Morphology Of Bitumen Research Articles

Aging evaluation of base and SBS modified bitumens under the coupling effect of multiple aging factors

• Four factors, heat, oxygen, UV and moisture are considered in bitumen aging simulation. • The temperature above 65 °C will have an obvious acceleration effect on the aging of bitumen. • The coupling effects of four factors on aging of bitumen are revealed. • UV radiation and moisture should not be neglected in the laboratory aging simulation. The thermal-oxidative aging of bitumen is extensively studied under the guidance of current norms in laboratory investigations, while the photo-oxidative aging is not standardized and the moisture is seldom considered. To evaluate the aging behaviors of bitumen under the coupling effect of multiple aging factors, two binders, a base bitumen and an SBS modified bitumen (SBSMB), were treated by different aging inducements, such as heat, oxygen, ultraviolet (UV) radiation and moisture, then their physical and rheological properties, morphology and chemical structures were investigated. Results indicate that two binders exhibit similar aging behaviors, the elevated aging temperature, prolonged aging time and coupled aging inducements will accelerate the aging process, and the aging susceptibility of two binders is higher at temperature above 65 °C or aging time within 10 days. The more aging inducements would cause more serious aging, the heat-oxygen-UV-moisture coupling aging causes the highest aging degree, indicating an obvious coupling effect in aggravating the deterioration of binders. Compared with thermal-oxidative aging, the UV or UV-moisture results in an entirely different surface morphology of bitumen, leaving a very rough, dry and pale surface. The transformations of chemical structures for two binders caused by various aging show a similar trend, but the variation extents of evaluated parameters of SBSMB is less than that of base bitumen under the same aging condition, indicating the modification of SBS could inhibit the aging of bitumen to some extent. Therefore, UV radiation and moisture should not be neglected in laboratory aging simulations.

Occurrence morphology of bitumen in Dengying Formation deep and ultra-deep carbonate reservoirs of the Sichuan Basin and its indicating significance to oil and gas reservoirs

Abundant bitumen can be discovered in the wells of Upper Sinian Dengying Formation in the Sichuan Basin and their peripheral outcrops sections. As the cracking product of a paleo-oil reservoir, the occurrence morphologies and distribution characteristics of bitumen in carbonate reservoirs can indicate the preservation, migration and other key information of (paleo-) oil and gas reservoirs. In order to provide reference and basis for the deep and ultra-deep oil and gas exploration in the Sichuan Basin and the basins in western China, this paper systematically studies the occurrence morphological characteristics of bitumen in deep and ultra-deep carbonate reservoirs in well Gaoshi 1 of the Sichuan Basin by carrying out thin section observation, scanning electron microscope-energy spectrum analysis and fluid inclusion organic geochemical analysis on the cores of the fourth member of Dengying Formation (Deng 4 Member). In addition, the coupling relationship between the occurrence morphology of bitumen and the key event of hydrocarbon accumulation is revealed. And the following research results are obtained. First, solid bitumen in the Deng 4 Member deep and ultra-deep reservoir has two types of occurrence morphology. The first type of bitumen adheres to pore walls in the shape of a rim or exists in pores in the form of sticky branch (e.g., Wells Chuanshen 1 and Gaoshi 1). There are more obvious shrinkage fractures and residual pores generated by in-situ thermal cracking in this type of bitumen. And combined with fluid inclusion and burial thermal history, it can effectively indicate that a paleo-gas reservoir has been preserved so far since the paleo-oil reservoir was thermally cracked into carbonaceous bitumen. The second type of bitumen is distributed in intra- and inter-neogenic mineral crystals in pores disorderly in the shape of grain and band (e.g., Wells Mashen 1 and Wutan 1) and it has obvious breaking edges. It reveals that after a paleo-oil reservoir was thermally cracked into carbonaceous bitumen, the paleo-gas reservoir suffered blowdown and gas escape and neogenic fluid minerals moved into reservoirs to fill in pores. In conclusion, the occurrence morphologies and distribution characteristics of bitumen in deep and ultra-deep carbonate reservoirs can effectively indicate the hydrocarbon accumulation and evolution process of paleo-oil and gas reservoirs.

Behavior comparison of films of Mexican bitumen and its asphaltene and maltenes fractions at interfaces

The oil industry has been focused on bitumens and heavy oils due to the depletion of petroleum reservoirs. For this reason, we studied the interfacial behavior comparison of films of bitumen and their asphaltene and maltene fractions by means of the Langmuir balance and Brewster angle microscopy at the air–water interface. The films were transferred by Langmuir-Blodgett technique onto mica and grids to be further analyzed by AFM and SEM at different surface pressures. We found that the isotherm behavior of the bitumen depends on the amount of its asphaltene and maltene fractions, although the isotherm behavior of asphaltene and maltene fractions are quite different. BAM images of the bitumen and asphaltene samples show the formation of two- and three-dimensional domains, being the asphaltene domains the most rigid and compact structures. Maltenes seems to form large areas of mono- or bi-molecular films, and their structures are like those reported for lipid monolayers. The AFM images for the bitumen morphology exhibited polydisperse mesostructures with spherical and disk-like shapes, while asphaltene images revealed disk-like microstructures and some of these microstructures coalesce, resulting in the formation of worm-like and other small structures. AFM images of the maltene film revealed that they form a fine plaster that might agglutinates the asphaltenes. SEM images of bitumen film show a smooth and slightly porous surface with some layer detachments, holes and bright spots embedded, while asphaltene images presented porous surfaces with spherical- or drumstick-like structures. Maltene SEM images showed a surface with irregular pores. The results support a better understanding of the bitumen, asphaltene, and maltene fractions and suggest that the interfacial behavior of bitumen presents a synergy between its asphaltene and maltene fractions.

Kerogen composition and maturity assessment of a solid bitumen-rich and vitrinite-lean shale: Insights from the Upper Jurassic Vaca Muerta shale, Argentina

Assessment of thermal maturity by solid bitumen reflectance measurements in vitrinite-lean or vitrinite-barren shales is widely used in unconventional shale gas and shale oil plays but the method is commonly challenged by the complexity in the measurements. The Upper Jurassic marine Vaca Muerta shale in the Neuquén Basin in western Argentina is both a prolific conventional source rock and a primary unconventional reservoir for oil and gas. The shale is rich in solid bitumen and lean or barren in vitrinite and offers an excellent opportunity to gain insight into thermal maturity assessment of a shale with a complex organic matter composition. The kerogen composition of a set of immature to highly mature Vaca Muerta shale samples was investigated by organic petrography and reflectance measurements were taken on vitrinite and solid bitumen. The results were integrated with available Rock-Eval data and stable carbon isotope values of shale gas (ethane and propane) collected at the same depth as the rock samples. The maceral composition of immature Vaca Muerta shale is highly sapropelic and oil-prone with Hydrogen Index values of 600 mg HC/g TOC or higher. The liptinite macerals consist primarily of alginite with minor amounts of inertinite and/or oxidized vitrinite. Indigenous vitrinite is generally scarce and in some samples absent. Vitrinite reflectance values range from 0.79%Ro to more than 1.94%Ro corresponding to early peak oil to dry gas maturity. Solid bitumen is abundant in all mature samples. Two general types of solid bitumen morphology were observed: (i) BR I, a dark reflecting porous variant disseminated in the clayey mineral matrix and (ii) BR II, a lighter reflecting more ‘dense’ textured variant. Bands of denser solid bitumen were commonly seen ‘flowing’ in more porous or weak zones in the matrix and around mineral grains. Degassing pores were frequently observed. Solid bitumen reflectance measurements on BR I and BR II provided two populations with different reflectance ranges. The correlation between vitrinite and BR II reflectances is considered to have highest confidence. The correlation can be expressed by the equation VReqv = (BR II + 0.3043)/1.026. The established VReqv-BR II correlation yields results comparable to other published correlations but also demonstrates significant discrepancy to others. This warrants caution when assessing the maturity of complex unconventional shale gas and oil plays by translating solid bitumen reflectance values into vitrinite reflectance equivalents using correlations not calibrated to that specific shale play. Both Hydrogen Index values and ethane and propane stable carbon isotope values of Vaca Muerta shale gas show strong correlations to VReqv derived from BR II. Thus, in cases with absence of vitrinite and questionable solid bitumen measurements reasonable maturities (vitrinite reflectance equivalents) can be inferred from these relationships.

Inverse Laplace Transform (ILT) NMR: A powerful tool to differentiate a real rejuvenator and a softener of aged bitumen

ILT is particularly useful when the signal is characterized by multi-exponential decay, for example in spin relaxation or in the dephasing of the NMR spin echo signal associated with sopra molecular aggregation under the influence of pulsed magnetic or internal field gradients. As novel approach to observe the real rejuvenating effect of the potential additive, an Inverse Laplace Transform of the NMR spin-echo decay (T2) was applied. The potentialities of a new, non-toxic and eco-friendly biocompatible additive on aged bitumen are explored for the first time as bitumen rejuvenator, by means of advanced rheological and Relaxometry-NMR measurements. Pristine, aged, and doped aged bitumen morphology have been investigated by SEM. The new rejuvenator helps to rearrange the structure of the aged bitumen (aiming at the original one), and this mechanism can be observed by ILTNMR analysis.

Compositional mapping of bitumen using local electrostatic force interactions in atomic force microscopy.

In recent years, many researchers have investigated bitumen surface morphology, especially the so-called bee-like structures, in an attempt to relate the chemical composition and molecular conformation to bitumen micromechanics and ultimately performance properties. Even though recent studies related surface morphology and its evolution to stiffness and stress localization, the complex chemical nature of bitumen and its time- and temperature-dependent properties still engender significant questions about the nature and origin of the observed morphological features and how they evolve due to exposure to various environmental and loading conditions. One such question is whether the observed surface features are formed from wax or from the coprecipitation of wax and asphaltene. Our prior work was mainly theoretical; it used density functional theory and showed that the coprecipitation theory may not stand, mainly because wax-asphaltene interactions are not thermodynamically favourable compared to wax-wax interactions. This paper presents a comprehensive approach based on experiments to study surface morphology of bitumen and conduct compositional mapping to shed light on the origin of the bee-like surface morphological features. We used Atomic Force Microscopy (AFM), with the main focus being on single-pass detection and mapping of local electric properties, as a novel approach to enhance existing compositional mapping techniques. This method was found to be highly effective in differentiating various domains with respect to their polarity. The results of our study favour the hypothesis that the bee-like features are mainly composed of wax, including a variety of alkanes.

Properties of Bitumen Containing Various Amounts of Organic Montmorillonite

AbstractThe effects of various amounts of organic montmorillonite (OMt) on the morphology and physical properties of bitumen before and after ultraviolet (UV) aging were investigated. The microstructures of OMt modified bitumens were characterized by X-ray diffraction (XRD) analysis. The morphology of the binders was analyzed by atomic force microscopy. According to the XRD results, OMt modified bitumens form an intercalated nanostructure. As a result of UV aging, OMt modified bitumens show lower viscosity aging index and softening point increments than unmodified bitumens, which are further decreased by increasing the OMt content, indicating the satisfactory UV aging resistance of OMt modified bitumen. However, the softening point increments and viscosity aging index decrease slowly when OMt content increases above 6% by weight. UV aging significantly influences the morphology of bitumen. The contrast between the matrix and dispersed domains is decreased and a single-phase trend occurs in the bitumen dur...

The Effect of Different Nanomaterials on the Long-term Aging Properties of Bitumen

Effect of expanded vermiculite (EVMt) and nano-zinc oxide on thermal-oxidative (pressurized aging vessel, in situ thermal aging) and ultraviolet (UV) aging was investigated. The results show that organic expanded vermiculite (OEVMt) modified bitumen forms an exfoliated nanostructure. The morphology of bitumen is significantly influenced by two nanomaterials according to atomic force microscopy. The influence of different nanomaterials on long-term aging resistance of bitumen depends on their structures and shielding function to UV radiation. Thermo-oxidative aging resistance of bitumen can be effectively improved with the introduction of OEVMt, while nano-zinc oxide has obvious improvements in UV aging resistance of bitumen.

Microstructures and thermal aging mechanism of expanded vermiculite modified bitumen

This work evaluates a novel bitumen modification through the use of expanded vermiculite (EVMt) which has been traditionally used as thermal insulation material. In order to improve the compatibility between EVMt and bitumen, EVMt was modified by octadecyl dimethyl benzyl ammonium chloride and marked as organo-expanded vermiculite (OEVMt). A new approach to determine the microstructures of OEVMt modified bitumen was reported by combining the results from X-ray diffraction analysis of OEVMt modified bitumen and the dissolving–filtrating procedure. Aging mechanism of the binders was revealed by using atomic force microscopy (AFM). The results show that OEVMt modified bitumen forms a semi-exfoliated nanostructure. As a result of thin film oven test (TFOT) and situ thermal aging, mass change rate and viscosity aging index are increased, while retained penetration and ductility are decreased of binders. However, these physical changes can be effectively prevented by OEVMt. Aging influences bitumen morphology significantly. TFOT leads to the association of the dispersed domains and the single phase trend of bitumen. These changes are accelerated by situ thermal aging. However, these morphology changes of bitumen are inhibited obviously with the introduction of OEVMt, indicating the good thermal aging resistance of OEVMt modified bitumen with semi-exfoliated nanostructure.

Effect of polyphosphoric acid on physical properties, chemical composition and morphology of bitumen

The effect of polyphosphoric acid (PPA) on chemical composition, physical properties and morphology of bitumen was investigated. The morphology of the binders was characterized by atomic force microscopy. The results show that the influence of PPA on chemical composition, physical properties and morphology of bitumens depends on the base bitumen. The colloidal index shows an obvious effect on the chemical composition and physical properties as well as morphology of bitumen during PPA modification. A strong correlation is observed between morphology and chemical composition as well as physical properties for different bitumens after PPA modification.

Influence of hindered phenol additives on the rheology of aged polymer-modified bitumen

Oxidation (aging) in polymer-modified bitumen occurs due to exposure in air at high temperatures. The aging mechanism tends to alter the physical and chemical properties of bitumen as reflected by the change in their rheological properties. In this study, a blend of SBR and hindered phenols (HPs) was used to improve the rheological characteristics of base (unmodified) and polymer-modified bitumen. Rheological properties were measured using a Rotational Viscometer, a Dynamic Shear Rheometer and a Bending Beam Rheometer. Stiffening indices and complex modulus indices were used to assess the effectiveness of the additives in the bitumen and its thermal stability, respectively. It was found that the additives were capable of increasing the stiffness at high temperature and reducing the hardening propensity of aged bitumen at intermediate and low temperatures. Bitumen morphology suggests that the degree of polymer network chain break-down was less severe when the HP was used in the bitumen. Performance testing of bituminous mixtures indicated that the HP additives enhanced the stripping resistance, improved rutting performance and extended the mixture service life.

Effect of aging on the morphology of bitumen by atomic force microscopy

Effect of aging on the morphology of bitumen was investigated. Two bitumens were aged according to the thin film oven test (TFOT), pressure aging vessel (PAV) test and ultraviolet (UV) radiation, respectively. The morphology of the binders before and after aging was characterized by atomic force microscopy. The physical properties and chemical compositions of the binders were also measured. The results showed that aging affected the bitumen morphology significantly. Aging increased the overall surface stiffness of the bitumen and made the bitumen surface more solid-like. The extent of these changes was dependent on aging conditions. TFOT decreased the contrast between the dispersed domains and the matrix, which contributed to the single-phase trend of the binders. The effect of PAV aging on morphology of the binders was dependent on the base bitumen. In one case, it further accelerated the single-phase trend of bitumen in comparison with that after TFOT. In the other case, it caused the phase separation of bitumen. In both cases, PAV aging increased the surface roughness of the binders obviously. As a result of UV aging, the contrast between the matrix phase and dispersed phase was increased due to the difference in sensitivity to UV radiation of the bitumen molecules, which caused or further promoted the phase separation in the binders. Regardless of the aging procedure carried out, a strong correlation was observed between the changes in morphology and physical properties as well as chemical compositions of the binders before and after aging.

Bitumen Morphology as Observed by Phase-Detection Atomic Force Microscopy

An analysis of the microstructure of several modified bitumen shown by phase detection Atomic Force Microscopy (AFM) is presented here. The phase detection and topographic AFM images, displayed three different types of microstructure: the so-called catana phase domains (beelike structures) dispersed in the peri-phase are present in most of the cases; para-phase domains are also observed in the neighbourhood of both catana and peri-phases. These results are consistent with the picture of bitumen as a heterogeneous mixture, as one should expect. The proportions of all these phases display a rather strong dependence on the nature of the modified bitumen considered, on the concentration of the modifier, as well as on the amount of aging of the mix.