【作者】 乔二伟；

【导师】 郑海飞；

【作者基本信息】 北京大学 ， 地球化学， 2007， 博士

【摘要】 目前对石油的稳定界限和压力的作用仍存在很大争议，而且以前的研究者在用热模拟实验等方法来研究原油或者烷烃的裂解时，很少有人曾考虑到压力因素，即使考虑了，由于受实验技术本身的限制，只能固定压力来升温且多为低压，这和实际的地质条件相差深远。同时对于在油气成因、油气包裹体及其高温高压实验研究等地质科学领域应用较广泛的压力标定方面也有很多工作需要去探索，目前基本上还没有对有机物作为压标进行详细研究的。针对上述三方面的问题，作者采用金刚石压腔高温高压实验技术，对主要液态饱和烃（正己烷、正庚烷、正十五烷、环己烷）及其二元混合物（环己烷－正庚烷混合物、环己烷－正十五烷混合物）和两相混合物（水－正庚烷混合物、水－环己烷混合物、水－正十五烷混合物）等三大类共九种物质进行了高温高压下激光拉曼散射光谱的研究。三种不同体系（纯态、混合态和水体系）中的液态饱和烃，无论是在常温或是高温下以及其是否结晶，它的CH3、CH2伸缩振动和环呼吸振动的拉曼峰均随压力增大而向高频方向移动，且一般情况下，反对称伸缩振动趋向于高频的速度明显快于相对应的对称伸缩振动，同时常温下的上述所有振动趋向于高频的速度明显快于相对应的高温下的振动。在加热过程中，均伴随着温度和压力两种相反的效应，但压力效应占据主导地位。它在液态饱和烃的加热分解过程中起了抑制作用，对于其在高温下的稳定起了重要作用。不同体系中的液态饱和烃在各自实验的温度和压力条件下，均保持了稳定，没有出现明显的分解现象。它们在300MPa以内，最高的稳定温度可以达到280-315℃，这可以代表石油稳定的最低界限，但它仍然高于以前的研究结果。液态饱和烃混合后，虽然环烷烃的拉曼位移和压标公式发生了一定的变化，但其稳定性、压力的作用及P-T之间的关系（等容线）并没有受到影响；平均C-H伸缩振动的拉曼位移也受到了混合作用的影响，但其P-p-T关系式并不改变。平均C-H伸缩振动的拉曼光谱可作为压力计应用于流体包裹体，特别是油气包裹体。其关系式为：P=75.56+0.3508T+60.7（23≤T≤405、P＜2160MPa）。水－液态饱和烃的两相混合物中，水对液态饱和烃的分解起到了一种抑制作用，从而可以使液态饱和烃在更高的温度下保持稳定。另外，水对油气的运移可能起着一定的作用。液态饱和烃的液/固平衡线和等容线结合起来除可以估算烃类流体包裹体的最小捕获压力外，还可被用来大致确定流体包裹体特别是油气包裹体中的烃类组成。环己烷可以作为压标使用，且在三种不同的体系中有相对应的校正公式，它们分别为：纯环己烷体系：P=60.337(Δ p)2933+0.818T+4.999（20℃≤T≤315℃、P≤1100MPa）P=79.488(Δ p)802+1.910T-44.910（20℃≤T≤315℃、P≤1100MPa）环己烷－正庚烷混合体系：P=144.865(Δ p)801+1.954T-75.355（20℃≤T≤315℃、P≤2100MPa）环己烷－正十五烷混合体系：P=135.484(Δ p)803+1.721T+64.045（20℃≤T≤405℃、P≤2100MPa）水体系：P=154.55(Δ p)2855+338.35（常温，0＜(Δ p)2855≤2.3cm-1）P=75.425(Δ p)2933+0.462T+20.285（20℃≤T≤300℃、P≤1550MPa）P=98.424(Δ p)802+1.99T-67.58（20℃≤T≤300℃、P≤1550MPa）正庚烷也可以作为压标使用，且在两种不同的体系中有相对应的校正公式，分别为：纯正庚烷体系：P=159.73(Δ p)2880-55.457（常温，0.35≤(Δ p)2880≤6.9cm-1）P=157.81(Δ p)2935+36.798（常温，-0.23≤(Δ p)2935≤6.4cm-1）P=70.476(Δ p)2965+0.0628T+29.036（20℃≤T≤315℃、P≤2000MPa）。水体系：P=122.13(Δ p)2880+1.3328（常温，-0.01＜(Δ)12880≤9.5cm-p）P=148.09(Δ p)2857-11.301（常温，-0.8≤(Δ p)2857≤7.8cm-1）P=126.72(Δ p)2935+171.66（常温，-1.35≤(Δ p)2935≤7.7cm-1）P=81.264(Δ p)2965+0.397T+96.691（20℃≤T≤315℃、P≤2200MPa）*注在以上各关系式中：P为压力，单位MPa；T为温度，单位℃；Δ p、 p为一定温度压力下，样品某振动的拉曼位移的偏移量（cm-1），即Δ p＝p-0和＝p-0， p、为某一温度压力下的拉曼位移，0、0为常温常压下的拉曼位移。更多还原

【Abstract】 At present the temperature of petroleum stability and pressure effect are still uncertain. Whenprevious scholar investigated cracking of oil or alkanes by thermal simulation experiment, fewpeople ever considered the role of pressure. Those people who thought pressure effect existed onlyincreased temperature at a constant pressure which was basically low because of limitedexperimental technologies. It is far from real geological condition. In addition, the issue is thepressure gauge extensively used in geology science such as the origin of petroleum, hydrocarboninclusion and experimental study under high temperature and high pressure, and at present,organic matter as a pressure gauge have not been nearly investigated. Mainly aiming at the abovethree scientific questions, we have studied the laser Raman scattering spectra of some liquidsaturated hydrocarbons, which can be commonly found in the petroleum, such as n-hexane、n-heptane、n-pentadecane、cyclohexane，and their mixture such as cyclohexane－n-heptaneblends、cyclohexane－n-pentadecane blends, and water－n-heptane blends、water－cyclohexaneblends、water－n-pentadecane blends by the experimental technique of diamond anvil cell. Wehave got some achievements as following.Whether at room temperature or at high temperature, and whether the liquid saturatedhydrocarbons became crystallized or not, the Raman bands of CH3and CH2stretchings and thering breathing mode of the liquid saturated hydrocarbons in ternary system (pure system、twoblends system of liquid hydrocarbon samples and water system) shifted to higher wavenumberswith increasing pressure, in general, not only the asymmetric stretching shifted to higherwavenumbers more quickly than corresponding to the symmetric stretching, but also at ambienttemperature above all these Raman bands shifted to higher wavenumbers more quickly thancorresponding to the vibrational mode at high temperature.In the process of increasing temperature, there were two opposite effects which weretemperatures and pressures, but pressure effects exert larger influence than temperature effects inliquid saturated hydrocarbons. Increasing pressure can retard thermal destruction of liquidsaturated hydrocarbons, so it is important for liquid saturated hydrocarbons to keep stable at hightemperature.Any visible changes didn’t occur in the liquid saturated hydrocarbons where were in ternarysystem and they kept their own usual state under their experimental temperatures and pressures.Their maximum stable temperature range from280℃to315℃below300MPa which imply theminimum stable temperature of petroleum, and it is higher than the results of previous studies.Although Raman shift and equation of pressure gauge of cyclohexane changed in two blendssystem of liquid hydrocarbons, the stability of liquid hydrocarbon and the role of pressure weren’taffected. The Raman shift of a mean C-H stretching vibrational mode was affected by mixture liquid hydrocarbons, but the equation of P-p-T wasn’t varied.The Raman spectrum of a mean C-H stretching vibrational mode can be used as a barometerof fluid inclusions, especially hydrocarbon inclusion, and its equation is as following:P=75.56+0.3508T+60.7（23≤T≤405、P＜2160MPa）Water retard the decomposition of liquid saturated hydrocarbons in water system, so liquidsaturated hydrocarbons can be kept stable at higher temperature. Moreover, water may play acertain role during primary migration of petroleum.The liquid/solid equilibrium line and isometric line of liquid saturated hydrocarbons can beused as not only estimating the minimum captured pressure of hydrocarbons, but also roughlydetermining the hydrocarbon component of fluid inclusions, especially hydrocarbon inclusion.Cyclohexane can be used as a pressure gauge, and it has different equations in three systemsas following:Pure cyclohexane system: P=60.337(Δ p)2933+0.818T+4.999（20℃≤T≤315℃、P≤1100MPa）and P=79.488(Δ p)802+1.910T-44.910（20℃≤T≤315℃、P≤1100MPa）.Cyclohexane－n-heptane blends system: P=144.865(Δ p)801+1.954T-75.355（20℃≤T≤315℃、P≤2100MPa）.Cyclohexane－n-pentadecane blends system: P=135.484(Δ p)803+1.721T+64.045（20℃≤T≤405℃、P≤2100MPa）.Water system: P=154.55(Δ p)2855+338.35（ambient temperature，0＜(Δ p)2855≤2.3cm-1）,and P=75.425(Δ p)2933+0.462T+20.285（20℃≤T≤300℃、P≤1550MPa）, and P=98.424(Δ p)802+1.99T-67.58（20℃≤T≤300℃、P≤1550MPa）.n-Heptane can be used as a pressure gauge, and it has different equations in two systems asfollowing:Pure n-heptane system: P=159.73(Δ p)2880-55.457（ambient temperature，0.35≤(Δ p)2880≤6.9cm-1）, P=157.81(Δ p)2935+36.798（ambient temperature，-0.23≤(Δ p)2935≤6.4cm-1）and P=70.476(Δ p)2965+0.0628T+29.036（20℃≤T≤315℃、P≤2000MPa）.Water system: P=122.13(Δ p)2880+1.3328（ambient temperature，-0.01＜(Δ p)2880≤9.5cm-1）, P=148.09(Δ p)2857-11.301（ambient temperature，-0.8≤(Δ p)2857≤7.8cm-1）, P=126.72(Δ p)2935+171.66（ambient temperature，-1.35≤(Δ p)2935≤7.7cm-1）, and P=81.264(Δ p)2965+0.397T+96.691（20℃≤T≤315℃、P≤2200MPa）.Note: P－Pressure (MPa)；T－Temperature (℃). Δ p、 are wavenumber shifts relative tothe line position at room temperature and pressure（in cm-1）. i.e. Δ pis p-0and is p-0. pand are Raman shifit at a certain temperature and pressure,0and are Ramanshifit at room temperature and pressure.更多还原