光变可作为评价镜质体富氢类型的方法

根据对中国煤和烃源岩中镜质组光变详细的光度学分析结果,建立优质体光变特征与煤阶(成热度)和镜质体类型的相关关系,提出光变型式和幅度可作为评价镜质体富氢类型的新方法.石油窗或沥青化作用阶段富氢镜质体以明显正光变为特征,表现为荧光强度明显增高,荧光光诺向短波长“黄移”.富氢镜质体明显正光变与其中流动相含量较高有关.利用镜质体光变特征区分镜质体类型在炼焦配煤、煤和陆源有机质烃源岩评价和镜质体反射率抑制校正中都具有重要意义.      

FAMM技术在松辽盆地源岩成熟度评价中的应用

采用FAMM技术分析松辽盆地晚白垩世青一段优质烃源岩认为镜质体具有富氢特点,镜质体反射率受到的抑制程度为0.08％ ～0.21％,平均为0.12％.与此同时,建立了实测镜质体反射率与等效镜质体反射率的关系,指出利用实测镜质体反射率评价烃源岩时可能低估了其成熟度.该技术有助于正确恢复盆地的古地温史和热史,能够有效地指导石油勘探.     

古生界干酪根热演化模拟实验

我国南方下古生界页岩中有着丰富的页岩气资源,但因其时代老,成熟度高,且缺乏镜质体,其有机质热演化程度评价成为一个技术难题,对相关页岩气地质研究造成困扰。已有研究表明,干酪根H/C原子比和O/C原子比会随着有机质热演化程度的增加呈现规律性变化,但是对于缺乏镜质体的下古生界干酪根,以及高过成熟阶段干酪根却鲜有研究,其元素演化规律如何?其元素组成与镜质体反射率之间是否存在明确的定量关系?值得研究。为此,针对二叠系大隆组的泥岩和蓟县系洪水庄组页岩,在350～550℃温度范围内开展了系列干酪根热演化模拟实验,测定了各模拟实验温度下所得干酪根的镜质体反射率(R_O)和C、H、O元素组成,发现干酪根H/C原子比和O/C原子比与有机质成熟度之间具有高度的统计学相关关系。结果显示:①在开展烃源岩演化热模拟实验时,对于在泥盆纪以前沉积缺乏镜质体的烃源岩样品而言,利用与烃源岩样品镜质体反射率R_O值相近的煤样来标定样品热演化进程的方法是可行的;②在热演化进程中,干酪根的H/C、O/C原子比值均会随着有机质成熟度的增加发生规律性的变化,不同类型干酪根的H/C原子比值表现出沿相同路径不断降低的演化特征,而O/C原子比值表现出沿不同路径不断降低但最终趋同的演化特征;③实验中涉及的3种类型干酪根的H/C、O/C原子比(R_(H/C)和R_(O/C))与用镜质体反射率R_O(%)所表征的有机质热演化程度之间均体现同一规律,并存在良好的数学相关关系,可以表达为LgR_O=-0.133 1-1.190 5 LgR_(H/C)-0.054 4LgR_(O/C),适用于该实验中涉及的3种类型干酪根,适用RO值范围为0.6%～3.5%。     

东海盆地西湖凹陷烃源岩成熟度厘定——FAMM分析的证据

镜质体反射率是评价烃源岩有机质成熟度的主要指标之一,已有研究表明,镜质体反射率（R_o）除受控于有机质热演化程度外,还受烃源岩有机质类型等因素的影响,镜质体富氢程度制约镜质体反射率的抑制程度,影响了R_o测值的准确性。多组分荧光变化（FAMM）技术可有效解决镜质体反射率的抑制问题。利用FAMM技术和镜质体反射率分析方法,对取自东海盆地西湖凹陷9口钻井的10件平湖组烃源岩样品进行了成熟度分析,结果显示样品的镜质体反射率存在不同程度的抑制,抑制校正值介于0.01%~0.25%,个别样品稍有增强现象。根据FAMM分析结果,以TWT1井为例,厘定了该井区平湖组烃源岩的成熟度,认为TWT1井区平湖组烃源岩的现今成熟度应处于0.90%~1.41%,而不是实测镜质体反射率分析结果显示的0.77%~1.21%。研究结果有助于合理评价平湖组烃源岩生烃潜力及油气资源潜力。      

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.     

异常低的镜质体反射率(抑制作用)——生油岩研究的一个重要问题

镜质体反射率在石油地球化学中是一种很有用的工具,但目前研究中还存在一些问题,其中一个主要问题只有少数研究者认识到了,这就是镜质体反射率的反常下降(R_o 抑制作用)。丰富的文献资料表明,镜质体反射率是被相当浓度的富氢煤素质抑制,或者被富氢煤素质本身抑制。作者提出 R_o 抑制作用的原因是镜质体的富氢和高活化能。作者建议用实验验证该假定。     

'HNMR自旋晶格弛豫时间T_1作为有机质成熟度指标的探讨

作者以海拉尔盆地3口井23块泥岩干酪根样品进行了‘HNMR T_1测定,给出了干酪根‘HNMRT_1与最大热解温度Tmax和镜煤反射率R°之间的关系,並对实验结果进行了探讨。     

HNMR自旋晶格弛豫时间T1作为有机质成熟度指标的探讨

作者以海拉尔盆地3口井23块泥岩干酪根样品进行了‘HNMR T₁测定,给出了干酪根‘HNMRT₁与最大热解温度Tmax和镜煤反射率R°之间的关系,並对实验结果进行了探讨。      

荧光变异能够替代镜质体反射率作为石油勘探中测定热成熟度的一种…

多煤组份荧光变异（ＦＡＭＭ）技术与镜质体反射率密切相关。直到目前，沉积岩中分散有机质（ＤＯＭ）的荧光变异研究被认为还存在着许多技术上的难题。随着光学显微探针的引进，配以小型连续波的气体激光发射稳定的兰色射线，聚焦到样品１－２μｍ点上，已成为常规分析方法。ＦＡＭＭ技术比镜质体反射率更先进，这是 将资料分为二个参数，一个参数与成熟度有关；另一个参数与煤组分的氢丰度有关。这就使得应用单一参数的镜质体反射     

有机质反射率的数字图像实现方法

有机质反射率参数是烃源岩评价和盆地热演化史研究的基础数据。目前有机质反射率的测量工作主要依靠人工手动方法，人为主观因素对测量结果影响较大。从图像传感技术出发，探寻镜质体反射率与灰度图像之间的相互关系，尝试建立利用镜质体灰度图像表征反射率值的方法。分别对标准物质和地质样品开展了镜质体反射率和灰度级的对应测量工作，发现两者具有极好的重合特征，表明利用灰度级定量镜质体反射率的方法具有可行性。但对于高过成熟阶段，两者的关系尚有待深化研究。      

ORGANIC FACIES OF EARLY CRETACEOUS SYNRIFT LACUSTRINE SOURCE ROCKS FROM THE MUGLAD BASIN, SUDAN

Cuttings samples from eight wells in the Muglad Basin have been analysed using a combination of organic geochemistry and palynofacies. The lacustrine Aptian-Albian shales of the Abu Gabra Formation, previously identified as the main source rock, have an overall mean TOC of 1.43% (n = 146), with those from the NW part of the basin (Sharaf area) being approximately twice as organic-rich as those from the SE (Heglig area). The Abu Gabra Formation contains two distinct organic facies: a lower interval dominated by higher TOC values (1.5–2.3%), higher measured hydrogen indices (338–546), higher amorphous kerogen contents (>80%), and heavier δ¹³C_TOC values (> −27%₀); and an upper, less rich interval (mean TOC 1.4%, mean HI 83, δ¹³C_TOC approximately −28%₀). The isotopic contrast between the upper and lower units may potentially be of stratigraphic use. The organic facies differences appear to reflect deteriorating preservation of the organic matter (higher dissolved oxygen, possibly due to shallower conditions resulting from lower rates of subsidence). Use of S2 v. TOC plots suggests corrected true mean hydrogen indices of around 800 in the richer facies (corresponding to a Type I kerogen). Mean random vitrinite reflectance, pyrolysis Tmax values, and visually determined fluorescence colours indicate that the samples studied are mostly immature, or at most in the earliest part of the oil window (<0.7% VR_o); biomarker data suggest that the vitrinite reflectance values may be suppressed by up to 20%.     

煤系烃源岩热模拟演化过程的地球化学参数特征――以准噶尔盆地侏罗系煤系烃源岩为例

在准噶尔盆地侏罗系煤系烃源岩热模拟实验研究中 ,经过对原样和不同温度点热模拟残余物进行可溶有机质抽提和族组成分析、残渣干酪根处理、Ro 值测定和 TOC测定 ,并对部分样品系列进行色谱和质谱分析后发现 ,煤系烃源岩在不同热演化阶段表现出的地质地球化学特征具有相当大的差异。低演化阶段和热降解阶段天然气的形成是不同热力学条件和成气母质化学反应的结果。在低演化阶段 ,源岩镜质组反射率增长幅度并不太大 ,通常 Ro<0 .7%。原始可溶有机质和热模拟残余可溶有机质的分析结果表明 ,烃类气主要来源于原始可溶有机质的脱基团作用和大分子沥青质及干酪根边缘烃 (极性组分 )的热降解。在有机质热降解―热裂解阶段 ,烃源岩经地质埋深增温 ,热演化进程相对加快、镜质组反射率迅速递增、Ro 值从 0 .5 5 %～ 0 .70 %迅速增大到 1 .40 %～1 .70 % ,可见热动力作用足以破坏干酪根结构烃并将其降解形成油气。该阶段是干酪根经热降解大量排烃的阶段 ,其地球化学参数特征主要表现为干酪根结构烃热降解产物的特征。     

用漫反射光谱测定方法研究干酪根成熟度

用紫外／可见光／近红外漫反射光谱仪测定济阳均陷东营凹陷沙河街组8个干酪根样品的漫反射光谱，发现在波长600-1000nm范围，谱线的斜率与镜质体反射率(0．27%-0．67%)之间有很好的线性负相关关系。干酪根的漫反射光谱测定有可能成为评价有机质成熟度的一种筒单、快速、定量的新方法。图3表1参12     

塔里木盆地库车坳陷中生界烃源岩有机质成熟度

对库车坳陷主要探井和１３个露头剖面近１６０个中生界源岩样品镜质体反射率进行了实测分析,并利用地震测线人工井模拟计算镜质体反射率,初步明确了库车坳陷三叠—侏罗系源岩有机质成熟度的分布规律。依南２井三叠系—侏罗系源岩实测镜质体反射率为１０３％～１４３％,阳１井中、下侏罗统实测镜质体反射率为０９５％～１１０％各个露头剖面镜质体反射率存在很大差异,露头剖面成熟度区域上总体呈现西部高（Ｒｏ高达１８１％～１８３％）东部低（Ｒｏ在０５６％～０７９％）,中部介于东西部之间,北部低（Ｒｏ在０５７％～０６８％）南部高的特点。在逆冲带,由于近晚期逆冲断层将深部烃源层推到浅部或地表,即使埋深很浅,实测镜质体反射率仍较高     

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.     

烃源岩有机质热演化过程中碳氢含量的变化

本文通过对大量地化数据(包括模拟试验数据)的回归分析,给出了根据干酪根类型和成熟度(R_o)求出烃源岩降解残碳率和氢碳原子比的经验方程。     

江汉盆地下第三系烃源岩有机岩石学研究

作者采用有机岩石学全岩分析技术,系统研究了江汉盆地下第三系烃源岩的显微组分组成、生烃组分及有机质热演化。江汉盆地烃源岩形态显微组分含量明显偏低,平均仅占全岩体积的1.5%。显微组分组成中富含腐泥组,相对发育镜质组和壳质组,贫惰性组。有机质类型多为Ⅱ、Ⅰ型。藻类体、矿物沥青基质是该区主要生烃组分。文中利用镜质体反射率R_o及富氢组分和非烃馏分的荧光参数探讨了江汉盆地烃源岩有机质演化特征,提出了有机质的热演化阶段的划分方案。      

A REASSESSMENT OF THE RANGE OF KEROGEN MATURITIES IN WHICH HYDROCARBONS ARE GENERATED

The ranges of vitrinite reflectance values, defining zones in which oil and gas generation occur, are examined from several points of view. Geochemical consideration of coalification reactions, kerogen compositions, iso-reflectance lines, spore colour and fluorescence, electron-spin resonance, extract data and reservoir temperatures point to the following approximate ranges: oil generation 1.0–2.0% R_o, wet gas and condensate 1.5-3.0% R_o, methane 2.0–5.0 % R_o. Biogenic methane can be formed at < 0.6% R_o. and hydrogen generation from kerogen appears to be possible above 5.0% R_o. These results point to hydrocarbon generation under hotter, deeper conditions than those proposed in most previous schemes. As a consequence, reflectance ranges are broadened for traces of vitrinite in possible reservoirs: oil < 0.4-1.3% R_o, methane < 0.4-3.0% R_o     

ORGANIC GEOCHEMICAL CHARACTERIZATION AND SHALE GAS POTENTIAL OF THE PERMIAN BARREN MEASURES FORMATION,WEST BOKARO SUB‐BASIN,EASTERN INDIA

This study investigates the shale gas characteristics of the Permian Barren Measures Formation (Gondwana Supergroup) in the West Bokaro sub‐basin of the Damodar Valley Basin, eastern India. A total of 23 core shale samples collected from a borehole located in the western part of the sub‐basin were analysed using organic geochemical techniques and scanning electron microscopy. The samples are black carbonaceous shales composed chiefly of quartz, mica and clay minerals. Rock‐Eval pyrolysis data show that the analysed samples contain a mixture of Type II and Type III kerogen with TOC values of 2.7 to 6.2%. Rock‐Eval T_max values ranging from 443 to 452 °C correspond to calculated vitrinite reflectance of approximately 0.8–0.9%. A cross‐plot of hydrogen index versus T_max indicates that the samples have reached peak oil to wet gas maturities. A pristane/n‐C₁₇ versus phytane/n‐C₁₈ cross‐plot, together with biomarker parameters such as the dominance of C₂₉ over C₂₇ and C₂₈ steranes and high moretane/hopane ratios (0.22–0.51), demonstrate that the shale samples contain terrigenous organic matter deposited in a suboxic environment. Scanning electron microscopy images of shale samples show the presence of a complex, mostly intergranular pore network. Both micropores (>0.75μm) and nanopores (<0.75μm) were observed. Some pores are elongated and are associated with layer‐spaces in sheet silicate minerals; others are non‐elongated and irregular in shape. The organic geochemical parameters and the observed pore attributes suggest that the Barren Measures Formation has good shale gas potential.