【作者】 赵玉建；

【导师】 刘永建； 方文军；

【作者基本信息】 大庆石油学院 ， 油气田开发工程， 2008， 博士

【摘要】 对于稠油油藏而言,由于稠油中沥青质等重质组分的含量比常规原油高得多,造成稠油的粘度高、开采难度大。目前开采稠油的主要技术是蒸汽吞吐和蒸汽驱技术,但这类技术只能暂时降低稠油的粘度,而不能从根本上解决稠油粘度高、流动困难等不利因素所导致的一系列开采难题。为此,本文针对沥青质等重质组分在油田开发中带来的问题,深入研究了稠油中沥青质井下裂解机理及应用技术,这对稠油油藏的有效开发具有重要意义和实用价值。本文利用元素分析、红外光谱、核磁共振、热重分析等现代测试手段来检测石油沥青质的组成、结构以及热稳定性,再结合沥青质化学结构推测理论模型并进行模拟实验。通过1H和13C NMR等测定的实验数据得到了沥青质基本结构单元的平均分子式和结构参数,推测出了辽河、大庆及华北原油中沥青质分子模型的结构,为加深对沥青质的微观认识和研究提供了新方法及可靠依据。针对沥青质在热采条件下的裂解反应机理进行了分析研究,且通过热重分析手段着重研究了沥青质的热稳定性,探讨了热裂解过程的动力学规律,并建立适用于大庆、辽河稠油中沥青质的活化能分布模型(DAEM),对沥青质的热裂解动力学进行了深入研究。研究结果表明,沥青质分子量的下降主要是桥链硫醚和稠环之间的桥链及侧链脂肪结构单元断裂的结果,而且后者是沥青质在井下催化裂解的主要原因,脂肪侧链和桥链的断裂主要按本位取代的机理进行;引入活性基团氢,可以消除自由基,阻滞反应链的增长,实现不可逆降黏;加入供氢剂可以加强稠油井下裂解降粘效果。对沥青质的热重(TG/DTG)分析表明:沥青质在300℃以下,没有明显的热裂解失重;从300℃至430℃,以较慢的速率产生挥发质;沥青质裂解主要发生在430℃至550℃范围,峰值温度在470℃至480℃。在近临界水体系中,以环烷酸镍与环烷酸亚铁为催化剂分别对辽河油田四种稠油中沥青质进行了催化裂解正交试验,考察了反应温度、反应时间、催化剂用量对沥青质转化率的影响,得到了适宜四种沥青质催化裂解的反应条件。在近临界水条件下,催化裂解后的沥青质中S元素含量有明显的下降,C元素、H元素、O元素、N元素含量也均有不同程度的下降。由于C-C、C-H键断裂程度比其它杂元素化学键断裂程度小,因此裂解后的沥青质中C、H元素含量略有上升。同时,由于不同区块油样的沥青质含氧基团类型不同,有些沥青质中O元素相对其它元素裂解掉的较少,因此O元素的含量反而上升。另外,经红外光谱测定发现,在近临界水条件下催化裂解后的沥青质中的环烷环及烷基链上的C-H键有不同程度的断裂,芳环数以及-CH2-的数量也有减少。通过对热采条件下油藏矿物的水/岩反应的研究,证实油藏矿物经水热处理后,其表面性质发生了改变,尤其是新矿物相的生成,使其催化活性有所增强。室内实验结果表明,油藏矿物对沥青质井下裂解具有催化作用,在反应体系中加入10%的油藏矿物,可使沥青质的平均相对分子质量降低程度增加10%左右;在沥青质裂解反应体系中,加入的油藏矿物可与催化剂NiSO4产生协同催化作用,使沥青质平均相对分子质量进一步降低,降低程度由28.5%提高到36.6%。基于Olah发明的煤的解聚方法,结合辽河油田稠油及油砂样品,进行了超强酸催化裂解稠油及其沥青质实验研究。实验结果表明,超强酸催化剂HF:BF3是裂解沥青质、使其轻质化的高效可用化学剂。依据上述前期研究成果,结合油田热采的实际条件,在室内开展了沥青质在稠油热采工程中的应用基础研究,提出了稠油热采工程中应用沥青质的新方案,即沥青质不完全燃烧供热生产入井蒸汽,用沥青质燃烧残余物制备高效热采稠油蒸汽添加剂,并研究可行的现场实施工艺技术。室内实验研究表明,欢喜岭稠油燃烧残余物可用作热采稠油蒸汽添加剂,胜利油田单家寺稠油燃烧残余物不可用。更多还原

【Abstract】 It was widely ackowledged that high viscosity makes it difficult to develop heavy oil due to more contents of heavy component such as asphaltene in heavy oil than that in regular oil. Steam flooding and steam stimulation were the major technologies to develop heavy oil at present. By using these technologies, the viscosity of the heavy oil can be reduced temporarily, while the problems in development caused by the high viscosity, poor fluidity of heavy oil can not be solved radically. This dissertation set out to deal with the problems caused by heavy component in reservoir development and carried out a further reserch on the thermolysis and viscosity reduction mechanism of asphaltene. It was a kind of technology with significance and practical value to develop heavy oil reservoir more efficiently.Composition, structure and thermal stability of asphaltene were detected by element analysis, infrared spectrum, nuclear magnetic resonance, and thermogravimetric analysis. The model experiment was carried out on the basis of presumed chemical structure model of asphaltene. With experimental data of 1H and 13C NMR, the average molecular formula and the structure parameters of basic structural unit of asphaltene were obtained, and the molecular models of asphaltene in crude oil of Liaohe, Daqing and Huabei were conjectured, which provided new methods and reliable basis for further studying the microcosmic structure of asphaltene.The pyrolysis mechanism of asphaltene under thermal recovery condition was studied. Thermal stability of asphaltene was emphatically studied by thermogravimetric analysis. The dynamics law was investigated in the thermolysis process, and DEMA of asphaltene in heavy oil from Daqing and Liaohe oilfields were established. It was shown that the breaking of bridged chain between thioether and fused ring and the breaking of side chain of fat structure unit result in reduction molecular weight of asphaltene. The latter was the major contribution to catalytic pyrolysis underground. The breaking of side chain and bridged chain of fat structure unit proceed as mechanism of ipso substitution. The introduction of active hydrogen in aquathermolysis reaction could capture free radical, which was beneficial to prevent the interlinkage of reactant chain, realizing the irreversible reduction of viscosity. The adding of hydrogen donor make it more effective to pyrolyze asphaltene and reduce viscosity of heavy oil. It was shown in thermogravimetric analysis(TG/DTG) that there were no obvious phenomena below 300℃; volatile substance was produced at a low rate between 300℃and 430℃; thermolysis mostly occured between 430℃and 550℃, and the peak temperature was between 470℃and 480℃.In near-critical water system, orthogonal experiments of catalytic pyrolysis of four asphaltene types from Liaohe heavy oil were carried out using nickel naphthenate and ferrous naphthenate as catalysts. The effects of reaction temperature, reaction time, catalyst amount on conversion rate of asphaltene were studied and the proper reaction conditions were obtained respectively. Under such conditions, sulfur contents of asphaltene were reduced obviously and it was found that the contents of carbon, hydrogen, oxygen, nitrogen also decreased in some degree. Because the breaking of C-C and C-H chemical bonds was less than that of other chemical elements, carbon and hydrogen contents increased slightly after thermolysis reaction. Due to diferent types of oxygen-containing groups contained in diferent asphaltene and less pyrolyzed mount of oxygen than other elements, oxygen contents of some types of asphaltene might increase in the contrary. In addition, it was found by infrared spectrum that the breaking of C-H chemical bonds on naphthenic and alkyl chains of pyrolyzed asphaltene was in different degree in near-critical water system. Aromatic rings and -CH2- were decreased as well.Through the study on water-rock reaction, it was proved that surface properties of oil reservoir minerals were changed after hydrothermal treatment. The formation of new minerals made its catalytic activity more active. Experimental results suggested that oil reservoir minerals have a catalytic effect on the thermolysis underground. The average molecular weight of asphaltene was reduced by 10% when adding 10% of oil reservoir minerals. The minerals also took synergetic catalysis action with Catalyst NiSO4, which could further reduce average molecular weight, increasing the molecular weight reduction ratio from 28.5% to 36.6%.On the basis of disaggregation of coal developed by Olah, Catalytic pyrolysis experiment of asphaltene by super acid were carried out by using heavy oil samples from Liaohe oilfield. It was shown that HF:BF3 was a high efficient chemical agent to pyrolyze and light asphaltene.According to above results and combining thermal recovery conditions in the field, experimental study on application of asphaltene for thermal recovery engineering of heavy crude was carried out. The new scheme proposed was to make use of asphaltene in thermal recovery engineering of heavy crude. The steam was produced by the energy from incomplete combustion of asphaltene, and the burning residue was used to prepare high effective steam additive. The results of laboratory experiment show that burning residue of asphaltene in heavy oil from Huanxiling oilfield could be used as steam additive while that from Shanjiasi oilfield was useless.更多还原