Comparative characterization of hydrocarbon structures and 232Th and 226Ra concentrations in Caspian Sea sediments

An integrated study of the hydrocarbon composition of bituminous substances has been performed, and the amount of the natural radionuclides ²³²Th and ²²⁶Ra in the surface layer of Caspian Sea sediments has been determined. The ²²⁶Ra concentration in the sediment increases with the increasing bitumen content. A comparative analysis of the amount of bitumen hydrocarbon structures in sediments and the ²³²Th and ²²⁶Ra natural radionuclides has shown that the ²³²Th and ²²⁶Ra concentration in the sediment increases with increasing amount of aromatic structures in chloroform-extracted bitumen. The concentration of ²²⁶Ra in the sediments increases with the increasing amount of polycyclic aromatic structures and decreases with an increase in the amount of monocyclic substituted aromatics. This fact indicates the preferential accumulation of ²²⁶Ra in sediments with a less reduced organic matter, which is typical of modern sediments in the early stages of diagenesis.     

页岩不同类型干酪根内甲烷吸附行为的分子模拟

目前对于页岩中不同类型有机质干酪根对甲烷的吸附影响规律尚不清楚。为此,根据页岩干酪根的元素含量、分子结构构建了腐泥型、混合型和腐殖型的干酪根分子模型,利用巨正则蒙特卡罗方法和分子动力学模拟方法研究甲烷在干酪根中的吸附行为,并进行了实验验证。进而探讨了温度、地温梯度、干酪根分子组成、比表面积对甲烷—干酪根吸附系统的影响,以及甲烷在页岩干酪根内的微观吸附机理。结果表明:(1)腐殖型干酪根对甲烷的吸附量最大,混合型次之,腐泥型最小;(2)干酪根的化学结构对甲烷的吸附有着重要的影响,富含芳香族的干酪根对甲烷具有更强的亲和力,碳、硫原子对甲烷在干酪根中吸附的影响较大;(3)甲烷在干酪根中吸附属于物理吸附,温度越高甲烷吸附量越小,平均等量吸附热均小于42 k J/mol;(4)随着地层深度的增加,甲烷吸附量先增加后减少,在地层深度介于2 000~2 500 m甲烷绝对吸附量达到峰值,地温梯度越小相同埋深下甲烷吸附量越多;(5)甲烷吸附量与干酪根的比表面积呈线性正相关关系。     

Hydrothermal transformation of heavy oil and organic matter from carbonate rocks of oil fields of Tatarstan

In laboratory model experiments were identified features of hydrothermal transformation of heavy oil and organic matter productivity of carbonate rocks from Bashkirian stage of deposits of the Middle-Carboniferous of Tatarstan territories. Experiments were conducted at temperature of 360?°C in hydrogen environment in presence of aqueous phase. The impact of hydrothermal factors on rocks leads to decrease in content of insoluble OM - kerogen and increase content of free hydrocarbons. With increase in content of saturated and aromatic hydrocarbons, content of resin-asphaltene components decreases. Changes in composition lead to significant reduction in density of heavy oil from 0.9254 to 0.8273?g/cm³.     

Modeling of catagenetic transformation of saturated and alkylaromatic petroleum hydrocarbons

Thermolysis of crude oil at a temperature of 350°C for 1 h with and without aluminosilicates has been conducted in the isothermal regime mode. The composition of liquid and gaseous thermolysis products has been analyzed. The amount of resins and asphaltenes in the liquid products of thermal or thermocatalytic treatment decreases and that of oils increases as compared with the crude oil. The individual composition of saturated hydrocarbons (alkanes, steranes, terpanes) and alkylaromatic compounds (benzenes, naphthalenes, and phenanthrenes homologoues) has been studied. It has been shown that thermolysis increases the amount of thermodynamically more stable m- and p-isomers of alkyltoluenes, and the β-isomers of alkyl-naphthalenes and alkylphenanthrenes. Geochemical parameters for the composition of alkyl substituted benzenes, naphthalenes, and phenanthrenes have been calculated.     

Composition of the high-molecular-mass components of oil- and bitumen-bearing rocks and their hydrothermal transformation products

Natural oil- and bitumen-bearing rock samples from Tatarstan multiage deposits with different concentrations of organic matter (OM) and different compositions and types of hydrocarbon fluids have been investigated. It has been shown that hydrothermal treatment in the flow mode in a reducing atmosphere leads to a decrease in the amount of soluble and insoluble OM in the rocks and improves the quality of recovered hydrocarbon fluids owing to a regular decrease in the concentration of the resinous-asphaltenic components, total sulfur, vanadyl porphyrin complexes, and trace elements, and an increase in the proportion of lighter hydrocarbons. Characteristic features of the hydrothermal transformation of the OM of domanik bituminous rock associated with the degradation of insoluble kerogen, which is an additional source of hydrocarbons and heteroatomic compounds, have been revealed.     

中国陆表海碳酸盐岩有机质的生烃潜力

有机质类型指标中反映母质来源的指标并不能完全代表生烃能力的大小.目前积累的大量分析数据表明,许多地区沉积的贫有机质海相碳酸盐岩O/C原子比H/C原子比落在干酪根类型图上的Ⅲ型区域,同一套地层中碳酸盐岩干酪根H/C明显低于泥岩,碳酸盐岩干酪根镜检可发现无定形组微粒化、藻类体出现黑心结构、存在大量类似镜质组的显微组分,均表明其有机质生烃降解率很低(只相当于Ⅲ型干酪根),这是氧化的沉积环境对有机质改造的结果,符合有机相的分布规律.在研究其生烃数量与机制时,不宜采用有机碳丰度很高、原始降解率很高的低成熟泥灰岩的模拟实验结果.     

Transformation of residual oil in producing formations of the Romashkino oil field during hydrothermal treatment

Changes in the composition of organic matter of rocks and residual oil from multiage deposits of the Romashkino oil field in a reducing environment in a continuous-flow aqueous system were studied. It was shown that, as a result of the action of hydrothermal factors, the amount of hydrocarbon fractions increases and the amounts of alcohol-benzene-extractable resins, asphaltenes, and total sulfur decrease in organic extracts obtained from the rocks after hydrothermal experiments. The concentration of free radicals, as well as tetravalent vanadium (which is present in the form of vanadyl prophyrin complexes) and other heavy metals, in asphaltenes decreases. The hydrothermal treatment of petroliferous rock leads to the degradation of the structure of insoluble kerogen and unrecoverable components of residual oil, as well as to the washout of free hydrocarbons from the rock with the aqueous phase, n-Alkanes; ethyl, butyl, and octyl phthalates; furan; acids; and unsaturated oxygen-containing compounds with the isoprenoid structure were detected in the products of hydrothermal experiments isolated from aqueous extracts.     

煤在热演化过程中结构变化的核磁共振波谱

对塔里木盆地库车坳陷侏罗系阳霞组煤中的可溶有机质采用不同的抽提方法得到干酪根,并对干酪根在不同热模拟温度下的结构组成变化特征进行测定,得到核磁共振的相关数据。研究结果表明,干酪根的结构主要由三部分组成：脂族结构、芳香结构和含氧官能团。随热演化进行,脂族结构和含氧官能团不断脱落,芳香结构不断发生缩合。通过对三个系列的比较,可以得出不同的抽提方法,导致了初始状态烃类含量的不同,进而参数的变化趋势也有所不同。在热模拟过程中,随温度升高,脂族结构不断发生脱落,含氧集团因活化能较低而发生断裂,分解脱氧生成CO2和H2O,而芳核本身的性质与数量并无太大变化。     

热演化过程中干酪根碳同位素组成的变化

通过测定一个Ⅰ型干酪根在不同热演化阶段的残余率和残余部分的碳同位素组成,揭示其在热演化过程中的变化规律,从而为有效气源岩的定量判识与评价提供同位素方面的依据。研究表明,在产甲烷早期(R_o<1.5%),干酪根的碳同位素组成变化较明显,可达3.8‰;当R_o达到1.5%～2%时,随着热演化程度的增加,残余干酪根的δ13C略微呈现出逐渐贫13C的趋势,变化幅度约为2‰;当热演化程度较高(R_o>2%)时,干酪根的碳同位素组成则变化不大,变化幅度小于0.8‰。      

Group Composition of Hydrocarbons and Hetero Compounds in Stepwise-Thermolysis Products of Asphaltenes from Usa Oil

The group composition of hydrocarbons (HC) and hetero compounds in the products of stepwise thermolysis of asphaltenes from crude oil of the Usa oilfield at temperatures of 120, 230, 370, 500 and 750°C has been studied. The volatile thermolysis products formed at each step of the process have been studied by gas chromatography–mass spectrometry. It has been found that the main products of stepwise thermolysis of asphaltene molecules are alkylbenzenes (AB) and saturated aliphatic hydrocarbons (SAH), aromatic fragments obtained at 370°C are mainly separate structural blocks of asphaltene molecules, and benzothiophenes (BT) predominate over dibenzothiophenes (DBT) as structural units of asphaltene molecules. It has been shown that with an increase in the process temperature, the alkylbenzenes/saturated aliphatic hydrocarbons ratio (AB/SAH + Alkenes) increases by a factor of 6 to 7; the phenanthrene/alkylbenzenes (PN/AB) ratio and the polycyclic aromatic hydrocarbons/alkylbenzenes (PAH/AB) ratio decrease by ten- and twofold, respectively; and the naphthalenes/alkylbenzenes (NP/AB) ratio increases by two times.     

THE APPLICATION OF ELECTRON SPIN RESONANCE AS A GUIDE TO THE MATURATION AND TYPING OF ORGANIC MATTER IN THE NORTH SEA

In early electron spin resonance (ESR) analysis of North Sea wells, maturation of organic matter (OM) was expressed in terms of maximum palaeotemperature (MPT) based on North American calibrations that did not consider the influences of kerogen composition or overpressure. In the North Sea, the MPTs were anomalous in overpressured sequences and relative to other indices of OM maturation such as vitrinite reflectance, so the ESR method was abandoned there in geochemical studies. However, early empirical study of North Sea ESR data indicated that, in relation to functions that linked temperature and pore pressure, some ESR parameters were predictable without reference to MPTs. In order to re‐evaluate ESR parameters as indices of OM maturation, the physical factors (temperature and pressure) which affect OM maturation are related in the present paper to the ESR parameters “g” (spectral position) and Ng (spin density) at six well locations in the northern North Sea. A third ESR parameter, W (line width), is not an effective guide to maturation levels due to its complex relationship to the physical factors and kerogen types. However, cross‐plots of W versus “g” and Ng appear to be as effective as pyrolysis for kerogen typing. Levels of maturation investigated in the North Sea wells range through the equivalent vitrinite reflectance values of about 0.50–1.50%. The values of “g” and Ng have been differentiated for kerogen type, but undifferentiated values of “g” have also been studied. Regression analysis has shown that there are linear relationships between the ESR parameters “g” and Ng, and the physical factors present‐day temperature (To), “effective” temperature (Te), and differential pressure (Pd). Correlation coefficients for both “g” (undifferentiated and differentiated) and Ng (differentiated) relative to the physical factors are high; the highest values are for “g” and Ng relative to Te and Pd (r =?0.950 for “g” differentiated or undifferentiated, r = 0.944–0.976 for Ng differentiated, respectively). However, correlation coefficients were lower for “g” and Ng relative to To. More frequent high correlation coefficients and larger sample populations suggest that “g” (undifferentiated) is a more reliable index of OM maturation than Ng(differentiated). However, the estimation of levels of OM maturation is improved if both indices are used together. The ESR method appears to be effective both for estimating levels of OM maturation and for kerogen typing. It has a number of potential advantages over other geochemical methods: firstly, it is more sensitive for estimating OM maturation than most other methods; secondly, it can be used to analyze organic matter which is as old as Proterozoic; thirdly, it does not destroy the samples analyzed.     

SUPERCRITICAL EXTRACTION OF ISRAELI MISHOR ROTEM OIL SHALE 1. BATCH EXTRACTION WITH TOLUENE

ABSTRACT

Recovery of organic material from Israeli Mishor Rotem oil shale with toluene under supercritical conditions was investigated. The rate of solubilization, change of structural aspects and molecular weights of solubilized products with time were investigated. Experiments to recover organic material from shale were performed in a stainless steel high pressure autoclave. Shale Sample was charged in a sintered glass crucible suspended from the cap of the autoclave; toluene was the solvent in all experiments. Solvent/shale ratio was 20; experimental temperature was 34O^°C. The gaseous products were analyzed by gas chromatography. Molecular weights of the organic material recovered was measured by gel permeation chromatography technique. FTIR spectra of the organic material recovered and fractions isolated by extractive and chromatographical methods were measured. The amount of kerogen remaining in the spent shale was determined by oxidative derivative thermal gravimetry. A steady state in the production of solubles was reached within 60 minutes at 340^°C with a yield of 60 percent. After this time no further amounts of organic material was recovered. The molecular weights of the recovered organic material decreased at extended times after the steady state was reached. It appeared that the structure of the organic material recovered remained unchanged until the steady state condition is reached whereupon some structural changes occurred. At extended times the organic material was converted into more aromatic and less hydroxyl containing structures of lower molecular weight. The organic material recovered upon reaching steady state was fractionated into 63 percent oils (pentane solubles) and 32 percent asphaltenes (toluene solubles). The oile contained aliphatics and monoaromatic structures and the asphaltenes contained polyaromatic polar structures. Gases which constituted 4 percent of the initial kerogen were produced during the heating period to 340^°C. The amount of carbon monoxide produced remained constant and amounts of hydrogen, carbon dioxide and methane decreased after supercritical conditions were attained.     

应用13C核磁共振波谱分析吐哈盆地干酪根结构变化

吐哈盆地是中国较大的煤系含油气盆地之一,成烃母质大多处于低成熟阶段。为研究油气形成过程中干酪根大分子结构的变化,对盆地侏罗系八道湾组的煤与碳质泥岩干酪根,进行了热解实验,借助于13C核磁共振波谱分析,研究了不同成熟度下干酪根结构的特征与变化。结果表明,随热演化程度的增加,煤与碳质泥岩干酪根中的脂肪族类明显降低、氧接芳碳脱落、芳香结构轻微缩合,在低成熟演化阶段表现尤为明显。脂肪链中亚甲基次甲基含量大于甲基含量,是吐哈盆地轻质低成熟油储量多于低成熟气的主要原因。     

A Geochemical Framework for Understanding Residue Properties

Crude oils, and the residual fractions thereof, vary widely in many relevant properties. Thus, a detailed characterization of a single residue stream or even a number of residue streams from one region may not be very relevant in a different part of the world. We have therefore attempted to develop a framework for understanding residue properties in a generic fashion. A detailed analysis of 11 vacuum residue fractions from a wide variety of crude oils resulted in a general model for understanding the composition and processability of residue streams. This model is based on the geochemical origin (kerogen type) and the maturity of the crude oil. The different origin of kerogen I (paraffinic) residues, compared with the more conventional kerogen II residues, is reflected in a large number of properties and also in a larger variability in these properties. However, upon maturation, the average properties of kerogen I residues and kerogen II residues converge so that mature residues of both kerogen types have much in common (low S content, low metals content, high H/C ratio etc). Maturation is found to have a negative effect on the stability and coking tendency of the residue fraction. NMR data reveal that the asphalthenes become more aromatic upon ageing, whereas the maltenes (non-asphalthenes) become less aromatic, thus causing an increasing gap in aromaticity between these fractions. Significant differences in asphaltene molecular structure between kerogen I and kerogen II residues were observed. The analytical data suggest that the concept of kerogen type and maturity may be a useful tool in describing and understanding residue characteristics and assist in optimizing feedstock selection for residue conversion processes and other residue applications (fuel oils, bitumen), as well as in understanding fouling and coking phenomena. Further research is required to establish the trends shown in this paper.     

The composition of aromatic destruction products of Domanic shale kerogen after aquathermolysis

In this article we studied a sample of Domanic rock with high kerogen content obtained from Volga-Ural oil and gas basin. A laboratory modeling of the catagenesis process was carried out in order to establish the transformation mechanism of organic matter. The composition of liquid products resulting from kerogen pyrolysis was investigated. The kerogen fragments fall in aromatic hydrocarbons fraction. Alkyltoluenes also exist in saturated hydrocarbon fractions due to alkyl substitutes. The thermal influence changes the ratios of relative content of ortho-, para- and meta-isomers. Heavy aromatic hydrocarbons content increases by increasing temperature and kerogen macroelements ratio changed under thermal effect that is an indicator for maturation process of organic matter.     

Spectroscopic Studies on Some Crude Oils from The North Western Desert,Egypt

Abstract

A direct method for crude oil evaluation based on spectral techniques is demonstrated in this article. This method is demonstrated for four crude oils from the El-Faras and Raml oil fields in the North Western Desert in Abu Gharadeg Basin, Egypt. The crude oils have been studied by ¹³C nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. Several parameters calculated from the ¹³C NMR and FTIR spectra provide useful information about the maturity of the organic matter in term of relative aliphatic, aromatic, and carbonyl/carboxyl concentrations; aliphatic chain length; and type and degree of substitution of aromatic structures. These spectra techniques may provide valuable information about the aromaticity and diverse functionalities that are important to the thermal history of the crude oil samples. Results showed that the composition of crude oil samples have higher aliphatic compounds than that of the aromatic compounds.     

Transformations of hydrocarbons of Ashal’hinskoe heavy oil under catalytic aquathermolysis conditions

The influence of temperatures of 250, 300, and 350°C on the character of changes in the group and hydrocarbon compositions of heavy oil from the Ashal’chinskoe field in laboratory experiments on the simulation of oil aquathermolysis processes under reservoir conditions has been revealed. The experiments have been carried out in the presence of kaolin as a rock-forming mineral, using oil-soluble iron carboxylate and tetralin as a proton donor. It has been shown that temperature elevation to 300 and 350°C increases the amount of saturated fractions by factors of 1.5 and 1.75, respectively, and decreases the resin content almost by half in comparison with the initial oil. The proportion of n-alkanes and light alkylcyclohexane and trimethylalkylbenzene homologues in the saturated fractions increases as a result of cracking reactions involving the preferential degradation of high-molecular-weight resins. A noticeable increase in the amount of newly formed hydrocarbons and asphaltenes at the temperature of 350°C indicates that not only intensive cracking processes, but also condensation processes occur under these conditions. Changes in the quantitative and qualitative composition of the proton donor tetralin by its dehydrogenation to form naphthalene and hydrogenation to yield the cis- and trans-isomers of decalin have been revealed.     

Production of aviation fuel by bioethanol conversion on zeolite catalysts

The catalytic process of two-stage conversion of ethanol into jet fuel, wherein the second step is the hydrogenation of aromatic hydrocarbons obtained in the first step, has been studied. It has been shown that at 400°C and an ethanol space velocity of LHSV = 2 h^–1, aromatic hydrocarbons are produced, which are hydrogenated on a Pt/C catalyst in an autoclave at 80–100 atm and T = 200–250°C for 1.5 h with a final yield of naphthenic hydrocarbons on a fed ethanol basis of 15–20%.     

应用固体13C NMR 技术研究碳酸盐烃源岩的生烃潜力和热演化程度

应用固体¹³CNMR技术对不同类型、不同演化程度碳酸盐岩干酪根的化学组成和结构特征进行了研究,结果表明干酪根结构中的脂碳是油气的主要贡献者;剖析了油、气潜力碳在不同演化阶段的变化特征.对芳碳率、芳氢率、芳核平均结构尺寸等参数的分析表明,后者是最有效的热演化衡量标尺,并建立了芳核平均结构尺寸与镜质体反射率的关系.     

Distribution and interrelation of the main structural-group composition parameters of Western Siberia crude oils according to NMR data

The distribution and the degree of correlation of 14 main and most easily measured characteristics of the structural-group composition of Western Siberia crude oils have been studied. It has been shown that the distribution pattern of the parameters greatly differs from the normal distribution and substantially varies, with the distributions of the quantities that reflect the concentration and composition of aromatic components being the most complex. The trends of variation in composition of the oils in basic stratigraphic plays have been revealed. The necessity of calculating Spearman’s instead of Pearson’s pair correlation coefficients for determining the degree of interrelation between the parameters has been shown. It has been demonstrated that the conclusions made earlier on the basis of Pearson’s linear correlation coefficients about interrelations between the composition parameters and their correlation with the mode of occurrence are not quite certain; all of them need to be verified. Strong interrelation of many composition parameters has been proved, and the necessity of studying in detail the feasibility of their joint use for comparative analysis of oil samples has been suggested. A strong negative correlation between the parameters reflecting the concentration of the aromatic and n-alkyl components has been revealed.