Fingerprinting of biomarker characteristics of some Egyptian crude oils in Northern Western Desert as evidence for organic matter input and maturity level assessment

This study describes the fingerprinting of crude oils from different Egyptian oil formations using gas chromatography (GC) and gas chromatography mass spectrometry (GC–MS). The samples were obtained from Gindi, Abu El gharadig, south deep Abu El gharadig, Dahab- Merier and Faghur basins from Western Desert. Diagnostic biomarkers parameters applied in this study provide evidences about the source of organic matter, the depositional environment and maturity of the studied oils. The results showed that the crude oils of Faghur basin are believed to be originated from mixed source predominately terrestrial with chief contribution of clastic rocks deposited under oxic conditions. However, the crude oils from Gindi, Abu El gharadig, South deep Abu El gharadig and Dahab- Merier basins were generated from marine carbonate source rock deposited under anoxic depositional environment.     

Burial and thermal history simulation of the subsurface Paleozoic source rocks in Faghur basin,north Western Desert,Egypt: Implication for hydrocarbon generation and expulsion history

Paleozoic Zeitoun, Desouqy and Dhiffah formations represent source rocks to hydrocarbon in Faghur basin, north Western Desert, Egypt. They are characterized by a sufficient amount of organic matter belonging to kerogen type III and mixed type II/III, which are in maturation stage. A 1D-basin modeling was performed by using geological and geochemical data of the Paleozoic source rocks from five wells in Faghur basin, north Western Desert, Egypt. These data used in 1D basin modeling for constructing and understanding of burial and thermal geo-histories of Faghur basin and for simulating and predicting the timing of petroleum and expulsion for the Paleozoic source rocks in the studied wells. Burial and thermal history models indicate that the Zeitoun Formation entered onset of oil generation in the studied wells during Late Cretaceous (100.10–91.65 my) with transformation ratio (TR) 10–25, peak oil during Late Cretaceous (91.65–79.30 my) with TR 25–50 and late oil stage at Late Cretaceous (79.30 my-0) to present day with TR 50–60.45. Desouqy Formation entered onset of oil generation also during Late Cretaceous (94.43–73.60 my) with TR 10–25 in the studied wells, peak oil during Late cretaceous (73.60–62.40 my) with TR 25–50 and Late oil stage during Late Cretaceous to present day (62.40 my-0) with TR 50–61.82. Dhiffah Formation entered onset of oil generation in the studied wells during Early to Late Cretaceous (102.11–92.27 my) with TR 10–25, peak oil during Late Cretaceous (92.27–86.40 my) with TR 25–50 and late oil stage at Late Cretaceous to present day (86.40 my-0) with TR 50–67.27. No cracking oil to gas in the studied Paleozoic source rocks in the studied wells. These basin modeling results also suggest that the Paleozoic source rocks act as an effective source rock where a significant amount of petroleum is expected to be generated and expelled to any nearby prospect reservoir rocks in the Faghur basin.     

API gravities,vanadium, nickel,sulfur, and their relation to gross composition: Implications for the origin and maturation of crude oils in Western Desert,Egypt

In the present study, the geochemical analyses of API gravities, vanadium, nickel, sulfur, and bulk composition were performed on eight samples from productive wells in Gindi, South Deep Abu-gharadig, Abu-gharadig, Dahab-Merier, and Faghure basins locates in the North Western Desert. The results were used to describe the source organic matter input, depositional environment, assess the degree of thermal maturity, and to correlate between crude oils to determine the genetic relationship between hydrocarbon generation and their source rock for the studied oil samples. The results showed that a wide range of crude oil parameters exists in this data, indicating that a variety of oil types is represented. Crude oils range from unaltered to altered by vanadium, nickel, and sulfur concentrations, V/Ni and saturate fraction were used to classify the oils. Oils are classified into two groups. Group I contains oil samples from Gindi, South deep Abu-gharadig and Abu-gharadig, and Dahab-Merier that are generated from organic matter input deposited in marine environment under anoxic to suboxic conditions. Group II from Faghur basin possess high Pr/Ph ratios suggesting high contribution of terreginous organic matter deposited under relatively oxic conditions.     

Geochemical characterization of aromatic hydrocarbons in crude oils from the Tarim,Qaidam and Turpan Basins, NW China

Based on the systematic study of aromatic hydrocarbons in over 100 crude oil samples collected from the Tabei and Tazhong uplifts in the Tarim Basin, the western depression area in the Qaidam Basin and the Tabei depression in the Turpan Basin, the geochemical characteristics of the marine (Tarim Basin), saline lacustrine (Qaidam Basin), and swamp (Turpan Basin) oils were investigated. The marine oils from the Tarim basin are characterized by relatively low abundance of diaromatic hydrocarbons such as biphenyl and naphthalene, and relatively high abundance of triaromatic hydrocarbons including phenanthrene, dibenzothiophene and fluorene. In contrast, the swamp oils from the Turpan Basin are dominated by the highest relative abundance of diaromatic hydrocarbons and the lowest relative abundance of triaromatic hydrocarbons in all the oil samples in this study. The relative abundance of diaromatic and triaromatic hydrocarbons in the saline lacustrine oils from Qaidam Basin is between that in Tarim oils and Turpan oils. Aromatic parameters based on the isomer distributions of dimethylnaphthalenes (DMN), trimethylnaphthalenes (TMN), tetramethylnaphthalenes (TeMN) and methylphenanthrenes (MP), i.e., 1,2,5-trimethylnaphthalene(TMN)/1,3,6-TMN ratio, 1,2,7-TMN/1,3,7- TMN ratio, (2,6- +2,7-)-dimethylnaphthalenes (DMN)/1,6-DMN ratio, 1,3,7-TMN/(1,2,5- +1,3,7-)-TMN, 1,3,6,7-TeMN/(1,3,6,7- +1,2,5,6- +1,2,3,5-)-TeMN ratio and MP index, may reflect the diversity of organic source input, thermal maturity and depositional environments. In addition, the dibenzothiophenes (DBTs)/fluorenes(Fs) and dibenzofurans (DBFs)/Fs ratios were found to the very useful and effective in determining genetic types of crude oils for the marine, saline lacustrine, and swamp depositional environments, and for oil-oil correlations.     

Geochemical characterization of aromatic hydrocarbons in crude oils from the Tarim,Qaidam and Turpan Basins,NW China

Based on the systematic study of aromatic hydrocarbons in over 100 crude oil samples collected from the Tabei and Tazhong uplifts in the Tarim Basin, the western depression area in the Qaidam Basin and the Tabei depression in the Turpan Basin, the geochemical characteristics of the marine (Tarim Basin), saline lacustrine (Qaidam Basin), and swamp (Turpan Basin) oils were investigated. The marine oils from the Tarim basin are characterized by relatively low abundance of diaromatic hydrocarbons such as biphenyl and naphthalene, and relatively high abundance of triaromatic hydrocarbons including phenanthrene, dibenzothiophene and fluorene. In contrast, the swamp oils from the Turpan Basin are dominated by the highest relative abundance of diaromatic hydrocarbons and the lowest relative abundance of triaromatic hydrocarbons in all the oil samples in this study. The relative abundance of diaromatic and triaromatic hydrocarbons in the saline lacustrine oils from Qaidam Basin is between that in Tarim oils and Turpan oils. Aromatic parameters based on the isomer distributions of dimethylnaphthalenes (DMN), trimethylnaphthalenes (TMN), tetramethylnaphthalenes (TeMN) and methylphenanthrenes (MP), i.e., 1,2,5-trimethylnaphthalene(TMN)/1,3,6-TMN ratio, 1,2,7-TMN/1,3,7-TMN ratio, (2,6-+2,7-)-dimethylnaphthalenes (DMN)/1,6-DMN ratio, 1,3,7-TMN/(1,2,5- +1,3,7-)-TMN, 1,3,6,7-TeMN/(1,3,6,7- +1,2,5,6- +1,2,3,5-)-TeMN ratio and MP index, may reflect the diversity of organic source input, thermal maturity and depositional environments. In addition, the dibenzothiophenes (DBTs)/fluorenes(Fs) and dibenzofurans (DBFs)/Fs ratios were found to the very useful and effective in determining genetic types of crude oils for the marine, saline lacustrine, and swamp depositional environments, and for oil-oil correlations.     

GEOCHEMICAL CHARACTERIZATION OF POTENTIAL JURASSIC/CRETACEOUS SOURCE ROCKS IN THE SHUSHAN BASIN, NORTHERN WESTERN DESERT, EGYPT

Some 180 core and cuttings samples of shales and limestones from the Middle Jurassic – Late Cretaceous succession (Khatatba, Masajid, Alam El-Bueib, Alamein, Kharita, Bahariya and Abu Roash Formations) were collected from wells Ja 27–2, Tarek-1 and Jb 26–1 in the central, structurally-low part of the Shushan Basin and from well Lotus-1 in the structurally-elevated western part of the basin. All samples were screened for total organic carbon (TOC) content. Selected samples were then analyzed by Rock-Eval pyrolysis, and extracted for biomarker analyses. Visual kerogen analysis and vitrinite reflectance measurements were also undertaken and oil - source rock correlations were attempted. The results indicate that the thermal maturity of the samples can be correlated closely with burial depth. Samples from the central part of the basin are more mature than those from the west. Samples from the central part of the basin (except those from the Albian Kharita Formation) have reached thermal maturities sufficient to generate and expel crude oils. Extracts from the Middle Jurasic Khatatba and Early Cretaceous Alam El-Bueib Formations can be correlated with a crude oil sample from well Ja 27–2.
In well Lotus-1 in the west of the basin, four distinct organic facies can be recognized in the Jurassic-Cretaceous interval. One of the facies ("facies 4") has a sufficiently high TOC content to act as a source rock. Thermal maturities range from immature to peak oil generation, and the top of the oil window occurs at approximately 8000 ft.     

Applications of Polycyclic Aromatic Hydrocarbons to Assess the Source and Thermal Maturity of the Crude Oils from the Lower Indus Basin,Pakistan

Abstract

A suite of six crude oils from Lower Indus Basin, Pakistan, were analyzed for geochemical characterization of source organic matter (OM) and thermal maturity. Distribution of polycyclic aromatic hydrocarbons (PAHs), alkylnaphthalenes, alkylphenanthrenes, alkyldibenzothiophenes, and aromatic biomarkers were reported from aromatic fractions of the crude oils. The aromatic hydrocarbons parameters revealed a higher thermal maturity of OM of source rock-generated Lower Indus Basin oils. Calculated vitrinite reflectance values from the methylphenanthrenes index 1 (MPI-1) and methyldibenzothiophene ratio (MDR) indicate that most of the oils reached a late oil generation window of thermal maturity. PAH distributions revealed the oils of two different origins are present in the Lower Indus Basin; two oil samples indicate aquatic source of OM and the aromatic biomarker distributions of retene, 1-MP, and 1,7-DMP indicate a significant contribution of land plant OM in the other four oils. This is the first study to report the distribution of aromatic hydrocarbons from Lower Indus Basin crude oils.     

有机质碳同位素的成熟分馏作用及地质意义

本文以各种热模拟实验产物的稳定碳同位素分析为基础,对有机质热演化产物的油、油族组份。气态烃、残渣的稳定碳同位素动力分馏机制进行探讨。同时提出区分低演化凝析油(煤系产物)与高成熟凝析油(原油裂解产物)的新方法,为识别天然气成因类型提供了新的途径。      

Mango轻烃参数的开发与应用

通过对塔里木盆地５４０个原油样品轻烃资料的系统研究，发现石油中４个异庚烷的比值（Ｋ１）不是一个常数，其变化范围在０．７４０～１．５４０之间，导致Ｋ１值变化的主要原因可能是烃源岩沉积介质中酸性催化剂催化作用的强弱。探讨了２，３二甲基戊烷／２，４二甲基戊烷比值与常用成熟度参数（庚烷值、甲基菲指数１、甲基菲指数２、Ｃ２９甾烷异构化比值）之间关系，结果表明２，３二甲基戊烷／２，４二甲基戊烷比值是一个有效的成熟度参数。利用Ｍａｎｇｏ提出的Ｃ７烃类形成动力学模式关系图及环优势参数，对塔里木盆地原油进行了对比与成因分类。图５表１参１２（邓春萍摘     

准噶尔盆地春光区块沙湾组原油芳烃特征

为查明准噶尔盆地西北缘车排子地区的油气来源,对春光区块中新统沙湾组40个原油样品进行GC-MS分析,全面系统地研究了芳烃类生物标志物的分布和组成特征,并探讨了其地质地球化学意义。春光区块沙湾组原油中检测到了丰富的芳烃,为判断有机质成熟度、母质类型、油气充注和运移方向提供了依据。春光区块沙湾组原油处于成熟阶段,形成于陆相成油环境,其母质有一定高等植物输入的贡献,且不同类型原油的母质有所差异;根据五甲基萘指数与甲基二苯并噻吩指数比值,研究区沙湾组原油来源于西南和东南2个方向,轻质原油距离烃源区近,油源单一,而中质和重质油距离烃源区较远,中质油为混源油,重质油则为高度降解油。     

松辽盆地白至系泥岩粘土矿物的成岩演变规律与油、气分布的关系

白垩系泥岩样品经提纯分离,取<2μ的粘粒供x-射线衍射分析和失重分析.部分样品测定了泥岩交换性阳离子的组成和镜质体反射率.     

Oil-source correlation and the impact of oil-filling process on geochemical composition of the different states of oils in the Upper Triassic Chang 7 Formation,Ordos basin,China

Five crude oil samples from five wells and 33 oil-containing sandstone reservoir rock samples from six wells of Chang 7 sub-unit were systematically studied to determine hydrocarbons in these oil reservoirs whether are the mixtures of oil components derived from different source rocks or from the same source rock during oil filling process over geological times. Sequential extraction was applied to the oil-containing reservoir rocks to deserve the free and adsorbed oils. The distribution of alkanes, hopanes and steranes and the correlation diagram of Pr/n-C₁₇ versus Ph/n-C₁₈ show that these oil components and crude oils have similar parent materials. And on this basis we compared the thermal maturity of the crude oils, the free oils and adsorbed oils and found that the thermal maturity of these oils is different. The cross plot of C₂₉αα-20S/(20S+20R) versus C₂₉ββ/(αα+ ββ) and the correlation diagram of Pr/n-C₁₇ versus Ph/n-C₁₈ both show that the crude oils have highest thermal maturity, followed by the free oils and then the adsorbed oils. The ratios of ∑C₂₁^?/∑C₂₂⁺ for the crude oils and free oils are greater than the adsorbed oils, indicating the crude oils and free oils have suffered more thermal stress and extensive cracking than that of the adsorbed oils. These geochemical data reveal that hydrocarbons in these oil reservoirs and crude oils were derived from the same source rock with different thermal maturity over geological times.     

芳烃参数重建原油成熟度及其在哈山地区的应用

原油成熟度由于不能采用实验方法直接测定,多利用生标物参数进行判识。常用的生标物成熟度参数多为定性分析,且不适用于高成熟阶段的原油样品。以低热演化程度的烃源岩样品为研究对象,通过进行高温热模拟实验,分析了不同热演化阶段下液态烃产物的芳烃特征,探讨各芳烃参数与实测热成熟度的关系。结果显示,甲基菲、三甲基萘等参数与热成熟度具有较好的相关性,据此建立了各参数与热成熟度的拟合公式;并对哈山地区油砂样品进行了成熟度判识,其中二叠系、三叠系和侏罗系原油成熟度较低,白垩系原油成熟度较高。      

江汉盐湖盆地原油及生油岩中生物标记化合物的特征及其地质意义

江汉盆地是一个比较典型的中新生代陆相盐湖盆地。它的特定的高盐度、强还原性地质环境使下第三系生油岩及原油有其特殊性。本文试图利用通过红外、紫外、荧光、色谱-质谱等多种手段分析江汉盆地生油岩及原油(以潜江凹陷潜江组为主)而取得的有关卟啉、菲、萜烷、甾烷等生物标记化合物的资料,结合过去取得的镍、钒等分析结果,进一步总结盐湖盆地生油岩及原油的特征,并据此对沉积环境、原油及生油岩的演化程度以及油源对比等问题,进行初步探讨。     

莺-琼盆地原油成熟度研究

运用反映原油整体面貌及反映原油组成的成熟度参数对莺-琼盆地原油(凝析油)进行综合研究后认为,莺-琼盆地原油(凝析油)主体可能是成油高峰期的产物,但有程度不同的未熟―低熟原油的混入。凝析油并不一定是高温裂解的产物,在相应地质条件下,正常的成熟度也可形成凝析油。金刚烷业已用于原油成熟度研究,但在莺―琼盆地未熟―低熟油样品抽提物中均发现了单、双金刚烷,说明金钢烷不一定只受高温条件的控制,其形成还可能受沉积环境的影响,故将金刚烷参数用作成熟度指标时要慎重。     

塔里木盆地塔河油田原油中双金刚烷分布特征与油气运移

研究了塔里木盆地塔河油田原油中双金刚烷的分布特征，探讨了该油田油气的充注期次和运移方向，结果表明，原油中双金刚烷指标值反映了原油的成熟度，并且指示研究区4区和6区原油充注时间较早、9区原油充注时间较晚，其它油区原油充注时间介于上述二者之间；原油中双金刚烷指标值分布特征显示出塔河油田下奥陶统油气存在2个充注方向，一是由南向北，并且油气成熟度相对较低，可能主要代表了早期的油气运移，另一个是由东向西，原油成熟度相对较高，可能主要代表了晚期的油气运移。根据原油成熟度和运移方向特征，认为塔河油田的早期油气起源于满加尔坳陷，晚期油气起源于满加尔坳陷和草湖坳陷，主力烃源岩层为寒武-奥陶系。     

塔里木盆地顺北油气田1号和5号断裂带奥陶系油气藏特征

综合运用油气地球化学分析技术对顺北油气田1号和5号主干断裂带奥陶系油气藏进行研究,并结合油气物理性质和烃类相态特征等数据资料来开展不同断裂带上油气藏特征精细对比,从而探讨不同断裂带油气藏特征差异成因。结果表明,两条不同断裂带油气藏的油气源特征相似,均来自于还原性较强的腐泥型生烃母质,且均处于高成熟演化阶段,但顺北1号断裂带为未饱和挥发油藏,顺北5号断裂带为未饱和轻质油藏,1号断裂带油气成熟度明显高于5号断裂带。两条断裂带油气藏特征出现差异主要与顺北地区不同的油气充注过程和后期改造作用有关:顺北地区可能存在3期油气充注,5号断裂带油气藏为前两期油气的混合充注,最早一期油气遭到破坏,以第二期油气充注为主,而1号断裂带油气藏以最晚的第三期油气充注为主;两条断裂带油气藏均未经历明显的热裂解作用,但是1号断裂带原油经历轻微的硫酸盐热化学还原改造作用(TSR),而5号断裂带早期充注原油经历过生物降解作用(BSR)。不同的油气充注过程是导致顺北地区不同断裂带油气藏特征差异的主要因素。     

东营凹陷南斜坡东段原油的地球化学特征

东营凹陷南斜坡东段古近系原油具有“多源和远源”的复杂油源条件,原油成因分类成为该区油气地质研究中的一个难点。通过系统分析45处样点共61个原油及岩石氯仿抽提物的生物标志化合物构成特征,对该区原油进行了成因分类和油源判别。该区存在着3种成因类型原油。Ⅰ类原油具有m(Pr)/m(Ph)比值低、甾类化合物异构化程度低和伽马蜡烷相对含量高的特征,反映出Ⅰ类原油可能主要来自沙四上亚段生油岩;Ⅱ类原油的m(Pr)/m(Ph)比值高,甾类化合物异构化程度高和伽马蜡烷相对含量低,表明原油可能主要来自沙三下亚段生油岩;Ⅲ类原油的m(Pr)/m(Ph)比值较高,甾类化合物异构化程度较低,伽马蜡烷相对含量极高,并且相对富含三环萜烷和C₂₉规则甾烷,而δ¹³C值明显偏轻,表明该区可能存在一套尚未落实的生油岩。多种成因类型原油的存在表明,断陷盆地缓坡带油源多样、油气运移和聚集过程复杂,该类构造单元仍存在很大油气勘探潜力。     

原油中吡咯类含氮化合物的分布型式

不同类型原油的实验结果表明:原油中存在咔唑、苯并咔唑及二苯并咔唑3类吡咯类化合物,且以前两类为主。两大系列同系物的相对丰度呈正态分布。咔唑、苯并咔唑的分布型式除与原油母质类型有关外,还受油气运移及热成熟作用的影响。高等植物输入较多的原油相对富集烷基苯并咔唑和二苯并咔唑;油气运移距离增加,咔唑系列相对富集;成熟度增加,低分子量化合物富集。由于原油中吡咯类化合物的取代位优先且局限于某些特定的部位,所以其分布型式存在多种同分异构体。不同的同分异构体可能与干酪根先质的结构有关。