Water‐Based Bitumen Recovery from Diluent‐Conditioned Oil Sands

Important process development aspects leading to more efficient bitumen recovery from diluent‐conditioned oil sands by water‐based methods are discussed. Bitumen viscosity of 0.5–2 Pa·s is required at the processing temperature and can be reduced to this level by bitumen dilution with an organic solvent. Oil sand porosity, however, poses a restriction on the amount of diluent that can be accepted by the oil sand. Also oil sand‐diluent conditioning time is an important process parameter and can vary from a few minutes for oil sands with low‐viscosity bitumen to several hours if viscosity of the bitumen is high. Additionally, the bitumen separation efficiency during digestion and flotation can be enhanced by reducing the bitumen/water interfacial tension through addition, for example, of tripolyphosphate to the aqueous phase.     

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.     

Thermo‐physical properties of n‐pentane/bitumen and n‐hexane/bitumen mixture systems

The gravity drainage as a result of viscosity reduction is the main governing mechanism of the solvent‐aided thermal bitumen recovery processes. Therefore, the density and viscosity of the diluted or heated bitumen are essential to predict the oil production rate. In this paper, we report thermo‐physical properties of n‐pentane/bitumen and n‐hexane/bitumen mixtures. The density and viscosity of Athabasca bitumen diluted with n‐pentane and n‐hexane were measured at different temperatures (30 to 190 °C), pressures (2 to 8 MPa), and solvent mass fractions (0.05 to 0.5). Various correlations and mixing rules proposed in the literature were examined to calculate the density and viscosity of the diluted bitumen. This study proposes appropriate mixing rules and generalized parameters for predicting the density and viscosity of solvent‐bitumen systems. Our findings will find applications in the design and simulation of heavy oil and bitumen solvent‐aided thermal recovery processes.     

Analysis of Solvent‐Diluted Bitumen from Oil Sands Froth Treatment Using NIR Spectroscopy

Process control and optimization of bitumen froth treatment during oil sands processing require rapid analysis of asphaltene content in bitumen, solvent‐tobitumen ratio (S/B), and the density of solvent‐diluted bitumen. NIR spectroscopy was employed to meet this requirement. The NIR system comprised a spectrometer with no moving parts coupled with a double‐pass transflectance probe via a fiber‐optic cable. Quantitative calibration models were established using partial leastsquares regression in latent variables. The standard errors of calibration were 0.20 wt% for 0 to 20 wt% asphaltenes in bitumen, 1.1 wt% for 20 to 100 wt% asphaltenes in bitumen, 0.1 for S/B of solvent‐diluted bitumen, and 0.0017 g/mL for density of solvent‐diluted bitumen. It was shown that the process conditions could be monitored through the spectral scores from principal component analysis.     

溶剂抽提法分离印尼油砂的实验研究

利用溶剂抽提法对印尼油砂进行萃取分离实验,综合考察了剂砂比、抽提温度、抽提时间、抽提次数等操作条件对油砂沥青提取的影响,确定较佳的油砂分离条件。结果表明,印尼油砂更适合采用溶剂抽提法分离,从油砂沥青提取率、操作成本和环保多角度考虑,在超声波的作用下,剂砂比为2．5,抽提温度40℃,抽提时间30min,抽提3次的条件下,油砂沥青的提取率较高,达到20．31％。     

Solvent screening for non‐aqueous extraction of Alberta oil sands

Non‐aqueous extraction of bitumen from oil sands has the potential to reduce fresh water demand of the extraction process and eliminate tailings ponds. In this study, different light hydrocarbon solvents, including aromatics, cycloalkanes, biologically derived solvents and mixtures of solvents were compared for extraction of bitumen from Alberta oil sands at room temperature and ambient pressure. The solvents are compared based on bitumen recovery, the amount of residual solvent in the extracted oil sands tailings and the content of fine solids in the extracted bitumen. The extraction experiments were carried out in a multistage process with agitation in rotary mixers and vibration sieving. The oil sands tailings were dried under ambient conditions, and their residual solvent contents were measured by a purge and trap system followed by gas chromatography. The elemental compositions of the extraction tailings were measured to calculate bitumen recovery. Supernatants from the extraction tests were centrifuged to separate and measure the contents of fine solid particles. Except for limonene and isoprene, the tested solvents showed good bitumen recoveries of around 95%. The solvent drying rates and residual solvent contents in the extracted oil sands tailings correlated to solvent vapour pressure. The contents of fine solids in the extracted bitumen (supernatant) were below 2.9% for all solvents except n‐heptane‐rich ones. Based on these findings, cyclohexane is the best candidate solvent for bitumen extraction, with 94.4% bitumen recovery, 5 mg of residual solvent per kilogram of extraction tailings and 1.4 wt% fine solids in the recovered bitumen. © 2012 Canadian Society for Chemical Engineering     

Prediction of bitumen content in oil sand based on FT-IR measurement

FT-IR spectra of bitumen are utilized to propose simple prediction method of bitumen content in oil sand. Analysis and fractionation of Athabasca oil sand were carried out by standard method. A fraction of bitumen dissolved in tetrahydrofuran (THF) was 9.1 wt% and insoluble fraction was found as concomitantly clean clay (sand). The asphaltene fraction of oil sand was 1.42 wt%, which has higher sulfur content and lower H/C molar ratio than that of maltene. The clean clay and bitumen were used to prepare clay/bitumen composites. FT-IR spectra of different clay/bitumen composite were measured and compared. From analysis of the absorbance data, the empirical equation to predict bitumen content in oil sand was acquired using linear least square fitting. Using this equation, bitumen content of Athabasca oil sand was predicted to have a value of 10.5 wt% which is similar to 9.1 wt% of bitumen content extracted by THF solvent from oil sand.     

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。     

Application of microbial enhanced oil recovery technology in water‐based bitumen extraction from weathered oil sands

When using the water‐based extraction processes (WBEPs) to recover bitumen from the weathered oil sands, very low bitumen recovery arisen from the poor liberation of bitumen from sand grains is always obtained. Application of microbial enhanced oil recovery (MEOR) technology in WBEPs to solve the poor processability of the weathered ore was proposed. It was found that processability of the microbial‐treated weathered ore was greatly improved. The improved processability was attributed to the biosurfactants production in the culture solution, alteration of the solids wettability, degradation of the asphaltene component, and the decrease of the bitumen viscosity, which collectively contributed to the bitumen liberation from the surface of sand grains. Although it still has many issues to be solved for an industrial application of the MEOR technology in oil sands separation, it is believed that the findings in this work promote the solution to the poor processability of the weathered ore. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2985–2993, 2014     

Understanding Water‐Based Bitumen Extraction from Athabasca Oil Sands

The current state of knowledge on the fundamentals of bitumen recovery from Athabasca oil sands using water‐based extraction methods is reviewed. Instead of investigating bitumen extraction as a black box, the bitumen extraction process has been discussed and analyzed as individual steps: Oil sand lump size reduction, bitumen liberation, aeration, flotation and interactions among the different components that make up an oil sand slurry. With the development and adoption of advanced analytical instrumentations, our understanding of bitumen extraction at each individual step has been extended from the macroscopic scale down to the molecular level. How to improve bitumen recovery and bitumen froth quality from poor processing ores is still a future challenge in oil sands processing.     

Novel polymer aids for low‐grade oil sand ore processing

In the present study, a hybrid Al(OH)₃‐polyacrylamide (Al‐PAM) was synthesized and used in combination with a partially hydrolyzed polyacrylamide (HPAM) to process a low‐grade oil sand ore. It was found that Al‐PAM was capable to improve bitumen froth quality and tailings settling. But it led to deterioration in bitumen recovery due to the formation of large bitumen lumps during the bitumen extraction process. To resolve this problem, HPAM was added in combination with Al‐PAM as a dual system. The use of the dual system at a low dosage achieved a holistic improvement in bitumen recovery, froth quality, and tailings settling. To understand the role of Al‐PAM and the dual system in the bitumen extraction process, bitumen‐clay, bitumen‐bitumen, and clay‐sand interaction and adhesion forces were directly measured using an atomic force microscope (AFM). The measured forces indicate that bitumen recovery and tailings settling are controlled by the colloidal interaction and adhesion forces between the oil sand components.     

A SAPONIFICATION CYCLE FOR SOLVENT RECOVERY FROM SAND SURFACES FOLLOWING BITUMEN EXTRACTION

A saponification cycle utilizing a fatty acid/heptane solvent blend was studied as a method for removing solvated bitumen from sand surfaces in a tar sands processing unit prior to disposal of the tailings. In this process, the fatty acid portion of the solvated bitumen was saponiffied with caustic resulting in an in-situ soap which aided in washing the organics off the sand surfaces. The wash liquid was then desaponified with hydrochloric acid to reconstitute the fatty acid, which went into the organic phase with the bitumen and heptane. This solvated bitumen stream was processed by an amphiphilic phase shift reaction to separate out the bitumen and recover the solvent for recycling back to the contactor. The aqueous phase from the desaponifier is brine and must be discarded. The saponification/desaponification kinetics and the phase behavior of this cycle were investigated as they apply to this process. Saponification cycle experiments showed that the fatty acid portion of the solvent could by fully recovered and used repeatedly. Bench-scale washing experiments showed that this saponification cycle promoted the removal of the viscous, solvated bitumen from sand surfaces.     

脱油沥青喷雾造粒过程影响因素分析

利用重油梯级分离耦合萃余残渣喷雾造粒的方法将脱油沥青制成沥青粉,为脱油沥青提供了良好的应用前景.在连续溶剂脱沥青装置上考察了影响脱油沥青造粒的主要因素,原料为加拿大油砂沥青、委内瑞拉常压及减压渣油、中东减压渣油,溶剂为正丁烷、正戊烷、正己烷及其混合溶剂,萃取塔底温度分别为130、146、160℃,而副溶剂温度为130℃...     

Role of mineral flotation technology in improving bitumen extraction from mined Athabasca oil sands: I. Flotation chemistry of water‐based oil sand extraction

The role of surface hydrophobicity in water‐based oil sand extraction is examined from the perspective of mineral flotation separation. Although anionic carboxylates (sulphonates) released from bitumen are helpful for charging bitumen and liberating bitumen from sand grains, their presence in oil sand slurries tends to make bitumen and bubbles less hydrophobic. In addition, solid hydrophobization under oil sand extraction conditions can occur through different mechanisms of carboxylate adsorption. It is the hydrophobized fine solids that present challenges for achieving a high bitumen recovery with a good froth quality, due to their competition with bitumen for attachment to bubbles. While chemisorption of carboxylates contributes to hydrophobization of heavy minerals present in oil sands, carboxylate adsorption activated by hydrolyzed metal cations alters silica and clays from hydrophilic to hydrophobic. Different adsorption mechanisms of calcium on silica, clays, and other minerals are analyzed to explain why fine solids of varying mineralogy in combination with calcium affect bitumen extraction differently. Metal ions that activate solid hydrophobization under oil sand extraction conditions are identified from dynamic attachment of solids from mature fine tailings (MFT) to bitumen. To mitigate the effect of fines on oil sand extraction, selective flocculation of fine solids is recognized as especially feasible for bitumen flotation recovery from oil sand middling streams. Future research in reducing or eliminating caustic addition, understanding the role of inorganic anions, and searching for feasible techniques for treating MFT based on different mineralogy and surface properties, are briefly discussed.

     

Gas Analysis by In Situ Combustion in Heavy‐Oil Recovery Process: Experimental and Modeling Studies

Enormous efforts have been made to facilitate produced‐gas analyses by in situ combustion implication in heavy‐oil recovery processes. Robust intelligence‐based approaches such as artificial neural network (ANN) and hybrid methods were accomplished to monitor CO₂/O₂/CO. Implemented optimization approaches like particle swarm optimization (PSO) and hybrid approach focused on pinpointing accurate interconnection weights through the proposed ANN model. Solutions acquired from the developed approaches were compared with the pertinent experimental in situ combustion data samples. Implication of hybrid genetic algorithm and PSO in gas analysis estimation can lead to more reliable in situ combustion quality predictions, simulation design, and further plans of heavy‐oil recovery methods.     

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.     

有机溶剂萃取加拿大油砂应用研究

介绍了溶剂作为萃取剂分离油砂的技术,溶剂萃取油砂过程包含两个阶段:沥青相向溶剂的溶解过程和沥青、溶剂与砂粒的分离过程。考察了单一溶剂甲苯、丙酮、乙酸乙酯和甲苯/正庚烷、丙酮/正庚烷、乙酸乙酯/正庚烷组成的复合溶剂体系在相同条件下对油砂沥青的萃取率,在此基础上进一步对比了不同溶剂体系对沥青四组分饱和分、芳香分、胶质和沥青质的萃取效果,同时考察了不同浓度的沥青-溶剂溶液的表面张力,结果表明在油砂萃取过程中沥青-溶剂体系的表面张力主要取决于所选溶剂的种类,而沥青的浓度对溶液表面张力的影响不大。混合溶剂体系甲苯/正庚烷、丙酮/正庚烷、乙酸乙酯/正庚烷相比纯溶剂萃取率较高,其沥青溶液表面张力较低,是良好的分离油砂溶剂体系。     

Effect of Operating Temperature on Water‐Based Oil Sands Processing

Operating temperature is one of the most important controlling parameters in oil sands processing. Considering the massive energy consumption and green house gas emission, lowering the processing temperature is highly desirable. To achieve such an ambitious goal requires a comprehensive understanding on the role of temperature in oil sands processing. This paper provides an overview of major findings from existing studies related to oil sands processing temperature. The relation between temperature and bitumen recovery is discussed. The effect of temperature on the physiochemical properties of oil sand components, such as bitumen viscosity, bitumen surface tension and surface potentials of bitumen and solids, is analyzed. The interactions between bitumen and solids and between bitumen and gas bubbles as a function of temperature are recounted. Also discussed is the role of chemical additives in oil sand processing. It has been found that temperature affects nearly all properties of oil sands among which bitumen viscosity and bitumen‐solids adhesion impose a prominent impact on bitumen recovery. The use of selected chemical additives can reduce bitumen viscosity and/or the bitumen‐solids adhesion, and thus provide a possible way to process oil sands at a low temperature while maintaining a high bitumen recovery.     

不同有机溶剂对新疆油砂沥青的组成性质影响

油砂作为一种非常规石油资源,越来越受到人们的重视。油砂沥青的含量和性质对其开发有着重要的影响。有机溶剂抽提可以测定油砂沥青的含量。本文研究了3种溶剂对新疆油砂的抽提能力,并对不同溶剂抽提得到的新疆油砂沥青进行了性质分析。结果表明,新疆油砂含油率（甲苯测）为11.75%,属于中品位油砂矿;甲苯、氯仿和石油醚3种不同溶剂对新疆油砂沥青进行抽提,发现3种溶剂抽提能力的大小关系为氯仿＞甲苯＞石油醚;抽提过程中,氯仿表现出对胶质和沥青质较强的萃取能力,而石油醚对沥青质的萃取能力几乎为0,采用氯仿可以更准确地测定油砂沥青的含量。氯仿抽提得到新疆油砂沥青及其组分的杂原子含量和分子量高于甲苯和石油醚抽提的。由红外谱图发现,氯仿抽提得到的油砂沥青的含氧、含硫官能团的吸收峰强度大于甲苯和石油醚抽提的,表明氯仿对油砂沥青中极性物质的抽提能力更强。     

Water content of light n‐alkanes: New measurements and cubic‐plus‐association equation of state modeling

Light hydrocarbon gases such as methane, ethane, propane, and butane or other so called gaseous solvents have been suggested as steam additives to improve bitumen recovery and energy efficiency. The water content of these gases is one of the key requirements in the simulation and design of solvent‐aided thermal heavy oil recovery processes. In this work, we present new experimental data for the water content of these gases at high temperatures (up to 493.15 K) and moderate pressures (P < 6 MPa). The experimental data was regenerated using the cubic‐plus‐association equation of state. The Soave–Redlich–Kwong equation of state is used to treat the physical interactions. The association interactions are captured using Wertheim's first‐order thermodynamic perturbation theory. A set of binary interaction parameters is proposed to calculate the water content of methane, ethane, propane, and n‐butane at the operating conditions of the thermal heavy oil and bitumen recovery processes. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1384–1389, 2017