Separation and characterization of bitumen from Athabasca oil sand

Separation and chemical analysis was investigated using bitumen samples from Athabasca oil sand in Alberta. Fractionation according to solubility and polarity has been used to separate bitumen into its fractions. The solvent de-asphaltening was performed by n-pentane solvent (solubility fractionation), and the polarity fractionation using Fuller’s earth allows maltene to separate into SARA components (saturates, aromatics, resins and asphaltenes). The SARA components are analyzed comprehensively using elemental analysis (EA), Fourier-transformed infrared (FTIR), ultraviolet-visible spectroscopy (UV-vis), high performance chromatography (HPLC) and thermogravimetric analysis (TGA). EA (C, H, N, S), heavy metals (Ni, V) concentrations, FT-IR and UV-vis tests provided the explanation of chemical composition. From IR spectra, maltene and saturates/aromatics (sat/aro) contained more aliphatic compounds than resin or asphaltene. Also, IR spectrum of sat/aro was similar to crude oil and VGO (vacuum gas oil). Different UV signal data clearly indicates the contribution of aromatic constituents in the fractions. Using optimized analysis conditions of HPLC, we successfully separated the peaks for bitumen and its fractions. The characteristic peak pattern of SARA (saturates, aromatics, resins, asphaltenes) fractions was observed, and also the peak pattern of sat/aro was similar to that of crude oil and VGO. However, TGA results revealed that thermal behavior for sat/aro was similar to that of crude oil but different from that of VGO. Also, from the comparison between decomposition temperature of TGA and boiling point, their correspondence was found.     

Remote bitumen content estimation of Athabasca oil sand from hyperspectral infrared reflectance spectra using Gaussian singlets and derivative of Gaussian wavelets

Modeling of the total bitumen content, TBC, in Athabasca oil sands was undertaken on the basis of its hyperspectral reflectance spectra. Spectra (8 cm⁻¹ resolution) were obtained that covered both the short-wave infrared and thermal infrared (TIR: 3.00-30.00 μm). Two methods, Gaussian fitting and wavelet analyses, were investigated to identify useful bitumen features as well as the best removal of the baseline. We aim to obtain the best determination of the TBC for a suitable suite of test and validation oil sands samples. The Gaussian model relied explicitly on features at 2.282 and 2.532 μm though these were only two of 10 features simultaneously fit with a quadratic baseline to the range of 2.230-2.603 μm of the spectra. The wavelet model relied on bitumen features selected at 2.274, 2.396 and 3.725 μm that could be isolated from the baseline and noise. Both models yielded similar dispersion in their estimates of TBC (±∼1-2%) while the wavelet model proved to be more robust when applied to the validation and blind data suites. We also considered the effects of using the L2 optimization (classical least-squares) and L1 optimization (minimization of largest outlier) schemes for both models. Both schemes produced similar results for the model suite of samples for TBC but the L1 was superior when applied to the validation and blind data suites. The wavelet model using the L1 optimization appeared to be quite robust producing estimates of TBC (±∼1.0-1.7%).     

油砂沥青超声波减粘工艺研究

油砂沥青粘度较大,自然状态下不易流动,严重影响了管道输送及加工,针对目前油砂沥青研究中存在的问题,采用超声波进行了减粘的实验研究。实验综合考察了超声波作用时间、温度、超声波频率、超声波功率等因素对减粘效果的影响。实验结果表明,在适当的超声作用时间(20 min)、适宜的温度(30℃)、适宜的超声波频率(20 kHz)和超声波功率(250 W)的条件下,油砂沥青的减粘率可达80%以上。经超声波处理后的油砂沥青粘度略有恢复,但仍远低于处理前的粘度,超声波减粘效果良好。     

Effect of supercritical water on upgrading reaction of oil sand bitumen

The advantages of supercritical water (SCW) as a reaction medium for upgrading oil sand bitumen were investigated through a comprehensive analysis of the output product, which includes gaseous products, middle distillate, distillation residue, and coke. Canadian oil sand bitumen mined by the steam assisted gravity drainage method was treated in an autoclave at 420-450 °C and 20-30 MPa for up to 120 min with three kinds of reaction media: SCW, high-pressure nitrogen, and supercritical toluene. The yields of gaseous products indicated that a very small amount of water was involved in the upgrading reaction. The analytical results of the middle distillate fractions were almost the same using water and nitrogen at 450 °C. The distillation residues produced in SCW had lower molecular weight distributions, lower H/C atomic ratios, higher aromaticities, and consequently more condensed structures compared to those produced in nitrogen. The coke produced using SCW also had lower H/C values and higher aromaticities. Judging from all the analytical results, the upgrading of bitumen by SCW reaction was primarily considered to be physical in nature. As a result, it is possible to highly disperse the heavy fractions by SCW. This dispersion effect of SCW led to intramolecular dehydrogenation of the heavier component and prevention of recombination reactions, and consequently gave the highest conversion.     

Preparation of bitumen from oil sand by centrifugation

Centrifugation was shown to have certain advantages over solvent extraction for the separation of bitumen from oil sand for research purposes. No fractionation of the bitumen during centrifugation was detected by chemical analysis. Some limitations of the method are pointed out.     

Preparation of bitumen from oil sand by ultracentrifugation

Ultracentrifugation was investigated as a means to obtain solvent-free bitumen from oil sand. The bitumen from three oil sands of varying grades was separated by placing the sands in specially designed tubes and centrifuging for 2 h at 198 000 at 20 °C. For all grades of oil sand, approximately 70% of the bitumen was recovered. The recovered bitumen was compared to the residual remaining on the sand, and to that extracted by the conventional Soxhlet technique. The ultracentrifuged bitumen contained some emulsified water and a small amount of fine solids. The solvent-extracted material was water-free, but contained a small amount of residual solvent and fine solids. The ultracentrifuge caused some fractionation of the bitumen, resulting in a product slightly enriched in asphaltene components compared to the solvent-extracted material. The residual bitumen remaining on the sand was correspondingly slightly depleted in asphaltenes. However, as evidenced by gas Chromatographic simulated distillation data, ultracentrifugation did retain the light (180–220 °C) components of the bitumen which were lost during the solvent removal step following solvent extraction. Other analyses such as density, viscosity and elemental composition verified that ultracentrifugation resulted in some fractionation of bitumen components.     

油砂沥青分离技术研究进展

油砂作为一种储量丰富的非常规石油资源,越来越受到世界各国的广泛关注。对于油砂的加工利用,其前提就是油砂沥青的分离,因此对其技术的研究十分必要。本文首先介绍了油砂的组成及分类,然后着重对几种主要油砂分离技术（热水洗法、有机溶剂萃取法、超临界流体萃取法、超声波辅助萃取法、离子液体萃取法和热解干馏法）的优缺点进行了汇总,并详细分析了它们各自的分离流程。其中,热水洗法、有机溶剂萃取法和热解干馏法是目前研究相对成熟的3种方法,而其他方法虽然分离效果相对高,但是对工艺条件和设备的要求较高,导致较高的投资和运行成本,因此还需要对这些油砂沥青分离工艺进行更加深入的研究,以满足工业化应用的要求。最后,对油砂沥青分离技术的发展前景进行了展望。     

油砂沥青质对油砂沥青中甲苯残留的影响

利用热重质谱联用仪（TG-MS）分析了三种油砂沥青（印尼油砂沥青、伊朗油砂沥青、加拿大油砂沥青）中的甲苯残留以及油砂沥青质含量对油砂沥青中甲苯残留的影响,并在此基础上,进一步研究了油砂沥青质中的甲苯残留。结果发现,不同油砂沥青中甲苯残留量存在一定差异,其中印尼油砂沥青中的甲苯残留量最多。进一步对沥青质质量分数分别为10%、19%、30%的油砂沥青样品进行热重质谱实验,发现随着油砂沥青中沥青质含量的增加,甲苯的残留量会成倍增加。以加拿大油砂沥青质为例,研究了油砂沥青质对溶剂残留的影响,发现油砂沥青质具有对甲苯分子的夹带能力,导致甲苯分子在超过自身沸点40℃以上才能从沥青质中分离出来。油砂沥青中其他组分的存在也会加剧沥青质对甲苯的夹带作用。此外,研究还发现,在350~650℃时,油砂沥青质可以热解产生甲苯,而且油砂沥青中的沥青质含量越高,热解生成的甲苯越多。     

Multielement analysis of Nigerian bitumen by TXRF spectrometry and the physical constants characterization of its hydrocarbon component

The Total reflection X-ray fluorescence (TXRF) Spectrometry analytical technique was used for the elemental characterization of bitumen extracted from Nigerian Oil sands. Twelve elements—K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As and Pb were detected and their concentrations, the enrichment factors and correlation determined. Very high enrichment factors were obtained for V, Cr, Ni, Cu, Zn, As and Pb. This has implication for environmental degradation during exploration, refining, transportation and/or marketing of the bitumen. The correlation matrix result indicated that some of the trace elements detected have common sources or similar chemical properties. Samples of the extracted bitumen were also subjected to solvent deasphaltened using n-pentane to obtain maltene and asphaltene. Oil (Hydrocarbon) component was eluted from maltene using n-pentane in a glass chromatographic column, which has been packed with activated neutral alumina of grade Brock Mann 1, type 507 C. The physical characteristics (API gravity, refractive index, viscosity, surface tension and melting point) of the oil eluted from the bitumen were determined. The percentage oil composition (36.98%) was comparable to equivalent values obtained for oil from Athabasca (48.10%) and Venezuela (40.30%) oil sands indicating that Nigerian oil sand is a rich source of petrochemicals. The results of physical characteristics also show that oil could be useful for lubrication purpose.     

Effect of calcium ion and montmorillonite clay on bitumen displacement by water on a glass surface

Experiments were conducted to study the effect of calcium ion and montmorillonite clay on bitumen displacement by an aqueous phase on a glass surface. Upon exposure to an aqueous environment containing calcium ion and clays, a thin coating of bitumen on a glass surface displaced spontaneously in the inward radial direction. The initially circular bitumen disk took the shape of a spherical droplet. The dynamic and static contact angles of bitumen on the glass surface were estimated by measuring the contact radius of bitumen with time. The dynamic and static contact angles in the presence of calcium ion and clays are compared with the case when no calcium ion and clays are present. At pH 9, the static contact angle decreased significantly in the presence of calcium ion having a concentration higher than 25 ppm. For a given temperature and at a pH of 9, the initial dynamic angle variation with time was affected less by the presence of clays than with the case of calcium addition. There was no synergetic effect on the dynamic and static angles due to the presence of both calcium ion and clays. In the presence calcium and clays, the results would suggest a negative impact on bitumen liberation from sand grains in the industrial process of bitumen extraction from oil sands. In all cases, the contact angle is measured through the bitumen phase.     

新疆油砂水洗分离提油工艺研究

以新疆风砂16#油砂为测试样品进行油砂水洗分离影响因素的分析.实验综合考察了加热温度、分离试剂质量分数、加热时间、剂砂质量比等因素对油砂分离的影响.通过正交实验得出油砂水洗分离的最佳工艺操作条件为:分离温度90℃、ω(分离剂)=5%、分离时间20 min、剂砂质量比为2:1,追加实验结果表明在此操作条件下,油砂出油率最高可达94%以上.分离残砂经两次清洗后砂中含油丰<1%、pH值<8、砂中试剂总质量分数≤0.7%,达到排放标准,对环境无污染.     

Clay minerals in nonaqueous extraction of bitumen from Alberta oil sands: Part 1. Nonaqueous extraction procedure

A non-aqueous bitumen extraction process was studied where only toluene and heptane, with no water additions, were used to extract bitumen from two Alberta oil sands ore samples. One sample had a high bitumen (13.5 wt.%) and low fines (5.3 wt.% < 45 μm) contents, while the other sample had an intermediate bitumen (10.5 wt.%) and high fines (23.3 wt.%) contents. Bitumen recovery and product quality were measured under different process conditions such as the ratio of toluene to heptane and settling time. The Dean Stark procedure was used to determine the solids, bitumen and water contents of the extraction products. In addition, the water content was determined by the Karl Fischer titration method. High bitumen recovery was obtained for both oil sands ore samples although the high fines ore sample was more sensitive to the extraction conditions, especially the toluene to heptane ratio. A product with high purity, containing more than 99.5 wt.% bitumen on a solvent-free basis, was produced at room temperature under the optimum extraction conditions tested. The optimum settling time to achieve a pure product was less than 10 min, based on solids and water contents in the supernatant.     

Viscous characteristics of a Utah tar sand bitumen

The viscous behaviour of an extracted tar sand bitumen has been experimentally examined and the results summarized in this Paper. The material studied was from the Asphalt Ridge, Utah area. The viscosity of the bitumen has been determined as a function of temperature (293–422 K), toluene (solvent) content (0–10%), composition (0–14.6% asphaltenes), oxidation and shear history. In all cases studied, the Arrhenius plots were significantly non-linear at temperatures s> 373 K, with viscous behaviour becoming less sensitive to toluene content with increasing temperature. Low temperature behaviour was strongly dependent on toluene content. The presence of asphaltenes in the bitumen was shown to be a strong viscosity enhancer. Oxidation and shear history were also shown to measurably increase the bitumen viscosity.     

Upgrading of bitumen with formic acid in supercritical water

Upgrading of bitumen was examined with formic acid in supercritical water (SCW) from 673 to 753 K and at a water/oil ratio from 0 to 3. Decomposition of bitumen in SCW + HCOOH gave higher conversions of asphaltene and lower coke yields than those of pyrolysis or with only SCW. Decomposition of bitumen was also conducted in SCW + H₂, SCW + CO, toluene and tetralin, which revealed that decomposition of asphaltene was promoted and coke formation was suppressed when using SCW + HCOOH. In SCW + HCOOH, an increase in the water/oil ratio promoted both decomposition of asphaltene and suppression of coke formation. Formic acid in SCW seemed to enhance the conversion of bitumen to lower molecular weight compounds because formic acid seems to produce active species in SCW. The low temperature region (ca. 723 K) was suitable for upgrading bitumen with formic acid in SCW since coke formation was strongly promoted at high temperature (>753 K). A reaction model was proposed and the model predicted that hydrogenation of the asphaltene core was important for the suppression of coke formation.     

Non-isothermal programmed pyrolysis studies of oil sand bitumens and bitumen fractions: 1. Athabasca asphaltene

Characteristic pyrolysis thermograms for 12 gases have been obtained for Athabasca asphaltene, using a combination of non-isothermal, programmed pyrolysis (ambient to 1200 K at 3 K min^?1) and gas chromatography. Such thermograms provide information for the characterization of asphaltenes in the form of gas yields, specific rates and Arrhenius kinetic parameters. All thermograms comprised more than one peak. These peaks lie in distinct temperature zones and are associated with primary and secondary cracking and coking reactions. Useful insights into the structure of Athabasca asphaltene and, indirectly, the composition of its pyrolytic cokes have been obtained. The present results provide a body of useful reference material which may be useful for monitoring processes, which may chemically modify the asphaltene fraction of bitumens and heavy oils, and for comparative studies of asphaltenes from a variety of sources.     

Bitumen—sand interaction in oil sand processing

Bitumen—sand interaction was studied as a function of pH, particle size, temperature and solvent addition to bitumen. Sand particles can be easily detached from the bitumen surface at pH> 6. At pH < 6, strong attachment between bitumen and sand is observed. The bitumen—sand interaction is also particle-size dependent: the finer the particles, the stronger the attachment. The detachment of coarse particles from bitumen can be achieved by increasing the alkalinity of the solution, but not for fine particles, indicating that the particle size is one of the critical factors affecting liberation of bitumen from sand. Increasing temperature has two effects: it is not only reduces the viscosity to facilitate bitumen liberation, but also increases the electrostatic repulsion between sand and bitumen. This is confirmed by the DLVO theory and is in agreement with the batch extraction results on real oil sands.     

A benchmark assessment of residues: comparison of Athabasca bitumen with conventional and heavy crudes

Compared to benchmark crude oils, bitumen does not respond well to conventional upgrading processes. In order to improve our understanding of this problem, we compare the chemical and physical properties of fractions from super critical fluid extraction of bitumen pitch with the corresponding fractions of residua from Venezuelan heavy oil, a Saudi Arabian light crude and a Chinese Daqing conventional crude.Relatively minor differences in chemical structure were observed between the corresponding residua fractions from Athabasca bitumen, Venezuelan heavy oil and Saudi Arabian light crude. Only the Chinese Daqing showed significant variance; this sample is much more aliphatic and has greater geometrical dimensions than the corresponding samples from the other residua.The end-cut from Athabasca bitumen pitch contained ultra-fine solids together with much higher levels of nickel, vanadium and nitrogen than the conventional crude end-cuts. These components are among the most intractable in upgrading and could be responsible for the problems encountered in bitumen upgrading, especially by catalytic processes.     

Displacement of bitumen from reconstituted oil sands by aqueous solutions

A simple method has been developed for modelling the recovery of bitumen from packed beds of oil sand by water or caustic solution displacement. Batches of reconstituted oil sand were prepared by intimately mixing predetermined amounts of sand, water, and bitumen, thereby permitting the composition of the oil sand to be controlled and varied within a wide range. Dilution of the bitumen with hexadecane facilitated the mixing process and allowed experiments to be performed at low temperatures while maintaining oil-water viscosity ratios comparable to those prevailing at the higher temperatures encountered during hot water or steam displacements in the field. The effects of a wide range of compositional and operational variables were studied using a two-level fractional factorial design technique and the findings are discussed. Of particular interest are the observations that the density and initial connate water saturation of the oil sand exert significantly more effect on bitumen recovery efficiency for the case of water displacement than for caustic solution displacement.     

Coking of athabasca bitumen: effect of oxidation and sand

The effect of low temperature oxidation on the ultimate coke residue from Athabasca bitumen was examined quantitatively for extents of oxidation up to 100 mg O₂/g bitumen. The residue yield was found to increase linearly with extent of oxidation. When sand was introduced during the oxidation or pyrolysis processes, a smaller increase in coke yield was observed.     

沥青砂油页岩的开发技术与应用

沥青砂和油页岩属于非常规能源,储量均大于常规石油储量。当今世界越来越面临能源资源匾乏的严峻挑战,开发沥青砂和油页岩越来越引起人们的重视。本文在调研了国内外沥青砂和油页岩现状的基础上,研究了沥青砂油页岩开发的主要技术原理,分析了各种异地开采和就地开采技术应用现状及其发展趋势。研究表明,我国大多数沥青砂油页岩资源埋藏较浅,适合采用异地开采技术,可移动式矿区开采技术将是异地开采技术的发展趋势,就地开采技术是未来沥青砂油页岩开采技术的重点。