Physical and mechanical properties and microstructures of submarine soils in the Yellow Sea

In recent years,the exploration of seabed has been intensified,but the submarine soils of silt and sand in the Yellow Sea area have not been well investigated so far.In this study,the physical and mechanical properties of silt and sand from the Yellow Sea were measured using a direct shear apparatus and their microstructures were observed using a scanning electron microscope.The test results suggest that the shear strength of silt and sand increases linearly with the increase of normal stress.Based on the direct shear test,the scanning electron microscope was used to observe the section surface of sand.It is observed that the section surface becomes rough,with many“V”‐shaped cracks.Many particles appear on the surface of the silt structure and tend to be disintegrated.The X‐ray diffraction experiment reveals that the sand and silt have different compositions.The shear strength of sand is slightly greater than that of silt under high stress,which is related to the shape of soil particles and the mineral composition.These results can be a reference for further study of other soils in the Yellow Sea;meanwhile,they can serve as soil parameters for the stability and durability analyses of offshore infrastructure construction.

Effect of Fe_(2)O_(3)on the Structure,Physical Properties and Crystallization of CaO-Al_(2)O_(3)-SiO_(2)Glass

The calcium aluminosilicate-based glasses(CaO-Al_(2)O_(3)-SiO_(2),CAS)with different Fe_(2)O_(3)content(0.10wt%,0.50wt%,0.90wt%,and 1.30wt%)were prepared by traditional melt-quenching method.The glass network structure,thermal and mechanical properties,and crystallization behavior changes were investigated by nuclear magnetic resonance spectrometer,Fourier-transform infrared spectro-photometer,X-ray diffractometer,differential scanning calorimetry and field emission scanning electron microscope measurements.The change of Q^(n)in glass structures reveals the glass network connectivity decreases due to the increasing content of Fe_(2)O_(3)addition,resulting in the increasing of non-bridging number in glass structure.The glass densities slightly rise from 2.644 to 2.681 g/cm^(3),while Vickers’s hardness increases at first,from 6.469 to 6.901 GPa,then slightly drops to 6.745 GPa,with Fe_(2)O_(3)content increase.There is almost no thermal expansion coefficient change from different Fe_(2)O_(3)content.The glass transmittance in visible range gradually decreases with higher Fe_(2)O_(3)content,resulting from the strong absorption of Fe^(2+)and Fe^(3+)ions.The calculated activation energy from thermal analysis results first decreases from 282.70 to 231.18 kJ/mol,and then increases to 244.02 kJ/mol,with the Fe_(2)O_(3)content increasing from 0.10wt%to 1.30wt%.Meanwhile,the maximum Avrami constant of 2.33 means the CAS glasses exhibit two-dimensional crystallization.All of the CAS glass-ceramics samples contain main crystal phase of anorthite,the microstructure appears lamellar and columnar crystals.

Physical-Rheological Properties and Performances of Rejuvenated(Styrene-Butadiene-Styrene)Asphalt with Polymerized-MDI and Aromatic Oil

Traditional asphalt rejuvenators,like aromatic oil(AO),are known to be effective in improving the low-temperature properties and fatigue performances of aged SBS(styrene-butadiene-styrene)modified asphalt(SBSMA)binders and mixtures.However,these rejuvenators inevitably compromise their high-temperature properties and deformation resistances because they dilute asphalt binder but do not fix the damaged structures of aged SBS.In this study,a highly-active chemical called polymerized 4,4-diphenylmethane diisocyanate(PMDI)was used to assist the traditional AO asphalt rejuvenator.The physical and rheological characteristics of rejuvenated SBSMA binders and the moisture-induced damage and rut deformation performances of corresponding mixtures were comparatively evaluated.The results showed that the increasing proportion of AO compromises the hightemperature property and hardness of aged SBSMA binder,and an appropriate amount of PMDI works to compensate such losses;3%rejuvenator at mass ratio of AO:PMDI=70:30 can have a rejuvenated SBSMA binder with a high-temperature performance similar to that of fresh binder,approximately at 71.4°C;the use of AO can help reduce the viscosity of PMDI rejuvenated SBSMA binder for improving its workability;PMDI can help improve the resistance of AO rejuvenated SBSMA binder to deformation,especially at elevated temperatures,through its chemical reactions with aged SBS;moisture induction can enhance the resistance to damage of rejuvenated mixtures containing AO/PMDI or only PMDI;and the rejuvenator with a mass ratio of AO:PMDI=70:30 can lead the rejuvenated mixture to meet the application requirement,with a rut depth of only 2.973 mm,although more PMDI can result in a higher resistance of rejuvenated mixtures to high-temperature deformation.

Key Physical Factors Affecting Spatial-temporal Variation of Labile Organic Carbon Fractions by Biochar Driven in Mollisols Region of Northeast China

Biochar is widely used to improve soil physical properties and carbon sequestration. However, few studies focuse on the impact of maize stalk biochar on labile organic carbon(LOC) pool and the relationship between physical properties and LOC fractions. A field positioning experiment was performed in Mollisols region of Northeast China to evaluate the influence of maize stalk biochar on the spatial distribution and temporal changes of physical properties and LOC fractions. Maize stalk biochar treatments included C1(1.5 kg·hm^(-2)), C2(3 kg·hm^(-2)), C3(15 kg·hm^(-2)), C4(30 kg·hm^(-2)), and CK(0). The results showed that maize stalk biochar increased soil water contents(SWC) and soil porosity(SP), but reduced bulk density(BD). Maize stalk biochar reduced dissolved organic carbon(DOC) contents in the 0-20 cm soil layer, ranging from 0.25 g·kg^(-1) to 0.31 g·kg^(-1) in harvest period, while increased in the 20-40 cm soil layer. In addition, the application of biochar had a significant impact on the spatial distribution and temporal change of SWC, BD, SP, DOC, hot-water extractable carbon(HWC), acid hydrolyzed organic carbon(AHC Ⅰ, Ⅱ), and readily oxidized organic carbon(ROC). High amounts of maize stalk biochar up-regulated the contents of soil organic carbon SOC, HWC, AHC Ⅰ, AHC Ⅱ, and ROC. In addition, SWC and SP were the key physical factors to affect LOC fractions. In conclusions, maize stalk biochar could improve physical properties, and then influence LOC fractions, and maize stalk biochar could be used as an organic amendment for restoring degraded soils governed by their rates of addition.

Physical and Chemical Properties of Horns Sheaths Particles for the Manufacture of Composite Materials

Salvaged cow horns from slaughterhouses have been transformed into fine particles for a physical characterization that has led us to determine the humidity rate (2.34% ± 0.054%), the actual density situated between 0.586 g/cm3 and 0.732 g/cm3, the swelling rate (12%), and one chemical characterization that permitted us to determine the rate of dry matters (97.05%), of mineral matters (2.5%), of protein matters (94.52%). From these weak values, it can easily be seen that cow horn case doesn’t absorb much water and improve the mechanical characteristics of the composite;the high rate of protein shows that keratin which is the structural molecule favors its gripping as reinforcing element in the manufacturing of composite materials.

Studies of Soil Physical Property on Different Abandoned Lands in the Minqin Oasis,Downstream of the Shiyang River

The vast area of farmland was abandoned at downstream of the Shiyang River because of decreased water recourse. To ensure the ecological safety of Minqin Oasis and to provide management basis for the abandoned land, soil physical properties were observed and studied. The authors analyzed land with abandonment time of 1 year, 2 years, 3 years, 4 years, 5 years, 8 years, 15 years, 24 years and 31 years. Samples were took at the 0-40 cm layer of soil to measure the bulk density, porosity and grain composition of soil in the different abandoned lands. Results showed that the tendency of clay content was decreasing, conversely, the fine sand increased at the layer of 0-10 cm of different abandoned lands.The changes of grain content reached a peak at the fourth year after the land was abandoned, then varied slightly. The variation of grain content of abandoned land was obvious with the extension of the abandonment year. The soil bulk density decreased and porosity increased with the extension of the abandonment year. The difference of porosity and soil bulk density at the range of 0-40 cm of different abandoned land decreased after the land abandoned for 3 years. The quality of soil was decreased, while the soil permeability was improved. The soil physical properties changed obviously in 3 to 4 years after abandonment, so it is the key time for land management.

Physical dispersion state and fluorescent property of Eu-complex in the Eu-complex/silicon rubber composites

The fluorescent complex Eu（TTA）2（Phen）（MA） （HTTA=2-Thenoyltrifluoroacetone, Phen=1,10-phenanthroline, MA=Maleic an- hydrider） was synthesized and characterized with elemental analysis, infrared spectrum （IR）, scanning electron microscope （SEM）, X-ray Diffraction（XRD）, differential scanning calorimetry（DSC）, and fluorescent measurement. To explore the effect of different physical dispersion state of Eu-complex on the fluorescent property of the Eu-complex/silicon rubber composites, various quantifies of Eu（TTA）2（phen） （MA） were mixed with silicon rubber （SIR） and peroxide to form uncured composites. These composites were vulcanized to obtain cured Eu-complex/SiR composites at 250 ℃, which was higher than the melting-point of Eu-complex. The SEM, XRD, DSC, and the fluorescent measurement of these composites showed that both the complex molecules dispersed in the silicon rubber during the melting process and the parent Eu-complex particles had positive effects on fluorescent property, whereas the re-crystallized Eu-complex particles and the aggregating complexes formed during the melting-process had negative effects on fluorescent property. For the uncured composites, their fluorescent intensities almost did not change with the increasing amount of Eu-complex. Furthermore, for the composites with small content of Eu-complex, their fluorescent intensities decreased significantly after curing, and this difference in fluorescent intensity became smaller as the content of Eu-complex increases.

A study on physical property of crustal material and seismogenic environment in northeastern Pamir

2-D crustal structure and velocity ratio are obtained by processing S-wave data from two wide-angle reflec-tion/refraction profiles in and around Jiashi in northeastern Pamir, with the result of P-wave data taken into con-sideration. The result shows that: 1) Average crustal velocity ratio is obviously higher in Tarim block than in West Kunlun Mts. and Tianshan fold zone, which reflects its crustal physical property of 'hardness' and stability. The relatively low but normai velocity ratio (Poisson's ratio) of the lower crust indicates that the 'downward thrusting' of Tarim basin is the main feature of crustal movement in this area. 2) The rock layer in the upper crust of Tianshan fold zone is relatively 'soft', which makes it prone to rupture and stress energy release. This is the primary tectonic factor for the concentration of small earthquakes in this area. 3) Jiashi is located right over the apex or the inflection point of the updoming lower crustal interface C and the crust-mantle boundary, which is the deep struc-tural background for the occurrence of strong earthquakes. The alternate variation of vp/vs near the block bounda-ries and the complicated configuration of the interfaces in the upper and middie part of the upper crust form a par-ticular structural environment for the Jiashi strong earthquake swarm. vp/vs is comparatively high and shear modulus is low at the focal region, which may be the main reason for the low stress drop of the Jiashi strong earthquake swarm.

Single Crystal Growth and Physical Property Characterization of Non-centrosymmetric Superconductor PbTaSe_2

We report on the single crystal growth and superconducting properties of PbTaSe2 with the non-centrosymmetric crystal structure. By using the chemicM vapor transport technique, centimeter-size single crystals are success- fully obtained. The measurement of temperature dependence of electricaJ resistivity p（T） in both normal and superconducting states indicates a quasi-two-dimensional electronic state in contrast to that of polycrystalline samples. Specific heat C（T） measurement reveals a bulk superconductivity with Tc ≈ 3.75K and a specific heat jump ratio of 1.42. All these results are in agreement with a moderately electron-phonon coupled, type-g Bardeen-Cooper-Schrieffer superconductor.

Physical property characteristics of Yanchang Formation reservoir in the southwest of Ordos Basin and their controlling fac-tors： taking Chang 3 and Chang 4 ＋ 5 reservoirs in Longdong area as an example

分析鄂尔多斯盆地西南部陇东地区延长组储层物性特征及其控制因素，发现沉积和成岩控制储层物性。沉积微相带不同，储层物性就不同；成岩作用中压实-压溶作用、胶结作用对储层物性具有破坏作用，溶蚀作用是储层物性改善的关键因素。沉积微相带是控制油气藏储层展布的内在因素，成岩作用是储层形成过程中控制物性演化的外部因素。

Impacts of solid physical properties on the performances of a slurry external airlift loop reactor integrating mixing and separation

Solid physical properties are vital for the design, optimization, and scale-up of gas–liquid–solid multiphase reactors. The complex and interactional effects of the solid physical properties, including particle diameter, density, wettability, and sphericity, on the hydrodynamic behaviors in a new external airlift loop reactor(EALR) integrating mixing and separation are decoupled in this work. Two semi-empirical equations are proposed and validated to predict the overall gas holdup and liquid circulating velocity satisfactorily, and then the individual influence of such solid physical properties is further investigated. The results demonstrate that both the overall gas holdup in the riser and the liquid circulating velocity in the downcomer increase with the contact angle, but decrease with particle size, density, and sphericity.Additionally, the impact of the particle size on the liquid circulating velocity is also profoundly revealed on a micro-level considering the particle size distribution. Moreover, the axial solid concentration distribution is discussed, and the uniformity of the slurry is described by the mixing index of the solid particles. The results show that a more homogeneous mixture can be achieved by adding finer particles other than attaining violent turbulence. Therefore, this work lays a foundation for the design, scale-up, and industrialization of the EALRs.

Electronic structure and physical property of TiAl

Using a new developed valence bond theory of intermetallic compound, the electronic structure and properties of TiAl were analysed systematically. It was determined that the valence electronic structure of Ti and Al atom in TiAl to be [ (4sf)0.42 (4sc) 1.36 (3dc)2.22]Ti and[ (3sf)0.39 (3sc)0.59 (3dc)2.02 ] Al respectively. According to these electronic structure, lattice constant, cohesive energy, potential curve, bulk modulus and temperature dependence of linear thermal expansion coefficient have been calculated, most of the theoretical values of these properties are in good agreement with experiment ones.

Physical Property Model of MnO-SiO_2 System

From the viewpoints of coexistence theory of the slag structure, the investigation on the structural units of MnO-SiO2 system and the chemical reactions between them has been carried out. The relationships between the physical propenies of the slag and the mass action concentrations of its have been set up at certain temperature and slag composition range, which based on the thermodynamic data of the chemtical reactions between the units and the method of linear regression. The calculated data from the model are in good agreement with the measured results. These calculated values are more accurate and systematic than those from other expirical and semi-expirical formulas used at present.

Physical and emulsifying properties of pea protein:influence of combined physical modification by flaxseed gum and ultrasonic treatment

This study characterized and compared the physical and emulsifying properties of pea protein(PP)and its modified proteins(ultrasound treated-PP(PPU),flaxseed gum(FG)treated PP(PPFG)and ultrasound treated-PPFG(PPFGU)).The results showed FG triggered the formation of loosely attached complex with PP via physical modification under gentle magnetic stirring at pH 7.0,while ultrasound played an important role in reducing protein size,increasing surface hydrophobicity and molecular fluidity onto oil-water interface.So ultrasound further enhanced the interaction of PP with FG,and produced the PPFGU complex with smaller droplet size,higherζ-potential and lower turbidity.Further,combination of FG and ultrasound improved the physical properties of PP with higher viscosity,stiffer gels(defined as higher elastic modulus),stronger hydrophobic properties,better thermal stability,and fast protein absorption rate.Therefore,the PPFGU coarse emulsion performed highest emulsifying activity index(EAI)and emulsion stability index(ESI)that the stabilized nanoemulsion obtained smallest droplet size,higherζ-potential,and longest storage stability.The combination of FG and ultrasonic treatment will be an effective approach to improving the emulsifying property and thermal stability of PP,which can be considered as a potential plant-based emulsifier applied in the food industry.

Fabrication, Characterization and Thermophysical Property Evaluation of SiC Nanofluids for Heat Transfer Applications

Nanofluids(NFs) are nanotechnology-based colloidal suspensions fabricated by suspending nanoparticles(NPs) in a base liquid. These fluids have shown potential to improve the heat transfer properties of conventional heat transfer fluids. In this study we report in detail on fabrication, characterization and thermo-physical property evaluation of SiC NFs, prepared using SiC NPs with different crystal structures,for heat transfer applications. For this purpose, a series of SiC NFs containing SiC NPs with different crystal structure(α-SiC and β-SiC) were fabricated in a water(W)/ethylene glycol(EG) mixture(50/50 wt%ratio). Physicochemical properties of NPs/NFs were characterized by using various techniques, such as powder X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM),Fouriertransform infrared spectroscopy(FTIR), dynamic light scattering(DLS) and Zeta potential analysis.Thermo-physical properties including thermal conductivity(TC) and viscosity for NFs containing SiC particles(α- and β- phase) weremeasured. The results show among all suspensions NFs fabricated with α-SiC particles have more favorable thermo-physical properties compared to the NFs fabricated with β-SiC.The observed difference is attributed to combination of several factors, including crystal structure(β- vs. α-), sample purity,and residual chemicals exhibited on SiC NFs. A TC enhancement of ～20% while 14% increased viscosity were obtained for NFs containing 9 wt% of particular type of α-SiC NPs indicating promising capability of this kind of NFs for further heat transfer characteristics investigation.

Digital mapping of soil physical and mechanical properties using machine learning at the watershed scale

Knowledge about the spatial distribution of the soil physical and mechanical properties is crucial for soil management,water yield,and sustainability at the watershed scale;however,the lack of soil data hinders the application of this tool,thus urging the need to estimate soil properties and consequently,to perform the spatial distribution.This research attempted to examine the proficiency of three machine learning methods(RF:Random Forest;Cubist:Regression Tree;and SVM:Support Vector Machine)to predict soil physical and mechanical properties,saturated hydraulic conductivity(Ks),Cohesion measured by fall-cone at the saturated(Psat)and dry(Pdry)states,hardness index(HI)and dry shear strength(SS)by integrating environmental variables and soil features in the Zayandeh-Rood dam watershed,central Iran.To determine the best combination of input variables,three scenarios were examined as follows:scenarioⅠ,terrain attributes derivative from a digital elevation model(DEM)+remotely sensed data;scenarioⅡ,covariates of scenarioⅠ+selected climatic data and some thematic maps;scenarioⅢ,covariates in scenarioⅡ+intrinsic soil properties(Clay,Silt,Sand,bulk density(BD),soil organic matter(SOM),calcium carbonate equivalent(CCE),mean weight diameter(MWD)and geometric weight diameter(GWD)).The results showed that for Ks,Psat Pdry and SS,the best performance was found by the RF model in the third scenario,with R2=0.53,0.32,0.31 and 0.41,respectively,while for soil hardness index(HI),Cubist model in the third scenario with R2=0.25 showed the highest performance.For predicting Ks and Psat,soil characteristics(i.e.clay and soil SOM and BD),and land use were the most important variables.For predicting Pdry,HI,and SS,some topographical characteristics(Valley depth,catchment area,mltiresolution of ridge top flatness index),and some soil characteristics(i.e.clay,SOM and MWD)were the most important input variables.The results of this research present moderate accuracy,however,the methodology employed provides quick and costeffective information serving as the scientific basis for decision-making goals.

Selection and thermal physical characteristics analysis of in-situ condition preserved coring lunar rock simulant in extreme environment

With the increasing scarcity of Earth’s resources and the development of space science and technology,the exploration, development, and utilization of deep space-specific material resources(minerals, water ice, volatile compounds, etc.) are not only important to supplement the resources and reserves on Earth but also provide a material foundation for establishing extraterrestrial research bases. To achieve large depth in-situ condition-preserved coring(ICP-Coring) in the extreme lunar environment, first, lunar rock simulant was selected(SZU-1), which has a material composition, element distribution, and physical and mechanical properties that are approximately equivalent to those of lunar mare basalt. Second, the influence of the lunar-based in-situ environment on the phase, microstructure, and thermal physical properties(specific heat capacity, thermal conductivity, thermal diffusivity, and thermal expansion coefficient)of SZU-1 was explored and compared with the measured lunar rock data. It was found that in an air atmosphere, low temperature has a more pronounced effect on the relative content of olivine than other temperatures, while in a vacuum atmosphere, the relative contents of olivine and anorthite are significantly affected only at temperatures of approximately-20 and 200 ℃. When the vacuum level is less than100 Pa, the contribution of air conduction can be almost neglected, whereas it becomes dominant above this threshold. Additionally, as the testing temperature increases, the surface of SZU-1 exhibits increased microcracking, fracture opening, and unevenness, while the specific heat capacity, thermal conductivity,and thermal expansion coefficient show nonlinear increases. Conversely, the thermal diffusivity exhibits a nonlinear decreasing trend. The relationship between thermal conductivity, thermal diffusivity, and temperature can be effectively described by an exponential function(R^(2)>0.98). The research results are consistent with previous studies on real lunar rocks. These research findings are expected to be applied in the development of the test and analysis systems of ICP-Coring in a lunar environment and the exploration of the mechanism of machine-rock interaction in the in-situ drilling and coring process.

Differences of tuffaceous components dissolution and their impact on physical properties in sandstone reservoirs: A case study on Paleogene Wenchang Formation in Huizhou-Lufeng area, Zhu I Depression, Pearl River Mouth Basin, China

The element geochemical characteristics and diagenetic alteration products of tuffaceous components in sandstone reservoirs of Paleogene Wenchang Formation in typical subsags of the Huizhou-Lufeng area of the Zhu I Depression,Pearl River Mouth Basin,were identified through microscopic analysis and quantitative analysis of main and trace elements.The impacts of dissolution of different tuffaceous components on physical properties of reservoirs were discussed through quantitative characterization of reservoir physical properties.The results show that there are mainly four types of tuffaceous components in the study area,which are acidic,intermediate,basic and alkaline tuffaceous components.The acidic tuffaceous components evolved in a process of strong alteration and weak dissolution of alteration products,with a large amount of kaolinite precipitated during alteration to disenable the improvement of porosity and permeability.The intermediate and alkaline tuffaceous components evolved in a process of strong dissolution of tuffaceous components and strong alteration of residual tuffaceous components;the dissolution of tuffaceous components created intergranular pores,but the alteration products such as autogenic quartz,apatite and illite deteriorated the pore structure;ultimately,the dissolution of tuffaceous components resulted in the increase of porosity but no increase of permeability of the reservoir.The basic tuffaceous components dominantly evolved in a process of dissolution of tuffaceous components to strong dissolution of alteration products;both tuffaceous components between particles and laumontite generated from alteration can be strongly dissolved to create pores;thus,the dissolution of tuffaceous components can significantly increase the physical properties of the reservoir.

GIS-Based Assessment of Soil Chemical and Physical Properties as a Basis for Land Reclamation in Toshka Area, Aswan, EGYPT

The accurate assessment of soil properties is a crucial factor for composing and implementing reclamation plans. The main objective of this study was to evaluate soil chemical and physical properties and calculate the chemical and fertility index for assisting land reclamation in Toshka area. The Toshka area is located between latitudes 31°32'N and 31°36'N and longitudes 32°40'E and 32°60'E. GIS was used to select 16 sites. The results revealed the soil has undesirable characteristics. The soil pH ranged from slightly alkaline to moderately alkaline. Furthermore, it was characterized as saline (with a ECe of 4.65 - 11.45 dS⋅m−1) and moderately calcareous soil (with CaCO3 at 11.85% - 17.20%). The soil had a low soil organic matter content which did not exceed 0.18%. The soil was dominated by a sandy loam texture (62.50%) followed by a sandy clay loam texture (18.75%). The bulk density, total soil porosity and saturated hydraulic conductivity values varied with 1.38 - 1.55 Mg⋅cm−3, 41.85% - 48.45% and 1.20 - 3.34 cm⋅h−1, respectively. The chemical index ranged from low to moderate quality. The correlations between the parameters osculated between negative and positive. Therefore, the soil may be reclaimed if the soil properties are improved and crop selection is optimized for this soil.

Effects of cementation on physical properties of clastic rock-originated weathering crust reservoirs in the Kexia region,Junggar Basin,NW China

Cements are widely developed in clastic rock-originated weathering crust(CWC)reservoirs in the Kexia region along the northwestern margin of the Junggar Basin and significantly affect reservoir physical properties and oil and gas distribution in this area.Focusing on the CWC reservoirs at the top of both the Permian Jiamuhe Formation and the Triassic Karamay Formation,this study analyzed the types and characteristics of cements in the reservoirs and explored their effects on reservoir physical properties based on thin sections,SEM images,XRD results,and tests of physical properties.The main results are as follows.The cements in the CWC reservoirs in Kexia region mainly consist of carbonate minerals(41.5%),clay minerals(27.8%)and zeolite minerals(30%),as well as small amount of siliceous minerals.Among them,the carbonate minerals are dominated by siderite and calcite,the clay minerals mainly include kaolinite,interstratified illite/smectite(I/S)and chlorite,and the zeolite minerals primarily comprise heulandite and laumontite.These different types of multiphase cements are generally paragenetic or associated and affect reservoir physical properties to different degrees.Specifically,the carbonate and clay cements of the early diagenetic stage reduced the reservoirs’average porosity from 21%to 15%.The dissolution of some carbonate and zeolite cements in the early A substage of the middle diagenetic stage restored the average porosity to 18%,and the cementation in the late A substage decreased the average porosity to 13%again,of which about 4%was reduced by carbonate cements.The average porosity of the CWC reservoirs gradually decreased to the current value of approximately 10%in the B substage of the middle diagenetic stage.The impact of cementation on the CWC reservoirs can reach as far as 70 m below the unconformity.Moreover,the types and contents of cements vary with their depth below the unconformity surface,leading to the development of multiple zones with high cement content and the differentiated oil and gas distribution.