Sulfides in petroleum

The homologous series of terpenoid sulfides previously reported to be present in Athabasca bitumen have been detected in a variety of petroleums from the Western Hemisphere. All 22 samples examined, ranging in age from Devonoan to Cretaceous, contained the terpenoid sulfides. A method is described for the isolation of sulfides from petroleums based on the selective oxidation of sulfides to more polar sulfoxides which are easily removed from the mixture and their subsequent reduction to sulfides. The sulfide content in the petroleum maltenes examined ranged from 0.3 to 16.1% w/w. In addition to the bicyclic and tetracyclic terpenoid sulfides a new series of tricyclic terpenoid sulfides has been identified, and the details of the isoprenoid side chain have been elucidated for all three homologous series. The distributions by carbon number of the bicyclic and tetracyclic homologous series of terpenoid sulfides show pronounced variations which are attributed to thermal maturity and degree of water washing of the petroleum, thus the ability to identify terpenoid sulfides should provide a useful tool for oil-oil and oil-source rock correlation studies. The bicyclic and tricyclic terpenoid sulfides have the same carbon framework as the carotenoids which suggest that these sulfides were accessory pigments in photosynthesis.     

向斜成藏理论及其石油地质意义

传统的石油成藏理论适用于中高渗透储层,流体的渗流特征是达西渗流,主要作用力是浮力,油气分布在构造高部位或砂体高部位,主要是寻找圈闭。但是在低超低渗透储层和致密储层中,流体的渗流特征是非达西渗流,传统理论不再适用,油水不能发生正常的重力分异,流体在超压作用下以幕式排烃方式发生初次运移,石油在储层中运移要以非达西渗流方式通过变形才能缓慢通过,这种运移必然降低流速产生滞留效应导致石油在低部位大量滞留并聚集成连续油藏。这种滞留油藏的产生,可以形成背斜区圈闭含油、斜坡区相对高部位含水、而相对低部位却连续含油的油水倒置现象。由于滞留油藏无需构造和岩性边界圈闭,无需统一压力系统和油水边界,改变了传统上的圈闭找油模式,拓展了油气藏的概念,形成了低超低渗透储层、非常规、致密油等成藏研究的理论基础。向斜成藏理论的提出,是对传统石油成藏理论的重要补充,拓展了油气勘探领域,使油气勘探从构造高部位转向构造低部位,增大了石油资源量,对勘探开发具有重要的指导作用。     

Hydrogen in petroleum geochemistry

950 samples were analysed to study the possibility of using information on hydrogen in the evaluation of regional, zonal and local hydrocarbon potential. The main method for identifying that hydrogen is of natural origin is by comparison with the δD of hydrogen of technical origin that is ?792‰. As an added criterion for recognizing the origin of hydrogen in wells the investigation of changes in gas composition within the borehole section is proposed. The distribution of hydrogen in the free and adsorbed states and the role of hydrogen in hydrocarbon gas formation have been evaluated. These data combined with tests on hydrogen absorption establish a difference between oil and gas generation in terrigenous and carbonate rocks caused by different types of organic matter and by the ability of hydrogen to be preserved in the crystal lattice of carbonate minerals. This absorbed hydrogen promotes HC generation and also changes the physical properties of limestones producing fundamentally different styles of fracture genesis.     

Catagenesis and composition of petroleum: Origin of n-alkanes and isoalkanes in petroleum crudes

Distribution of n-alkanes and isoalkanes in ca. 50 petroleum crudes have been examined by the gas chromatography. Molar distributions of n-alkanes with respect to their c atom numbers in the majority of crudes follow the exponential law, which signifies a random, chemical nature of n-alkane-generating processes occurring in the catagenesis stage of petroleum maturation. Similar distributions of n-alkanes were found in the products of mild thermolysis of heavy n-alkanes.Isoalkanes represent a major, 10–25%, petroleum component. The principal types of isoalkanes in crudes are monomethyl-branched, with the branches randomly positioned in the chains, and dimethyl-branched with one of the methyl groups predominantly in the second position in the chains. Thermolysis studies of individual n-alkanes, alkanoic acids, and esters in the presence of various minerals provided an explanation of the n-alkane and isoalkane distributions. Selected heavy n-alkanes are initially formed in decarboxylation reactions of heavy n-alkanoic acids and esters. Extensive thermocracking produces mixtures of lighter n-alkane and α-olefins. The olefins, in the presence of acidic clays, are converted in cationic reactions into mixtures of predominantly mono- and dimethyl-branched isoalkanes.     

中国浅层油气藏的特征及其资源潜力分析

中国多年来对浅层地区未进行有效的勘探开发和给予应有的重视.对渤海湾盆地等主要大中型盆地浅层油气藏的类型、分布特征和地质特征等的分析表明,中国浅层油气在地质上总体具有埋藏浅、成因复杂、受构造-岩性等复合性影响显著、储量规模与丰度大小不一、油藏类型多且分布广、资源量分布不均等特征,在勘探和开发上具有易勘探、成本低和易出砂出水、稳产难度大等优点和不足.指出中国浅层油气的潜力区域在东部,对浅层油气资源潜力进行了分析,认为浅层油气资源潜力很大,要重视浅层油气资源的勘探开发,重视新理论、新技术、新方法等在浅层隐蔽油气藏勘探开发过程中的应用.     

中国浅层油气藏的特征及其资源潜力分析

中国多年来对浅层地区未进行有效的勘探开发和给予应有的重视。对渤海湾盆地等主要大中型盆地浅层油气藏的类型、分布特征和地质特征等的分析表明,中国浅层油气在地质上总体具有埋藏浅、成因复杂、受构造-岩性等复合性影响显著、储量规模与丰度大小不一、油藏类型多且分布广、资源量分布不均等特征,在勘探和开发上具有易勘探、成本低和易出砂出水、稳产难度大等优点和不足。指出中国浅层油气的潜力区域在东部,对浅层油气资源潜力进行了分析,认为浅层油气资源潜力很大,要重视浅层油气资源的勘探开发,重视新理论、新技术、新方法等在浅层隐蔽油气藏勘探开发过程中的应用。     

Structure proof and significance of stereoisomeric 28,30-bisnorhopanes in petroleum and petroleum source rocks

Two C₂₈H₄₈-pentacyclic triterpanes were isolated from Monterey shale. X-ray crystallography of a crystal containing both compounds proved their structures as 17β,18α,21α(H)-28,30-bisnorhopane and 17β,18α,21β(H)-28,30-bisnorhopane. Several differences are found between 28,30-bisnorhopanes and the regular hopanes. Unlike the regular hopane epimers, for practical purposes the three epimeric 28,30-bisnorhopanes [17α,21β(H)-, 17β,21α(H)-, and 17β,21β(H)-]cannot be distinguished by their mass spectra. Special conditions are needed to separate them by gas chromatography. The diagenetically first-formed epimer is thought to be 17α,21β(H)- because it predominates in immature shales. The order of thermodynamic stability is 17β,2lα(H) < > 17α,21β(H) > 17β,21β(H), and all three epimers are present in petroleum. 25,28,30-Trisnorhopanes can be analyzed in similar fashion and are found to have similar thermodynamic characteristics. The percent of the ring D/E cis epimer of 28,30-bisnorhopane and/or 25,28,30-trisnorhopane is a useful maturation parameter similar to the 20S/20R sterane ratio. Evidence indicates 25-demethylation of 28,30-bisnorhopane to 25,28,30-trisnorhopane during advanced stages of biodegradation. Hence, percent ring $\text{D}\text{E}$cis 25,28,30-trisnorhopane has an application to maturation assessment in heavily biodegraded oils.     

Degradation of petroleum contaminants in oil

The treatment of diesel-contaminated soil with hydrogen peroxide oxidation is investigated in this paper. The factors influencing reactions such as initial oil content, H2O2 dosage, pH-value, catalyst and so on are studied. The results indicate that it is feasible to remediate diesel-contaminated soil by adding oxidant directly at room temperature because of higher absolute removal content although the degradation efficiency is low for the contaminated soil of 1%, 2% and 5% initial oil content. The more the H2O2 dosage, the better the degradation efficiency; it is economical and efficient to add 4 mL H2O2 to 10 g diesel-contaminated soil （2% or so） directly in-situ chemical oxidation （ICO）. For the contaminated soil of 5% initial oil content, when pH-value is 5-8 and H202 dosage is 20 mL, the removal efficiency reaches more than 96%; when pH-value is 1-3 and volume ratios of H2O2 to Fe^2＋ are 1 ： 1, 2：2, the degradation efficiencies are all very high （i.e., 86%-88% or so）. It can be concluded that the degradation efficiencies are comparative when adding 1 mL or 2 mL H2O2 of Fenton Reagent or adding 4 mL of H2O2 only to 10 g diesel-contaminated soil.     

Distribution of carbazole derivatives in petroleum

Carbazole, its alkyl derivatives and higher benzologs have been selectively isolated from six different crude oils. In all samples, benzocarbazoles are major constituents of a series which may extend up to dibenzocarbazole derivatives. The distribution includes unsubstituted parent compounds and shows a maximum content of methyl and dimethyl substituted species. Sixteen individual constituents have been identified by means of comparison with reference compounds using gas chromatography, mass spectrometry and high resolution spectrofluorimetry. So far, no generally acceptable explanation has been given for the origin of these compounds, which presumably are the most stable ones in their respective series of aromaticity. Thus, carbazole derivatives may result from a complex sequence of reactions during kerogen formation, not allowing the recognition of precursing molecules. The geochemical significance of this series of nitrogen compounds needs to be clarified, requiring further studies.     

Acidic compounds in biodegraded petroleum

Twelve oil samples have been characterised by titration, FT-IR and chromatographic analysis to determine the differences between the organic acid composition of biodegraded and non-biodegraded oils. The biodegraded oils have higher total acid and total base contents, both by titration and extraction. The molecular weight ranges of the extracted acids are lowest in the biodegraded oils, and the equivalent weight calculations indicate a dominance of multi-functional molecules. Gel permeation chromatography gives a molecular weight range with most of the molecules between 300 and 500 g/mol. FT-IR shows that the extracted acids from biodegraded oils are more carboxylic and aliphatic while the non-degraded oils are more phenolic. Molecular analysis of the derivatised extracts give UCM envelopes for biodegraded oils, and no molecular identification. The results indicate that the acidic constituents in biodegraded oils are a product of the biodegradation, as the composition is very different from the non-biodegraded oils.     

Stochastic geometry in petroleum geology

Many aspects of the generation, migration, trapping, and discovery of petroleum, as well as its primary and enhanced recovery, depend upon geometry. The scale of the relevant geometric features varies all the way from that of continental margins and basins down to the pores and fissures in reservoir rocks. Because the spatial complexity is so great for each of these processes, it is reasonable to describe them statistically. The primary purpose of this paper is to survey possible ways in which statistical or stochastic geometry enters and might be used in petroleum geology and engineering. While it offers some new theory, this paper does not directly suggest any specific new methods for the estimation of hydrocarbon resources or reserves. This deficiency is mainly due to the current lack of relevant data. When data are available the point of view explained herein will be fruitful. The survey ties together many topics in a novel way.     

Primary migration theory of petroleum and its application to petroleum exploration

Current concepts of oil and gas generation by thermal decomposition of kerogen are reviewed. Primary oil migration mechanisms requiring large quantities of water to serve as a carrier for the movement of oil from source rock to reservoir are discussed. Previous investigators regarded the expulsion of interlayer water from montmorillonite and montmorillonite-illite mixed-layer minerals by transformation during diagenesis as the most important source of the carrier water.The process of diagenesis is subdivided into three stages based on the results of experimental compaction studies on montmorillonite clay, on studies of the expulsion mechanism of interlayer and interstitial waters, and on the observed changes in pores and mineral grains in argillaceous sediments during these stages. As a result, we concluded that the migration of oil chiefly occurs during the late compaction stage when the sediment's porosity ranges from 30 to 10%.This conclusion implies that a large amount of oil can move during the period when the active generation of oil corresponds with the primary migration of carrier water. For instance, in the oil-bearing Miocene sediments of the Akita area of northern Japan, the oil generation temperature ranged from 100 to 150°C and the average migration depth was between 1300 and 2600 m. Therefore, the possibility of large oil pool formation will be high in the basin where the paleo-geothermal gradient is about 5.0°C/100 m. In fact, it is expected that the paleo-geothermal gradients in the vicinities of large oil fields will be very close to this value.Prediction of the type and amount of hydrocarbons in the exploration area will be possible by an examination of the paleo-geothermal gradient in the area and by a study of the relation between absolute porosity and burial depth of argillaceous rocks.     

An invariance in the carbazoles of petroleum

A remarkable invariance in the ratio of 1,3-dimethylcarbazole （DMC） to 1,6-DMC was discovered in crude oils from the Pearl River Mouth Basin, South China Sea. The remarkably invariant ratio is kept at a constant of about unity regardless of their concentrations, sources or maturities for the sampies. In combination with the molecular structures of 1,3- and 1,6-DMCs, the invariance might indicate that the nitrogen compounds share a common precursor with a skeleton of 1-methylcarbazole and are formed through methylation at C3 and C6 with an essentially identical rate.     

Identification of some diterpenoid hydrocarbons in petroleum

19-Norisopimarane and isopimarane have been synthesized from isopimara-9(11), 15-diene-3β, 19-diol. Analysis of the alkane fractions of an Australian crude oil by GC-MS showed the presence of nine diterpenoid hydrocarbons (diterpanes), of which one was bicyclic two were tricyclic and six were tetracyclic.19-Norisopimarane and isopimarane were identified by comparison of their mass spectra and GC retention times with those of the synthetic standards. ent-Beyerane, 16a(H)-phyllocladane, 16)β(H)-phyllocladane, ent-16α(H)-kaurane and labdane were also identified by comparison with authentic reference compounds. The remaining two compounds were tentatively identified as rimuane and as a 17-nortetracyclic diterpane on the basis of mass spectral evidence. The diterpanes are probably derived from conifer resins.     

岩相古地理研究与油气勘探

古地理学已具有200余年的悠久历史。它的发生、发展与沉积学和地层学的发展密切相关。古地理学的理论发展和相关的技术进步在勘探开发沉积矿产资源等方面发挥了重要作用,开拓了在河流、三角洲及滑塌浊积扇、深水重力流沉积、滩坝、礁以及碳酸盐岩建隆中找油的新领域。中国岩相古地理的研究为推动油气资源勘探开发起到了不可替代的作用,已在不同地区和地质层位中找到了极为丰富的油气资源。中国含油气盆地油气勘探表明,岩相古地理控制了油气成藏的基本要素组合和油气资源的分布,地层和岩性圈闭的发育和分布受控于古地理条件的改变。中国原油地质储量的13％、55.3％和12.6％分别分布在河流、三角洲和水下扇的沉积物中。讨论了未来岩相古地理研究应采取的指导思想、工作方法和面临的重要科学问题,指出多信息、多尺度、多元化和数字化的古地理研究必将在未来沉积矿产勘探开发和综合利用中发挥积极的重要作用。     

Thermal reservoir modeling in petroleum geomechanics

Thermal oil recovery processes involve high pressures and temperatures, leading to large volume changes and induced stresses. These cannot be handled by traditional reservoir simulation because it does not consider coupled geomechanics effects. In this paper we present a fully coupled, thermal half‐space model using a hybrid DDFEM method. A finite element method (FEM) solution is adopted for the reservoir and the surrounding thermally affected zone, and a displacement discontinuity method is used for the surrounding elastic, non‐thermal zone. This approach analyzes stress, pressure, temperature and volume change in the reservoir; it also provides stresses and displacements around the reservoir (including transient ground surface movements) in a natural manner without introducing extra spatial discretization outside the FEM zone. To overcome spurious spatial temperature oscillations in the convection‐dominated thermal advection–diffusion problem, we place the transient problem into an advection–diffusion–reaction problem framework, which is then efficiently addressed by a stabilized finite element approach, the subgrid‐scale/gradient subgrid‐scale method. Copyright © 2008 John Wiley & Sons, Ltd.     

On nonlinearity of petroleum formation

A nonlocal dynamic model of petroleum formation is used to explore possible causes and consequences of the nonlinear behavior of large petroleum systems. As a result of this nonlinearity, migration and accumulation of oil starts only after hydrocarbons in a reservoir reach a threshold amount. Significant differences in the amount of in-place resources in macroscopically similar petroleum systems may be associated with minor random changes in initial conditions.     

中国石油安全评价及建议

石油安全对一个国家的经济发展具有重大意义。随着中国经济的持续快速增长,以及受国内石油资源短缺、石油地缘政治等因素的影响,国内石油供需矛盾进一步加剧,石油安全问题日益显现。为科学地评价中国石油安全的程度,先从国内资源禀赋、国内生产能力、国际市场可得性和国家应急保障能力4个方面设计了石油安全评价指标体系;然后,再采用德尔菲法、主成分分析法,选取国内原油储采比、国内原油储量替代率、国内石油消费对外依存度、国内石油进口集中度、国际原油价格和国内石油储备水平6个要素指标,构成一个新的综合指标,即石油安全度;最后,以石油安全度为工具,对中国近年来石油安全的形势进行了定量评价。     

GPS测量在石油物探中的应用探讨

石油物探GPS测量的主要任务是建立平面、高程控制，作为石油物探测量的控制依据，为石油地球物理勘探提供1954年北京坐标系和1956年黄海高程系的野外点位、成果数据及相关图件。GPS测量采用的是WGS-84坐标系统，阐述如何将GPS测量成果转换为高斯正投影成果的应用。     

复合型含油气系统的特征与描述 : 以塔中含油气系统为例

通过对塔中含油气系统的研究，发现它难以用传统的含油气系统方法来描述。它主要有二个油源区三套生油岩，发育有三套储层；不同油源在不同时期生成的油气在储层内共生、甚至相互混合，使油气成因复杂。据此提出了它是一个复合型含油气系统。在此基础上，进一步指出复合型含油气系统的特点是多油源、多期成烃、油气成因复杂，出现在迭合型盆地。并针对这些特点，初步提出了工作思路及描述方法。