Shale Oil Yield Research Articles

Pyrolytic hydrocarbon generation characteristics of the Chang 7 shale based on different experimental methods: Implications for shale oil and gas in the Ordos Basin

Shale oil and gas resources are abundant in the Chang 7 shale of the Yanchang Formation in Ordos Basin. To determine the characteristics and influencing factors of hydrocarbon generation evolution of the Chang 7 shale, a series of thermal simulation experiments were conducted on low‐maturity shale and kerogen samples. The results indicate that the maximum yield of shale oil are 294.5 and 304.3 mg/g TOC for kerogen sample at heating rates of 20 and 2°C/h, and the corresponding experimental temperatures are 360.2°C and 408.0°C, respectively. The utilization of lower heating rates is favourable for shale oil generation and it is recommended to employ a lower heating rate during in situ heating processes to maximize the economic benefits. The formation of crude oil cracking gas begins when simulating temperature exceeds 528.0°C (Easy Ro 2.6%) at a heating rate of 20°C/h and 480.0°C (Easy Ro 2.5%) at a heating rate of 2°C/h, as indicated by the carbon isotopic composition of gaseous hydrocarbons. The maximum oil production rate of the rock powder sample is 159.8 mg/g TOC, which is lower than that of the kerogen sample. It suggests that certain minerals in the Chang 7 shale may impede hydrocarbon generation. After the addition of pyrite, the highest yield of shale oil is 213.96 mg/g TOC, 33.9% higher than the yield of the original rock powder sample, reflecting the positive catalytic effect of pyrite on hydrocarbon generation of Chang 7 shale. Under geologic conditions, pyrite catalytic hydrocarbon generation may act primarily on the migration of organic matter by macromolecules, which considerably increases the probability of direct contact between pyrite and organic matter. Therefore, the organic‐rich shale with high pyrite content in Chang 7 member is the preferred target for in situ conversion of shale oil and gas in the Ordos Basin.

Heterogeneity of Organoclay Complexes in Shale Regulates the Generation of Shale Oil.

Organic matter (OM) and clay minerals are important components in shale, which are intimately associated with each other in the form of organoclay complexes. The diverse mineral-OM associations result in varying OM occurrences, which possess distinct hydrocarbon generation potential and ultimately affect the accumulation of shale oil. Therefore, the investigation of the heterogeneity of organoclay complexes is crucial to gaining a comprehensive understanding of the varying exploration potential of shale oil resources. In the present study, shale samples from three intervals in Dongying Depression were collected to investigate the mineralogical and organic characteristics of the organoclay complexes, aiming to explore their impact on the yield and composition of shale oil. Results showed that the smectite gradually converted into illite, which was accompanied by the release of OM from clay mineral interlayers and the desorption of chemically adsorbed OM. The yield and composition of shale oil cannot solely be explained by the OM content and types in the shale. Instead, they are intricately linked to the evolution of minerals and OM occurrence. From the perspective of the heterogeneity of organoclay complexes, despite the abundant OM content in shallower intervals (Es3x), the shale oil formation remains limited due to the low degree of mineral evolution and the stabilization of the adsorbed OM by clay minerals. Consequently, this leads to a higher proportion of resin, which is not conducive to the mobility of shale oil. In contrast, despite the OM content varying slightly in the deeper interval (Es4s), the elevated smectite illitization degree promotes the desorption of OM and its conversion into hydrocarbons. This results in a substantial increase in shale oil formation and a higher proportion of saturates, greatly enhancing the mobility of shale oil. These findings are profoundly significant for understanding shale oil generation and accumulation.

Experimental and numerical investigation on the pyrolysis of oil shale particles in a bubbling fluidized bed

The efficient utilization of oil shale resource is beneficial to environment and the resource diversity. In this work, a bubbling fluidized bed (BFB) reactor was first used to pyrolyze Huadian oil shale experimentally, mainly focusing on the influence of fluidization flow rates. The yield of shale oil, char and non-condensable gas varies little at different fluidization flow rates, but the components in shale oil are different due to the secondary cracking, such as the fractions and species of aliphatic hydrocarbons, aromatic hydrocarbons and non-hydrocarbons. Then, the dense discrete phase model (DDPM) was used to track the trajectories of oil shale particles with different diameters in a bubbling fluidized bed. Population balance model (PBM) coupled Eulerian model was used to well describe the bubbling status of bed materials to characterize the hydrodynamic behaviors. Furthermore, a segmented kinetic model was compiled by UDF module to illuminate the pyrolysis of oil shale particles. The multi-phase reactive flow modeling clearly indicated the distribution of oil shale particles and gaseous products in BFB reactor, as well as pyrolysis time and the secondary cracking at different fluidization flow rates. In summary, this work provides a reference basis for complete pyrolysis of oil shale particles in a bubbling fluidized bed and generating shale oil with high yield and good quality.

In-situ pyrolysis of oil shale in pressured semi-closed system: Insights into products characteristics and pyrolysis mechanism

In-situ conversion of oil shale involving kerogen cracking and hydrocarbon migration occurred in a semi-closed system under high pressure. Due to the insufficient understanding of the pyrolysis characteristics and mechanism of oil shale under these conditions, this study presented a systematic investigation of the coupling effects of temperature and pressure on oil shale pyrolysis within a semi-closed system. At 500 °C, the shale oil yield of 8 MPa declined by 65.7 %, while the gas yield increased by 93.7 % when compared to atmospheric pressure. The trend of shale oil yield exhibited variations with increasing temperature, depending on the pressure, and a demarcation point was observed at 2 MPa. The GC-MS and simulated distillation results of shale oil revealed that pressure promoted the generation of light components and accelerated the conversion of alkenes to alkanes and aromatics. The release temperature of gases increased under pressure, encouraging the production of alkane gas while reducing the hydrogen yield. Additionally, the pressure enhanced the combustion performance of semi-coke. As the pyrolysis temperature increased, the combustion performance of semi-coke deteriorated under low pressure, whereas the trend was reversed under high pressure. Finally, the pyrolysis mechanism for oil shale coupling of temperature and pressure was proposed.

Effect of methanol on the pyrolysis behaviour of kerogen by ReaxFF molecular dynamics simulations

ABSTRACTA series of molecular dynamics simulations were performed using the ReaxFF reactive force field to investigate the pyrolysis of Longkou oil shale kerogen in the presence of methanol. The roles of methanol in kerogen pyrolysis were deeply explored to reveal the microscopic mechanism of methanolysis by analyzing the distribution of products, the consumption of methanol, and the formation processes of typical products at different temperatures. The results demonstrate that the yield of shale oil in the presence of methanol is consistently higher than that of kerogen direct pyrolysis at the same temperature, which is consistent with the trend of oil yield with temperature reported by previous methanolysis experiments. Methanol supplies a large number of small radicals under the pyrolysis condition, which can facilitate the breakage of weak bonds and take part in the formation of products through combining with the radical fragments generated by the pyrolysis of kerogen. This study will provide theoretical guidance for understanding the methanolysis process of oil shale.

Hydrous Pyrolysis of Source Rocks with Different Maturity in Dongying Sag, Bohai Bay Basin, China: Implications for Shale Oil Exploration and Development

Shale oil yield, movability, and reservoir brittleness are three factors that must be focused on for shale oil exploration and development. The yield and composition of hydrocarbons and mineral composition have changed significantly during diagenesis, affecting the yield and movability of shale oil and the brittleness of the rock. In this study, the source rocks at different depths in the Dongying Sag were subjected to hydrous pyrolysis, and the yield and composition of pyrolyzed hydrocarbons and mineral composition were systematically analyzed. The brittleness index (BEI), weighted average specific surface area (SSAWA), and polarity index (PI) have been established to quantitatively characterize the brittleness and adsorption capacity of rock as well as the mobility of shale oil. The results suggest that diagenetic evolution controls rocks’ brittleness and adsorption capacity by changing their mineral composition. In the low-temperature stage, the mineral transformation is not obvious, and the BEI and SSAWA fluctuate in a small range. In the high-temperature stage, the rapid smectite illitization leads to an increase in the brittleness and a decrease in the adsorption capacity. In addition, the nonpolar components such as saturates and aromatics in the pyrolyzed hydrocarbons gradually increased with the increasing temperature, enhancing the mobility of the shale oil. Based on the three evaluation indexes of BEI, PI, and SSAWA, and combined with the changes in hydrocarbon yields during hydrous pyrolysis, we comparatively analyzed the differences in the mobility and yields of original soluble organic matter as well as pyrolyzed hydrocarbons of the source rocks at different depths. Based on the above results, it can be concluded that the shale in the depth range of 3300–3795 m is a favorable area for shale oil exploration and development in the study area. This work suggests that predicting the sweet spot for shale oil exploration and development requires more attention to the impact of diagenetic evolution on the composition of minerals and hydrocarbons.

Advancements and Environmental Implications in Oil Shale Exploration and Processing

This comprehensive review presents a holistic examination of oil shale as a significant energy resource, focusing on its global reserves, extraction technologies, chemical characteristics, economic considerations, and environmental implications. Oil shale, boasting reserves equivalent to approximately 6 trillion barrels of shale oil worldwide, holds substantial potential to augment the global energy supply. Key extraction methods analyzed include surface mining, modified in situ, and true in situ conversion processes, each exhibiting distinct operational parameters and efficiencies. The review further delves into the chemical aspects of oil shale retorting and pyrolysis, highlighting the critical role of variables such as retorting temperature, residence time, particle size, and heating rate in determining the yield and composition of shale oil and byproducts. Economic analyses reveal that capital and operating costs, which vary according to the specific extraction and processing technologies implemented, are crucial in appraising the economic feasibility of oil shale projects. Lastly, the review acknowledges the potential environmental hazards linked with oil shale development, such as groundwater contamination and harmful emissions. It emphasizes the importance of rigorous monitoring programs, environmental impact assessments, sustainable technologies, and innovative strategies like co-combustion and comprehensive utilization systems in mitigating such impacts. The review underlines the need for a balanced approach that harmonizes technological advancement, economic viability, and environmental sustainability in oil shale exploitation.

Chemical Looping Enhanced Oil Shale-to-Liquid Fuels Process: Modeling, Parameter Optimization, and Performance Analysis

The solid heat carrier moving bed with internals is an advanced oil shale retorting technology. However, the retorting gas produced by pyrolysis is generally used as fuel gas. The content of CO, H2, and CH4 in the retorting gas is high, and direct combustion leads to resource waste and environmental pollution. In addition, heteroatomic sulfur and nitrogen, as well as unsaturated hydrocarbons, reduce the quality of shale oil. To solve these problems, this paper proposed a chemical looping enhanced oil shale-to-liquid fuels (CLeSTL) process. The chemical looping hydrogen production technology is applied to convert retorting gas to hydrogen, and the hydrogen produced is used for shale oil hydrogenation to improve the oil quality. In this paper, the new process is modeled and simulated; then technoeconomic analysis is carried out. Technical analysis shows that shale oil yield is increased from 65% to 95.7% and the yield of light fraction is increased from 20% to 64%–83%. Economic analysis shows that the CLeSTL process with ligh fraction hydrogenation has the highest investment profit rate and large profit space. In addition, when the oil price is lower than 50 USD/bbl, the investment profit is 5%, which shows strong anti-risk ability.

Hydrocarbon regulation and lower temperature pyrolysis of balikun oil shale kerogen

Oil shale kerogen is a kind of composite nature of fossil energy polymer. Kerogen pyrolysis is a feasible and alternative strategy to produce fossil fuels from shales. However, the disadvantages including the high energy consumption, the high cost, and the low hydrocarbon conversion, significantly hinder the development and utilization of unconventional hydrocarbon resources. Herein, the hexagonal crystal structural layered double hydroxides (LDHs) with the Ni/Fe ratio of 5.64:2.36 is proposed as pyrolysis catalyst to improve the catalytic efficiency, the selectivity of target hydrocarbons, and lower the temperature for the process of kerogen pyrolysis. As a result, needle-like nanoscale NiFe-LDHs are prepared successfully to perform the fast thermal upgrading of Balikun oil shale kerogen. The catalytic pyrolysis performance has been observed that the temperature for maximum conversion (Tmax) is 401.18 °C, presenting a Tmax reduction of 37.84 °C, the yield of shale oil is increased by 7.83 wt%. And during 350°C– 400°C, a progressive increment of 147.67%, 230.86%, and 310.61% is obtained corresponding to the content of C1-C5, C6-C14, and C14 + hydrocarbons, respectively. This finding enriches the catalyst candidates for kerogen pyrolysis and provides new insights into industrial applications of in-situ pyrolysis technology for oil shale recovery processes.

Experimental investigation on the pyrolysis process and product distribution characteristics of organic-rich shale via supercritical water

Low-medium maturity organic-rich shale reservoirs have garnered increasing attention due to their enormous oil and gas generation potential. In this study, the pyrolysis conversion process and product distribution characteristics of shale core samples via supercritical water (SCW) were investigated. The yield of shale oil increased from 4.5 wt% at 385 °C to 15.13 wt% at 425 °C, with the maximum formation rate of shale oil ranging from temperatures of 405 °C to 425 °C. The thermal bitumen reached 15.11 wt% at 405 °C before rapidly decreasing to 3.2 wt% at 425 °C. In the pyrolysis process of shale cores via SCW, the intermediate thermal bitumen produced by thermal cracking of kerogen was retained in the cores and continued to be decomposed into shale oil and gas with the increase of SCW temperature. Simultaneously, a large number of pores were formed in the core matrix due to the massive decomposition of kerogen and thermal bitumen. The increase in SCW temperature greatly decreased the heavy components as well as increased the light components in shale oil. Additionally, aliphatic hydrocarbon cracking or Diels-Alder type aromatization reactions resulted in an increase in aromatic hydrocarbons and a decrease in the H/C atomic ratio of shale oil. Raising SCW temperature increased the content of C2-C5 hydrocarbon gases and the alkenes/alkanes ratio, which was related to the secondary cracking. The important findings of the pyrolysis conversion process and product distribution characteristics of shale cores via SCW not only enrich the theoretical basis in this area, but also provide strong support for the use of SCW in the in-situ conversion of low-medium maturity organic-rich shale reservoirs.

Response model of fluid–rock ratio to reservoir space in primary formation of shale oil during hydrous pyrolysis

ABSTRACT Due to the presence of geological fluid under actual geological conditions, water–rock interaction will occur between the fluid and reservoir. Thus, to analyse the influence of the water–rock interaction on storage space during the organic matter evolution stages, this study conducted a series of simulation experiments on shales by using a closed autoclave: four temperatures, 250°C, 300°C, 350°C, 400°C, and five fluid–rock ratios (FRRs), 0:20, 4:20, 10:20, 15:20, and 20:20. Low pressure N2 adsorption measurement was conducted on the solid residues. The experimental results show that the effect of temperature on the yield and pore structure of oil shale was the same as the result when the FRR was = 0:20, 4:20 and = 10:20, 15:20, 20:20, respectively. This result showed that temperature remained the main factor that affected the thermal evolution of hydrocarbon generation. Additionally, temperature was beneficial to the generation and storage of shale oil within a certain range, but only occupied the storage space of shale oils or connected a certain storage space beyond a certain range. The variation trend of shale oil yield with increasing FRR under the same simulated temperatures, 250°C and 400°C, was most affected by the FRR, but little change occurred at 300°C and 350°C. This further proved that the ratio of fluid to rock was an indirect acting factor, which affected the evolution of organic matters and then the development of pore structures. Before the oil window (350°C), the lower evolution degree, the higher water content and the more significant effect. In the higher evolution stage, the higher the water content, and the more complete the kerogen reaction, which was also more conducive to the development of pore structures. Therefore, this study promotes the establishment of linear equations on FRR to the gas adsorption capacity, which further provides a theoretical basis and guidance for the exploration and development of shale oil.

Enhanced pyrolysis of Huadian oil shale at high temperature in the presence of water and air atmosphere

The liquid water injected at a high temperature combined with oxygen pyrolysis of oil shale is firstly studied. The pyrolysis was conducted at different temperatures and water to oil shale mass ratios (W/OS) in a self-reformed Fischer Assay retort under an air atmosphere to identify the effect of water on the distribution and characteristics of the oil shale products. The shale oil yield at a W/OS ratio of 0.5:10 was higher than that of the no water case under an air atmosphere and the highest yield was approximately 450 °C. With the same shale oil yield as that obtained from the Fischer Assay, the pyrolysis temperature decreased by approximately 78 °C with a W/OS of 0.5:10 under an air atmosphere. Pyrolysis of oil shale with different W/OS ratios significantly increased the shale oil yield from 17.03% to 20.00% and decreased the semicoke yield from 68.42% to 68.20% with an increasing W/OS from 0:10 to 1.5:10 under an air atmosphere at 450 °C. As the W/OS increased to 0.75:10, the alkane and alkene contents increased, while the aromatic hydrocarbon content decreased. Water increased the content of the heavy fractions in the shale oil by weakening the adsorption of macromolecular compounds on the minerals and prompting oil migration. The presence of water slightly increased the H/C and S contents in the shale oil but reduced the content of N. The effect of water on the distribution and characteristics of the products was caused by multiple control mechanisms in the pyrolysis process, including chemical, migration, the interaction with oxygen effect.

A Comparative Study of Different Quality Oil Shales Developed in the Middle Jurassic Shimengou Formation, Yuqia Area, Northern Qaidam Basin, China

Oil shales are developed in the Shale Member of the Middle Jurassic Shimengou Formation in the Qaidam Basin, China. The oil shales can be classified into three quality groups (low-, medium-, and high-quality oil shales) through a comprehensive analysis protocol that includes Rock-Eval pyrolysis, total organic carbon (TOC) content, proximate analysis, gas chromatography-mass spectrometry (GC-MS), X-ray diffraction (XRD), major and trace element analyses, and maceral analysis. The low-quality oil shales mainly contain type II1 kerogen, the medium-quality oil shales mainly contain type I-II1 kerogen, and the high-quality oil shales mainly contain type I kerogen. All are immature to early thermally mature. The oil yield of the oil shales is directly related to their quality and are positively correlated with TOC content and calorific value. All studied samples were deposited under anaerobic conditions but in different paleoenvironments. The low-quality oil shales were mainly deposited in fresh-water environments, whereas the high-quality oil shales were usually developed in highly saline and reducing environments. Salinity stratification and evidence of algal blooms that are conducive to organic matter enrichment were identified in both medium- and high-quality oil shales, the latter having the highest paleoproductivity and the best preservation conditions. In summary, shale quality is controlled by a combination of factors, including algal abundance, preservation conditions, the existence of algal blooms and salinity stratification, and paleoproductivity. This study reveals how these different factors affect the quality of oil shales, which might provide an in-depth explanation for the formation process of lacustrine oil shales.

Enrichment control factors and exploration potential of lacustrine shale oil and gas: A case study of Jurassic in the Fuling area of the Sichuan Basin

Well Taiye 1 in the Fuling area of the eastern Sichuan Basin has obtained a high-yield industrial gas flow (7.5 × 104 m3/d gas and 9.8 m3/d oil) from the Middle Jurassic Lianggaoshan Formation, presenting a good test production effects, which means the realization of a major breakthrough in the exploration of Jurassic lacustrine shale oil and gas in the Sichuan Basin. In order to further determine the exploration potential of lacustrine shale oil and gas in this area and realize the large-scale efficient development and utilization of lacustrine shale oil and gas, this paper analyzes the geological conditions for the accumulation of lacustrine shale oil and gas in this area by using the drilling data of 10 key wells, such as wells Taiye 1 and Fuye 10. Then, the main factors controlling the enrichment of lacustrine shale oil and gas are discussed, and the exploration potential and favorable target zones of Jurassic lacustrine shale oil and gas in the Fuling area are defined. And the following research results are obtained. First, the quality Jurassic semi-deep lake shale in the Fuling area is characterized by high organic matter abundance, high porosity and high gas content, and it is the geological base of shale oil and gas enrichment. Second, the developed large wide and gentle syncline, good preservation condition and higher pressure coefficient (generally >1.2) are the key to the enrichment and high yield of shale oil and gas. Third, the developed microfractures in lacustrine shale are conducive to the enrichment and later fracturing of shale oil and gas. In conclusion, the Lianggaoshan Formation lacustrine shale in the Fuling area is widely distributed with moderate burial depth, developed microfractures and moderate thermal evolution, and its shale gas resource extent and shale oil resource extent are 1 922 × 108 m3 and 2800 × 104 t, respectively, indicating greater potential of shale oil and gas exploration, so shale oil and gas is the important field of oil and gas reserves and production increase in this area in the following stage.

Effect of Retorting Temperature on the Pyrolysis Characteristic of Longkou Oil Shale

Oil shale samples from Longkou City, Shandong Province, China, were pyrolyzed in a fixed bed reactor at retorting temperature varied from 400 to 550°C under nitrogen atmosphere with heating rate of 15°C/min. The influence of retorting temperature on the yield and characteristics of shale oil and retorting gases were determined. It was observed that the oil yield increased to the maximum value, 15.68 wt%, as the retorting temperature increased from 440 to 550°C. And increasing retorting temperature improved also gas yields, but reduced the char yield. The contents of H2, CO2, and CH4 in the retorting gas increased with the rising of retorting temperature. The ratio of alkane/alkene hydrocarbon (C1-C5) decreased because of the secondary cracking reactions of gas phase in the high temperature. The carbon and nitrogen contents of shale oil increased with increasing retorting temperature, while those of hydrogen and oxygen decreased. The sulfur content was not significantly affected by the retorting temperature. In addition, the shale oil obtained from 550°C had the lowest aromatic content, 25.12 wt%, and the highest saturate content, 50.03 wt%, compared to the other retorting temperatures due to the cracking of aliphatic compounds. The alkanes with 8-34 carbons and alkenes with 8-27 carbons were detected in the shale oil. The concentration more than 20 mg/goil was C23-C30 in the range of 400-550°C. The total content of n-alkanes decreased to 369.25 mg g-1oil, and that of n-alkene reached the maximum value at 550°C, 181.62 mg/goil, with the rise of retorting temperature. It was demonstrated that the higher temperature was beneficial to promoting the reaction of aromatization, dehydrogenation, fraction, and other reactions in the pyrolysis process.

Effects of Associated Minerals on the Co-Current Oxidizing Pyrolysis of Oil Shale in a Low-Temperature Stage.

Low-temperature co-current oxidizing pyrolysis, which can achieve high recovery of hydrocarbons without significant oil loss, has great potential to reduce the huge external energy required for oil shale conversion. However, this promising method is far from being fully understood, especially the unknown competing mechanism of different types of inorganic minerals in promoting or inhibiting hydrocarbon generation. In this study, the raw Huadian oil shale (HD-R), its carbonate-free (HD-C-F), and carbonate-silicate-free (HD-CS-F) samples obtained through acid treatment are used to investigate the effects of associated minerals on the oil shale co-current oxidizing pyrolysis. The results of shale oil yields of HD-R, HD-C-F, and HD-CS-F were 41.53, 22.38, and 33.97%, respectively, indicating that silicates inhibited, while carbonates catalyzed the formation of shale oil during the co-current oxidizing pyrolysis. Meanwhile, silicates increase the alkane content and decrease the alkene content in shale oil via promoting the combination of hydrogen radicals and alkyl radicals. On the contrary, alkali metals and alkaline earth metals in carbonates inhibit the binding activity of hydrogen radicals and alkyl radicals, concurrently enhancing the release of hydrogen-free radicals of alkyl radicals to form more alkenes. The removal of carbonates could enhance the conversion of organic carbon into hydrocarbons, and the silicates will strengthen the conversion process. It is hoped that this experiment can further enrich and perfect the basic theory of oil shale pyrolysis and provide a reliable reference for the pretreatment of oil shale conversion.

The enhancement on oil shale extraction of FeCl3 catalyst in subcritical water

The coupling effect of subcritical water and FeCl3 on the extraction of bulk Huadian oil shale was experimentally investigated. The results showed that, with the addition of FeCl3, the yield of shale oil in subcritical water extraction was enhanced by 58.5 % at 20 h and the time required for the maximum shale oil production was reduced by 43 %. The group compositions of shale oil and residual bitumen as well as the elemental analysis of residual kerogen revealed that FeCl3 could trigger the pyrolysis reaction networks of kerogen by promoting the cleavage of heteroatom bonds, and accelerate the decomposition of asphaltenes in residual bitumen. GC-MS analysis of n-alkanes in shale oil and residual bitumen showed that FeCl3 promoted the secondary cracking of saturated hydrocarbons in residual bitumen rather than in shale oil due to the adsorption of Fe3+ in shale matrix. The solid-state 13C NMR analysis of the residual kerogen indicated that the polycondensation of kerogen was inhibited and the ring-opening reaction of aromatic structure was promoted in the presence of FeCl3. In addition, the acidic FeCl3 solution induced the decomposition of carbonate minerals in oil shale matrix to provide additional mass transfer channels for the migration of bitumen products.

Effects of secondary reaction of primary volatiles on oil/gas yield and quality in oil shale pyrolysis

The reaction behaviors of primary volatiles from oil shale pyrolysis were investigated using a two-stage reactor under different in-situ thermal reaction conditions. The reaction parameters of secondary reactor, such as, reactor temperature, atmosphere and residence time, were studied for their effects on the pyrolysis oil/gas yield and quality. The results showed that the reaction temperature had profound influence on the oil and gas yield. The pyrolyzed shale oil and gas yield reduced by 15% and increased by 20% (mass) respectively, with the temperature of 2nd stage reactor increasing from 600 to 650°C under optimized reaction condition of 1st stage. Comparing with nitrogen atmosphere, the liquid oil yield could be enhanced by 5% when steam was added as the reaction atmosphere in the second stage, and the corresponding oil was mainly concentrated in the gasoline and diesel distillations (that is, boiling point <350°C). The GC-MS analysis illustrated that the secondary reaction at the residence time of 0–3 s was mainly pyrolysis while the presence of steam could increase the content of aromatics in the oil and meanwhile suppress the condensation of aromatics. When the residence time was greater than 3–5 s, the secondary reaction was mainly condensation of poly-aromatics, which led to the increase of coke. Meanwhile, the gasoline and diesel oil yield remained stable, and the VGO fractions decreased by about 30%.

Influence of particle size and temperature on the yield and composition of products from the pyrolysis of Jimsar (China) oil shale

The influence of particle grain size and retorting temperature on the yield and composition characteristics of products evolved from the pyrolysis of oil shale for a range of sizes from granules to large blocks (6−20, 20−30, 30−50 and 50−55 mm) is investigated. The results show that oil shale particle size has no significant effect on the yield of shale oil and non-condensable gas, and the highest yield of shale oil is achieved at the retorting temperature of 520 °C. The generation of C1-C5 hydrocarbon gases has two main temperature ranges (350−500 °C and 500−600 °C) due to the temperature gradients in oil shale particles and packed beds, and the secondary reactions of carbonaceous residues and retained oil. The main constituents of shale oil are aliphatic hydrocarbons, aromatic hydrocarbons and heteroatom-containing compounds ranging from the number of carbon atoms C6-C26. And the chemical composition of non-condensable gases and shale oil has certain regularity changes with the changing of particle size and retorting temperature, which is attributed to the important effect of particle size and retorting temperature on the secondary reactions of pyrolysis products during diffusing out of oil shale particles and packed bed.

Studies of the Bubbling Fluidized Bed Retorting of Dachengzi Oil Shale: 1. Effect of Retorting Temperature

Fluidized bed retorting of oil shale is a potential technology with high shale oil yield. However, there are few studies on the composition distribution of the products of this technology. In this ...