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沥青质是一种分子量分布范围非常大的有机分子混合物，根据沥青质沉积为一不可逆过程和沥青质中分子量大的组分比分子量小的组分具有更强的沉积趋势的认识，章首次提出了原油体系沥青质沉积时存在一次沉积和多级沉积两种不同的沉积方式和过程的观点，通过实验室分析，验证了这一观点并建立了可描述多级沉积过程的数学模型，通过模型计算可以很好地拟合多级沉积的实验结果。     

无机盐与沥青质的协同作用对油藏润湿性的影响

选用两种原油沥青质样品,对沥青质在岩石孔隙表面吸附所引起的润湿性改变进行了实验研究。测定结果表明,岩样润湿性改变的程度主要与沥青质的来源和岩样所含盐水的组成有关。盐水中无机阳离子的类型对沥青质所引起的油藏岩石润湿性改变有十分重要的作用。在浓度相同的情况下,阳离子价数越高,对润湿性的影响越大。盐水中的无机阴离子对沥青质引起的润湿性改变影响很小。在油气开采过程中,地层水和注入水的离子组成,特别是所含阳离子的类型,是影响油藏岩石润湿状态的一个不可忽视的因素。     

Effect of heavy asphaltene on stability of residual oil

An asphaltene fractionation method was developed in order to investigate the effect of heptane (n-C7) insoluble asphaltene (C7-asphaltene) on residual oil stability. C7-asphaltene was separated into heavy and light fractions by a new method using a binary solvent system of toluene and heptane (n-C7). It was found that the heavy fraction of C7-asphaltene in residual oil, extracted by this method, consisted of highly condensed polynuclear aromatics. Our new fractionation method and the Heithaus stability evaluation method were applied to hydroprocessed residual oils. The peptizability of heavy fraction of C7-asphaltene defined by the Heithaus method decreased in accordance with structural condensation of that fraction. On the other hand, light fraction of C7-asphaltene was considered to influence the peptizing power. We proposed a new conceptual model: light asphaltenes would perform as peptizing material as well as resin, and heavy asphaltene would be peptized in oil. This model introduced from our new asphaltene fractionation method could be more effective for understanding the destabilization phenomenon of residual oil.     

A new technique for treatment of permeability damage due to asphaltene deposition using laser technology

This study proposes a new technique for cleaning deposited asphaltenes using laser energy. Two series of experiments were carried out to achieve this objective. In the first one, one-inch column of bitumen mixed with limestone was placed above powdered limestone column in a flow cell. In the second series of experiments, actual consolidated limestone cores were subjected to flow of asphaltenic crude oil to simulate the damage process (i.e. permeability reduction). Both unconsolidated and consolidated limestone samples were subjected to a laser energy using laboratory diode modules at various laser intensity and treatment time intervals.Experimental results indicated that exposure of the above-mentioned permeability damaged limestone samples to laser energy caused asphaltene disruption and resulted in recovery of damaged permeability. The increase of laser intensity increased the recovered permeability and the optimum time duration is measured to be 1 h at laser intensity of 19 mW/h. Simultaneous pumping is required during the laser treatment to avoid the re-precipitation of the disrupted asphaltene.     

Contribution of organic and mineral compounds to the formation of solid deposits inside petroleum wells

Deposit samples collected from three Mexican wells, their asphaltene and residue fractions as well as the sediment and asphaltene fractions separated from the corresponding crude oils were characterized. An appreciable amount of minerals such as CaCO₃, BaSO₄, NaCl, quartz and iron compounds were detected in the deposit compositions. Additionally, aromatic factors and structural parameters such as interlayer distance and crystallite diameters were calculated from the (γ) and (002) characteristic bands from the X-ray diffractograms of the deposits, deposit-asphaltene, oil-asphaltenes as well as oil-sediments. FTIR, elemental analysis and thermal techniques were also used to elucidate the sample compositions. The stages of the deposit formation inside petroleum wells include steel surface corrosion products formed in situ by the presence of brine and sulfur bearing compounds and adsorption or chemisorption of organic compounds on the modified tubing steel surface and mineral pores. Moreover, the high amount of vanadium and nickel indicates a time-dependent process of accumulation of some organometallic compounds independent of the oil-asphaltene amount.     

Effects of Catalyst Properties on Asphaltenes Composition During Hydrotreating of Heavy Oils

Three NiMo commercial catalysts were used for carrying out hydrotreating (HDT) experiments in a high-pressure pilot plant. Maya crude oil was employed as HDT feed. All hydrotreated products and their corresponding precipitated asphaltenes fractions were characterized by elemental analysis and metals contents. Extraction of asphaltenes was carried out according to the method described in ASTM D-3279. It was observed from our characterization results that while nitrogen and metals content in asphaltenes increase sulfur decrease as the reaction temperature is increased. This different behavior was attributed to the localization of each heteroatom in the asphaltene molecule. Pore size of catalysts showed the major influence on hydrotreated product asphaltenes composition.     

Determination of Algerian Hassi-Messaoud asphaltene aromaticity with different solid-state NMR sequences

Algerian oil well deposit derived asphaltene fraction was characterized by different MAS/NMR sequences to investigate asphaltene aromaticity and the best cross-polarization contact time. The aromaticity was estimated by single pulse sequence (SP), Hahn-echo (HE), cross-polarization (CP) and variable cross-polarization (VACP) sequences. The values found ranging from 0.58 to 0.48 are of the same order of magnitude as ones published in the literature. The discrepancies between the values are thought to be relevant to both the specificity of each sequence and the asphaltene structure. Spectra band de-convolution enables us the determination of the average number of carbon atoms per side chain according to each sequence. The obtained values spanning from 3 to 7 are also sequence nature dependent.     

Heavy-organic particle deposition from petroleum fluid flow in oil wells and pipelines

Suspended asphaltenic heavy organic particles in petroleum fluids may stick to the inner walls of oil wells and pipelines. This is the major reason for fouling and arterial blockage in the petroleum industry. This report is devoted the study of the mechanism of migration of suspended heavy organic particles towards the walls in oil-producing wells and pipelines. In this report we present a detailed analytical model for the heavy organics suspended particle deposition coefficient corresponding to petroleum fluids flow production conditions in oil wells. We predict the rate of particle deposition during various turbulent flow regimes. The turbulent boundary layer theory and the concepts of mass transfer are utilized to model and calculate the particle deposition rates on the walls of flowing conduits. The developed model accounts for the eddy diffusivity, and Brownian diffusivity as well as for inertial effects.     

Applying Grid partitioning based Fuzzy inference system as novel algorithm to predict Asphaltene precipitation

Asphaltene precipitation is one of challenging problems in petroleum and chemical engineering so the importance of investigation of Asphaltene precipitation is clear. The asphaltene deposition effects on wellbore plugging, wettability alteration and facility damages. In order to solve these problems, a novel investigation based on Grid partitioning based Fuzzy inference system algorithm to predict precipitated asphaltene in terms of dilution ratio, temperature and carbon number of precipitant was developed. The predicting algorithm performance was evaluated statistically and graphically. The coefficients of determination (R²) for training and testing phases 0.9973 and 0.9900 respectively which confirm the great accuracy and high potential of predicting algorithm for estimation of precipitated asphaltene so this algorithm can be used as high accurate and simple software for prediction of asphaltene behavior in crude oil.     

轮南和塔河油田稠油沥青质钌离子催化氧化研究

运用钌离子催化氧化(RICO)技术,研究了轮南和塔河油田以及TD2井稠油沥青质。在轮南和塔河油田稠油沥青质分子结构中,键合在沥青质芳核结构中的官能团以烷基侧链为主,烷基桥次之,此外还有一定的支链烷烃及生物标志物,这些化合物绝大部分是以C-C键键合在沥青质结构中的。沥青质中的芳核体系大多以萘、菲、联苯型为主,高度缩合的芳核结构较少。轮南和塔河油田稠油沥青质RICO产物具有较高的一元和二元酸比值,甾烷酸的异构化参数均大于0.40,表明原油具有较高的成熟度;一元酸和甾烷酸的分布均与典型寒武系生源的TD2井稠油具有明显的差异,指示轮南和塔河油田稠油源于中上奥陶统烃源岩。