Spectroscopic characterization of the maltene fraction of Nigerian bitumen for potential health-risk assessment

This study was carried out on maltene fraction of Nigerian bitumen to infer the environmental and health implications of its uses and also to characterize the fossil fuel. Bitumen was extracted from the oil sands obtained from six locations in Southwestern Nigeria using toluene via Soxhlet extraction and then deasphalted using n-pentane. The organic components of the maltenes were investigated using Fourier transform infrared spectroscopy, while the elemental content was determined using inductively coupled plasma-optical emission spectrometry (ICP-OES) and the radioactivity levels were measured using a sodium iodide (NaI)-based Gamma Spectrometry Detector System. The IR spectra of the maltene indicated the presence of various organics and heteroatoms, corroborating the fact that maltene is composed of high molecular weight polycyclic constituents comprising nitrogen, sulfur, and oxygen heteroatoms. The result of the elemental concentrations revealed that sulfur with the mean value of 2.155 μg/g comparatively has the highest concentration in the samples, followed by Fe (1.25μg/g), while Mn has the least value (0.075) μg/g. The values of the analyzed elements were comparatively lower in the maltene fraction than in the bitumen and higher molecular weight fractions of Nigerian bitumen, but higher than the maltene fraction of Nigerian crude oil (except Cr and Ni). The result of the cross-plot analysis between maltene and bitumen using their elemental mean concentrations as variables indicated significant strong and positive correlation (R² = 0.81) between them, indicating very strong inter-element and geochemical relationships between them. The elements showed close clustering, indicating similar sources or similar chemical affinity. The average activity concentrations of ²³⁸U, ²³²Th, and ⁴⁰K determined with a view to ascertaining the radiological health consequences associated with the burning of this maltene fraction were 1.66 ± 1.07, 0.72 ± 0.49, and 15.93 ± 3.37 Bqkg^?1, respectively. These values are below the standard values in radiation protection. The radiological health consequences associated with the burning of maltene fraction of Nigerian bitumen were insignificant with no radiological hazard to the general public, but long exposure may pose an intrinsic health hazard.     

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.     

Enhancement of the thermal design of bitumen emulsion tanks by Scale Analysis,CFD models and experimental tests

The present paper applies Scale Analysis, numerical simulations and experimental tests to enhance the thermal design of a commercial mobile bitumen emulsion tank for road pavement. The objective is the reduction of diesel oil consumption with the lowest increment in heating time. The complexity of heat transfer in the system lies on the highly three dimensional behaviour of the fluid flow and the large disparity between characteristic length scales to be considered. Besides, the main heat transfer mechanism depends on the location. In spite of these difficulties, the proposed design achieves a reduction of 40% in diesel oil consumption with only a 28% increase in heating time.     

Influence of aggregate mineralogical composition on water resistance of aggregate–bitumen adhesion

The effects of aggregate mineralogical composition on moisture sensitivity of aggregate–bitumen bonds were investigated using four aggregate types (two limestone and two granite) and two bitumen grades (40/60 pen and 70/100 pen). Moisture sensitivity (or water resistance) of the aggregate–bitumen bonds were characterized using retained strength obtained from three different tensile tests (peel, PATTI and pull-off). The results showed significant differences in the amount of moisture absorbed by a given aggregate which suggested strong correlations between aggregate mineral composition and moisture absorption. For most of the aggregate–bitumen bonds, failure surfaces transformed from cohesive to adhesive with conditioning time thereby confirming the strong influence of moisture on aggregate bonds. The three tensile tests used in this study showed similar rankings in terms of moisture sensitivity but the pull-off test was found to be the most sensitive. The effect of bitumen on moisture sensitivity was found to be lower than the effect of aggregates, with the moisture absorption properties of the aggregates depending strongly on certain key minerals including clay, anorthite and calcite. Strong correlations were also found between mineral compositions and moisture sensitivity with clay and anorthite having strong negative influence while calcite showed positive effect on moisture sensitivity. Previous studies have identified various mineral phases like albite, quartz, and k-feldspar, as detrimental in terms of moisture sensitivity. The results appear to support the extension of the existing list of detrimental aggregate minerals to include anorthite and clay while supporting the case of calcite as a moisture resistant mineral.     

Tar mats and residual oil distribution in a giant oil field offshore Abu Dhabi

This paper describes how geochemical data (Rock Eval analysis, SARA composition) combined with wireline log interpretation allows for the recognition of the distribution and continuity of bitumens in a main reservoir of an offshore giant field in Abu Dhabi. The integration of new geochemical data with data and field information provided by the oil company ZADCO allows for the recognition of two types of bitumen rich levels in the main reservoir of the field: a) one corresponding to bitumen rich main reservoir intervals associated with high resistivity and high oil saturation, these intervals can be called “tar mats”, b) the other corresponding to low oil saturated intervals, and can be classified as “heavy residual oil”.In terms of lateral and vertical distribution, the tar mats are found at the crestal area of the Present-day structure and are located at the base of the reservoir unit above a tight limestone which plays a role of being a vertical permeability barrier. The tar mats seem to be independent of the Present-day OWC and are not related to biodegradation processes. The heavy residual oil is mainly located in the Northeast and the Southeast parts of the field and close to the OWC but it is also present all around the field except 1) in the west, in the area of the spill point and 2) in the Northwest area where direct contact between mobile oil and water is detected.Study of the structural evolution demonstrates that a tilting of the field began at Dammam age time (Eocene). The tilting of the structure led to a reduction of the structural closure in the West followed by the leakage of part of the originally trapped oil.Numerical modeling of such a geological scenario leads to a distribution of fluids (water, movable oil and residual oil) very close to the one observed at Present-day time in the field. This modeling allows a prediction of the extension and distribution of the residual heavy oil within the studied reservoir and can be used to better define an optimal production scheme. The effects of the residual heavy oils on the fluid circulation are difficult to evaluate, depending on the distribution of the bitumen in the pore network.     

紫外光老化对沥青化学族组成和物理性能的影响

在较高温度下对两种基质沥青（AH-70、AH-90）进行了紫外光氧老化，研究了紫外光对两种沥青化学族组成和物理性能的影响。结果表明：在紫外光的连续辐照下，两种沥青的饱和分、芳香分和沥青质含量的变化趋势基本相同，即饱和分含量变化很小，芳香分含量明显降低，沥青质含量显著增大，而两种沥青的胶质含量变化有明显差异：AH-70的胶质含量先略微增大后又减小最后基本不变；AH-90的胶质含量先稍微增大而后持续减少，总减少量明显比AH-70多。沥青族组分的变化直接影响其物理性能，在老化过程中，沥青的软化点、针入度和延度的变化与沥青的族组成的变化表现出良好的对应关系。     

利用测井资料研究和评价生油岩

本文首先介绍生油岩及其定性、定量评价指标，然后介绍用测井资料研究生油岩的依据及其地球物理特征，最后利用回归分析得到氯仿沥青“Ａ”、有机碳ＴＯＣ、吸附烃面积Ｓ１＋热解烃Ｓ２及二氧化碳面积Ｓ３与自然伽玛ＧＲ、电阻率Ｒｔ的相关关系。     

非生物(无机)成因油气基础科学问题

为了更好地了解原油、沥青的成因,对克拉玛依油田沥青、塔里木盆地干酪根和沥青、辽河油田下第三系干酪根和沥青A以及原油进行了Pb、Sr、N d同位素研究,结果表明:准噶尔、塔里木和辽河3个盆地的沥青及原油的Pb同位素均显示出了壳-幔相互作用的特征,也均表现出不同于干酪根Pb同位素组成的特征(干酪根的Pb同位素组成明显表现出壳源的特征);克拉玛依沥青的Rb-Sr等时线年龄及初始Sr比值(87Sr/86Sr)I(即IO)与达尔布特断裂带附近金矿的成矿年龄和IO相一致,表明沥青与金矿的金均来自相同的深部源区。指出在准噶尔盆地通过深部地震测深所获得的中地壳低速层存在的信息支持了这样一个假说,油气可能为非生物(无机)成因。     

Rheological characteristics of synthetic road binders

Most adhesives and binders, including binders for asphalt mixture production, are presently produced from petrochemicals through the refining of crude oil. The fact that crude oil reserves are a finite resource means that in the future it may become necessary to produce these materials from alternative and probably renewable sources. Suitable resources of this kind may include polysaccharides, plant oils and proteins. This paper deals with the synthesis of polymer binders from monomers that could in future be derived from renewable resources. These binders consist of polyethyl acrylate (PEA) of different molecular weight, polymethyl acrylate (PMA) and polybutyl acrylate (PBA), which were synthesised from ethyl acrylate, methyl acrylate and butyl acrylate, respectively, by atom transfer radical polymerization (ATRP). The fundamental rheological properties of these binders were determined by means of a dynamic shear rheometer (DSR) using a combination of temperature and frequency sweeps. The results indicate that PEA has rheological properties similar to that of 100/150 penetration grade bitumen, PMA similar rheological properties to that of 10/20 penetration grade bitumen, while PBA, due to its highly viscous nature and low complex modulus, cannot be used on its own as an asphalt binder. The synthetic binders were also combined with conventional penetration grade bitumen to produce a range of bitumen–synthetic polymer binder blends. These blends were batched by mass in the ratio of 1:1 or 3:1 and subjected to the same DSR rheological testing as the synthetic binders. The blends consisting of a softer bitumen (70/100 pen or 100/150 pen) with a hard synthetic binder (PMA) tended to be more compatible and therefore stable and produced rheological properties that combined the properties of the two components. The synthetic binders and particularly the extended bitumen samples (blends) produced rheological properties that showed similar characteristics to elastomeric SBS PMBs, although their precise viscoelastic properties were not identical.     

沥青改性用SBS市场分析及生产开发建议

通过对国内外苯乙烯类热塑性弹性体SBS产品在制鞋、沥青改性、聚合物改性和粘合剂等方面的市场及消费需求分析,预测了SBS产品在改性沥青行业的需求情况和发展趋势。随着国内高等级高速公路的快速发展,我国对改性沥青用SBS的需求量将会有较大的增长。针对我国目前的生产实际情况,提出了下一步改性沥青用SBS的生产开发建议。