The Mesozoic–Cenozoic organic facies in the Lower Tagus sub-basin (Lusitanian Basin,Portugal): Palynofacies and organic geochemistry approaches     

《Marine and Petroleum Geology》2014

Studies of the Mesozoic and Cenozoic sequence crossed by the Barreiro-4 borehole provide an improved understanding of the organic matter deposited in the Lower Tagus sub-basin (Lusitanian Basin, Portugal) and the implications for the potential source rock and depositional environment. This study focused on 43 samples (Middle Jurassic to Neogene) that were subjected to palynofacies and organic geochemistry analyses (Total Organic Carbon, Rock-Eval pyrolysis and molecular biomarker analysis). The palynofacies data indicate that the sequence contains mainly phytoclasts (non-opaque phytoclasts). However, the Middle Jurassic samples are dominated by Amorphous Organic Matter (AOM). Continental and/or marine palynomorphs are present in all the samples. The Cretaceous samples are characterized by small amounts of kerogen that have high contents of solid bitumen. The Total Organic Carbon (TOC) content is generally less than 1 wt.%. The Rock-Eval S1 and S2 parameters vary from 0.01 to 3.50 mgHC/g rock and 0.15 to 34.03 mgHC/g rock, respectively, with the highest values corresponding to the Cretaceous samples. The hydrogen index (HI) and oxygen index (OI) values range from 35 to 552 mgHC/g TOC and 4 to 180 mgHC/g TOC, respectively. The T_max values range from 416 to 437 °C. The biomarker analysis showed that n-alkanes with 15–30 carbon atoms are present and usually have a unimodal distribution with a predominance of low to medium molecular weight compounds. The CPI values range between 0.63 and 3.65, and the pristane/phytane ratios vary between 0.48 and 1.64, indicating alternation of oxic–anoxic conditions along the sequence. The distribution of terpanes shows small amounts of tricyclic and tetracyclic terpanes in most of the samples (except for some Cretaceous samples) and a predominance of pentacyclic terpanes. The amount of 17α (H),22,29,30-trisnorhopane (Tm) usually exceeds the amount of 18α (H),22,29,30-trinorneohopane (Ts). The 20S/(20S + 20R) and αββ/(ααα + αββ) ratios of the C29 steranes generally have values below the range of equilibrium, indicating an immature stage of the OM.  相似文献   

干酪根分子结构在低熟阶段的演化特征：基于红外光谱分析     

郭隽虹  ;邹艳荣  ;颜永何  ;屈振亚  ;王晓锋  ;蔡玉兰  ;彭平安 《地球化学》2014,(5):529-537

为研究低熟气形成过程中大分子结构的变化情况,对吐哈盆地侏罗系八道湾组的煤与碳质泥岩干酪根在不同升温速率下进行了热解实验,借助于红外光谱分析,研究了不同热模拟温度下干酪根结构的特征与变化。结果表明,随热演化的进行,煤与碳质泥岩干酪根的芳香结构不断缩合,含氧官能团不断脱落,碳质泥岩干酪根中的脂肪族类有所降低。吐哈盆地低熟气主要来源于煤与碳质泥岩干酪根中的含氧官能团--羧基与甲氧基,以及碳质泥岩干酪根上的脂肪族。从干酪根结构上揭示了低熟气主要来源于Ⅲ型有机质的原因。  相似文献   

Source Rock Characterization and Petroleum Systems in North Ghadames Basin,Southern Tunisia     

Dhaou AKROUT  Hassène AFFOURI  Riadh AHMADI  Eric MERCIER  Mabrouk MONTACER 《Resource Geology》2011,61(3):270-280

This paper presents geochemical analysis of drilled cutting samples from the OMZ‐2 oil well located in southern Tunisia. A total of 35 drill‐cutting samples were analyzed for Rock‐Eval pyrolysis, total organic carbon (TOC), bitumens extraction and liquid chromatography. Most of the Ordovician, Silurian and Triassic samples contained high TOC contents, ranging from 1.00 to 4.75% with an average value of 2.07%. The amount of hydrocarbon yield (pyrolysable hydrocarbon: S2b) expelled during pyrolysis indicates a good generative potential of the source rocks. The plot of TOC versus S2b, indicates a good to very good generative potential for organic matter in the Ordovician, Silurian and Lower Triassic. However, the Upper Triassic and the Lower Jurassic samples indicate fair to good generative potential. From the Vankrevelen diagram, the organic matter in the Ordovician, Silurian and Lower Triassic samples is mainly of type II kerogen and the organic matter from the Upper Triassic and the Lower Jurassic is dominantly type III kerogen with minor contributions from Type I. The thermal maturity of the organic matter in the analyzed samples is also evaluated based on the T_max of the S2b peak. The Ordovician and Lower Silurian formations are thermally matured. The Upper Silurian and Triassic deposits are early matured to matured. However, Jurassic formations are low in thermal maturity. The total bitumen extracts increase with depth from the interval 1800–3000 m. This enrichment indicates that the trapping in situ in the source rocks and relatively short distance vertical migration can be envisaged in the overlying reservoirs. During the vertical migration from source rocks to the reservoirs, these hydrocarbons are probably affected by natural choromatography and in lower proportion by biodegradation.  相似文献   

Pyrolytic characteristics and kinetics of the marine green tide macroalgae, Enteromorpha prolifera     

�Ի�  �ƻ���  ����  �Ŵ���  ���� 《中国海洋湖沼学报》2011,29(5):996-1001

The marine macroalgae Enteromorpha prolifera was one of the main algal genera that occurred in the widespread green tides in Qingdao, China, during the summers of 2007, 2008 and 2010. It is thus a plentiful source of biomass and could be used as a biofuel. In this study, the pyrolytic characteristics and kinetics of E. prolifera were investigated using thermogravimetric analysis (TGA) method. Cornstalk and sawdust were used as comparisons. Pyrolytic characteristics were studied using TG-DTG (thermogravimetry-derivative thermogravimetry) curves. Three stages in the pyrolytic process were determined: dehydration, dramatic weight loss and slow weight loss. E. prolifera was pyrolyzed at a lower initial temperature than the two terrestrial biomass forms. The apparent activation energy values for the three types of biomass were calculated and the mechanism functions were determined using 16 different mechanism functions, frequently used in thermal kinetics analysis. Activation energy values varied with mechanism function and the range of activation energy values for E. prolifera, cornstalk, and sawdust were 25-50 kJ/mol, 60-90 kJ/mol and 120-155 kJ/mol, respectively. This indicates that E. prolifera has low thermal stability for pyrolysis and good combustion characteristics.  相似文献   

地下水硝酸盐¹⁵N和¹⁸O同位素在线测试技术研究   总被引：1，自引：1，他引：0  

徐文  周建伟  刘存富  甘义群  刘运德  张彦鹏 《岩矿测试》2013,32(2):311-318

测定水和土壤的氮氧同位素组成能够识别硝酸盐来源和研究氮素的迁移转化过程,用在线高温热解法测试硝酸盐的15N和18O同位素是目前应用最广泛、最流行的高新技术.但是由于离子源内NO的干扰,使该方法测定的δ㈨O值不准确,而采用He稀释法则可有效减少该项干扰 本文选取4个国际标准样品(IAEA-No-3、USGS32、USGS34和USGS35)和一个实验室标准样品(CUGL-No-1),使用元素分析仪耦合MAT 253稳定同位素比值质谱仪(EA-IRMS),在8个月时间内对100多个地下水样品进行238次测试,对在线高温热解测试硝酸盐15N和18O技术进行了检验,验证其实用性.得到三点新认识:①用KNO3作为靶样品形式成本低,且便于和国际标准对比;②在线高温热解法测定标准和样品中硝酸盐的15N和18O同位素组成需样量仅为500μg的KNO3,一次选样可同时测定NO3的δ15N和δ 18O,消耗时间仅720 s,δ15N和δ 18O的测试精度分别为0.25‰、0.6‰,达到了国外相应水平,速度快,效率高;③He稀释法可减少离子源内NO对δ 18O测试的干扰,不必改变EA-IRMS系统的任何硬件.  相似文献   

原油热模拟实验中重排藿烷类变化特征及其意义     

陈菊林  张敏 《现代地质》2016,30(4):871-879

通过对TZ62井原油进行热模拟实验,探讨热演化程度对原油中重排藿烷类化合物形成分布的影响及其地球化学意义。实验发现：在400～500 ℃阶段,随着热演化程度的增加,原油中高碳数微晶蜡类长链化合物热裂解和原油中的沥青质热降解作用对重排藿烷的形成具有贡献作用。在500～550 ℃对应的原油裂解高峰阶段,藿烷类化合物浓度明显降低,且17α(H)-藿烷比重排藿烷类化合物具有更快的热裂解速率。在温度为550～600 ℃阶段,较高的热演化程度对17α(H)-藿烷甲基重排作用形成重排藿烷具有贡献作用。重排藿烷参数(17α(H)-重排藿烷/17α(H)-藿烷、Ts/Tm)在400～500 ℃变化较弱,几乎不受热演化程度的影响;在500～550 ℃的原油裂解高峰阶段,逐渐增大;在550～600 ℃发生反转,逐渐减小。重排藿烷参数可作为高成熟阶段原油成熟度判识的有效参数,其有效应用范围是生油窗晚期至原油裂解高峰期。  相似文献   

Interaction of coal and oil in confined pyrolysis experiments: Insight from the yield and composition of gas hydrocarbons     

《Marine and Petroleum Geology》2013

Isothermal pyrolysis experiments were performed for coal alone, oil alone and coal plus oil with oil/coal ratios ranging from 0.0065 to 0.1995 at 305 °C and 50 MPa for 72 h in confined systems (gold capsules). The results of these experiments reveal the interaction between coal and oil, demonstrating that oil retards the generation of gas hydrocarbons from coal cracking while coal accelerates oil cracking into gas hydrocarbons. The yields of gas hydrocarbons vary greater with oil/coal ratio in the experiments of coal B plus oil than coal A plus oil because coal A has a higher HI value than does coal B. Oil cracking rate could increase by up to 10 or even higher times in the experiments of coal plus oil compared with oil alone, deduced from the yields and chemical compositions of gas hydrocarbons. This result suggests that gas hydrocarbons, especially wet gases were largely generated from the cracking of oil or extractable bitumen in the experiments of coal plus oil with oil/coal ratio higher than 0.1.  相似文献   

Characteristics of high heating rate biomass chars prepared under N₂ and CO₂ atmospheres     

A.G. Borrego  L. Garavaglia  W.D. Kalkreuth 《International Journal of Coal Geology》2009,77(3-4):409-415

Partial substitution of coal by biomass in combustion systems in conjunction with advanced technologies for CO₂ capture and storage may result in a significant reduction of greenhouse gases emissions. This study investigates three biomass chars produced from rice husk, forest residuals and wood chips under N₂ and CO₂ atmospheres using a drop tube furnace (DTF) heated at 950 °C. The char constitutes an unburned residue which has been devolatilized under conditions resembling in thermal history those in full scale boilers. Higher weight losses were achieved under N₂ than under CO₂ for each type of biomass, and the highest weight loss was that of wood chips biomass, followed by forest residuals and then rice husk. The results indicate significant morphological differences between the biomass chars produced. The wood chips yielded thick-walled chars with a cenospheric shape very similar to those of low-rank vitrinite. The forest residual chars were angular in shape and often had a tenuinetwork structure, while the rice husk chars retained their vegetal structure. Overall, the studied biomass chars can be described as microporous solids. However, in the case of the rice husk, the silica associated to the char walls was essentially mesoporous, increasing the adsorption capacity of the rice husk chars. The atmosphere in the DTF affects the development of porosity in the chars. The pore volumes of the rice husk and forest residual chars prepared under a CO₂ atmosphere were higher than those of chars prepared under a N₂ atmosphere, whereas the opposite was the case with the wood chip chars. The chars that experienced the most drastic devolatilization were those with the lowest intrinsic reactivity. This indicates a more efficient reorganization of the chemical structure that reduces the number of active sites available for oxygen attack. Overall a similar morphology, optical texture, specific surface area and reactivity were found for the biomass chars generated under N₂ and CO₂, which is a similar result to that obtained for coal chars.  相似文献   

Characterization of organic matter in surface sediments of the Mackenzie River Basin, Canada     

Jesse Carrie  Hamed Sanei  Fariborz Goodarzi  Gary Stern  Feiyue Wang   《International Journal of Coal Geology》2009,77(3-4):416-423

The particulate organic matter in < 63 µm surface sediments from the Mackenzie River and its main tributaries was studied using Rock-Eval pyrolysis and organic petrology. The organic matter in the sediments is dominated by refractory residual organic carbon (RC) of mainly terrigenous nature, as indicated by abundant inertinite, vitrinite, and type III kerogen. Sediments from the tributaries contained significantly more algal-derived organic matter than from the main channel of the river, highlighting the importance of low-energy system dynamics in the tributaries, which allows modest algal production, more accumulation, and better preservation of autochthonous organic matter. This is particularly true for tributaries fed by lacustrine systems, which showed the highest S1 and S2 fractions, and consequently higher total particulate organic carbon (POC) in the basin. Organic petrology of the sediment samples confirms abundant liptinitic materials (i.e., fat-rich structured algae, spores and pollen, cuticles, and resins). Forest fire and coal deposits are also confirmed to contribute to the basin. Assuming that suspended and fine surfacial sediments have a similar OC composition, the Mackenzie River is estimated to deliver a total POC flux of 1.1 Mt C/yr to its delta, of which 85% is residual carbon with liptinitic OC (S1 + S2) and S3 accounting for another 9% and 6%, respectively.  相似文献   

平庄凹陷烃源岩有机质成熟度评价     

高玉娟  张亚明  王宇林 《西安地质学院学报》2009,(1):48-52

平庄凹陷盖层中发育九佛堂组、沙海组和阜新组3套烃源岩,虽然以往围绕煤矿生产展开了大量的煤田地质勘探工作,但石油、天然气勘探工作较少,研究程度较低。为了客观评价平庄凹陷的油气资源,需对烃源岩有机质成熟度进行评判。在对平庄凹陷烃源岩岩石热解、镜质组反射率、生物标志物参数分析的基础上,对平庄凹陷九佛堂组、沙海组烃源岩有机质热演化特征及演化阶段进行了系统研究。结果表明：平庄凹陷烃源岩各参数随埋藏深度的增加变化明显,具有纵向上的连续性和横向上的不均匀性;平庄洼陷烃源岩有机质成熟度处于未成熟—低成熟—成熟阶段,其中,九佛堂组烃源岩是盆地的主要成油岩系;四龙洼陷烃源岩有机质成熟度较低,对盆地成烃贡献不大。  相似文献