【作者】 赵法军；

【导师】 刘永建；

【作者基本信息】 大庆石油学院 ， 油气田开发工程， 2008， 博士

【摘要】 本文以辽河油田超稠油为研究对象,利用CWYF-Ⅰ型高温高压反应釜模拟热采时的井下条件,对稠油改质降粘行为开展了大量的基础实验研究,基于室内研究结果,揭示了改质降粘机理,优选出了降粘体系并用于矿场试验。1.研究了高温水作用下改质降粘反应,结果表明,辽河稠油发生水热裂解反应的最佳温度、时间和加水量条件分别是:反应温度240℃,反应时间为24h,加水量为30wt%。水在300℃高温条件下具有溶剂性质,大体上相当于丙酮在25℃的溶剂性质。水既可作酸催化剂,又可作碱催化剂。2.研究了外加催化剂作用下改质降粘反应,制备了四种过渡金属盐催化剂,优选出了改质降粘用催化剂油溶性有机镍盐C1。与未添加催化剂相比,在反应温度为240℃,加水量30wt%的体系中,添加0.1wt%的过渡金属有机酸镍催化剂,反应24h,稠油的降粘率可以增加30%左右,沥青质含量下降1.4wt%,胶质含量下降5.0wt%,芳香分含量增加3.5wt%,饱和分含量增加2.9wt%。稠油中C含量降低,H含量增加,H/C提高,而杂原子与C的比值下降。3.催化改质降粘反应前后稠油IR谱图表明,催化剂的加入发生了脱羧反应。催化改质降粘反应前后稠油中沥青质TG-DTA说明稠油中沥青质结构发生变化,在催化剂作用下,有一部分沥青质可以转化为烷烃可溶物。外加催化剂在改质降粘反应过程中的作用机理可以概括为,活化反应物,加速加氢反应速率,提高稠油供氢改质的转化率。催化剂与氢分子形成化学吸附键,改变氢分子的裂解途径,降低氢分子与自由基的反应活化能,加速了稠油有机分子加氢裂解反应。4.研究了供氢体作用下催化改质降粘反应,选择四氢萘、二氢蒽和甲酸、甲酸甲酯作为供氢体,优选出了甲酸作为供氢用剂,其加入量为7wt%。与未加供氢体的催化改质降粘反应后油样相比,轻组分增多,重组分明显下降。胶质和沥青质含量减小,芳香烃含量增加。稠油的H/C增加,S含量降低,稠油结构发生变化,粘度降低。5.供氢改质降粘反应前后稠油中沥青质IR谱图说明,稠油中沥青质在供氢催化改质降粘反应时所发生的化学结构的变化,稠油中沥青质TG-DTA曲线表明,稠油中沥青质耐热性下降。供氢体在改质降粘中作用机理主要是提供易于被夺取的氢,使部分自由基湮灭,降低了体系中自由基的浓度,抑制了缩合生焦反应。6.研究了助剂作用下改质降粘反应,选取尿素、碳酸铵和碳酸氢铵作为改质降粘反应用助剂。优选出了尿素作为改质降粘反应助剂,加入助剂尿素质量分数20%。与供氢催化改质降粘反应相比,稠油的平均族组成变化不明显,稠油中C原子含量、H原子含量及S、N、O原子含量基本不变。助剂尿素的加入没有改变稠油的结构,稠油结构的变化主要受改质降粘体系中催化剂、供氢体的影响较大。7.助剂作用下供氢催化改质降粘反应前后稠油及其沥青质的红外光谱结构分析表明,稠油IR图官能团吸收峰基本没有变化,助剂的加入基本没有改变稠油及其沥青质结构。饱和烃气相色谱分析表明,稠油中饱和烃经过改质降粘反应后部分长链发生裂解而生成了短链,使轻烃含量增加。稠油中沥青质热分析表明,经过助剂作用下供氢催化改质降粘反应后稠油中沥青质的稳定性下降。核磁共振谱结构分析表明,分析可得:δ_c14.10、δ_c22.67、δ_c28.98、δ_c31.92ppm处为烷基碳。δ_c14.10处的峰归属于与仲碳相连的CH₃碳原子,δ_c19.73处的峰归属于与季碳相连的CH₃碳原子,δ_c22.67、δ_c28.98、δ_c31.92ppm处为-CH₂-碳原子,δ_c128.21ppm处的峰归属于芳香环系内碳原子。反应后气体分析表明,稠油发生了明显的裂解反应。8.助剂作用下供氢催化改质降粘后稠油稳定性测试表明,稠油粘度反弹率不到3%。助剂的加入不仅具有一定的降粘作用,而且对供氢催化反应有协同增效作用。9.助剂尿素辅助蒸汽驱的作用体现在尿素高温热分解产生的CO₂和NH₃能够快速补充地层能量,而产生的NH₃和原油中的环烷酸、长链脂肪酸等组分发生反应,生成具有表面活性的皂类物质对稠油具有很好的降粘作用。CO₂在油相中溶解使原油体积膨胀、粘度降低,增加液体的内动能;另一部分充满地层孔隙,扩大蒸汽波及面积,有利于原油回采。10.揭示了改质降粘反应过程中存在竞争反应,提出了竞争反应简化的化学模型,为深入开展稠油井下改质降粘研究提供了依据。11.在辽河油田选择了具有代表性的杜32-53-33、曙1-32-41和齐40-03-18三口试验井进行改质降粘矿场试验,试验周期初期15～20天内,稠油降粘率＞70%,且在30天内都保持较高的降粘率＞60%。改质降粘处理后的稠油化学组成分析结果表明,采出油族组成中饱和烃、芳香烃含量增加、胶质、沥青质含量降低。进一步证实了井下改质降粘开采稠油技术的可行性。更多还原

【Abstract】 This paper taking Liaohe oilfield extra heavy oils,under the simulated thermal recovery condition,fundamental experiments were carded out in the high temperature high pressure CWYF-Ⅰtype reactor to study the viscosity reduction upgrading behavior of heavy oil.Based on laboratory results,the mechanism of viscosity reduction upgrading was revealed,the viscosity reduction chemical system was selected optimally and tested on field.1.Results from reaction of viscosity reduction subjected to high temperature water showed that the optimum condition for Liaohe heavy oil to occur aquathermolysis were: reaction temperature 240℃,reaction time 24h,water adding amount 30wt%.Water at high temperature of 300℃owned the property of solvent,which was nearly equivalent to the solvent property of acetone at 25℃.Water could act as both of acid catalyst and alkali catalyst.2.Viscosity reduction upgrading reactions with catalyst were investigated.Four kinds of transition metal catalysts were prepared,and oil-soluble organic nickel salt C1 was selected optimally to be used in the viscosity reduction reaction experiments.At the same reaction condition of 240℃,24h and 30wt%water,compared to the reaction without catalyst,the viscosity reduction ratio of oil sample from the reaction with 0.1wt%catalyst C1 increased about 30%,and the Contents of asphaltene and resin decreased 1.4wt%and 5.0wt%relatively,while the aromatic and saturate increased with a value of 3.5wt%and 2.9wt%.The content of element C in the heavy oil reduced,while the value of element H increased,resulting in the increasing of H/C ratio.The ratio of heteroatom to carbon reduced.3.IR spectrograms of heavy oils before and after viscosity reduction reaction showed that the introduction of catalyst caused the heavy oil to occur decarboxylation reaction. Structure change of asphaltene was detected from the TG-DTA of asphaltene in heavy oil before and after catalyzed viscosity reduction reaction,part of asphaltene changed into paraffin-soluble matter.The mechanism catalyst played in the viscosity reduction reaction process could be summarized as:activate the reactants,speed up the hydrogenation reaction rate and increase the conversion rate of hydrogenation reaction.Catalyst might form chemisoptive bond with hydrogen molecular,change the fragmentation pathway of hydrogen molecular,reduce the activation energy between hydrogen molecular and free radical,accelerate the hydrocracking of heavy oil organic molecular.4.Catalyzed viscosity reduction upgrading reactions with hydrogen donor were investigated.Formic acid was selected optimally from the alternative chemicals of tetrahydronaphthalene,dihydrogenanthracene,formic acid and methylformate,and its dosage was 7wt%.Compared to the oil sample from reaction without hydrogen donor,the light components increased,the heavy components reduced obviously.The contents of asphaltene and resin decreased and that of the aromatic and saturate increased.The value of H/C ratio of heavy oil increased.The content of element S in the heavy oil reduced,the structure of heavy oil changed,viscosity reduced.5.IR spectrograms of heavy oils before and after reaction with hydrogen donor showed that the structure of asphaltene in heavy oil changed.TG-DTA curve of asphaltene in heavy oil showed that the thermostability of asphaltene weakened.The mechanism hydrogen donor played in the viscosity reduction reaction process was to supply hydrogen to deactivate part of the free radicals,decreasing its concentration in the reaction system,so as to inhibit the condensation reactions.6.Viscosity reduction upgrading reactions with auxiliary agent were investigated.Urea was selected optimally from the alternative chemical auxiliary agents of ammonium carbonate,urea and ammonium hydrocarbonate,and its dosage was 20wt%.Compared to the oil sample from reaction without auxiliary agent,there was no obvious change on group compositions,the contents of atom C,H,S,N and O nearly kept unchanged.As a result,the introduction of urea did not change the structure of heavy oil.The structure was influenced mainly by the catalyst and hydrogen donor.7.Infrared spectrum analysis on heavy oil and asphaltene in it before and after viscosity reduction reaction with auxiliary agent showed that there was no significant change on the absorption peak of functional group of heavy oil.Namely,the introduction of auxiliary agent basically did not change the structure of the heavy oil and asphaletne.Gas chromatographic analysis on the saturate indicated that after the reaction,part of the long chain cracked into short chain,increasing the content of light hydrocarbons.Thermal analysis on asphaltene showed that the thermostability of asphaltene in heavy oil after reaction with auxiliary agent weakened.Nuclear magnetic resonance spectra showed that the peaks atδ_c14.10,δ_c22.67,δ_c28.98 andδ_c31.92ppm were ascribed to alkyl carbon;the peak atδ_c14.10 was ascribed to the CH₃ carbon bonding with the secondary carbon atom; the peak atδ_c19.73 was ascribed to the CH₃ carbon bonding with the quaternary carbon atom;the peaks atδ_c22.67,δ_c28.98,δ_c31.92ppm were -CH₂- carbon atom;the peak atδ_c128.21ppm were ascribed to the carbons in the aromatic ring. 8.Stability test on heavy oil after catalyzed reaction with hydrogen donor and auxiliary agent showed that the viscosity rebounding rate was no more than 3%.The addition of auxiliary agent had not only some degree of viscosity reduction function,but also synergistic interaction to the catalyzed reaction with hydrogen donor.9.The mechanism of urea assisted steam flooding was that the CO₂ and NH₃ generated by the thermal decomposition of urea at high temperature would supply reservoir energy rapidly,and NH₃ would react with the naphthenic acid,long chain fatty acid,etc.in the crude oil,forming surface active soap-like materials,which had positive effect on the viscosity reduction.Part of CO₂ will dissolve in oil,make it swell,reduce its viscosity, increase the internal kinetic energy;other CO₂ will fill the formation pores,enlarge the steam sweep area,which is helpful to recover oil.10.It was revealed that there existed competitive reactions in the viscosity reduction reaction process.The simplified chemical model of competitive reaction was brought forward,which provided the basis to study deeply the downhole viscosity reduction upgrading of heavy oil.11.Field tests of downhole viscosity reduction upgrading were carried out on three representative oil wells of Du32-53-33,Shul-32-41 and Qi40-03-18 in Liaohe oilfield.In the initial 15 to 20 days of the test period,the viscosity reduction ratio of heavy oil was higher than 70%,and the value kept above 60%within 30 days.Chemical composition analysis on heavy oil after upgrading process indicated that the content of asphaltene and resin decreased and that of the aromatic and saturate increased,which further identified that it was feasible to recover heavy oil by downhole viscosity reduction upgrading technology.更多还原