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1.
The Linnan subsag is the main oil producer of the Linpan oil zone. Based on the oil group composition, gas chromatography data and biomarker analysis, it was indicated that crude oils from different oilfields varied greatly in group composition and showed obvious heterogeneities in the aspects of precursor type, crude oil maturity and hydrocarbon depositional environment. According to the characteristics of source rocks, three oil populations can be distinguished, i.e., the southern, northern and transitional oil populations. Furthermore, on the basis of post-reservoir reworking processes, the medium conditions of hydrocarbon-generating environment and differences in maturity, six oil families and twelve sub-families were distinquished. An integrated study suggested that the factors leading to such heterogeneities in crude oil composition mainly include different source rocks, multi-stage oil/gas charging, geo-chromatographic effects during oil/gas migration, reservoir heterogeneities and various post-reservoir secondary alterations.  相似文献   

2.
The upper tertiary to quaternary is the main target layer for oil and gas exploitation in Mainland China, especially crude oil production in the Bohai Basin accounts for approximately 40% of China’s crude oil production. Therefore, a study of the Upper Tertiary to Quaternary has important significance for science and practical applications. In this study, using the receiver function method, Ps and later phase extraction, the sedimentary thickness and an accurate estimate of velocity ratio can be obtained. The technique is simple, its calculation results are unique, and it can be applied to a study of the sedimentary layer. The technique is promising for oil and gas exploration.  相似文献   

3.
By PVT fractionation experiments to model phase-controlled and gaw-washing fractionations during the formation of petroleum reservoirs,the authors measured the physical and chemical properties of products formed in different fractionation staes and made a correlative analysis of the influence of depressurization and gas washing on oil/gas molecular composition and the rule of fractionation.The analytical results showed that gas washing is an important factor affecting the physical properties of crude oils.and also can be regarded as a good genetic interpretation of marine wax-high oils in the Tarim region,Xinjiang,China.Phase-controlled and gaw-washing fractionations can lead to the formation of condensates and their differences in chemical composition from crude oils are a direct reflection of evaporating fractionation.Phasecontrolled and gaw-washing fractionations have a great influence on the composition of molecular compounds and relevant parameters.So phase-controlled and gas-washing fractionations during the formation of petroleum reservoirs are not only favorable to identifying different processes of formation of petroleum reservoirs,but also to the scientific application of routine geochemical parameters.  相似文献   

4.
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5.
Measurements of the absolute and relative concentrations of nitrogen-containing compounds in crude oils from different reservoir strata (Ordovician, Silurian and Carboniferous) in the Tazhong region of the Tarim Basin, Xinjiang, China, showed that even though there are quite a number of factors affecting the distributional and compositional characteristics of neutral nitrogen-containing compounds in crude oils, the distributional and compositional characteristics of crude oils whose source conditions are approximate to one another are influenced mainly by the migration and fractionation effects in the process of formation of oil reservoirs. In addition, crude oils in the Tazhong region show obvious migration-fractionation effects in the vertical direction. Carboniferous crude oils are characterized by high migration parameters and low compound concentrations, just in contrast to Ordovician crude oils. This indicates that crude oils from shallow-level oil reservoirs were derived from those of deep-level oil reservoirs via faults, unconformable contact or carrier beds. Crude oils from the Tazhong region show some migration-fractionation effects in the lateral direction, but mixing of crude oils derived from different hydrocarbon source rocks in the process of formation of oil reservoirs made it more complicated the migration and accumulation of crude oils, as well as the formation of oil reservoirs.  相似文献   

6.
Based on the analysis of the hydrocarbon geochemical characteristics in the Kuqa petroleum system of the Tarim Basin, this study discusses the causes and controlling factors of the phase diversities and their differences in geochemical features. According to the characteristics and differences in oil and gas phase, the petroleum system can be divided into five categories: oil reservoir, wet gas reservoir, condensate gas-rich reservoir, condensate gas-poor reservoir and dry gas reservoir. The causes for the diversities in oil and gas phases include diversities of the sources of parent material, maturity of natural gas and the process of hydrocarbon accumulation of different hydrocarbon phases. On the whole, the Jurassic and Triassic terrestrial source rocks are the main sources for the hydrocarbon in the Kuqa Depression. The small differences in parent material may cause diversities in oil and gas amount, but the impact is small. The differences in oil and gas phase are mainly affected by maturity and the accumulation process, which closely relates with each other. Oil and gas at different thermal evolution stage can be captured in different accumulation process.  相似文献   

7.
In this study,12 crude oil samples were collected and analyzed from the Ordovician reservoir in the Halahatang Depression,Tarim Basin,China.Although the density of oil samples varies considerably,based on saturated hydrocarbon gas chromatographic(GC),saturated and aromatic hydrocarbon gas chromatographic-mass spectrometric(GC/MS) and stable carbon isotopic composition analyses,all the samples are interpreted to represent a single oil population with similar characteristics in a source bed or a source kitchen,organic facies and even in oil charge history.The co-existence of a full suite of n-alkanes and acyclic isoprenoids with UCM and 25-norhopanes in the crude oil samples indicates mixing of biodegraded oil with fresher non-biodegraded oil in the Ordovician reservoir.Moreover,according to the conversion diagram of double filling ratios for subsurface mixed crude oils,biodegraded/non-biodegraded oil ratios were determined as in the range from 58/42 to 4/96.Based on oil density and oil mix ratio,the oils can be divided into two groups:Group 1,with specific density>0.88(g/cm3) and oil mix ratio>1,occurring in the north of the Upper Ordovician Lianglitage and Sangtamu Formation pinchout lines,and Group 2,with specific density<0.88(g/cm3) and oil mix ratio<1,occurring in the south of the pinchout lines.Obviously,Group 2 oils with low densities and being dominated by non-biodegraded oils are better than Group 1 oils with respect to quality.It is suggested that more attention should be paid to the area in the south of the Upper Ordovician Lianglitage and Sangtamu Formation pinchout lines for further exploration.  相似文献   

8.
Production and storage-transportation of crude oil can not only give rise to soil pollution but also destroy ecological environment. Degradation of microbes for oily soil was studied with the instnunent, Geofina Hydrocarbon Meter (GHM), by experimental analysis qualitatively and quantitatively in the paper. Analytical result showed that the crude oil could be considerably degraded by eating-oil microbes in oily soil and the number of eating-oil microbes increased while the working hours of oil-well rising. As a result, contaminated oil could be degraded more quickly by a lot of eating-oil microbes in the soil. At the same time, the degradation rate of contaminated oil increased gradually as the time went on. In addition, amount of gaseous component in the oily soil samples increased with degraded time and the microbes could selectively consume contaminated oil strongly, so biedegradation might alleviate the degree of contamination and destruction to the soil and environment in the process of oil product  相似文献   

9.
The values of grains containing oil inclusions (GOI) in 120 reservoir sandstone samples from the central Junggar Basin of Northwest China were investigated. The sandstones are characterized by different types of hydrocarbon production and shows. The values range from 0.015% to 19.9%, and show a fairly good correlation with the hydrocarbon production/shows, which are qualitatively suggestive of reservoir hydrocarbon abundance and petroleum migration. Thus, it may be implied that the values can reflect hydrocarbon migration, being not controlled mainly by the other influencing factors. Further correlation between the values and the reservoir hydrocarbon production and show types indicates that the GOI method can be used in hydrocarbon migration study when the petroleum type of a reservoir is normal oil or gas alone, but it should be used with caution when light oil charges the reservoirs or a complex hydrocarbon migration event takes place. The case study in the central Junggar Basin using the method presents some new understanding on hydrocarbon migration. Thus, the method may help to solve specific petroleum geological problems, and can be treated as a routine tool in hydrocarbon migration study.  相似文献   

10.
Origins of High H_2S-bearing Natural Gas in China   总被引：2，自引：0，他引：2  
Natural gas containing hydrogen sulphide （H2S） has been found in several petroliferous basins in China, such as the Sichuan Basin, Bohai Bay Basin, Ordos Basin, Tarim Basin, etc. Natural gas with higher HES contents （HES 〉5 % mol.） is mostly distributed in both the gas reservoirs of Dukouhe, Luojiazhai, Puguang and Tieshanpo, which belong to the Triassic Feixianguan Formation in the northeastern Sichuan Basin and those of the Kongdian-Shahejie formations in the northeastern Jinxian Sag of the Jizhong Depression, Bohai Bay Basin. In the Sichuan Basin, the HES contents of natural gas average over 9% and some can be 17 %, while those of the Bohai Bay Basin range from 40 % to 92 %, being then one of the gas reservoirs with the highest H2S contents in the world. Based on detailed observation and sample analysis results of a total 5000 m of core from over 70 wells in the above-mentioned two basins, especially sulfur isotopic analysis of gypsum, brimstone, pyrite and natural gas, also with integrated study of the geochemical characteristics of hydrocarbons, it is thought that the natural gas with high HES contents resulted from thermochemical sulfate reduction （TSR） reactions. Among them, the natural gas in the Feixianguan Formation resulted from TSR reactions participated by hydrocarbon gas, while that in the Zhaolanzhuang of the Jinxian Sag being the product of TSR participated by crude oil. During the consumption process of hydrocarbons due to TSR, the heavy hydrocarbons were apt to react with sulfate, which accordingly resulted in the dry coefficient of natural gas increasing and the carbon isotopes becoming heavier.  相似文献   

11.
Abundant organic inclusions are present in the Qinglong antimony deposit. However, the source rocks of these organic matters have not been reliably identified. Recently, a paleo–oil reservoir was found in the Qinglong antimony deposit. In view of similar components of gaseous hydrocarbon, we propose that the organic matters observed in inclusions in Qinglong antimony deposit would come from this paleo–oil reservoir. We used the Re–Os dating method to determine the age of the bitumen from this paleo–oil reservoir, and obtained an isochron age of 254.3±2.8 Ma. The age indicates that the oilgeneration from source rock occurred in the early Late Permian, earlier than the Sb mineralization age(~148±8.5 Ma) in the Qinglong antimony deposit area. After oil generation from Devonian source rock, first and secondary migration, the crude oil have probably entered into the fractures and pores of volcanic rocks and limestone and formed a paleo–oil reservoir in the western wing of Dachang anticline. As burial process deepened, the crude oil has turned into natural gas, migrates into the core of Dachang anticline and formed a paleo–gas reservoir. The hydrocarbons(including CH_4) in the reservoirs can serve as reducing agent to provide the sulfur required for Sb mineralization through thermal chemical reduction of sulfates. Therefore, the formation of oil–gas in the area is a prerequisite for the Sb mineralization in the Qinglong antimony deposit.  相似文献   

12.
Based on the studies of geological history during the Paleozoic time. depoaitional esvironment, the evolution of organisms, the content of organic substances and the distribution of oil-generatlng strata, various indicators concerning oil generation are discussed and. compared in terms of Organic substance composition, the alkane and isopronoid in saturated hydrocarbon, characteristic functional group of the aromatic hydrocarbon and its structure, element composition and free radical concentration in asphaltene as well as carbon isotopes. The following conclusions can be drawn: (1) During the Later Paleozoic, the mud stone of the two oil-generating depressions of the Ponhsi Group on the western part of the basin was the most important reservoir and the black mud stone and limestone were secondary in importance. (2) Both the Ordovicoan Machiakou limestone and the shale of grapholithic facies are main oil (gas) generating strata in the western part of the basin. The Changhsia Group of the middle Cambrian system may also be oil-generatlng but is of little consequence. (3) Oil and gas formation in the Upper and. Lower Paleozoic groups represent two. different evolutionary stages. In the Upper Paleozoic group the petroleum formed is a kind of light oil, and large quantities of natural gas had been formed from the coal-bearing Taiyuan and Shansi Groups as a result of metamorphism. In response to the action of temperature and. presses over the prolonged geological period, oil sad gas formation in the lower Paleozoie group corresponds to a more advanced evolutionary stage, during which the generation of natural gas is the dominant process in comparation with oil condensation. Therefore the lower Paleozoic group is believed to be more promising for gas prospecting.  相似文献   

13.
Forty-six crude oil samples were selected from the Ordovician in the northwestern part of the Tahe oilfield for detailed molecular geochemical and isotopic analysis, including group compositions, carbonhydrogen isotopes and gas chroma-tograms of saturated hydrocarbons, as well as the characteristics of terpane, sterane and other biomarkers, indicating that crude oils are of the same origin from different districts in the Tahe oilfield and were derived from the same source kitchen (or oil source formation), i.e., mainly stemming from marine hydrocarbons. Detailed studies of oil physical properties of 25-honpane revealed that such oils have heavy or thick oil qualities due to biodegradation. Comprehensive assessment in terms of five maturity parameters shows that the oils from the Ordovician with Ro values varying from 0.80% to 1.59% are widely distributed in the northwest of the Tahe oilfield.  相似文献   

14.
This paper,based on the fundamental inorganic chemical and organic geochemical characteristics of oilfield waters from the Turpan Depression,presents the contents of organic matter,the distribution of low-carbon fatty acids and the contents of aromatic hydrocarbons as well as their principal ultraviolet absorption spectral and fluorescence spectral characteristics in oilfield waters from different oil/gas-bearing areas.The oil/gas reservoirs in this depression are classified in terms of their conserving conditions.In additon,the paper also discusses the chemical characteristics of oilfield waters from different types of oil/gas reservoirs with an emphasis on the characteristics of their localization in the γNa/γCa-γN a/γCl correction diagram.On this basis it is attempted to expound the fundamental geochemical characteristics of oilfield waters from the Turpan Depression and their geological significance.  相似文献   

15.
<正>In the process of oil and gas exploration,Hydrocarbon Assesment become more and more important.In this paper,the effection to hydrocarbon of the physical properties of the third member of Shahejie Formation in Dawangzhuang area is analyzed.By logging data analysis,the oil-saturation grade of Es3 in Dawangzhuang region can be divided into rich in oil,oil imersiond,oil  相似文献   

16.
<正>So far there has been no common opinion on oil source of the Chepaizi swell in the Junggar Basin.Therefore,it is difficult to determine the pathway system and trend of hydrocarbon migration, and this resulted in difficulties in study of oil-gas accumulation patterns.In this paper,study of nitrogen compounds distribution in oils from Chepaizi was carried out in order to classify source rocks of oils stored in different reservoirs in the study area.Then,migration characteristics of oils from the same source were investigated by using nitrogen compounds parameters.The results of nitrogen compounds in a group of oil/oil sand samples from the same source indicate that the oils trapped in the Chepaizi swell experienced an obvious vertical migration.With increasing migration distance,amounts and indices of carbazoles have a regular changing pattern(in a fine linear relationship).By using nitrogen compounds techniques,the analyzed oil/oil sand samples of Chepaizi can be classified into two groups.One is the samples stored in reservoir beds of the Cretaceous and Tertiary,and these oils came from mainly Jurassic source rock with a small amount of Cretaceous rock;the other is those stored in the Jurassic,Permian and Carboniferous beds,and they originated from the Permian source.In addition,a sample of oil from an upper Jurassic reservoir(Well Ka 6), which was generated from Jurassic coal source rock,has a totally different nitrogen compound distribution from those of the above-mentioned two groups of samples,which were generated from mudstone sources.Because of influence from fractionation of oil migration,amounts and ratios of nitrogen compounds with different structures and polarities change regularly with increasing migrating distance,and as a result the samples with the same source follow a good linear relationship in content and ratio,while the oil samples of different sources have obviously different nitrogen compound distribution owing to different organic matter types of their source rocks.These conclusions of oil source study are identical with those obtained by other geochemical bio-markers. Therefore,nitrogen compounds are of great significance in oil type classification and oil/source correlation.  相似文献   

17.
In the future time the exploration of marine oil and gas will be one of the significant domains in China. In this paper the biomarker assemblage characteristics of oilshow in the Nanlinghu Formation of the Majiashan profile, which is located in Chaoxian County, south of Anhui Province, are described in the light of gas chromatography/mass spectrometric （GCMS） analysis on the qualitative and quantitative basis. Based on the investigation of the biomarker assemblage characteristics of possible source rocks developed in the area studied, a conclusion is drawn that the oilshow was generated from the Nanlinghu Formation source rocks （abbreviated as Tin）, instead of the Qixia Formation source rocks （abbreviated as P1q）. It is pointed out that the Tin is of strong potential for future oil exploration, and therefore much attention should be paid to it.  相似文献   

18.
The uplift is a positive structural unit of the crust. It is an important window for continental dynamics owing to its abundant structural phenomena, such as fault, fold, unconformity and denudation of strata. Meanwhile, it is the very place to store important minerals like oil, natural gas, coal and uranium. Giant and large-scale oil and gas fields in China, such as the Daqing Oilfield, Lunnan-Tahe Oilfield, Penglai 19-3 Oilfield, Puguang Gas Field and Jingbian Gas Field, are developed mainly on uplifts. Therefore, it is the main target both for oil and gas exploration and for geological study. The uplift can be either a basement uplift, or one developed only in the sedimentary cover. Extension, compression and wrench or their combined forces may give rise to uplifts. The development process of uplifting, such as formation, development, dwindling and destruction, can be taken as the uplifting cycle. The uplifts on the giant Precambrian cratons are large in scale with less extensive structural deformation. The uplifts on the medium- and small-sized cratons or neo-cratons are formed in various shapes with strong structural deformation and complicated geological structure. Owing to changes in the geodynamic environment, uplift experiences a multi-stage or multi-cycle development process. Its geological structure is characterized in superposition of multi-structural layers. Based on the basement properties, mechanical stratigraphy and development sequence, uplifts can be divided into three basic types ? the succession, superposition and destruction ones. The succession type is subdivided into the maintaining type and the lasting type. The superposition type can be subdivided into the composite anticlinal type, the buried-hill draped type, the faulted uplift type and the migration type according to the different scales and superimposed styles of uplifts in different cycles. The destruction type is subdivided into the tilting type and the negative inverted type. The development history of uplifts and their controlling effects on sedimentation and fluids are quite different from one another, although the uplifts with different structural types store important minerals. Uplifts and their slopes are the main areas for oil and gas accumulation. They usually become the composite oil and gas accumulation zones (belts) with multiple productive formations and various types of oil and gas reservoirs.  相似文献   

19.
The geochemical characteristics of crude oils and reservoir core extracts from the Kuche petroleum system are described and studied systematically by means of various geochemical techniques and methods to acquire molecular information. The results suggest crude oils from the petroleum system can be divided into two groups: marine oils and non-marine oils. The former represents the dominant oils found in the area. Tar mats were firstly discovered and determined accurately in terrestrial oil and gas reservoirs, with Lower Tertiary sandstone reservoirs in the Yaha oilfield of the Tarim Basin. However, based on the ratio of 20S/(20S 20R)C29 sterane as a maturity parameter, lacustrine oils filled into the Tertiary reservoirs in the direction toward the western part of the petroleum system. In contrast, according to the fact that methylcyclohexane indices of eastern oils are greater than those of western oils, the location in which coalgenerated oils filled into the Tertiary reservoirs lies in the eastern part of the petroleum system.  相似文献   

20.
Crude oil samples taken from the southern part of western Qaidam Basin were analyzed with GC/MS in order to understand the geochemical characteristics of crude oils. The results reveal that most crude oils are characterized by high abundance of gammacerane and C35 homohopane, which are the representative characteristics of saline lacustrine crude oils. Based on the variation of the ratios of gammacerane/C30 hopane （G/H） and C35 homoho-pane/C34 homohopane （C35/C34H）, two crude oil groups, A and B, are identified. Group-A crude oils mainly occurr in the north of the study area, with higher ratios of G/H （〉0.8） and C35/C34H （〉1.2）, whereas group-B crude oils, selected from the south of the study area, show lower ratios of G/H （〈0.8） and C35/C34H （〈1.0）. In addition, group-A crude oils are distinguished into three subgroups in accordance with their different ratios of G/H and C35/C34H and different distribution characteristics of n-alkanes, isoprenoids and steranes. These may be helpful for understanding the distribution characteristics of crude oils in the southern part of western Qaidam Basin and providing clues to the forthcoming exploration of crude oils and gas.  相似文献   

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