)of infants had low,medium,and high responses to HepB,respectively.Logistic regression analysis showed that cesarean section(OR:8.58,95%CI:3.11-23.65,p<0.001)and birth weight<3.18 kg(OR:5.58,95%CI:1.89-16.51,p=0.002)were independent risk factors for infant nonresponse to HepB,and cesarean section(OR:7.63,95%CI:4.64-12.56,p<0.001),formula feeding(OR:4.91,95%CI:1.47-16.45,p=0.001),maternal antiHBs negativity(OR:27.2,95%CI:10.67-69.35,p<0.001),paternal non-response history of HepB(OR:7.86,95%CI:2.22-27.82,p=0.014)and birth weight<3.22 kg(OR:4.00,95%CI:2.43-6.59,p<0.001)were independent risk factors for infant low response to HepB.In cases where birth weight and genetic factors are unmodifiable and maternal anti-HBs effects are controversial,it makes sense to enhance infant response by changing delivery and feeding patterns.Conclusions:Natural vaginal delivery and breastfeeding are beneficial to the infant’s immune response to HepB.

Characteristics of volatile compounds removal in biogas slurry of pig manure by ozone oxidation and organic solvents extraction

Biogas slurry is not suitable for liquid fertilizer due to its high amounts of volatile materials being of complicated composition and peculiar smell. In order to remove volatiles from biogas slurry efficiently, the dynamic headspace and gas chromatography-mass spectrometry were used to clear the composition of volatiles. Nitrogen stripping and superfluous ozone were also used to remove volatiles from biogas slurry. The results showed that there were 21 kinds of volatile compounds in the biogas slurry, including sulfur compounds, organic amines, benzene, halogen generation of hydrocarbons and alkanes, some of which had strong peculiar smell. The volatile compounds in biogas slurry can be removed with the rate of 53.0% by nitrogen stripping and with rate of 81.7% by the oxidization and stripping of the superfluous ozone. On this basis, the removal rate of the volatile compounds reached 99.2% by chloroform and n-hexane extraction, and almost all of odor was eliminated. The contents of some dissolved organic compounds decreased obviously and however main plant nutrients had no significant change in the biogas slurry after being treated.

SIMULATION OF OCEAN RESPONSES TO AN IDEALIZED LANDFALLING TROPICAL CYCLONE USING A COUPLED ATMOSPHERE-WAVE-OCEAN MODELING SYSTEM

Oceanic responses to a hypothetical landfalling tropical cyclone(TC) are studied by using a coupled atmosphere-wave-ocean modeling system(CAWOMS). A set of experiments are conducted to compare the effects of atmosphere-wave-ocean interaction on ocean responses in coastal and deep waters. The results show that in a three-way coupled atmosphere-wave-ocean system, the resonse to a tropical cyclone is considerably different in coastal water and deep water. In a three-way coupled system, air-sea interactions tend to increase coastal storm surge, inundation, significant wave heights and ocean currents in shallow coastal areas as a result of waveenhanced air-sea heat and moisture fluxes. But the change is little in sea surface temperature and mixed-layer structure due to the well-mixed nature in the coastal zone. In contrast, in a three-way coupled system, air-sea interactions enhance sea surface cooling, increase mixed layer depth in deep waters largely due to the tendency of a wave-enhanced TC to induce strong mixing and entrainment in the upper ocean. A stronger TC also strengthens the surface currents and significant wave height in the offshore waters. The inclusion of waves in air-sea interactions fundamentally changes the dynamic and thermodynamic coupling between tropical cyclone and the underlying ocean. In the absence of TC-wave consideration, a negative feedback between the TC and the upper ocean mixed layer results in a weakening of the TC system and a cooling in the offshore upper ocean and therefore reduces coastal storm surge, flooding areas, significant wave height and ocean currents. Only in a TC-waveocean three-way coupled system, air-sea interaction may correspond to a stronger TC due to wave-induced airsea heat and moisture fluxes which compensate the effect of negative feedback between the TC and the upper ocean. In coastal waters, the negative feedback between the TC and the ocean mixed layer is fairly weak. Airsea interaction is dominated by the positive TC-wave feedback. As a result, air-sea interaction increases coastal storm surge, inundation, currents and significant wave height.