【作者】 刘春天；

【导师】 刘永建；

【作者基本信息】 大庆石油学院 ， 油气田开发工程， 2005， 博士

【摘要】 随着全球经济的不断发展,世界各国对石油的需求量愈来愈大,综合考虑常规原油的开采现状和稠油储量,可以预测稠油将在今后的国家能源战略中占据重要地位。稠油油藏的一个显著特点是在地层条件下,稠油的粘度高、相对密度大、流动能力差,用常规技术难以经济有效地开发。目前开采稠油的主要方法是注蒸汽热力采油法。热采过程中,高温水与稠油之间发生的水热裂解反应能强化注蒸汽技术,把孔隙介质作为天然化学催化反应器,在井下就地改善稠油质量,不可逆地降低稠油粘度,是一项具有广阔应用前景的稠油开采新技术。目前,针对我国稠油水热裂解所做的动力学研究较少,至今尚未见到相关的报道。为此,本文通过理论分析、室内实验和数值计算等方法,深入研究了稠油水热裂解反应及其动力学,为现场采油生产提出合理建议,成功地提高了稠油质量和采收率,取得了较为满意的效果。本文的主要研究内容及创新点是: (1)分析了注蒸汽热采过程中的稠油水热裂解反应机理热作用下的稠油转化是裂解和缩合相平行的顺序反应;杂原子组成的桥键是稠油结构中较薄弱的环节,在注蒸汽热采条件下很容易断裂,生成自由基“碎片”,对稠油水热裂解反应具有重要影响;引入活性基团氢,可以捕获烃自由基和活性碎片,阻滞反应链的增长,实现稠油不可逆降粘;高温水的参与使稠油水热裂解反应按照酸碱催化机理进行;储层矿物和金属离子对稠油水热裂解反应具有催化作用。(2)计算了稠油水热裂解模型化合物的平衡组成采用噻吩和四氢噻吩作为稠油水热裂解模型化合物,计算热力学平衡组成,分析温度、压力、进料比等反应条件对平衡产物分布的影响。结果表明,当水/四氢噻吩、水/噻吩摩尔进料比分别小于3和4 时,提高水/四氢噻吩和水/噻吩摩尔进料比有利于脱硫和生成更多气体。提高反应温度,降低反应压力有利于生成更多的气体,但不利于脱硫。当水/四氢噻吩、水/噻吩摩尔进料比分别大于3 和4时,进料比、温度和压力对平衡组成的影响较小。(3)考察了反应条件对稠油水热裂解反应的影响根据室内实验结果,考察有、无储层矿物、有、无催化剂存在时,水热裂解反应条件对稠油性质的影响,包括稠油粘度、分子量、气体产量、烃分布和四组分含量等性质随反应温度和反应时间的变化特征。研究结果表明,稠油粘度和分子量随着反应温度的提高和反应时间的延长而减小,实现了稠油轻质化;储层矿物和催化剂的存在促进了稠油水热裂解反应,提高了稠油改质程度。不同储层矿物对稠油水热裂解反应的催化作用存在差异。(4)分析总结了注蒸汽热采条件下储层矿物的转化规律,建立了储层矿物变化的定量计算方法分析总结了注蒸汽热采条件下常见储层矿物的一般变化规律;根据辽河油田热采资料,确定注蒸汽后粘土矿物含量在平面上发生了变化,变化规律与温度密切相关;建立了一种根据注入水、吐出水的化学成分,利用质量作用定律及质量守恒定律,计算储层矿物溶解/沉淀量的定量方法。(5)建立了有、无储层矿物存在时的稠油水热裂解反应集总动力学模型分别建立了有、无储层矿物存在时的稠油水热裂解反应动力学模型。对于无储层矿物存在时的稠更多还原

【Abstract】 With the increase of the global economy, the oil and gas demanding is also increasing. The decrease in the exploitation and production of the conventional oil indicates that the exploration of heavy oil becomes crucial in the nation’s energy strategy. The remarkable characteristic of heavy oil reservoir is that the oil has high viscosity, high density and low mobility. This characteristic makes it difficult to produce the heavy oil economically efficient using conventional techniques. The primer production method currently using in the industry is steam injection. The effect steam injection is reinforced by a mechanism called aquathermolysis, which is a reaction happened between steam and heavy oil at high temperature in the subsurface porous media. This mechanism improves the quality of heavy oil in-situ, and decrease the viscosity of the heavy oil permanently. The production of the heavy oil using the mechanism of aquathermolysis reaction is a latest technique and it has a broad future so far. Hardly any paper is published on the study of aquathermolysis of heavy oil mechanism. Therefore, the mechanism and kinetics of aquathermolysis reaction are intensely studied in this paper. The study was accomplished using methods of theoretic analysis, laboratory experiment and numerical computation. The study results were applied to heavy oil production in the industry. The production results indicate that the oil recovery was improved and the quality of heavy oil was improved dramatically. The Main contents and innovations of this study include the following: (1) The mechanism of aquathermolysis reaction during steam injection process The transforms of heavy oil during heat-degradation include collateral reactions of cracking and polymerization. In heavy oil’s structure, the bridge-bonds that consisted of heteroatoms are weak; thus these bonds are easily to be broken under steam injection condition. This break of bridge-bonds can stimulate a series of favorable reactions, which is very important in aquathermolysis reaction. The active hydrogen induced by aquathermolysis reaction can capture free structure and hydrocarbon fragment, which helps to prevent the interlinkage of reactant chain. As a result, the viscosity of the heavy oil is irreversibly reduced. The aquathermolysis reaction follows the acid-alkali catalysis route when high temperature steams present. The present of formation mineral and metal ions can also catalyze the reaction. (2) Equilibrium compositions of model compounds for the aquathermolysis reaction of heavy oil Thiophene and tetrahydrothiophene were used as model compounds for the aquathermolysis reaction of heavy oil. Based on the equilibrium composition calculation, the effects of temperature, pressure and feed ratio on equilibrium were analyzed. The results show that the reaction lacks water when the ratio of water/tetrahydrothiophene is less than 3 and that of water/thiophene is less than 4. In addition, high temperature and low-pressure conditions during aquathermolysis reactions help to produce plenty of gaseous products. However, these conditions are unfavorable in desulfurization of the oil. The results also show that the water is enough for the reaction when the ratio of water/tetrahydrothiophene is more than 3 and that of water/thiophene is more than 4. For these ratios, the equilibrium reaction is affected slightly by the temperature, pressure and feed ratio. (3) The effects of reaction conditions on aquathermolysis reaction of heavy oil Base on the results of indoor experiments, the effects of reaction conditions (temperature and time) on the quality of heavy oil are analyzed with and without the presence of the formation mineral and the catalyst. The effect objects include viscosity, molecular weight, gas yield, the distribution of hydrocarbon and four compositions. The results indicate that viscosity and molecular weight of heavy oil decrease with time and the increasing of temperature. Meanwhile, heavy oil is significantly lightened. Besides, the presences of mineral and metal ions catalyze the aquathermolysis reaction and improve the quality of heavy oil; different minerals have different catalysis effects. (4) The transform rule and quantitative calculation of mineral The transform rule of mineral during steam injection is summed up. The contents of mineral change in plane with temperature nearly. A quantitative method of calculating the amount of mineral varieties is developed on the basis of quality action and conversation law using the injected and produced water data. (5) The development of two different lumping kinetic models for the aquathermolysis reaction of heavy oil to the different existent conditions of mineral. Two different lump kinetic models are developed for the aquathermolysis reaction of heavy oil with and without mineral present. When the formation mineral is absent, it is appropriate to employ the four-lump model of gas, C5-C15, C16-C30 and C31+. On the other hand, when the formation mineral is present, it is better to employ the five-lump model of gas, saturate, aromatic, resin and asphaltene. (6) The calculation of parameters in kinetics models using a direct method and the establishment of the model. A direct method was developed by combine the methods of Runge-Kutta, Monte-Carlo and complex method. This method was used to calculate the parameters in kinetic models. The calculation results show that that the presence of the formation mineral and metal ions reduces the active energies in the cracking of heavy compositions. This energy reduction helps to produce more light oil component products aquathermolysis reaction. Moreover, the experimental data and the model prediction are consistent. This suggests that the lump model explains well the reaction mechanism of aquathermolysis of heavy oils at the absence of formation minerals. (7) Practical applications of laboratory research for oil recovery in Liaohe Oil Field. The research results were applied to seven heavy oil wells in different districts of Liaohe oil field from 2003 to 2004. The production history showed that the cumulative oil recovered during the production period increased 2661.8 tons; on average, each well increases oil recovery of 380.3 tons. The ratio of cost to benefit is 1:3.6. It was observed that the viscosities of heavy oils reduced dramatically after recovered. In recovered heavy oil, the amount of saturate and aromatic components increased; meanwhile, the amount of resin and asphaltene components decreased. This indicates that our improvement in aquathermolysis reactions significantly enhances the qualities and reduces the viscosity of heavy oils. Furthermore, the improvement in aquathermolysis reactions reservoir facilitate the recovery of heavy oil reservoir economically more efficient.更多还原