共查询到20条相似文献，搜索用时 46 毫秒
1.
A number of bitumen samples have been recovered from vugs and fractures in outcropping Tertiary basalts of the Queen Charlotte Islands off the west coast of British Columbia, Canada. n-Alkanes and acyclic isoprenoids are not present and the polycyclic biomarker distribution of the four samples analyzed by GC and GC-MS has been altered. One sample contains no remaining recognizable biomarkers. Two bitumens were also obtained from Lower Jurassic potential source rocks, including one from the Sandilands Formation, which was considered previously to be the most likely source of the Tertiary bitumens. Although these two bitumens were also taken from outcrops, they are considerably less biodegraded. The Sandilands Formation bitumen contains 28, 30-bisnorhopanes and since these compounds were not detected in the Tertiary bitumens, there is no evidence from the initial results for a Sandilands Formation contribution to the hydrocarbons in the Tertiary basalts. The presence of 18α(H)-oleanane in the saturate fraction of two of the Tertiary bitumens from widely separated locations indicates that they are at least partially sourced from Tertiary organic matter.Because the distribution of biomarkers in some samples has been severely affected by biodegradation, the asphaltenes of the bitumens were hydrously-pyrolysed and the saturate fractions of the resulting pyrolysates analysed for possible additional information on the origin of the bitumens. The pyrolysates from the more degraded samples contain compounds not detected in the saturate fractions of the original bitumen and show some of the expected characteristics of the original non-degraded bitumen. However, the compounds most useful for correlation are not present in the pyrolysates apparently due to their non-incorporation into the kerogen macromolecule. Our results suggest that hydrous-pyrolysis of asphaltenes is of limited use in the correlation of biodegraded samples and in determining their origins. 相似文献
2.
《Applied Geochemistry》1993,8(3):245-254
The Porphyrin Maturity Parameter (PMP), which is derived from the vanadyl porphyrin distribution, is an excellent parameter for: (1) identifying the zone of hydrocarbon generation from marine source rock extracts; and (2) determining from oils the thermal maturity of their source rocks at expulsion.The PMP is measured using a methodology which is inexpensive, reliable and faster than earlier methods, allowing it to be used as a routine exploration tool. The PMP may be a more reliable maturity indicator for marine organic matter than some conventional methods such as vitrinite reflectance. Unlike most conventional maturity parameters guided by processes other than kerogen conversion, the reactions causing PMP evolution directly monitor the generation of bitumen and the concurrent thermal degradation of kerogen.Measurements on hydrous pyrolyzates from the Monterey Formation (offshore California), source rock bitumens from the Devonian-Mississippian Bakken Shale (Williston Basin), and Miocene Monterey equivalent source strata (San Joaquin Basin, California) illustrate the method. In all cases reviewed so far, PMP begins increasing at the onset of hydrocarbon generation and increases systematically and predictably as kerogen decomposition proceeds.In oils generated from high-S marine kerogens, PMP reflects the maturity of the source rock at the time of oil expulsion, provided that the oil does not undergo subsequent reservoior maturation or mixing with in-situ bitumen. 相似文献
3.
M.D Lewan 《Geochimica et cosmochimica acta》1983,47(8):1471-1479
Acquiring crude oils that have been expelled from the same rock unit at different levels of thermal maturation is currently not feasible in the natural system. This prevents direct correlation of compositional changes between the organic matter retained in a source rock and its expelled crude oil at different levels of thermal maturation. Alleviation of this deficiency in studying the natural system requires the use of laboratory experiments. Natural generation of petroleum from amorphous type-II kerogen in the Woodford Shale may be simulated by hydrous pyrolysis, which involves heating crushed rock in contact with water at subcritical temperatures (<374°C). Four distinct stages of petroleum generation are observed from this type of pyrolysis; (1) pre-oil generation, (2) incipient-oil generation, (3) primary-oil generation, and (4) post-oil generation.The effects of thermal maturation on the δ13C values of kerogen, bitumen, and expelled oil-like pyrolysate from the Woodford Shale have been studied through these four stages of petroleum generation. Similar to the natural system, the kerogens isolated from the pyrolyzed rock showed no significant change in δ13C. This suggests that the δ13C value of kerogens may be useful in kerogen typing and oil-to-source rock correlations. δ13C values of bitumens extracted from the pyrolyzed rock showed an initial decrease during the incipient-oil generation stage, followed by depletion during the primary- and post-oil generation stages. This reversal is not favorable for geochemical correlation or maturity evaluation. Saturated and polar components of the bitumen show the greatest δ13C variations with increasing thermal maturation. The difference between the δ13C of these two components gives a unidirectional trend that serves as a general indicator of thermal maturation and is referred to as the bitumen isotope index (BII).δ13C values of the expelled pyrolysates show a unidirectional increase with increasing thermal maturation. The constancy and similarity of δ13C values of the aromatic components in the expelled pyrolysates and bitumens, with increasing thermal maturation, encourages their use in oil-to-oil and oil-to-source rock correlations. Isotopic type-curves for expelled pyrolysates indicate that they may be useful in oil-to- oil correlations, but have a limited use in oil-to-source rock correlations. 相似文献
4.
The triterpenoid hydrocarbons of some West Australian shales have been examined by GC-MS. In addition to the common 17α(H),21β(H)-hopanes, 17β(H),21β(H)-hopanes and 17β(H),21α(H)-moretanes, 28,30-bisnorhopane, 25,28,30-trisnorhopane and 25-norhopanes were identified in the organic extracts. In contrast, pyrolysates of the solvent-extracted sediments contained only the common hopane and moretane series, indicating that 28,30-bisnorhopane, 25,28,30-trisnorhopane and 25-norhopanes are not bonded to kerogen, but rather are present in the sediments as free hydrocarbons. 相似文献
5.
准噶尔盆地西南缘四棵树凹陷主要分布侏罗系、白垩系和古近系3套潜在烃源岩,其中侏罗系八道湾组烃源岩有机质丰度较高,有机质类型以Ⅲ型为主,部分为Ⅱ2型,生烃潜力较高;三工河组烃源岩有机质丰度、类型明显偏差,生烃潜力较低;西山窑组泥岩有机质丰度较高,但由于受西山窑组沉积末期构造抬升导致地层剥蚀的影响,烃源岩厚度较小,总体上生烃条件较差;白垩系烃源岩在四棵树凹陷最大厚度可达300 m,处于低熟阶段,生烃潜力较小;古近系烃源岩有机质丰度较高、类型好,但成熟度偏低,生烃条件较差。侏罗系八道湾组烃源岩处于主要生油阶段;白垩系烃源岩已达到生烃门限,处于低熟—中等成熟阶段;古近系烃源岩成熟度偏低,目前仍处于未熟到低熟阶段。油源对比表明,四棵树凹陷北部斜坡及车排子凸起带原油主要来源于四棵树凹陷及沙湾凹陷侏罗系烃源灶,后期受到白垩系低熟油源灶的侵染,古近系烃源岩的油源贡献有限。 相似文献
6.
Ger Van Graas 《Organic Geochemistry》1986,10(4-6)
Biomarker distributions in a suite of asphaltenes and kerogens have been analysed by flash pyrolysis directly coupled to a GCMS system. Attention has been focussed on biomarkers of the sterane and triterpane types. The sample suite under investigation consists of sediments with different kerogen types and some crude oils. Biomarker distributions in the pyrolysates have been compared with the “free” biomarkers in the corresponding saturated hydrocarbon fractions.The analyses show significant differences between the distributions of the free biomarkers and those in the pyrolysates. The latter have lower amounts of steranes while diasteranes are absent or present at low concentrations only. In the triterpane traces a shift of maximum intensity from C30 (free compounds) to C27/C29 is observed. Furthermore, the pyrolysates contain a set of triterpenes (not present among the free compounds), and there is a selective loss of “non-regular” triterpanes that are present in the saturated hydrocarbon fractions. The observed differences between pyrolysates and free hydrocarbons can be explained partly by the processes occurring during pyrolysis such as bond rupture and subsequent stabilisation of primary pyrolysis products. To a certain extent these differences also show that maturation processes occurring in sediments have effects on free biomarker molecules different from those on molecules that are enclosed in a macromolecular matrix (kerogen or asphaltenes).Differences between biomarker distributions of asphaltene and kerogen pyrolysates are relatively small. A comparison with the pyrolysates from extracted whole sediments suggests that these differences are mainly caused by interactions between the organic material and the mineral matrix during pyrolysis.Oil asphaltenes behave differently from sediment asphaltenes as their pyrolysates are more similar to the corresponding saturated hydrocarbon fractions, i.e. the differences described above are observed to a much smaller extent. This different behaviour appears to be the result of coprecipitation of a part of the maltene fraction with the oil asphaltenes. 相似文献
7.
Hydrous and anhydrous closed-system pyrolysis experiments were conducted on a sample of Mahogany oil shale (Eocene Green River Formation) containing Type-I kerogen to determine whether the role of water had the same effect on petroleum generation as reported for Type-II kerogen in the Woodford Shale. The experiments were conducted at 330 and 350 °C for 72 h to determine the effects of water during kerogen decomposition to polar-rich bitumen and subsequent bitumen decomposition to hydrocarbon-rich oil. The results showed that the role of water was more significant in bitumen decomposition to oil at 350 °C than in kerogen decomposition to bitumen at 330 °C. At 350 °C, the hydrous experiment generated 29% more total hydrocarbon product and 33% more C15+ hydrocarbons than the anhydrous experiment. This is attributed to water dissolved in the bitumen serving as a source of hydrogen to enhance thermal cracking and facilitate the expulsion of immiscible oil. In the absence of water, cross linking is enhanced in the confines of the rock, resulting in formation of pyrobitumen and molecular hydrogen. These differences are also reflected in the color and texture of the recovered rock. Despite confining liquid-water pressure being 7-9 times greater in the hydrous experiments than the confining vapor pressure in the anhydrous experiments, recovered rock from the former had a lighter color and expansion fractures parallel to the bedding fabric of the rock. The absence of these open tensile fractures in the recovered rock from the anhydrous experiments indicates that water promotes net-volume increase reactions like thermal cracking over net-volume decrease reactions like cross linking, which results in pyrobitumen. The results indicate the role of water in hydrocarbon and petroleum formation from Type-I kerogen is significant, as reported for Type-II kerogen. 相似文献
8.
Alexander Chakhmakhchev Masaru Suzuki Amane Waseda Kuniaki Takayama 《Organic Geochemistry》1997,27(7-8)
Siliceous sourced Tertiary oils from the Circum-Pacific area of Japan, Russia and the U.S.A. have a heavy carbon isotope composition, monomodal n-alkane distributions, and nearly identical regular sterane compositions with a predominance of C27 homologues. These are consistent with open marine depositional environments dominated by diatomaceous organic matter. However, a number of alkane and biomarker parameters such as Pr/Ph, CPI, relative concentration of 28,30-bisnorhopane, and the C35/C34 homohopane ratio indicate more oxic depositional environments for the source rocks of Japan and Russia. In contrast to the California Monterey Formation sourced oils, petroleums with low maturity levels from the North Sakhalin basin, Russia and the Akita basin, Japan have lower concentrations of asphaltenes and sulphur and are characterized by higher API gravities. A correlation of extractable organic matter from source rocks vs the least matured petroleums demonstrates that oil expulsion in siliceous shales of the Akita basin occurs at a maturity level corresponding to Ro≥0.65%, which is in the range of the conventional oil window (Ro = 0.6−1.1%). 相似文献
9.
川东北飞仙关组储层固体沥青地球化学特征及其气源指示意义 总被引：6，自引：1，他引：5
运用有机岩石学、有机地球化学、催化加氢热解、GC—IRMS等方法和技术,深入研究了川东北飞仙关组储层固体沥青及可能烃源岩的地球化学特征。研究认为,飞仙关组储层固体沥青反射率高,双反射明显,为非均质结构储层焦沥青;在碳酸盐岩储层的各种孔隙中,呈脉状、球粒状、角片状或块状等他形充填,具有中间相结构和镶嵌状结构特征,反映其高温热变质成因;元素组成有S/C高、H/C低的特点,其固体碳同位素组成与长兴组烃源岩干酪根相似。储层固体沥青的可能烃源岩发育于还原—弱氧化咸水沉积环境,有机质来源于水生藻类;氯仿沥青“A”饱和烃甾萜类生物标志物对比表明,上二叠长兴组烃源岩是主要来源,飞仙关组、下志留统烃源岩亦有贡献;催化加氢产物饱和烃及其正构烷烃单体碳同位素组成显示,坡2井飞仙关组储层固体沥青与罐5井飞仙关组烃源岩具有明显的亲缘关系,这也可作为飞仙关组海槽相烃源岩对飞仙关组气藏有贡献的佐证。 相似文献
10.
在宜昌兴山下三叠统嘉陵江组灰岩晶洞和方解石脉中发现液体油苗。为查明其源岩,通过详细的野外剖面资料及密集采样,以有机碳含量0.5%为有效烃源岩下限,甄别出宜昌地区有三套有效烃源岩。通过烃源岩地球化学特征分析,发现萜烷、常规甾烷、甲藻甾烷等常规生物标志物的组成和分布趋于一致。高演化阶段的趋同性,已无法区分各套烃源岩,不能用于油源对比。但从三芳甾烷的组成和干酪根、氯仿沥青"A"稳定碳同位素组成特征,可以区分这三套烃源岩。油苗特征与上奥陶统五峰组—下志留统龙马溪组下部源岩相似,推测油苗来源于此源岩。 相似文献
11.
There are abundant bitumens and oil seepages stored in vugs in a Lower-Triassic Daye formation (T1d) marlite in Ni’erguan village in the Southern Guizhou Depression. However, the source of those oil seepages has not been determined to date. Multiple suites of source rocks of different ages exist in the depression. Both the oil seepages and potential source rocks have undergone complicated secondary alterations, which have added to the difficulty of an oil-source correlation. For example, the main source rock, a Lower-Cambrian Niutitang Formation (?1n) mudstone, is over mature, and other potential source rocks, both from the Permian and the Triassic, are still in the oil window. In addition, the T1d oil seepages underwent a large amount of biodegradation. To minimize the influence of biodegradation and thermal maturation, special methods were employed in this oil-source correlation study. These methods included catalytic hydropyrolysis, to release covalently bound biomarkers from the over mature kerogen of ?1n mudstone, sequential extraction, to obtain chloroform bitumen A and chloroform bitumen C from the T1d marlite, and anhydrous pyrolysis, to release pyrolysates from the kerogen of T1d marlite. Using the methods above, the biomarkers and n-alkanes released from the oil samples and source rocks were analysed by GC–MS and GC-C-IRMS. The oil-source correlation indicated that the T1d oil seepage primarily originated from the ?1n mudstone and was partially mixed with oil generated from the T1d marlite. Furthermore, the seepage also demonstrated that the above methods were effective for the complicated oil-source correlation in the Southern Guizhou Depression. 相似文献
12.
The composition of organic matter was investigated in the oil shales and country rocks of the Kashpir deposit. The analysis of the aromatic fraction of bitumen showed the presence of isorenieratene derivatives, which indicates the accumulation of the sequence under anoxic conditions in the bottom waters of a paleobasin. Special attention was given to the composition of organosulfur compounds from the bitumen of rocks and products of kerogen pyrolysis. The concentrations of hydrocarbon structures occurring in the bitumen in a free state and in sulfur-bearing derivatives are comparable. The composition of the pyrolysis products of kerogen depends on the concentration of organic carbon in the rock: carbon-rich rock varieties contain kerogen whose pyrolysis yields relatively high concentrations of organosulfur compounds and low total contents of n-alkanes/n-alkenes-1. 相似文献
13.
14.
Maher I. El-Soughier Amr S. Deaf Magdy S. Mahmoud 《Arabian Journal of Geosciences》2014,7(8):3051-3068
Palynological and palynofacies analyses were carried out on some Cretaceous samples from the Qattara Rim-1X borehole, north Western Desert, Egypt. The recorded palynoflora enabled the recognition of two informal miospore biozones arranged from oldest to youngest as Elaterosporites klaszii-Afropollis jardinus Assemblage Zone (mid Albian) and Elaterocolpites castelainii–Afropollis kahramanensis Assemblage Zone (late Albian–mid Cenomanian). A poorly fossiliferous but however, datable interval (late Cenomanian–Turonian to ?Campanian–Maastrichtian) representing the uppermost part of the studied section was also recorded. The palynofacies and visual thermal maturation analyses indicate a mature terrestrially derived organic matter (kerogen III) dominates the sediments of the Kharita and Bahariya formations and thus these two formations comprise potential mature gas source rocks. The sediments of the Abu Roash Formation are mostly dominated by mature amorphous organic matter (kerogen II) and the formation is regarded as a potential mature oil source rock in the well. The palynomorphs and palynofacies analyses suggest deposition of the clastics of the Kharita and Bahariya formations (middle Albian and upper Albian–middle Cenomanian) in a marginal marine setting under dysoxic–anoxic conditions. By contrast, the mixed clastic-carbonate sediments of the Abu Roash Formation (upper Cenomanian–Turonian) and the carbonates of the Khoman Formation (?Campanian–Maastrichtian) were mainly deposited in an inner shallow marine setting under prevailing suboxic–anoxic conditions as a result of the late Cenomanian and the Campanian marine transgressions. This environmental change from marginal to open (inner shelf) basins reflects the vertical change in the type of the organic matter and its corresponding hydrocarbon-prone types. A regional warm and semi-arid climate but with a local humid condition developed near/at the site of the well is thought to have prevailed. 相似文献
15.
Pyrolysis experiments were carried out on Monterey formation kerogen and bitumen and Green River formation kerogen (Type II and I, respectively), in the presence and absence of montmorillonite, illite and calcite at 200 and 300°C for 2–2000 hours. The pyrolysis products were identified and quantified and the results of the measurements on the gas and condensate range are reported here.A significant catalytic effect was observed for the pyrolysis of kerogen with montmorillonite, whereas small or no effects were observed with illite and calcite, respectively. Catalytic activity was evident by the production of up to five times higher C1–C6 hydrocarbons for kerogen with montmorillonite than for kerogen alone, and by the dominance of branched hydrocarbons in the C4–C6 range (up to 90% of the total amount at any single carbon number). This latter effect in the presence of montmorillonite is attributed to cracking via a carbonium-ion [carbocation] intermediate which forms on the acidic sites of the clay. No catalytic effect, however, was observed for generation of methane and C2 hydrocarbons which form by thermal cracking. The catalysis of montmorillonite was significantly greater during pyrolysis of bitumen than for kerogen, which may point to the importance of the early formed bitumen as an intermediate in the production of low molecular weight hydrocarbons. Catalysis by minerals was also observed for the production of carbon dioxide.These results stress the importance of the mineral matrix in determining the type and amount of gases and condensates forming from the associated organic matter under thermal stress. The literature contains examples of gas distributions in the geologic column which can be accounted for by selective mineral catalysis, mainly during early stages of organic matter maturation. 相似文献
16.
Thamer Khazal Al-Ameri Afrah Hasan Al-Ekabi Sameer Noori Al-Jawad 《Arabian Journal of Geosciences》2014,7(4):1433-1455
Seventy-two core and cutting samples of the Ratawi Formation from selected wells of central and southern Iraq in Mesopotamian Foredeep Basin are analysed for their sedimentary organic matters. Dinoflagellates, spores and pollen are extracted by palynological techniques from these rocks. Accordingly, Hauterivian and late Valanginian ages are suggested for their span of depositional time. These palynomorphs with other organic matter constituents, such as foraminifer’s linings, bacteria and fungi, are used to delineate three palynofacies types that explain organic matter accumulation sites and their ability to generate hydrocarbons. Palaeoenvironments of these sites were mainly suboxic to anoxic with deposition of inshore and neritic marine environments especially for palynofacies type 2. Total organic matters of up to 1.75 total organic carbon (TOC) wt.% and early mature stage of up to 3.7 TAI based on the brown colour of the spore species Cyathidites australis and Gleichenidites senonicus with mottled interconnected amorphous organic matter are used for hydrocarbon generation assessment from this formation. On the other hand, these rock samples are processed with Rock-Eval pyrolysis. Outcomes and data calculations of these analyses are plotted on diagrams of kerogen types and hydrocarbon potential. Theses organic matter have reached the mature stage of up to T max?=?438 °C, hydrogen index of up to 600 mg hydrocarbons for each gram of TOC wt.% and mainly low TOC (0.50–1.55). Accordingly, this formation could generate fair quantities of hydrocarbons in Baghdad oil field and Basrah oil fields. Organic matters of this formation in the fields of Euphrates subzone extends from Hilla to Nasiriyah cities have not reached mature stage and hence not generated hydrocarbons from the Ratawi Formation. Software 1D PetroMod basin modelling of the Ratawi Formation has confirmed this approach of hydrocarbon generation with 100 % transformations of the intended organic matters to generate hydrocarbons to oil are performed in especially oil fields of East Baghdad, West Qurna and Majnoon while oil fields Ratawi and Subba had performed 80–95 % transformation to oil and hence end oil generation had charged partly the Tertiary traps that formed during the Alpine Orogeny. Oil fields of Nasiriyah and Kifle had performed least transformation ratio of about 10–20 % transformation to oil, and hence, most of the present oil in this field is migrated from eastern side of the Mesopotamian Foredeep Basin that hold higher maturation level. 相似文献
17.
Eric Lehne Volker Dieckmann Rolando di Primio Andreas Fuhrmann Brian Horsfield 《Organic Geochemistry》2009,40(5):604-616
Asphaltenes extracted from crude oils are proposed to possess structural features of the related source rock kerogen. For the present study micro-scale sealed vessel pyrolysis (MSSV) and combustion isotope ratio mass spectrometry (GC–C–IRMS) were used to compare gas generation from a whole rock (type II-S kerogen) from southern Italy with that from related sulfur rich asphaltenes isolated from a low maturity heavy crude oil. The purpose of was to determine whether experimental pyrolysis of oil asphaltenes can be used to predict the timing and the chemical and isotopic composition of hydrocarbon gases generated from genetically related kerogen in the source rock during burial maturation. The results show that parameters such as (gas to oil ratio) GOR and oil and gas formation timing are very similar for these two sample types, whereas gas composition, product aromaticity and sulfur content are remarkably different. Slight differences in GOR are mainly due to differences in gas formation characteristics at very high levels of thermal alteration. Secondary gas formation from the whole rock covers a much broader temperature range under geological conditions than that from the asphaltene products. However, it is remarkable that both the onset and the maximum temperature are nearly identical under geological conditions. The observed differences in gas generation characteristics are supported by discrepancies in the carbon isotopic characteristics of the gas range compounds and indicate different precursors and/or mechanisms for gas generated from whole rock and asphaltenes. 相似文献
18.
漠河盆地早白垩世依列克得组火山岩系烃源岩有机地球化学特征 总被引：1，自引：0，他引：1
应用岩石热解、氯仿沥青抽提、饱和烃气相色谱和色谱-质谱等分析方法,对首次在漠河盆地依列克得组发现的烃源岩进行研究。 结果表明：烃源岩由煤、油页岩和页岩构成,有机碳(TOC)质量分数＞10%,干酪根类型主要为Ⅱ2,镜质体反射率（Ro）为0.56%~0.59%,属于低成熟阶段,烃源岩达到很好级别。烃源岩有机母质均以陆生高等植物输入为主,也有水生生物的输入,反映原始母质具有水生生物和陆源高等植物混源的特征。依列克得组沉积时期,湖盆水体含盐度及还原性具有较大的变化,处于淡水湖-咸水湖的交替状态,沉积水体分层比较明显,有利于有机质的保存和转化。 相似文献
19.
O. Amit 《Organic Geochemistry》1979,1(4):237-241
Kerogen from various samples of the Gevar'am Formation (Early Cretaceous, Israel) were analyzed for their elemental composition, and by I.R. and ESR spectroscopy. The results were compared with other organochemical characteristics of the basin (Amit, 1978, Bull. Am. Assoc. Pet. Geol., V. 62 p. 827–836). The types of organic material and their role in the formation of oil were investigated. It appears that the kerogen is mostly constituted of terrestrially derived organic matter. A small amount of marine-derived organic matter is also inferred. The kerogen of terrestrial origin is a poor oil producer and is expected to generate oil only at a higher stage of maturation than the Gevar'am Formation has attained. Any hydrocarbons that have been generated in this formation were probably generated from that part of the kerogen thought to be marine derived. Thus the Gevar'am Formation is considered as a potential source rock which has generated only a small amount of oil. 相似文献