Cracking Of Bitumen Research Articles

Solid bitumen Rhenium-Osmium (Re–Os) isotope geochronology and existing problems: Sampled of Sinian-Cambrian gas reservoir in Sichuan Basin, China

Understanding the key timings related to petroleum evolution is crucial for optimizing exploration targets and assessing oil/gas resources, attract petroleum geologists’ attention worldwide. Recently, hydrocarbon (oil and bitumen) Re–Os isotope dating has been innovatively applied to constrain the timing related to oil/gas generation, however, the resulting Re–Os isochron ages can be complex and challenging to interpret. This study utilizes various geochemical and geochronological data from Sinian to Cambrian natural gas reservoirs in the Sichuan Basin to reconstruct the hydrocarbon evolution process and discuss the significance of different bitumen Re–Os dating results. The gas accumulation in the Sinian-Cambrian reservoirs experienced four stages of evolution: (1) initial oil generation during the Ordovician to Silurian periods, (2) secondary oil generation during the Triassic period, (3) gas generation through thermal cracking of liquid oil from the Jurassic to Cretaceous periods, and (4) gas reservoir redistribution since the late Cretaceous. The Re–Os dates (ca. 485 Ma) of low maturity and biodegraded bitumen from the western Sichuan Basin record the oil generation during the Ordovician before the Caledonian tectonic event. The Re–Os dates (ca.184–128 Ma) of highly mature bitumen associated with MVT Pb–Zn deposits in northern Sichuan Basin provide insights into both liquid oil-cracking and thermochemical sulfate reduction (TSR) processes. The complex Re–Os dates (ca.414 Ma, ca.154 Ma) of highly mature bitumen from the central Sichuan Basin may represent different periods related to either oil or gas generation. Future studies should explore the genetic type, maturity, thermal cracking, or TSR degrees of bitumen to better understand the significance of Re–Os dates.

Enhancing aged SBS-modified bitumen performance with unaged bitumen additives

This study investigated the performance of SBS-modified bitumen (SBSMB) after aging and rejuvenation by utilizing macroscopic performance and microscopic characterization methodologies. The blending of aged SBS-modified bitumen (SBSPAV) with different proportions of SBSMB or 80–100 penetration grade base bitumen (90BB) was performed to produce SMB-rejuvenated bitumen (a blend of SBSMB and SBSPAV) and 90BB-rejuvenated bitumen (a blend of 90BB and SBSPAV). To evaluate high-temperature rutting behavior, multiple stress creep recovery (MSCR) tests were conducted on the binders, and the outcomes were analyzed using the Burgers model to elucidate their viscoelastic behaviors. Low-temperature performance was assessed using an asphalt binder cracking device (ABCD). Furthermore, the microscopic structure, roughness, and Young's modulus of the binders were investigated using an atomic force microscope (AFM). Thermal stability was assessed using a thermogravimetric analyzer (TGA). The findings indicated that SMB-rejuvenated bitumen exhibited favorable resistance to high temperatures and the ability to withstand heavy traffic loads. The stress sensitivity of 90BB-rejuvenated bitumen surpassed that of SMB-rejuvenated bitumen. The high-temperature performance rating of 90BB-rejuvenated bitumen displayed a continuous decline, indicating poor load-bearing capacity. Regardless of the unaged bitumen type, higher doses of unaged bitumen led to a gradual decrease in the rejuvenated bitumen's cracking temperature, indicating the enhancement of low-temperature performance of SBSPAV. However, both SMB-rejuvenated bitumen and 90BB-rejuvenated bitumen fell short of matching the performance level of pure SBSMB. AFM outcomes demonstrated that with increasing SMB dosage, the number of bee-like structures initially decreased before rising again, coupled with an increase in their volume. Conversely, an increase in 90BB dosage led to a gradual reduction in bee-like structures, accompanied by increased volume. The roughness of both SMB-rejuvenated bitumen and 90BB-rejuvenated bitumen exhibited improvements compared to SBSPAV, suggesting enhanced adhesion performance of the rejuvenated bitumen. TGA results unveiled lower thermal stability in 90BB-rejuvenated bitumen in comparison to SMB-rejuvenated bitumen. This study introduces a novel perspective on the design of SBS-rejuvenated bitumen.

Mechanism of water-induced alterations to nanoscale pores: Implications from anhydrous versus hydrous pyrolysis

In this study, shale samples from the Chang7 Member of Triassic Yanchang Formation in Ordos Basin, China were used to conduct artificially induced thermal maturity experiments from 250 °C to 450 °C for 72 h. The role of water in organic matter (OM) conversion and nanoscale porosity alterations were observed and discussed comprehensively by Rock-Eval pyrolysis, low pressure N2/CO2 adsorption, Fourier transform infrared spectroscopy (FTIR) and water-soluble organic acids (WSOAs) experiments. Results show that Rock-Eval pyrolysis parameters (Tmax, S1, and S2), TOC content, WSOAs and pore volume (PV) show slight changes below 350 °C while these parameters were considerably altered above 400 °C under two different pyrolysis conditions (anhydrous and hydrous), indicating that after 400 °C, the OM conversion and bitumen cracking will accelerate. In comparison to anhydrous pyrolysis, hydrous pyrolysis always has smaller Tmax, implying that water could inhibit OM thermal progression. Moreover, S1 of hydrous pyrolysis is approximately two times higher than that of anhydrous pyrolysis, which originates from water providing an exogenous source of hydrogen to generate excessive volumes of hydrocarbons, enhancing the conversion rate of OM. The WSOAs are 2 to 4 times greater under hydrous pyrolysis than anhydrous pyrolysis, denoting that the presence of water could improve the yield of organic acids via inhibiting the polycondensation of oxygen-containing functional groups and oxidizing organic components by hydroxyl radicals. Moreover, below 350 °C, pyrolysis shale residues exhibit a slightly smaller PV in hydrous pyrolysis, mainly due to the infilling effect of bitumen. However, exceeding 400 °C, PV that was obtained from low pressure N2 adsorption under hydrous pyrolysis conditions is found to be two times as large as the value under anhydrous pyrolysis conditions, which is attributed to the net-PV increase reactions such as thermal cracking, and the dissolution of organic acids. Furthermore, in anhydrous pyrolysis, the polycondensation of oxygen-containing functional groups and the carbon-carbon cross linking could be considered as the two main reaction pathways to release the sources of hydrogen. Collectively, the presence of water is significant for hydrocarbon generation and porosity evolution during thermal progression of OM at various stages.

Impact of thermal maturity on the diagenesis and porosity of lacustrine oil-prone shales: Insights from natural shale samples with thermal maturation in the oil generation window

Shale diagenesis controls the generation, migration and accumulation of hydrocarbons through time and has become a frontier area of study in the fields of sedimentology and petroleum geology. There have been only a few studies on the generation of organic pores in lacustrine shale oil reservoirs during the oil generation thermal evolution stage. In this study, lacustrine organic-rich shale samples at various stages of maturity, from the first member of the Songliao Basin Qingshankou Formation were investigated, and a thermal transformation law of macerals was established, based on organic petrology. The diagenetic alteration styles and sequences were investigated using a high-resolution field emission scanning electron microscope, and cathode luminescence. Furthermore, automated pore extraction technology enabled the examination of the characteristics and genetic process of organic and inorganic pores under the influence of thermal maturation. The results indicate that a small quantity of pre-oil bitumen is generated during the early oil mature stage (Ro: 0.7% - 0.9%), and that the generation of a large quantity of post-oil bitumen that occurs following the peak oil generation stage (i.e., late oil mature stage, Ro: 1.1% - 1.4%), is controlled by the unimodal distribution of the activation energy of Type I kerogen. Compaction intensity certainly influences pore volume reduction. Siliceous cementation primarily occurs during peak oil generation maturity and the subsequent thermal evolution stage. The pores formed in the oil generation window primarily arise from mineral dissolution and organic matter polycondensation. Following peak oil generation, the pores undergo iron dolomitization, smectite illitization, and bitumen cracking. The degree of development of inorganic pores, the most common pore type in shale oil reservoirs, appears to have a significant impact on the total porosity of a reservoir shale. During thermal evolution, the inorganic pore volumes show a decreasing trend. There is a secondary pore development stage, reached when Ro exceeds 1.2%, closely related to the transformation of clay minerals. According to the hydrocarbon generation kinetics and compaction model, organic pore volumes increase gradually at 0.7%Ro, reach their peak at 1.1%Ro, and then steadily decrease due to compaction. The organic pores are relatively well developed when Ro is >0.85% (at the start of the oil window). The shale oil reservoir's most favorable thermal evolution stage is late oil maturity stage that follows the oil generation peak.

Comparative study on pore structure characteristics of marine and transitional facies shales: A case study of the Upper Permian Longtan Formation and Dalong Formation in the Lower Yangtze area, south China

The Permian shale reservoir in the Lower Yangtze area of South China is regarded as a target with a high potential for shale gas exploration. To investigate the pore structure characteristics and evaluate reservoir quality, 32 shale samples from the Upper Permian Longtan Formation and Dalong Formation in the Lower Yangtze area were studied using a suite of techniques including total organic carbon (TOC) content, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), nitrogen (N2) and carbon dioxide (CO2) gas physisorption, mercury injection capillary pressure (MICP), petrographic observations, and fluid inclusion analysis. Petrographic observations reveal that the Longtan Formation is rich in vitrinite and inertinite, while the Dalong Formation contains a large amount of solid bitumen. Primary organic pores (POPs) are the original cellular pores that develop in inertinite. Vitrinite particles did not show visible pores. Solid bitumen infills fractures and occupies the interparticle (interp) space between the mineral grains in the Dalong Formation. A small number of speckled secondary organic pores (SOPs) were observed in the solid bitumen with diameters less than 10 nm. Both the TOC and quartz contents exhibit negative relationships with the pore volumes (PVs) for the Longtan and Dalong Formations, owing to the poor development of pores in the organic matter (OM) and occlusion of most mineral pores by migrated bitumen. There is a positive relationship between clay minerals and PVs owing to the sheet-like meso-pores and macro-pores in the clay minerals. The evolution of organic porosity is related to the differences in maceral composition and thermal maturity. Thermal cracking of residual oil and bitumen and the expulsion of gaseous hydrocarbons contributed to the formation of SOPs in marine shales. In contrast, vitrinite and inertinite in gas-prone shales do not display noticeable morphological changes across the entire thermal evolution process, owing to their low hydrocarbon generation potential.

Effects of Gilsonite on Performance Properties of Bitumen

The effectiveness of natural Gilsonite on the performance properties of modified bitumens was studied. Three samples having different ratios of Gilsonite that are 6%, 8% and 10% by weight of base bitumen which was PG 64-16 grade were prepared. The physical properties and storage stabilities of four samples were investigated by means of conventional tests. The short-term and long-term aging processes of bitumens were conducted with rolling thin oven and pressure aging vessel tests, respectively. Rheological properties of bitumens were examined by means of Superpave tests such as rotational viscosity, dynamic shear rheometer and bending beam rheometer. After the rheological study, the low and high temperature performance classes of bitumens were determined by the Superpave specification. The results showed that natural Gilsonite-modified bitumens provide improvement in rheological and physical properties of bitumen, and were found highly compatible with base bitumen. Gilsonite additive significantly increased stiffness and viscosity of bitumen, and improved the resistance against fatigue cracking and rutting of bitumen, without causing a reduction in thermal cracking resistance of bitumen.

Correlation of cracking behaviour at binder, mastic and asphalt concrete levels

Some years ago, performance methods for conformity testing of asphalt mixtures were introduced into the European standards defining performance properties such as low temperature resistance, stiffness, resistance to fatigue and permanent deformation. However, such tests are complex and require enormous efforts making it difficult to implement them into routine testing. The research project VEGAS, a collaboration between 3 research institutions from Germany Austria and Switzerland, aimed therefore to simplify the testing system, without sacrificing valuable information. Therefore, testing was reduced to the evaluation of volumetric properties and tests carried out on the binder and mastic only. The paper describes the experimental efforts carried out by Empa in Switzerland, related to low temperature cracking of bitumen and mastic and fatigue experiments on asphalt samples. Within the framework of the research, a new testing procedure using the Double Torsion Test method for low temperature crack propagation in mastic was evaluated. Additionally, asphalt plates were tested with a scaled traffic simulator and used for validating laboratory scale tests.

Differential impact of clay minerals and organic matter on pore structure and its fractal characteristics of marine and continental shales in China

Clay minerals and organic matter are commonly developed in shale sediments, and have an important influence on the pore structure and pore complexity of shale reservoirs. However, due to the complexity of shale pore structure and the diversity of influencing factors, the influence of organic matter, clay minerals and organo-clay composites on shale pore structure is still unclear. In this study, the effects of organic matter, clay minerals and organo-clay composites on pore structure and pore complexity of marine Longmaxi shale (LMX shale) and continental Ziliujing shale (ZLJ shale) were investigated qualitatively and quantitatively by field emission scanning electron microscopy (FE-SEM), N2 adsorption experiment with Frenkel-Halsey-Hill (FHH) model. The results comprehensively reveal the differential effect of organic matter and clay minerals, the most important pore-forming materials in shale, on the pore development of shale reservoir. Overall, the maceral type, maturity, illite, kaolinite and organo-clay composites are the main controlling factors for shale pore development and complexity. More specifically, maceral type and maturity have great influence on shale pore structure and pore complexity of all shale samples, while the effect of organic matter abundance could be ignored in continental shale. Solid bitumen is prone to develop secondary organic pores, while other macerals such as vitrinite and inertinite do not develop secondary pores with the increase of maturity. In the high-over mature marine LMX shale, a large number of secondary organic pores are generated after solid bitumen cracking and gas generation, which promotes the pore complexity. In the low-mature continental ZLJ shale, the solid bitumen has not reached the maturity of cracking gas, and the original bioclastic pores do not develop, leading to the weak development of organic pores and small contribution to pore complexity. Different clay mineral types have different effects on shale pore structure and pore complexity. The shale pore volume (PV) and specific surface area (SSA) increase with the increase of illite content, and the existence of illite enhances pore surface roughness and pore heterogeneity. However, the effect of kaolinite content on shale pore structure and pore complexity is completely opposite to that of illite. The formation of organo-clay composites protects the primary pores, and promotes the hydrocarbon generation and pore development of organic matter, which greatly increases the development of shale pores. The outcomes of this studies would provide better understanding on the pore formation mechanism of shale reservoir, which is of great significance for the accurate assessment of shale gas resources.

Effect of Temperature on Gas and Liquid Products Distribution in Thermal Cracking of Nigerian Bitumen

The increasing population growth resulting in the tremendous increase in consumption of fuels, energy, and petrochemical products and coupled with the depletion in conventional crude oil reserves and production make it imperative for Nigeria to explore her bitumen reserves so as to meet her energy and petrochemicals needs. Samples of Agbabu bitumen were subjected to thermal cracking in a tubular steel reactor operated at 10 bar pressure to investigate the effect of temperature on the cracking reaction. The gas produced was analyzed in a Gas Chromatograph while the liquid products were subjected to Gas Chromatography-Mass Spectrometry (GC-MS) analysis. Heptane was the dominant gas produced in bitumen cracking at all temperatures and the reaction products show a distribution of lighter hydrocarbons most of which are in the gasoline range. The product distribution of bitumen conversion depends strongly on the cracking temperature and the oil produced contains the valuable liquid fractions. The products of thermal cracking of bitumen can be classified into the following groups; alkanes, alkenes, amines, aromatics, alkanoic acids, alkanols, esters, ethers, ketones, sulphur compounds, and nitrogen compounds. The activation energies of the products formed were determined. The LNG produced all have unusually low values activation energy (hence easily converted) pointing to the high quality of Agbabu crude 
 The conversion process was affected by the reaction time and suggests that the transformation of bitumen into smaller fractions follows a definite reaction scheme in which the heavy oil transformed to lower fractions and was subsequently converted to smaller liquid fractions and gases.

Quartz types, origins and organic matter-hosted pore systems in the lower cambrian Niutitang Formation, middle yangtze platform, China

Quartz cementation is critical to shale reservoir properties, including porosity and geomechanical properties. Due to the small size of constituting components, our understanding on quartz origins in shales is still unclear. Recently, the application of high resolution scanning electron microscope (SEM) combined with cathodoluminescene (CL) technique has enabled major advances in our understanding of quartz cementation in shales. A suite of the Lower Cambrian Niutitiang shale samples were selected to study quartz types, origins and the effect of quartz cementation on porosity development by integrating geochemical analysis, nitrogen adsorption, SEM and SEM-CL imaging analysis.The results show that quartz primarily exists as five forms: silt-size/sand-size detrital quartz, siliceous skeletons, overgrowth nucleated around detrital quartz, matrix-dispersed microcrystalline quartz, and aggregates of euhedral quartz. Detrital quartz is characterized by angular shape, and bright luminescene. Quartz overgrowth can be easily identified by the characteristic non to low luminescene, indicative of authigenic origin. Matrix-dispersed microcrystalline quartz is typically less than 5 μm, and co-existed with clay minerals. Quartz aggregates are primarily composed of equate-sized euhedral quartz. Dissolution and re-precipitation of siliceous skeletons provides the major silica source for authigenic quartz (defined as quartz formed during diagenetic processes) in the Niutitang Formation. The distribution of secondary organic matter, primarily including residual bitumen and pyrobitumen, is always associated with aggregates of euhedral quartz, because the micrometer-scale and well-connected interparticle pore spaces between euhedral quartz crystals provide important storage sites for secondary organic matter, and abundant organic matter-hosted pores (organic pores) are generated during the thermal cracking of residual oil and bitumen to gas.

Carbon and hydrogen isotopic variations in gold tube gas pyrolysates from an Athabasca oil sand

Closed system gold tube pyrolysis experiments were conducted on an oil sand bitumen from the Athabasca region in western Canada to investigate gas isotope variation with heating temperatures. Experiments were carried out at 350–650 °C and a pressure of 50 MPa, with heating rates of 2 °C/h and 20 °C/h. The progressive cracking of bitumen and liquid oil lead to continuous release of methane with increasing pyrolysis temperatures, while the yields of wet gas components increase initially at the lower temperature range and then decrease drastically at high temperatures. A general trend of 13C- and 2H-enrichment in the gas products is seen with increasing pyrolysis temperatures due to thermal cracking of various hydrocarbon and non-hydrocarbon components. Isotopic variations can be quite extensive, commonly occurring for both hydrocarbon gases and CO2 as pyrolysis progresses. A carbon isotopic rollover (isotope of gas component shifting from 13C enrichment to 12C-enrichment with increasing temperature) occurs for bulk hydrocarbon gas components at low temperature (< 450 °C), while rollover only occurs for ethane and propane at high temperature (> 550 °C), where partial reversal (lower carbon numbered gas component becomes more 13C-enriched relative to higher carbon numbered ones) also exists. The isotopic values of CO2 show a wide range of variation with the highest δ13C value seen at the lowest temperature while the lowest δ13C value occurs at 500 °C and 550 °C for 2 °C/h and 20 °C/h, respectively. Relative 13C-enrichment occurs only in the high temperature range. The unusual carbon isotope ratios of CO2 in pyrolysates is likely related to biodegradation influence on the precursors, but further investigation is still called for. Hydrogen isotopic values of hydrocarbon gases show even more dramatic variation than that seen for carbon. While methane is progressively 2H-enriched to 650 °C, ethane and propane are relatively 2H-enriched when the pyrolysis temperature is < 500 °C, while the trend is inverted at higher temperatures. Data presented here clearly deviate from the trajectories expected by simple equilibrium or Rayleigh-type kinetic cracking models. Dynamic generation, destruction and mixing processes govern the final isotopic signature in an associated gas product. Isotopic rollover and reversal seem to be a common phenomenon during thermal evolution where heterogeneous precursors are available. While the reaction system of pyrolysis at high temperature differs completely from source rock evolution at low temperature and some artifacts are inevitably involved, the isotope behavior observed here may provide some insights into the complexity in natural cases and help our understanding of the mechanisms of isotopic evolution during thermal maturation.

Porous aluminosilicates catalysts for low and medium matured shale oil in situ upgrading

AbstractFor medium and low matured shale oil exploration, in situ upgrading could promote the oil recovery. There are two main disadvantages herein, high exploration temperature and large energy consumption. The new approach has been proposed to apply porous aluminosilicate catalysts for shale oil highly efficient upgrading at 350°C, H‐clin and Ni‐clin catalysts were prepared with natural clinoptilolite. Al‐SBA‐15 catalysts were synthesized by following one‐step crystallization procedure, and firstly employed for shale oil in situ upgrading. Kinetic studies of pyrolysis showed that the activation energy of organic matter conversion in shale was reduced from 113.80 kJ mol−1 to 37.28 kJ mol−1. After the catalyst addition, shale oil conversion temperature was declined, the reaction rate was increased, and the energy consumption of in situ upgrading was reduced. In Sinopec patented testing instrument, hydrocarbon generation and hydrocarbon expulsion unit, shale oil catalytic conversion showed increased hydrocarbon generation by 2%‐16%. Under the same reaction conditions, the Al‐SBA‐15 (Si/Al = 5) revealed the best activity for hydrocarbon generation, and the efficiency was elevated to 32.67%, twice as that of thermal conversion. The quality of catalytically produced oil was promoted, by improving the further cracking of bitumen to light oil and gas. The results have a breakthrough significance for intensifying the high‐efficiency hydrocarbon generation and expulsion process of low and medium matured shale oil.

Generation and expulsion process of the Chang 7 oil shale in the Ordos Basin based on temperature-based semi-open pyrolysis: Implications for in-situ conversion process

There is a substantial amount of oil shale resources in the seventh member of the Triassic Yanchang Formation (abbreviated as Chang 7) in the Ordos Basin, and its geological and geochemical characteristics are highly suitable for in-situ conversion process (ICP). A comprehensive characterization of its hydrocarbon generation, expulsion and retention features will help determine the optimum conditions for future field tests. However, typical thermal simulation experiments based on either open-system or closed-system are not applicable to provide data to construct the models. Therefore, in this study, eight parallel thermal simulation experiments, which were based on the newly designed temperature-based semi-open pyrolysis experiments were performed on the Chang 7 oil shale. The yields (including cumulative yields and net incremental yields) and compositional characteristics of the expelled oil, expelled gas, and retained oil were analyzed. Results show that the hydrocarbon expulsion has a coupling relationship with hydrocarbon generation that can be divided into four stages: (1) Slow hydrocarbon generation stage (300–320 °C, 0.53–0.55 %Ro). Minimal amounts of oil and gas are generated in this stage. The hydrocarbon expulsion efficiency increases rapidly. (2) Quick oil-generation stage (320–380 °C, 0.55–1.09 %Ro). The fast cracking of kerogen and thermal bitumen generates a large amount of oil. The hydrocarbon expulsion efficiency remains relatively stable. (3) The secondary oil cracking and quick gas-generation stage (380–420 °C, 1.09–1.66 %Ro). The oil yield begins to decrease after reaching its maximum and a large amount of hydrocarbon gas is generated. The oil generation capability of kerogen is basically exhausted. The hydrocarbon expulsion efficiency and gas/oil ratio increase rapidly at this stage. (4) The heavy hydrocarbon gas cracking stage (after 420 °C, 1.66 %Ro). The oil yield continues to decline, accompanied by the onset decline in the gas yield (except methane). At this time, the hydrocarbon expulsion efficiency continues to increase but at a rather low speed. Under the experimental conditions in this study, 1.24–1.66% Ro is considered a favorable thermal maturity interval, in which maximum oil production with relatively light components can be obtained and the hydrocarbon gas is abundant.

Role of bitumen and NSOs during the decomposition process of a lacustrine Type-II kerogen in semi-open pyrolysis system

The purpose of this work is to investigate the generation characteristics of bitumen, NSO compounds, oil, and HC compounds during the artificial maturation of a lacustrine Type-II kerogen (which has not been given enough attention before) in order to determine its decomposition process. The analysis is based on the data itself, on the premise of jumping out of the generally accepted sequential reaction model. By taking the kerogen of the Chang 7 shale as an example, seven parallel experiments, in the temperature range from 300 °C to 420 °C were conducted on newly designed temperature-based semi-open pyrolysis system. The overall products are classified into oil and bitumen according to their phase, the C15+ fractions are classified into C15+sat, C15+aro and NSOs based on chemical compositions, and the NSOs are further classified into n-pentane NSOs and DCM NSOs according to Behar et al., (2008) and (2010). Results show that large proportion of oil is not merely a result of thermal cracking of bitumen, but also directly from the decomposition of kerogen itself. Both C15+sat and C15+aro are generated as soon as kerogen starts to decompose. It is not until the initial productivity of kerogen is basically exhausted that NSOs become the main precursor of hydrocarbons. The comparison with Behar et al. [2008, organic geochemistry 39, 1–22] further reveals that, for Chang 7 kerogen, initial decomposition of kerogen generates much more HCs than DCM NSOs. These results contradict the sequential reaction model described as: kerogen → bitumen → oil or kerogen → NSOs → hydrocarbons. Instead, they confirm the “alternate pathway” mechanism proposed by Burnham et al. [ACS symposium, 1989] in which hydrocarbons can be formed immediately from kerogen in parallel with NSOs and the formation of the two species are controlled by bond-breaking reactions that are independent of each other. This study adds geochemical insights into the decomposition mechanism of lacustrine Type-II kerogen.

Partial Upgrading of Athabasca Bitumen Using Thermal Cracking

The current industry practice is to mix bitumen with a diluent in order to reduce its viscosity before it can be pumped to refineries and upgraders. The recovery of the diluent and its recycling to the producers, on the other hand, pose major environmental and economic concerns. Hence, onsite partial upgrading of the extracted bitumen to pipeline specifications presents an attractive alternative. In this work, thermal cracking of Athabasca bitumen was carried out in an autoclave at 400 °C, 420 °C and 440 °C in presence and absence of drill cuttings catalyst. At 400 °C, despite no coke formation, the reduction in viscosity was insufficient, whereas at 440 °C, the coke yield was significant, ~20 wt.%. A balance between yield and viscosity was found at 420 °C, with 88 ± 5 wt.% liquid, ~5 wt.% coke and a liquid viscosity and °API gravity of 60 ± 20 cSt and 23 ± 3, respectively. Additionally, the sulfur content and the Conradson carbon residue were reduced by 25% and 10%, respectively. The catalytic thermal cracking at 420 °C further improved the quality of the liquid product to 40 ± 6 cSt and 25 ± 2 °API gravity, however at slightly lower liquid yield of 86 ± 6 wt.%. Both catalytic and non-catalytic cracking provide a stable liquid product, which by far exceeds pipeline standards. Although small relative to the energy required for upgrading in general, the pumping energy requirement for the partially upgraded bitumen was 3 times lower than that for diluted bitumen. Lastly, a 5-lump, 6-reaction, kinetic model developed earlier by our group successfully predicted the conversion of the bitumen to the different cuts.

Full-scale pore structure and its controlling factors of the Wufeng-Longmaxi shale, southern Sichuan Basin, China: Implications for pore evolution of highly overmature marine shale

Shale gas primarily exists in nanopores in shale as different occurrence phases. Studies on pore structure characterization and its controlling factors are the key to understand shale gas occurrence and gas accumulation mechanism. Mercury intrusion capillary pressure (MICP), low-pressure N2 and CO2 adsorption were applied to quantify pore structure of all sizes for Wufeng-Longmaxi shale from southern Sichuan Basin, China. These shales are currently highly overmature, and their total organic carbon (TOC) contents range from 0.04% to 5.19%. Quartz content is positively correlated with TOC content in the clay-poor shales, whereas it exhibits no correlation with TOC in the clay-rich shales. Different relationships are likely due to difference in quartz origins, since the clay-poor shales contain more biogenic quartz than the clay-rich shales. Furthermore, multimodal pore size distributions were observed. Total pore volume, ranging from 1.41 to 3.03 cm3/100 g, is mainly provided by pores less than 10 nm in diameter, whereas most of the specific surface area, ranging from 19.55 to 36.64 m2/g, is provided by pores less than 2 nm in diameter. Organic matter contributes mostly to micro- and mesopore development. Clay minerals, mainly illite, also make a contribution to pore structure, especially in the organic-lean shales. The porosity development of micro- and mesopores is also controlled by thermal evolution of organic matter. Micro- and mesopores were developed at the immature to early mature stages due to pore rearrangement, expulsion of liquid hydrocarbon, and dissolution of unstable minerals. The following decrease during the late mature stage was mainly caused by oil and bitumen infill. Both micro- and mesopores were reopened at the postmature stage, which was driven by the secondary cracking of residual oil and bitumen. The final significant decline of micro- and mesopore volumes at the overmature stage was caused by persistent compaction and OM carbonization.

Biodegradation of 2,4,5-trichlorobiphenyl (PCB29) by marine-derived mesophotic fungi

In this study, Lower Paleozoic shale samples collected from Lower Cambrian Niutitang Formation, Upper Ordovician Wufeng Formation, and Lower Silurian Longmaxi Formation in different regions in the Sichuan Basin were analyzed using geochemical and petrophysical methods to characterize the difference in organic matter properties (including abundance, type and thermal maturity), pore development, mineralogy to shale gas resources potential. The studied marine shales all displayed excellent, high-quality organic matter richness and could be the strata for shale gas generation over geological time. There are four systematic geochemical and petrophysical variation trends that indicate that the overmature source rocks of the Sichuan Basin constitute a special shale gas reservoir system: (1) The measured δ13C values for sedimentary organic carbon (TOC) presents a distinct trend indicative of 13C enrichment, which indicates that the TOC may be related to the diversity of preserved phytoplankton in the different shale strata in the Sichuan Basin. This biont diversity and organism replacement process were confirmed by the biomarker distribution patterns in the sediments. (2) The bitumen “A” contents display negative correlation with sedimentary age and TOC, suggesting that most of the residual liquid hydrocarbons in those shales have been transformed into shale gas due to higher thermal maturity during the diagenetic transformation of the organic matter burial process, and the shale gas in reservoirs in those types of shales were mostly generated from the cracking of residual bitumen during a stage of relatively high thermal evolution. (3) The quartz and TOC present strongly positive relationship, suggesting that the increased quartz in most of the marine shales is a biogenic silica signal. (4) Total porosity displays a negative relationship with TOC and the quartz contents in the three Paleozoic marine shales, suggesting that re-precipitated pyrobitumen created by oil cracked to gas in overmature source rocks could be the reason leading to the lowest porosity and smaller pores in the most aged but most TOC-abundant shales. Skewing toward smaller pores will reduce the pore volume and result in larger internal surface areas and greater sorption energies, which should reduce the productive capacity of shale gas.

Destruction of High-Molecular Components of Natural Bitumens over Mesoporous Nickel-Containing Aluminosilicate Catalyst

The studies dealt with the influence of mesoporous aluminosilicate (MP-Al-Si) and its mixture with nanosize nickel powder (MP-Al-Si/Ni) on the product composition of cracking of natural bitumens (Tatarstan Republic) containing less than 7 % of ibp-200°C fractions in an autoclave reactor. Addition of mesoporous aluminosilicate (5 wt.%) to bitumen was shown to favor the deep destruction of high-molecular components and to increase the proportion of fractions boiling aut below 360°C. In the presence of the MP-Al-Si/1%Ni mixture, the coke formation slowed down to less than half, the content of ibp-360 °C fractions being increased by 14.2–14.7 wt % and that of the products tars and asphaltene destruction by 1.4–2.7 wt % against their contents in the bitumen cracking products in the presence of MP-Al-Si. The use of MP-Al-Si allows the effective processing of heavy hydrocarbon materials to gasoline and diesel fraction at low yields of gas and seal products.

Thermogravimetric Study of Cracking Products of Natural Bitumens

The cracking and extraction products for Kazakhstan’s oil sand bitumen were determined by thermogravimetric analysis (TGA). By means of this technique, changes in the physical and chemical compositions of natural bitumen occurred during thermal treatment were assessed. The bulk composition was determined and the elemental content of resin-asphaltene compounds evaluated. Microspheres isolated from fly ash after the combustion of coals, were used to catalyze the cracking of natural bitumen. According to elemental analysis, natural bitumen is prone to produce coke formation. Catalytic cracking has a positive effect on the properties of the bitumen obtained from Munaily Mola field. The kinetic reaction orders and activation energies for cracking of natural bitumen were determined fitting the experimental data to an Arrhenius equation. The derived activation energies give insight on the nature of the pyrolysis kinetics of resin-asphaltene.

Effect of mixing and vapor residence time on thermal cracking of bitumen in a Mechanically Fluidized Reactor

Fluid Coking™ is a non-catalytic carbon rejection process that is utilized to convert petroleum residues into more valuable light and middle distillates. In this process, heavy oil is sprayed into a fluidized bed of hot coke particles; the liquid heats up and undergoes endothermic thermal cracking to vapors, non-condensable gas and solid coke. This study shows that liquid distribution on hot coke particles affects the products yields and the liquid product quality. The vapor residence time also affects the products yields and the liquid product quality.The Mechanically Fluidized Reactor has been successfully developed and implemented for Fluid Coking applications. Multiple vapor phase residence times can be investigated simultaneously while reducing intrinsic errors present in a complex system such as coking. The impact of applied bed mixing and vapor phase cracking on Fluid Coking yields, as well as on product oil quality can, thus, be accurately evaluated.Applying mechanical mixing to the bed of coke particles results in better liquid distribution on coke particles and reduces coke yields. It also increases the yield of low viscosity, low molecular weight liquid at short vapor residence times. At long vapor phase residence times, however, vapors crack to gas, resulting in a concentration of higher viscosity, higher-molecular weight compounds in the liquid phase. The additional vapors that are produced in the bed thanks to enhanced mixing are more reactive and easily crack to gas at long vapor residence times. Realizing the full benefit of enhanced liquid distribution therefore requires minimization of the vapor residence time.