高温高压下烷烃-CO2-水混溶过程与模式——基于显微可视化热模拟和分子动力学模拟

含油气盆地深层-超深层地质流体类型多样,并在更加高温-高压条件下表现出更强的活跃性和未知性.本文以25～425℃、5～105MPa条件下的CH₄/C₃H₈/C₆H₁₄/C₈H₁₈-水和_C6H₁₄/C₈H₁₈-CO₂-水体系为例,利用原位可视化微米石英管模拟系统和分子动力学数值模拟平台,开展了低温低压到高温高压全过程条件下有机-无机流体混溶过程微观可视化热模式研究,系统探讨了各体系流体在温度压力增加过程中的混溶过程、规律和微观混溶机理.结果表明,不同烷烃-水和烷烃-CO₂-水体系的混溶不是瞬间完成的,实验过程中不同物质间的混溶程度整体上均随温压升高而逐渐增强,根据物理模拟实验可分为明显开始混溶、分段动态混溶和基本完全混溶3大阶段,结合物理热模拟和分子动力学数值模拟,又可将烷烃-水和烷烃-CO₂     

Effect of ground motion duration on inelastic displacement ratio of SDOF systems

In this paper,the influence of ground motion duration on the inelastic displacement ratio,C₁,of highly damped SDOF systems is studied.For this purpose,two sets of spectrally equivalent long and short duration ground motion records were used in an analysis to isolate the effects of ground motion duration on.The effect of duration was evaluated for observed values of C₁ by considering six ductility levels,and different damping and post-yield stiffness ratios.A new predictive ...     

Interactions between hydrocarbon-bearing fluids and calcite in fused silica capillary capsules and geological implications for deeply-buried hydrocarbon reservoirs

During the burial processes of deep/ultra-deep hydrocarbon reservoirs,the interactions between hydrocarbon-bearing fluids and reservoirs significantly affect the quality evolution of hydrocarbons and reservoirs;thus,this topic requires further investigation.In this study,the continuous evolution and the coupling mechanisms in various anhydrous and hydrous nC₁₆H₃₄-(water)-(calcite)systems in fused silica capillary capsules(FSCCs)were investigated using laser Raman spectroscopy,fluorescence color analysis,and fluorescence spectroscopy,and the mineral alterations were analyzed using scanning electron microscopy(SEM).The experimental results show that extensive organic-inorganic interactions occur in the systems if water is present,and different inorganic components have different effects on hydrocarbon degradation.Distilled water promotes freeradical thermal cracking and steps oxidation,forming more low-molecular-weight hydrocarbons,CO₂,and organic acids(e.g.,acetic acids)but suppresses the free-radical cross-linking,generating less high-molecular-weight hydrocarbons.However,in the presence of CaCl₂ water,the yields of hydrocarbon gases are lower than in the distilled water system because high concentrations of Ca ions inhibit the generation of free radicals.Calcites,which exhibit different surface reactivities in different fluid conditions,affect hydrocarbon degradation in different ways.In the anhydrous nC16H34-calcite system,calcites promote the generation of both hydrocarbon gases and high-molecular-weight hydrocarbons.In contrast,in the hydrous nC16H34-distilled(CaCl₂)watercalcite system,calcites promote the generation of hydrocarbon gases and suppress the generation of high-molecular-weight hydrocarbons.Calcite also reacts with organic acids via surface reactions to form secondary pores.Therefore,except for the formation temperature and pressure,organic-inorganic interactions are controlled by multiple factors,such as the water saturation,water type,water salinity,and the mineral content,resulting in different evolutions of the hydrocarbon degradation and reservoir properties.     

The contribution of bacteria to organic matter in coal-measure source rocks

On the basis of GC–MS analysis, a suite of nine coal-measure source rocks(Ro 0.51%–0.63%) from the southern margin of Junggar basin was found to contain many biomarkers for bacterially-generated hydrocarbons:hopane, sesquiterpene, C₂₃+ monomethyl alkanes(even carbon predominance), and C₂₄+ alkyl cyclohexane.Rock–eval and microscope analysis indicate that vitrinite(especially desmocollinite and homocollinite) plays a significant role in the generation of hydrocarbons in coalmeasure source rocks. Vitrinite performs this role by absorbing ultramicroscopic organic matter, generally in the form of resins or bacterial plastids. C₂₃+ monomethyl alkanes(even carbon predominance) and C₂₄+ alkyl cyclohexane series compounds are derived from bacterial metabolites of higher plants. The ultramicro organic matter adsorbed by vitrinite source rocks in the study area is probably ultramicro bacterial plastids. Because the organic matter of higher plants with low hydrogen content has been transformed into organic matter rich in hydrogen by bacteria, the hydrocarbon generation capacity of source rocks is greatly improved. In other words, in coal-measure source rocks, bacteria play an important role in hydrocarbon generation.     

Degassing of deep-sourced CO2 from Xianshuihe-Anninghe fault zones in the eastern Tibetan Plateau

A large number of gases are releasing from the medium-high temperature geothermal fields distributed along the large-scale strike-slip fault zones in the southeastern margin of the Tibetan Plateau.In this study,11 hot spring water and the associated bubbling gas samples were collected along the Xianshuihe-Anninghe fault zones(XSH-ANHFZ)and analyzed for chemical and isotopic compositions.The δ¹⁸_{H_(2}O) and δD_{H_(2}O) values indicate that hot spring waters are predominantly meteoric origin recharged from different altitudes.Most water samples are significantly enriched in Na⁺ and HCO₃ due to the dissolution of regional evaporites,carbonates and Na-silicates.³He/⁴He ratios of the gas samples are 0.025-2.73 times the atmospheric value.The ³He/⁴He ratios are high in the Kangding region where the dense faults are distributed,and gradually decrease with increasing distance from Kangding towards both sides along the Xianshuihe fault zones(XSHFZ).Hydrothermal fluids have dissolved inorganic carbon(DIC)concentrations from 2 to 42 mmol L^-1,δ¹³C_DIC from -6.9‰ to 1.3‰,δ¹³C_{CO_(2}) from -7.2‰ to -3.6‰ and Δ¹⁴C from -997‰ to -909‰.Combining regional geochemical and geological information,the CO₂sources can be attributed to deep-sourced CO₂from mantle and metamorphism of marine carbonate,and shallow-sourced CO₂from the dissolution of marine carbonate and biogenic CO₂.The mass balance model shows that 11±6% of the DIC is sourced from the dissolution of shallow carbonate minerals,9±8% formed by pyrolysis of sedimentary organic matter,80±9% derived from deep metamorphic origin and mantle-derived CO₂.Among them,the deep-sourced CO₂in Anninghe fault zones(ANHFZ)is merely metamorphic carbon,whereas ca.12% and ca.88% of the deep-sourced CO₂in the XSHFZ are derived from the mantle and metamorphic carbon,respectively.The average deep-sourced CO₂flux in the Kangding geothermal field is estimated to be 160 ta^-1.If all the hot springs in various fault zones in the southeastern margin of the Tibetan Plateau are taken into account,the regional deep-sourced CO₂flux would reach ca.10⁵ ta^-1.These results show that the deep-sourced CO₂released from nonvolcanic areas might account for a considerable proportion of the total amount of global deep-sourced carbon degassing,which should be paid more attention to.     

Geochemistry,zircon U–Pb geochronology,and Hf isotopes of S-type granite in the Baoshan block,constraints on the age and evolution of the Proto-Tethys

Geochemistry, zircon U–Pb geochronology, and Hf isotope data for the Early Paleozoic granites in the Baoshan Block reveal the Early Paleozoic tectonic evolution of the Proto-Tethys. The samples are high-K, calcalkaline, strongly peraluminous rocks with A/CNK values of 1.37–1.46, are enriched in SiO₂, K₂O, and Rb, and are depleted in Nb, P, Ti, Eu, and heavy rare earth elements,which indicates the crystallization fractionation of the granitic magma. Zircon U–Pb dating indica...     

Carbon dioxide partial pressure and its diffusion flux in karst surface aquatic ecosystems: a review

Carbon dioxide(CO₂) emissions from aquatic ecosystems are an important component of the karst carbon cycle process and also a key indicator for assessing the effect of karst carbon sinks. This paper reviewed the CO₂ partial pressure(pCO₂) and its diffusion flux(FCO₂) in karst surface aquatic ecosystems, mainly rivers, lakes, and reservoirs, and their influencing factors summarized the methods for monitoring CO₂ emissions in karst aquatic eco...     

Quantifying the impact of mineralogical heterogeneity on reactive transport modeling of CO2+O2 in-situ leaching of uranium

CO₂+O₂ in-situ leaching(ISL)of sandstonetype uranium ore represents the third generation of solution mining in China.In this study,reactive transport modeling of the interaction between hydrodynamic and geochemical reactions is performed to enable better prediction and regulation of the CO₂+O₂ in-situ leaching process of uranium.Geochemical reactions between mining solutions and rock,and the kinetic uranium dissolution controlled by O₂(aq)and bicarbonate(HCO₃-)are considered in the CO₂+O₂ ISL reactive transport model of a typical sandstone-hosted uranium ore deposit in northern China.The reactive leaching of uranium is most sensitive to the spatial distribution of the mineralogical properties of the uranium deposit.Stochastic geostatistical models are used to represent the uncertainty on the spatial distribution of mineral grades.A Monte Carlo analysis was also performed to simulate the uranium production variability over an entire set of geostatistical realizations.The ISL stochastic simulation performed with the selected geostatistical realizations approximates the uranium production variability well.The simulation results of the ISL reactive transport model show that the extent of the uranium plume is highly dependent on mineralogical heterogeneity.The uncertainty analysis suggests the effect of uranium grade heterogeneity was found to be important to improve the accurate capture of the uncertainty.This study provides guidance for the accurate simulation and dynamic regulation of the CO₂+O₂ leaching process of uranium at the scale of large mining areas.     

Trace element study in Tisa River and Danube alluvial sediment in Serbia

The contaminated sediment serves as a long-term source of toxic elements,since that mobility and transport in the environment of these elements are strongly influenced to associated solid phase.In this study,the modified Tessier sequential extraction procedure was applied for the fractionation of Cd,As,Hg,Cu,Zn,Cr,Pb,Ni and V in the sediments（Tisa River and canal sediments - Danube alluvial formation）,to obtain an overall classification of trace element pollution in these areas through its spatial distribution.Investigations of this region are important due to the widespread occurrence of metal mining activities throughout the Tisa and Danube drainage basins and possibilities of contamination with toxic elements at studies localities.Five steps of the sequential extraction procedure partitioned elements into CH₃COONH₄ extractable（F1）,NH₂OH·HC carbonate extractable and easily reducible（F₂）, H₂C₂O₄/（NH₄）₂C₂O₄ moderately reducible（F3）,H₂O₂-HNO₃ organic extractable（F4）,and HCl acid soluble residue （F5）.Analyses of the extracts were performed by flame atomic absorption spectrometry.To indicate the degree of risk of toxic elements,risk assessment code and contamination factor have been used.The results of partitioning study indicate that more easily mobilized forms（metals in adsorbed/exchangeable/carbonate forms or bound to amorphous Fe and Mn oxyhydroxides and Fe and Mn oxides） were predominant for copper,zinc,cadmium and lead,which can be used as indicators for input from anthropogenic source.In contrast,the largest amount of chromium and nickel were associated with the inert fraction,which reduced their solubility and rendered them immobile under natural conditions and indicative of natural origins.Most of remaining portion of metals was bound to ferromanganese oxides fraction.It is concluded that sequential extraction results proved useful to distinguish between anthropogenic and geochemical sources of elements in the sediments.     

Phase equilibrium modeling of zircon stability in mantle peridotite: Implication for crust-mantle interaction

Zircon is a common accessory mineral in various rocks,especially in the crustal ones.It is the best mineral for U-Pb dating.Meanwhile,trace elements and isotopes of the mineral can also provide much information concerning the formation and evolution of rocks.There are a growing number of reports of zircon existing in mantle peridotite.However,it is generally considered that zircon is unlikely crystallized in ultrabasic rocks due to SiO₂-unsaturation.In this paper,the SiO₂ activity and zircon/baddeleyite transition curve at different conditions were calculated through thermodynamic phase equilibrium modeling,to reveal the main factors affecting the SiO₂ activity and the stability of zircon/baddeleyite in ultrabasic and basic rocks,especially in mantle peridotite.These results provide a thermodynamic basis for interpreting the genesis and significance of zircon in mantle rocks.That is,the SiO₂ activity is mainly controlled by stable mineral assemblages and temperature-pressure conditions.The orthopyroxene+olivine assemblage in peridotite as an effective buffer restricts the SiO₂ activity in a relatively high range with a small variation.The upper temperature limit of zircon can reach more than 1500℃ with this mineral assemblage.During the low-temperature serpentinization of peridotite,the replacement of olivine and pyroxene by serpentine can result in a significant decrease of SiO₂ activity,and baddeleyite can be stabilized at<530℃ and<2.7 GPa.When peridotite is strongly metasomatized by the SiO₂-bearing fluid,the addition of SiO₂ can increase its activity and make zircon stable at low temperatures.The SiO₂ activity in ultrabasic-basic rocks is not only positively correlated with the SiO₂ content but also negatively correlated with the Ca and Na contents of rocks.This is because Ca and Na preferentially combine with Si and Al to form Si-rich minerals,such as clinopyroxene and feldspar.This process will consume excessive SiO₂,decreasing the SiO₂ activity.This may be the reason why zircon can be found in ultrabasic rocks,while baddeleyite can exist in some basic and alkaline rocks.The thermodynamic modeling can also reasonably explain the mutual transformation between zircon and baddeleyite in ultrabasic-basic rocks.Our results indicate that zircon can exist stably in mantle peridotite in a wide range of temperature-pressure conditions and its formation is related to melt/fluid metasomatism.That is,the presence of zircon in mantle peridotite is an important information carrier of crust-mantle interaction for deep material cycling.     

地幔过渡带Al2O3-SiO2-H2O体系的新含水相

俯冲板片是地表水进入深部地幔的潜在载体,而含水矿物是其中的关键所在.因此,新含水相的发现对认识整个地球内部的水循环过程及效应具有重要意义.研究使用2500吨Sakura型多面顶大压机在Al₂O₃-SiO₂-H₂O体系合成了两个新的含水相,Al₂SiO₆H₂和Al_5.5Si₄O₁₈H_3.5(以下分别记为Psi相和Phi相),合成条件是15.5GPa、1400℃和17.5GPa、1600℃.Cr³⁺的荧光光谱显示Psi相在687、693和705nm有特征峰,而Phi相在691、696和708nm有特征峰.单晶X射线衍射(SCXRD)结构精修表明两相属于单斜晶系(空间群P2₁),其理想化学式分别为Al₂SiO₆H₂和Al_5.5     

Geographic distribution of arsenic contamination in the Himalayan Rivers flowing through Pakistan: Implications for its natural source and effects of anthropogenic activities

Arsenic(As) in natural hydrological systems is known as a worldwide major environmental concern. A geochemical and sedimentological study was done to ascertain the origin and geographical distribution of As in surface water and fluvial sediment collected from the floodplains/basins of the River Indus and its four major tributaries that drain through the northern Pakistan. The hydrogeochemical compositions of all five rivers were similar with calcium(Ca²⁺) and bicarbonate(HCO₃     

The discovery of TiO2-Ⅱ,the α-PbO2-structured high-pressure polymorph of rutile,in the Suizhou L6 chondrite

We report the discovery of TiO₂-Ⅱ in the unmelted rock of the shocked Suizhou L6 chondrite.Natural TiO₂-Ⅱ was previously found in ultrahigh-pressure metamorphic and mantle-derived rocks,terrestrial impact structures,and tektite.Our microscopic,Raman spectroscopic,electron microprobe and transmission electron microscopic investigations have revealed:(1) All observed TiO₂-Ⅱ grains are related with ilmenite and pyrophanite;(2) TiO₂-Ⅱ occurs as needle-and ...     

Geochemistry and mineral chemistry of the armoor granitoids,eastern dharwar craton: implications for the redox conditions and tectono-magmatic environment

The mineralogical and geochemical characteristics of the K-rich granites from the Armoor granitic rocks in the northeastern portion of the Eastern Dharwar Craton(EDC) are presented.In order to understand its physicochemical conditions,the petrogenesis of the granitoid was explained from biotite chemistry and geochemical systematics.Studies of mineral chemistry expose that compositionally,K-feldspar and plagioclase in Armoor granite rocks range from An₀,Ab_3-5.9,Or_94-96....     

Evolutive characteristics of aromatics under high pressure and temperature of deep lithosphere

Pyrolysis of lignite in closed systems was conducted at temperatures from 400 to 700℃ and pressure from 1 to 3 GPa in order to investigate the evolutive characteristics of aromatics and the effects of pressure and temperature on the maturation of organic matter under the extreme conditions. The total yield of liquid hydrocarbons decreased with increasing pressure and the aromatics shows more mature with increasing temperature at a given pressure. The data indicate that high pressure significantly suppresses the thermal evolution of geological organic matter especially at lower temperature, but favors the cyclization, polymerization and aromatization of pyrolysate. The pressure effect on maturation of organic matter is nonlinear. Therefore, it can be inferred that sediment organic-matters in the subducted slab could be retained in the deep lithosphere, and the results are also significant for understanding the accumulation and preservation of petroleum in deep reservoirs.     

Plastic-Flow/Seismic" Network Systems and Tectonic Units in Central-Eastern Asia

The study of the netlike earthquake distribution indicates that in the central-eastern part of Asia continent there are two network systems: the central-eastern Asia system and the southeastern China system.As interpreted by the multilayer tectonic model,they might be a manifestation of the plastic-flow network systems in the lower lithosphere,including the lower crust and the mantle lid.Each network system is enclosed by different types of boundaries,including one driving boundary and some constraining and releasing boundaries.The two plastic-flow network systems with the Himalayan and Taiwan arcs as their driving boundaries play the role of controlling the intraplate tectonic deformation,stress field,seismicity,and subdivision of tectonic units.     

Carbon sinks/sources in the Yellow and East China Seas—Air-sea interface exchange,dissolution in seawater,and burial in sediments

The sinks/sources of carbon in the Yellow Sea(YS) and East China Sea(ECS), which are important continental shelf seas in China, could exert a great influence on coastal ecosystem dynamics and the regional climate change process. The CO_2 exchange process across the seawater-air interface, dissolved and particulate carbon in seawater, and carbon burial in sediments were studied to understand the sinks/sources of carbon in the continental shelf seas of China. The YS and the ECS generally have different patterns of seasonal air-sea CO_2 exchange. In the YS, regions west of 124°E can absorb CO_2 from the atmosphere during spring and winter, and release CO_2 to the atmosphere during summer and autumn. The entire YS is considered as a CO_2 source throughout the year with respect to the atmosphere, but there are still uncertainties regarding the exact air-sea CO_2 exchange flux. Surface temperature and phytoplankton production were the key controlling factors of the air-sea CO_2 exchange flux in the offshore region and nearshore region of the YS, respectively. The ECS can absorb CO_2 during spring, summer, and winter and release CO_2 to the atmosphere during autumn. The annual average exchange rate in the ECS was-4.2±3.2 mmol m~(-2) d~(-1) and it served as an obvious sink for atmospheric CO_2 with an air-sea exchange flux of 13.7×10~6 t. The controlling factors of the air-sea CO_2 exchange in the ECS varied significantly seasonally. Storage of dissolved inorganic carbon(DIC) and dissolved organic carbon(DOC) in the YS and the ECS were 425×10~6 t and 1364×10~6 t, and 28.2×10~6 t and 54.1×10~6 t,respectively. Long-term observation showed that the DOC content in the YS had a decreasing trend, indicating that the "practical carbon sink" in the YS was decreasing. The total amount of particulate organic carbon(POC) stored in the YS and ECS was10.6×10~6 t, which was comparable to the air-sea CO_2 flux in these two continental shelf seas. The amounts of carbon sequestered by phytoplankton in the YS and the ECS were 60.42×10~6 t and 153.41×10~6 t, respectively. Artificial breeding of macroalgae could effectively enhance blue carbon sequestration, which could fix 0.36×10~6–0.45×10~6 t of carbon annually. Organic carbon(OC) buried in the sediments of the YS was estimated to be 4.75×10~6 t, and OC of marine origin was 3.03×10~6 t, accounting for5.0% of the TOC fixed by phytoplankton primary production. In the ECS, the corresponding depositional flux of OC in the sediment was estimated to be 7.4×10~6 t yr~(-1), and the marine-origin OC was 5.5×10~6 t, accounting for 5.4% of the phytoplankton primary production. Due to the relatively high average depositional flux of OC in the sediment, the YS and ECS have considerable potential to store a vast amount of "blue carbon."     

Effects of elevated CO2 concentration on CH4 and N2O emissions from paddy fields: A meta-analysis

The inevitable rise of atmospheric CO₂ concentration plays an important role in regulating the carbon(C)and nitrogen(N)cycling in the rice-cropping system.Elucidating the effects of elevated CO₂ concentration(ECO₂)on CH₄ and N₂O emissions from paddy fields is essential for evaluating agricultural production in response to global climate change.In this study,we conducted a global meta-analysis to assess the overall effect of ECO₂ on CH₄ and N₂O emissions from paddy fields,aiming at providing a guideline for sustainable C and N management in paddy fields under future climate conditions.The results showed that,overall,ECO₂ significantly increased CH₄ emissions from rice fields by 23%(P<0.05),but reduced N₂O emissions by 22%(P<0.05).With a long duration(>10 yr)of ECO₂ ,ECO₂ significantly reduced CH₄ and N₂O emissions from paddy fields by 27%and 53%,respectively(P<0.05).Along with the increasing levels of ECO₂ ,the stimulating effect of ECO₂ on CH₄ emissions showed a trend of"weakening firstly and then strengthening",while its effect on N₂O emissions changed from stimulation to inhibition.Agronomy managements(e.g.,N application rates,straw incorporations,water regimes,and rice cultivars)affected the effects of ECO₂ on CH₄ and N₂O emissions from paddy fields.With no or half amount of straw incorporation,ECO₂ increased CH₄ emissions by 27% or 49%(P<0.05)from paddy fields,respectively,while non-significant effects on CH₄ emissions from paddy fields were observed under full straw incorporation.With the increasing amount of straw incorporation,the reductions in N₂O emissions from paddy fields were enhanced by ECO₂.Compared with a continuous flooding regime,intermittent irrigation weakened the promoted effect on CH₄ emissions but stimulated the inhibited effect on N₂O emissions from paddy fields under ECO₂.Therefore,under the future condition of ECO₂,it is recommended to adopt the appropriate agricultural management measures,such as combining straw incorporation and intermittent irrigation,and optimizing N application and using rice cultivars of high-yield with lower emissions.In addition,it is necessary to conduct comprehensive studies at multiscale,with multi-factor,and by multi-method to effectively reduce the uncertainty of quantifying the response of CH₄ and N₂O emissions from paddy fields to future ECO₂ .     

Temporal and spatial variation and stability of the oasis in the Sangong River Watershed, Xinjiang, China

The unique ecological landscapes are composed of the mountain systems with the obviousvertical differentiation, vast natural desert systems, and oasis systems on which the human beings rely for the existence in the arid areas in West China. Oases are the …     

Effects of abnormally high heat stress on petroleum in reservoir——An example from the Tazhong 18 Well in the Tarim Basin

An igneous intrusion of 94m thick was discovered intruding into the Silurian sandstone from Tazhong 18 Well. The petroleum previously preserved in the Silurian sandstone reservoir was altered into black carbonaceous bitumen by abnormally high heat stress induced by the igneous intrusion. The reflec-tance of the carbonaceous bitumen reaches as high as 3.54%, indicating that the bitumen had evolved into a high thermal evolution level. Similar to the Silurian samples from the neighboring Tazhong 11, Tazhong 12, Tazhong 45 and Tazhong 47 wells, the distribution of C27, C28 and C29 steranes of the car-bonaceous bitumen is still "V" -shaped and can still be employed as an efficient parameter in oil source correlation. The "V" -shaped distribution indicates that the hydrocarbons from the Tazhong 18 and the neighboring wells were all generated from the Middle-Upper Ordovician hydrocarbon source rocks. However, the oil source correlation parameters associated with and terpanes had been changed greatly by the high heat stress and can no longer be used in oil source correlation. The δ 13C values of the pe-troleum from the neighboring wells are between -32.53‰ and -33.37‰, coincident with those of the Paleozoic marine petroleum in the Tarim Basin. However, the δ 13C values of the carbonaceous bitumen from the Tazhong 18 Well are between -27.18‰ and -29.26‰, isotopically much heavier than the pe-troleum from the neighboring wells. The content of light hydrocarbons (nC14-nC20) of the saturated hydrocarbon fraction in the carbonaceous bitumen is extremely higher than the content of heavy hy-drocarbons. The light/heavy hydrocarbon ratios (ΣnC21-/ΣnC22 ) are between 4.56 and 39.17. In the saturated fraction, the even numbered hydrocarbons are predominant to the odd numbered, and the OEP (Odd to Even Predominance) values are between 0.22 and 0.49. However, the content of light hy-drocarbons in the petroleum from the neighboring wells is relatively low and the content of the even numbered hydrocarbons is almost equal to that of the odd numbered. Compared with the samples from the neighboring wells, the abundance of non-alkylated aromatic hydrocarbons, such as phenanthrenes, and polycyclic aromatic hydrocarbons (PAHs), such as fluoranthane, pyrene, benzo[a]anthracene and benzofluoranthene, are relatively high.