Chemistry and Technology of Fuels and Oils最新文献

This study focuses on the characterization of shale gas reservoirs in the Longmaxi Formation and their controlling factors in the east Sichuan Basin. Detailed mineralogical and reservoir characterization of shale samples in the region was carried out by various methods, including X-ray diffraction analysis and nitrogen adsorption experiments. The results show that the shale is mainly composed of clay minerals (illite content ranges from 34.9% to 55.7%), quartz and calcite. In terms of reservoir characteristics, the shale mesopore morphology is mainly “slit-type”, with BET specific surface area ranging from 7.12-25.63 m²/g and BJH pore volume from 0.0095-0.0262 mL/g. These reservoir characteristics show a significant positive correlation with the organic carbon content (1.82-3.87%). correlation. Petrographic analysis further reveals that the brittle mineral content has a significant effect on the brittleness, pore development and fracturing effectiveness of the rocks. In addition, diagenesis (including compaction, cementation, dissolution, and thermal evolution of organic matter) had a significant impact on the formation and characterization of shale pores. These findings provide a key scientific basis for understanding the geological characteristics and development potential of shale gas reservoirs in the Longmaxi Formation in the Sichuan Basin.

This research discovered that carboxylated cellulose nanofibrils (CNF) with cations of various structures can significantly reduce the number of nucleation sites for methane hydrate formation when compared to distilled water. The electrokinetic potential of CNF in water slightly affects the concentration of hydrate crystallization centers, but it does alter the work of their formation. The energy barrier increases as the absolute value of the electrokinetic potential of nanoparticles decreases. The study of the effect of various CNF salts on the kinetics of methane hydrate formation expands our understanding of the inhibition mechanism of hydrate formation. It’s assumed that a significant negative charge prevents the adsorption of like-charged hydrate nucleation centers on CNF. A decrease in the absolute value of zeta potential of CNF due to a change in cation facilitates this process. As a result, nuclei sorbed on colloidal CNF particles are stabilized on the surface, complicating their coalescence and crystal growth. The design of cellulose-based nanoparticles with varying zeta potential will allow the development of a colloid theory for controlling the formation of gas hydrates.

The adsorption properties of carbon materials for purification of petrochemical systems were predicted digitally. The mechanism of styrene adsorption in pores of various sizes was clarified more precisely and the styrene adsorption energies were calculated with and without taking account of the aqueous medium. The “structure-adsorption activity” relationship was established and the characteristics responsible for increase in adsorption capacity of carbon sorbents were identified: the expedient pore size of the carbon material of the adsorbent was determined to ensure sufficient effectiveness of styrene adsorption from aqueous medium. The experimental studies of styrene adsorption from aqueous medium using commercial AG-3 and BAU carbon sorbents confirm the validity of the established mechanisms.

This study proposed a solar thermal electrochemical photo (STEP) theory-based integrated device for highly efficient oilfield-produced wastewater (OPW) purification, combining photothermal and electric technologies. The major oil fields in China reaching the mid-to-late stage of high-water content extraction have substantially increased the amount of OPW, the complex composition of which makes degradation challenging. This research aimed to improve OPW treatment efficiency and reduce energy consumption and mining costs via innovative processes and integrated experimental devices. A solar five-field demulsification model was developed by combining filtration, distillation, condensation, and other processes using the solar STEP theory and incorporating the photocatalytic oxidation, thermal effect, electro-oxidation, air flotation, and flocculation derived from solar energy. The model enables the utilization of photocatalysts to harness solar power.and get the full spectrum energy hierarchical conversion utilization. The results showed that petroleum hydrocarbon removal was positively correlated with the environmental temperature and voltage. The device significantly improved the petroleum hydrocarbon removal rate at an optimized temperature and voltage. At 100°C and 3 V, the petroleum hydrocarbon removal rate reached 93%, confirming the efficiency and feasibility of the device in improving OPW treatment efficacy and environmental protection.

Deep water areas with soft subsea soils, conventional surface conductor into the mud depth is too deep, long waiting time for resting, prone to surface conductor sinking and submerged wellhead instability. In this paper, based on the basic principles of mechanics and the understanding of the structure of the surface conductor, a mechanical model of the bearing capacity of the surface conductor is established. Three types of expandable surface conductors were designed by changing the distribution of the expansion material, in contrast to conventional surface conductors. The bearing characteristics of different structural surface conductors are also investigated by changing the soil parameters from the strength of the submarine soil. The study has obtained: the load-bearing capacity comparison graph between conventional surface conductor and expandable surface conductor; the load-bearing capacity change of expandable surface conductor under the change of soil parameters and the change of expansion material section; and the load-bearing capacity improvement effect of the three expandable surface conductors designed in the paper compared with conventional surface conductors, using stress as the evaluation criterion. This paper provides technical support for the design of expandable surface conductors and provides a basis for numerical simulation of surface well construction.

This study focuses on the shale fracture characteristics and their developmental master factors in the southeastern Sichuan Basin, aiming to gain a deeper understanding of the fracture network in shale gas reservoirs and its impact on hydrocarbon exploration. Through geological investigation and core sample analysis of Longmaxi Formation shales within the Dingshan-Dongxi and Songkan formations, the characteristics and main controlling factors of shale fractures were deeply studied by using fracture measurements, chi-square projection method and electron microscopy. The results show that: the inclination of cracks is mainly dominated by high-angle cracks and upright cracks, with the upright cracks of the Silurian system accounting for 57.35%, and the high-angle cracks of the Triassic system accounting for 43.85%. The fracture filler is mainly calcite and pyrite, in which the calcite and the analysis of fracture density shows that the density of Silurian fracture lines is mainly 3-8 lines/m, accounting for 70.5% of the total number; the development of microfractures also plays an important role in shale gas storage and transportation, and there are various types of microfractures, including open and filled seams, which provide an important storage space for shale gas exploration; the degree of development of shale fractures is related to the mineral components, organic carbon content and thickness of the rock formation. The degree of shale fracture development is closely related to the mineral fraction, organic carbon content and formation thickness. Shales with high brittle mineral content and organic carbon content have a higher degree of fracture development, while the greater the thickness of the formation, the lower the fracture density. These findings indicate that the development degree and types of shale fractures vary significantly among different geological periods and tectonic blocks, and that their complexity and diversity have important implications for shale gas storage and transportation.

Tight gas is an extremely important unconventional oil and gas resource, and its efficient development can effectively alleviate the current tense energy situation. However, the geochemical characteristics and gas source analysis of fault adjusted tight gas reservoirs are currently insufficient. Therefore, based on experimental methods such as tight gas composition and hydrocarbon isotope determination, the geochemical characteristics of typical tight gas reservoirs were analyzed, and discussions were conducted on the genesis of tight gas and source rock properties in the study area. The research results found that the tight gas in the study area is mainly composed of light hydrocarbons, and the tight gas reservoir is an ideal geological body for carbon dioxide geological storage, with an estimated CO₂ burial value of up to 3.43·10⁹ tons. Meanwhile, high-temperature and high-pressure trapping environments can easily cause heavy hydrocarbons in the trap to break down into light hydrocarbons, resulting in a much higher δ¹³-C₁ value in the carbon isotopes of tight gas compared to other carbon isotopes. The light hydrocarbon components of typical tight gas reservoirs are mainly oil associated gas types, while the heavy hydrocarbon components are mainly coal derived gas types. Moreover, the average organic carbon content in the tight gas in the study area is 6.67%, indicating that its source rocks are type I and II-1 kerogen, derived from underlying humic source rocks. Finally, the study found that the δ¹³-CO₂ values of all dense gas samples ranged from 7.85% to 15.3%, and the carbon dioxide concentration was all below 6%, indicating that the source of carbon dioxide in dense gas is a mixed mode.

Coal additives impregnated with nickel and iron for use in Veba Combi Cracking technology are investigated. The morphology of the surface and pore space of a modified coal additive is presented. The additive is shown to be similar to lignite in terms of its elemental composition. A comparative assessment of the textural properties of the original and modified coal additive is carried out. A relationship between the composition of the coal additive and the final products of heavy residue cracking in the presence of hydrogen in the temperature range of 435–460°C and a pressure of 17 MPa is shown. Catalytically active metals present in the composition of the coal additive were shown to affect the conversion degree of resinous-asphaltene components, formation of coke-like substances, and yield of light distillate fractions. The catalytic activity of the nickel- and iron-impregnated coal additive in the process of tar thermal cracking in a hydrogen atmosphere is established. The results obtained confirm the positive effect of impregnation of coal additives with catalytically active centers. This effect consists in an increased conversion degree of high-molecular components of heavy residual oil feedstock, thus indicating the significant potential of Veba Combi Cracking technology.

With the gradual depletion of conventional petroleum resources, oil shale, as an important unconventional oil and gas resource, is of great significance to alleviate the global energy crisis and optimize the energy structure. In this study, we comprehensively assessed the organic matter abundance, type, maturity, and trace element characteristics of oil shale by collecting and analyzing oil shale samples from the Lower Permian region in the western part of the southern margin of the Junggar Basin, and by applying pyrolysis analysis and rock pyrolysis analysis. The study showed that the average value of total organic carbon (TOC) of the oil shale in the study area was 10.26%, of which 41.67% was medium-grade oil shale and 58.33% was low-grade oil shale, reflecting the overall abundance of medium-low organic matter. The average value of hydrocarbon potential was 40.83 mg/g. The hydrogen index of the oil shale samples ranged from 77 to 861.06 mg/g, with an average value of 405.56 mg/g. The organic matter type was mainly of the II₁ type (humic-sapropelic type), which accounted for 75% of the total, and the analysis of the highest pyrolysis peak temperature showed that 83.33% of the samples were in the low maturity-mature stage. Trace element analyses revealed that the oil shales in the study area were formed in a terrestrialweakly reduced depositional environment. Especially, the analysis of Sr/Ba, Th/U and B/Ga ratios indicated that the oil shale was mainly formed in freshwater-semi-saline environment. In addition, the analysis of V/(V+Ni) and U/Th ratios supports the reduced environment in which the oil shale was formed. The shale in the Dalongkou area has greater salinity values and higher organic matter productivity in the water body at the time of formation compared to the oil shale in the Cangfanggou area. The results of this study are important for understanding the geochemical properties and mineralization potential of the Lower Permian oil shales in the western part of the southern margin of the Junggar Basin.

The thermal and hydrothermal processing of polyvinyl chloride waste was studied. The liquid product in the hydrothermal processing of polyvinyl chloride with 10% aqueous NaOH contains the least amount of chloroaromatic hydrocarbons in comparison with thermal processing without water. A scheme was proposed for two-step processing of polyvinyl chloride, in which the first step entails hydrothermal or thermal treatment followed by hydrodechlorination of the resultant liquid product on sulfide catalysts. Industrial sulfide and nanoheterogeneous NiWS and NiMoS catalysts synthesized by the authors were studied in the hydrodechlorination of the chlorine-containing mixtures. The greatest activity in the hydrodechlorination process was found for an unsupported NiWS catalyst synthesized ex situ.