矿物低温催化混合酯水解及生烃动力学研究.doc

矿物低温催化混合酯水解及生烃动力学研究 脂肪酸及其衍生物是低熟油的重要生烃母质。研究发现,未熟烃源岩中含有丰富的脂肪酸,且分布在不同的碳数范围内,而脂肪酸酯是脂肪酸的主要赋存形式。因此,以混合脂肪酸酯为模型反应物,考虑各种影响因素的综合作用,进行矿物低温催化混合酯水解及生烃反应的动力学研究,探讨在接近实际地质条件下脂肪酸酯的生烃机制及其对低熟油产生和成藏的贡献,是一个具有理论意义和实际价值的研究课题。首先,对矿物低温催化混合酯水解及生烃反应的几个重要影响因素进行了考察1运用正交试验综合考察了反应温度、反应压力、pH值和盐度的影响,并结合正交试验结果的极差分析和灰色关联分析,对影响因素的显著性进行了评价。结果表明,反应温度的影响最大,其次是pH值,第三是反应压力,第四是盐度。2系统考察了几种无机盐对矿物低温催化混合酯水解及生烃反应的影响,对几种无机盐的影响作用进行了系统的划分,并分析了其影响机制。不同的盐类介质产生了不同的影响作用,氯化镁对水解反应起负的影响作用,硫酸钠对生烃反应起负的影响作用,所考察的其它盐类对反应均起正的影响作用粘土矿物催化下氯化钠对水解反应起负的影响作用。此外,无机盐的存在对矿物的催化活性也有一定的影响。其次,对未熟烃源岩的催化活性进行了评价,并考察了混合酯反应中各脂肪酸酯之间的相互作用1以粘土矿物为主要成分的未熟烃源岩,粘土矿物的低温催化作用是影响水解反应的主要因素;而碳酸盐矿物对混合酯的生烃反应则具有较好的低温催化作用。对于未熟烃源岩低温催化混合酯的生烃反应来说,其矿物组分中含有一定比例的粘土矿物和碳酸盐矿物则具有较好的催化生烃活性,这是同类研究中未曾得出的结论。此外,未熟烃源岩低温催化混合酯的生烃率大小趋势与方解石、白云石、黄铁矿、蒙脱石和伊利石的加权处理含量关系较好。2碳链不同的脂肪酸酯,其水解及生烃的难易程度也不同;在矿物低温催化混合酯水解及生烃反应中,由于各个脂肪酸酯之间存在有催化活性位的竞争,而使其水解率及生烃率都较单一脂肪酸酯的水解率及生烃率低。最后,进行了矿物低温催化混合酯水解及生烃反应动力学研究,并根据得到的动力学参数计算了相应的生烃年限和生烃潜量,同时对碳酸盐矿物低温催化脂肪酸酯的水解及生烃机理进行了初探1矿物低温催化混合酯的水解及生烃反应均符合总包一级反应动力学模型。对于天然矿物样品,其催化反应活化能的大小顺序为E_碳酸盐矿物﹤E_黄铁矿﹤E_粘土矿物,且随着温度的提高,矿物低温催化混合酯生烃反应的差异性减小。2根据实验结果以及前人的研究理论提出了较为合理的化学反应历程,并且认为溶剂水在反应中起到了非常重要的作用 Fatty acids and its ramifications are regarded as important precursors of low-mature oil. It has been found that immature oil source rocks are rich in fatty acids. Fatty acids have different distribution of carbon number and mainly exist in of fatty acid ester in immature oil source rocks. In this paper, mixed esters were chosen as the model reactant. Study on kinetics of hydrolysis and hydrocarbon generation of mixed esters catalyzed by minerals at low temperature was carried out, with considering complex effect of factors. The mechanism of hydrocarbon generation of fatty acid ester and its contribution to the ation and accumulation of immature oil were also discussed. This research subject has important significance both in theory and practice.Firstly, the effects of several important influential factors on the hydrolysis and hydrocarbon generation of mixed esters catalyzed by minerals were investigated 1 The effects of reaction temperature, reaction pressure, pH value and salinity were investigated by orthogonal experiments. By the range analysis and gray relation analysis based on the experimental data, the significance of influential factors was uated. The results show that the effect of reaction temperature is most important, the next is pH value, the third is reaction pressure and the fourth is salinity. 2 The effects of some inorganic salts on hydrolysis and hydrocarbon generation of mixed esters catalyzed by minerals at low temperature were investigated. The effects of inorganic salts were distinguished and their effect mechanism was analyzed too. The different inorganic salts have different effect on the reaction. Magnesium chloride exhibited inhibitive effect on hydrolysis and sodium sulfate inhibited hydrocarbon generation. The others promoted the reaction sodium chloride inhibited the hydrolysis of mixed esters catalyzed by clay minerals. Furthermore, the catalytic activity of minerals can be influenced by inorganic salts.Secondly, the catalytic activity of immature oil source rocks was uated and the interaction among esters was also investigated 1 The catalysis of clay minerals is the main influential factor in the hydrolysis of mixed esters catalyzed by immature oil source rocks in which the clay is dominant component at low temperature. Carbonate minerals have better catalytic effect on the hydrocarbon generation of mixed esters at low temperature. The immature oil source rocks whose carbonate and clay content is in a suitable ratio have better catalytic effect on hydrocarbon generation of mixed esters catalyzed by minerals at low temperature. These conclusions haven’t been reached in the similar study. Furthermore, the trend of hydrocarbon generation rate of mixed esters catalyzed by immature oil source rocks at low temperature is similar to the weighted contents of minerals in it. These minerals include calcite, dolomite, pyrite, montamorillonite and illite. 2 The activity of hydrolysis and hydrocarbon generation reaction of fatty acid ester is different because of their different carbon number. In the process of hydrolysis and hydrocarbon generation of mixed esters catalyzed by mineral at low temperature, the hydrolysis rate and hydrocarbon rate of each ester in reaction of mixed esters is lower than those of single ester. It can attribute to the competition for active sites among fatty acid esters.Finally, kinetics study on hydrolysis and hydrocarbon generation of mixed esters catalyzed by minerals at low temperature was carried out. Time and quantity of converting fatty acid esters into hydrocarbons were also accounted based on the kinetic parameters. Meanwhile, the mechanism of hydrolysis and hydrocarbon generation from fatty acid ester catalyzed by carbonate minerals at low temperature was preliminary discussed 1 Both the hydrolysis reaction and hydrocarbon generation reaction of mixed esters catalyzed by minerals at low temperature can be described by first order global reaction kinetic model. To natural mineral samples, the order of activation energy is E_carbonate﹤E_pyrite﹤E_clay. Moreover, with the increase of temperature, the difference of minerals’influence on hydrocarbon generation reaction decreased. 2 The reaction pathway was proposed based on experiment results and research results of previous investigators. Moreover, water has an important role in the reaction.;