【作者】 王民；

【导师】 卢双舫； 冯子辉；

【作者基本信息】 东北石油大学 ， 矿产普查与勘探， 2010， 博士

【摘要】 在火山岩油气藏研究中,储层岩性、岩相分类、孔渗变化、火山作用对烃源岩成熟度影响以及无机成因烃的形成机理等方面研究较多,对于火山作用的有机质成烃热效应几乎没有研究。研究火山作用的有机质成烃热效应可以为评价其对烃源岩生烃量的增减和油藏的热破坏程度提供技术手段,还有助于正确认识火山作用在油气成藏中的贡献和完善火山岩油气藏理论。这方面研究不仅需要建立火山岩体的热容模型、热传导模型,还需建立有机质成烃动力学模型。为此,建立了多个化学动力学模型及岩浆侵入体热传导模型,并建立了各模型参数优化求取方法。进一步在不同类型有机质的生烃(油、气)热模拟实验,获得产物产率与温度的关系数据基础上,对不同模型、不同实验体系结果、不同类型有机质生烃动力学特征的进行对比研究,并开展了动力学模型参数稳定性、烃源岩非均质性对动力学参数的影响以及岩浆侵入体规模、性质、与烃源岩时空匹配关系不同时对围岩成熟度、生烃热效应的影响研究。最后结合徐家围子、英台断陷烃源岩参数进行天然气资源量评价。本次研究对今后应用生烃动力学方法评价资源潜力以及定量评价火山热作用对烃源岩生烃量的增减有重要指导意义。取得以下成果和认识:(1)密闭体系下有机质、原油热裂解过程中总烃气质量产率下降的温度与重烃气质量产率的拐点温度并不相同,表明高温阶段甲烷的来源仍然存在有机质/原油的初次裂解贡献,不完全是重烃气(C2-5)裂解贡献,但对于组成相对简单的液态烃或纯化合物这两个温度比较接近。(2)TG-MS实验下煤岩生甲烷终止温度约为850℃,对应的Ro约为5.3%(10℃/min升温速率),密闭体系下煤岩在650℃时(Ro约为4.9%,升温速率2℃/hour)煤岩生气能力尚未结束,气态烃质量产率一直呈增长趋势,表明煤岩在高温阶段仍具有生甲烷能力。可能是密闭体系下低温阶段热解的正构烷烃(n-alkyl)产物通过环化和芳香化作用与沥青或者干酪根发生缩聚/再结合作用形成了具有较高热稳定性的产物,这一产物在高温阶段可以再次生成甲烷。而在开放体系下正构烷烃被载气携走,不具备这类反应发生条件。(3)热传导模型结合EasyRo%模型可以较好的拟合实测Ro数据,还可以方便地模拟计算二维、三维空间内温度场及成熟度史演化。岩浆侵入体的热作用范围是有限的,地质情况不同,影响范围广度也不同,对于相同厚度的侵入体,初始温度越高,作用范围越广,但一般X/D<3(X/D指接触面的距离与侵入体厚度的比值)。对于不同厚度侵入体而言,侵入体热作用影响范围X/D<2。(4)总包反应动力学方程简单,但不适合描述复杂有机质成烃过程,有机质生烃也不完全符合连串反应机理,可能结合连串反应和平行反应两种模型描述有机质生烃过程比较合适,但是这类模型参数标定比较复杂,实验室工作比较繁重。串联反应模型无论从动力学理论上还是标定动力学参数的结果上都不适合。从各模型在烃源岩潜力评价中应用情况及各模型参数的优化效果来看,活化能服从离散分布的平行一级反应模型描述有机质生烃过程最为合适。(5)随指前因子的增加,表观活化能逐渐增加,且不同类型干酪根的表观活化能按如下顺序排列E II2-III >E I >E II1。(6)以SFF模型描述有机质生烃特征,优化的动力学参数—指前因子由小到大变化,其优化效果也存在一个极值。随着指前因子的增加,活化能分布形态基本上不发生变化,但整体向活化能增高方向偏移,指前因子每增加10倍,平均活化能增加约12kJ/mol,以3.3℃/Ma的地质升温速率进行外推,TR0.5(成烃转化率为50%)对应的地质温度逐渐增加,但增加值逐渐减少。(7)采用SFF模型研究不同类型有机质成烃动力学参数特征表明湖相I型有机质样品化合物结构及化学键类型相对单一,以单个活化能分布形态为主,湖相II2及陆相III型有机质样品化合物结构的非均质性较强,活化能分布范围宽,且“优势活化能”所占反应的分数随其氢指数降低而降低。同时不同活化能分布间隔动力学模型地质外推结果显示,活化能分布间隔对成烃转化率的影响不大,可以采用适当个数的平行反应模型描述有机质成烃过程。地质外推表明,I型有机质生烃速率范围分布较窄,且曲线圆滑。II1型、II2—III型有机质生烃速率分布范围较宽,其中II2—III型有机质生烃速率存在多个局部高点,波动频繁。(8)采用MFF(Multiple Frequence Factor)模型可以避免采用SFF(Single Frequence Factors)模型出现的低估具有较低和较高活化能有机质的生烃潜力(反应分数)这一问题。(9)烃源岩非均质性对采用生烃动力学方法评价资源量有一定的影响,可以通过采用MFF模型和S2加权平均法获得的动力学参数进行资源评价。同时建议结合地质上其他数据(如S1、Tmax、S1+S2等)对动力学参数进行优选。(10)相同条件的侵入体对于具有不同初始Ro的有机质热成熟度和生烃的热效应并不相同,表现在Ro<0.9%(对应大量生烃前)时,热效应随着初始Ro的增加而逐渐增加,当初始Ro>0.9%(对应大量生烃后)之后,热效应随着初始Ro的增加而逐渐降低。因此,具有相同初始条件的侵入体可以导致不同的热影响范围。在烃源岩大量生烃前,岩浆侵位时间越晚对生烃的热效应也越大,反之,则越小。(11)对龙深1井侵入体附近泥岩有机质成熟度及地球化学参数进行了分析,表明随着与接触面距离的减小,围岩中有机质成熟度逐渐升高,由原来的1.6变化到2.1左右,岩石热解参数Tmax则逐渐增大,H/C和O/C值逐渐降低,围岩中TOC逐渐降低,氯仿沥青"A"先增加后降低。在两套侵入体之间,Tmax值变化呈现”V”字型特征,围岩中TOC出现先增大后降低的趋势。同样,围岩氢指数(HI)、热解烃S2也出现类似变化。(12)采用MFF模型结合龙深1井区埋藏史、热史对侵入体的生烃热效应进行了研究,表明在侵入体影响范围内,成气转化率迅速增长。侵入体不同距离处的生气史则表明在很短的时间内,生气转化率从0增加到80%以上。可见,将化学动力学模型、埋藏史模型、侵入体热传导模型和正常热史模型结合起来可以很好的研究有机质复杂的成烃过程。(13)评价结果显示英台断陷深层天然气生成总量为5.1×1012m3,资源量为1072×108~1608×108m3(运聚系数取1.6%~2.4%)。徐家围子断陷深层天然气总生成量为33.75×1012m3,资源量为5020×108~7530×108m3(运聚系数取1.6%~2.4%)。更多还原

【Abstract】 During the past 40 years volcanic reservoir exploration in China, many researches have been carried out, such as reservoir lithology, facies classification, porosity-permeability characteristics, volcanism on the source rock maturity and the formation mechanism of inorganic hydrocarbon, however, the hydrocarbon generation thermal effect of volcanism has not been studied. It is not only hopeful to provide a technical means for quantitative evaluating the net quantity of hydrocabon generation and the destroyed degree of oil reservior, which is caused by volcanism, but also helpful to recognize the contribution of volcanism to the petroleum exploration and perfect the theory of volcanic petroleum exploration. To achieve this target, the heat capacity model of magmatic intrusion, the heat conduction model and the chemical kinetics model of hydrocarbon generation should be established. Therefore, some chemical kinetic models and thermal conduction models have been established, so do parameters calibation methods. Based on thermal simulation experiments for different types OMs (organic matters) and the relation data between products yields and heating temperatures, comparison researches on different kinetic models, the products yields from different experiments and the hydrocarbon generation kinetic characteristics of different types OMs have been completed, meantime, the stability of kinetic models, the effect of source rock heterogeneity on kinetic parameters and the effects of intrusion dimensions, nature and the time-space range of source rock on country rock maturity and hydrocarbon geneartion thermal effect have been investigated. At last, combined source rock parameters and the above mentioned models, the natural gas resource of Xujiaweizi depression and Yingtai depression have been estimated. The research method and conclusions of this dissertation have important guiding significance to oil-gas resource potential appraisement and quantitative evaluating the net quantity of hydrocabon generation caused by thermal effect of mamatic intrusion. In a summary, the main conclusions and achievements of the dissertation are listed bellow:1. The tempeartue corresponding to C1-5 mass yields decreasing and the inflection point temperature of C2-5 mass yields are different when OM and oil cracking under closed system in the lab, which indicates that there is also the contribution of primary cracking from OM and oil to the methane source, not only the contribution of C2-5 cracking. However, the above two temperature should be colse for pure compund or oil with simpler compositions.2. The termination temperature of methane generation from coal sample under TG-MS experiment is about 850℃(with 10℃/min heating rate), and the corresponding Ro is about 5.3% calculated by extended EasyRo% model. However, the C1-5 mass yields increase all the while even at the end experiment temperature under the closed system experiment (the corresponding Ro is about 4.9% and with 2℃/hour heating rate), which indicates coal sample has gas potential at higher maturity stage. It may be caused by the recombined reaction of C6+ liquid hydrocarbons with kerogen or bitumen under closed environment, which will be formed new products with high thermal stability and the new formed products will generate methane at higher maturity stage. For open system, such as TG-MS experiment and Rock-Eval experiment, this recombined reaction cannot take place because the C6+ liquids are swept off by the carried gas.3. The measured Ro can be fitted by combining the thermal conduction model and the EasyRo% model, and the combined of the two models can be easily used to simulate the temperature fields and maturity evolution history caused by magmatic intrusion in two or three dimensions. The thermal effect scope of the magmatic intrusion is limited and the scope changes with different geological situations. For intrusions with the same thickness, the higher the initial temperature of intrusion, the heavier of the metamorphism degree and the deeper of the scope, however, the X/D ratio is smaller than 3 generally (D corresponds to the intrusion thickness and X corresponds to the distance from the contact surface and to the simulated depth). For intrusions with different thickness, the thicker of the intrusion, the deeper of the scope, and the X/D ratio is smaller than 2 generally.4. The kinetic equation in the overall reaction model is simple but can’t well simulate the complicated hydrocarbon generation process. The hydrocarbon generation process may not be fully consistent with the mechanism of consecutive reaction model, but it is appropriate to combine the consecutive reaction model and parallel reaction model to describe the hydrocarbon generation process. However, due to the complexity of the model and thus heavy experiment work in the lab. The Friedman type model is inappropriate from the view of kinetic theory and kinetic parameters. In view of the model application in source rock potential appraisement and the kinetic parameters optimization effect, the parallel first-order reaction model with a discrete distribution of activation energies is the best model for describing the hydrocarbon generation process.5. Apparent activation energy increase gradually with the increasing pre-exponential factor and the order of apparent activation energy from high to low for different types OMs is EII2-III, EI and EII1.6. Based on hydrocarbon generation characteristic described by SFF model, the pre-exponential factors change from low to high, an extreme value for residual errors occurs. And with the increasing pre-exponential factor, the distribution shape of activation energies are nearly the same, but the values of activation energies move toward to higher integrally. The average activation energies increase about 12kJ/mol for ten times increasing of pre-exponential factor, and the temperature corresponding to TR0.5 is higher, but the net increasing value change to small when extrapolating using a simple geological heating rate (3.3℃/Ma).7. The TR ratios obtained from experiment and the relationship of reaction fraction vs. activation energy reveal that the types of compound structures and chemical bonds of lacustrine facies type I OM are relative homogeneous, which with one dominating activation energy. And types of chemical bonds of lacustrine facies type II1 OM and the terrestrial type III OM is relative complex, which with a broad activation energy distribution. And the reaction fraction of the preponderant activation energy drops with the decrease hydrogen index. The study of the impact of activation energy distribution spaces on the geological extrapolation shows that different spaces have little effect to the hydrocarbon transformation ratio. Therefore, the parallel first-order reaction model with proper number activation energies can be better used to describe the hydrocarbon generation process. The geological extrapolation results of 18 samples kinetic parameters show that, the distribution range of hydrocarbon generation rate for different types of organic matter have different distribution profiles, of which type I organic matter features a narrow and smooth generation curve and types II1 and II2-III span over a wide range whilst type II2- III has many peaks and fluctuates frequently. Distribution width of hydrocarbon generation rate has relationship with its kinetic parameters, namely, the narrower the activation energies distribution is, the narrower the hydrocarbon generation rate distribution is, the smoother the hydrocarbon generation curve is, and vice versa.8. The comparison and analysis between MFF model and SFF model shows that MFF model can avoid miscalculating the hydrocarbon generation potential (reaction ratio) in the low and high evolution stages, which appears in SFF model.9. The heterogeneity of source rock has influence on oil-gas resource appraisement when using the hydrocarbon generation kinetic method, however, it can be avoid by combining the MFF model and the weighted averaged kinetic parameters for more samples. Meantime, it is recommended to confine the kinetic parameters using geological data, such as S1, Tmax and S1+S2 et al.10. The thermal effect of maturity and hydrocarbon generation caused by magmatic intrusions are different for OMs with different initial maturities, though intrusions with the same conditions. For example, thermal effect increases with the increasing initial maturity of OM if the vitrinite reflectance is smaller than 0.9%, but the thermal effect decreases with the increasing initial maturity of OM if the vitrinite reflectance is bigger than 0.9%. Therefore, intrusions with the same initial conditions can cause different metamorphism degrees. Before the hydrocarbon generation, the later the emplacement of intrusion, the greater the thermal effect of hydrocarbon generation, and vice versa.11. Analyzing results of maturity and geochemical index for mudstone near intrusions of Longshen1 well indicates that with the decreasing distance from contact surface, the maturity increases from 1.6% to 2.1%, the Tmax increase gradually, the H/C, O/C and TOC values decrease gradually and the chloroform bitumen“A”increases firstly then decreases. Between two intrusions the Tmax values takes on“V”shape, and so do TOC values. The HI and S2 values change as above mentioned rule.12. The research results of thermal effect for intrusions of Longshen1 well show that the gas generation TR increases quickly in the metamorphism range, for example it can be increase from 0 to 80% during a short period. It also shows that combining the kinetic model, burial model, thermal conduction model and normal thermal model can be a useful tool to describing the hydrocarbon generation process.13. The natural gas generation amount is 5.1×1012m3,and resource quantity is 1072×108~1608×108m(3the corresponding range of migration and accumulation coefficient is from 1.6% to 2.4%)for Yingtai depression. And the natural gas generation amount is 33.75×1012m3,and resource quantity is 5020×108~7530×108m3for Xujiaweizi depression.更多还原