The Rock-Eval technique in the last few decades has found extensive application for source rock analysis. The impact of shale particle crush-size and sample weight on key Rock-Eval measurements, viz. ...the S
2
curve (heavier hydrocarbons released during the non-isothermal pyrolysis-stage) and the S
4
curve (CO
2
released from oxidation of organic matter during the oxidation-stage) are investigated in this study. For high and low total organic carbon (TOC) samples of different thermal maturity levels, it is apparent that particle crush-size has a strong influence on the results obtained from Rock-Eval analysis, with the effect being stronger in high-TOC samples. In comparison to the coarser-splits, S
2
and pyrolyzable carbon (PC) were found to be higher for the finer crush sizes in all the shales studied. The S
4
CO
2
oxidation curve shapes of Permian shales show contrasting signatures in comparison to the Paleocene-aged lignitic shale, both from Indian basins. A reduced TOC was observed with rising sample weight for a mature Permian shale from the Jharia basin, while the other shales sampled showed no significant reduction. The results indicate that the S
4
CO
2
curve and the S
4
T
peak
, are strongly dependent on the type of organic-matter present and its level of thermal maturity. Sample weight and particle size both influence the S
2
-curve shapes at different heating rates. With increasing sample weights, an increase in S
2
-curve magnitude was observed for the shales of diverse maturities. These differences in the S
2
curve shape lead to substantially different kinetic distributions being fitted to these curves. These findings are considered to have significant implications for the accuracy of reaction kinetics obtained from pyrolysis experiments using different sample characteristics.
Source-rock properties and pore structural properties of Permian shales (Barakar Formation) were evaluated from two Indian basins, with contrasting thermal maturities. South Rewa basin shales were ...marked by lower thermal maturities, while higher thermal maturities were shown for the shales from the Jharia basin. However, one sample from the South Rewa basin showed unreliably high Rock-Eval Tmax. Examination of the S2 curve showed very low flame ionization detector (FID) value, and thereby indicating the unreliability of the Tmax. However, the Rock-Eval oxidation temperature-peak (S4Tpeak) was observed to show reliable maturity estimate for the sample. The results presented establish the reliability of S4Tpeak as a maturity proxy for shales marked by unreliable pyrolysis signatures. Fractal analysis of low pressure N2 gas adsorption data and pore size distribution trends revealed presence of complex porous structures within the Jharia basin shales, while showing less complicated simpler structures within the South Rewa shales. While two fractal dimensions were observed to be present in the thermally mature Jharia shales, the differences in slopes of the two fractal segments showed minimal variation for the South Rewa shales, indicating the influence of thermal maturity levels on fractal properties.
This paper examines the source rock potential and pore structural framework of Lower Permian shales belonging to Barren Measures and Barakar Formations of Jharia basin, eastern India. The Jharia ...basin contains prolific coking-coal reserves and, consequently, the organic-matter in this basin tends to be mature. Open system pyrolysis analysis reveals that the Barakar Formation shales are thermally more mature and organic-rich than the Barren Measures Formation. Analysis reveals that shales of the Barren Measures possess “fair” to “good” oil generation potential. The more mature shales of the Barakar Formation are gas prone. Detailed pore scale distribution and fractal metrics determined by low-pressure N
2
gas adsorption are observed to be higher for the Barren Measures Formation than the more mature and organically rich Barakar Formation shales possibly due to the inability of N
2
gas to access the ultrafine components of the complex pores in the Barakar Formation shales. Substantial concentration of pores, organic-rich character, and thermal maturity levels indicates that the studied horizons have unconventional source rock properties.
In the Mediterranean diet, olive oil serves as the predominant fat source and has been linked to a decreased risk of mortality related to cardiovascular diseases (CVD). Still, there is no conclusive ...evidence correlating olive oil consumption to CVD. The aim of this study is to assess the global research, current research trends, and knowledge mapping related to the correlation between the consumption of olive oil and CVD using bibliometric analysis. On August 19, 2023, a title‐specific literature search was conducted on the Scopus database using the search terms “olive oil” and “cardiovascular disease” with a date range of the past 50 years. Subsequently, bibliometric tools such as VOSviewer and Bibliometrix were employed to analyze and evaluate the obtained documents. The search yielded (n = 429) publications and showed an upward trend in the annual publication count over the last five decades. The publication number exhibited a gradual increase with a rate of 5.55%. The results also indicated that 2530 authors, 759 institutions, 47 countries, and 223 journals have publications in this research domain. The present bibliometric study will be a valuable research reference for describing the worldwide research patterns concerning the relationship between olive oil and CVD during the past 50 years. In the future, the application of olive oil for the treatment of CVDs may be an emerging research trend. Apart from this, collaborations among authors, countries, and organizations are expected.
The present bibliometric study will be a valuable research reference for describing the worldwide research patterns concerning the relationship between olive oil and CVD during the past 50 years.
The influence of degassing time and temperature on low-pressure gas adsorption (LPGA) behavior of shales was examined in this study. Two organic-rich shales of contrasting maturity, reactivity and ...organic matter type, were crushed to <1 mm and <212 μm grain-sizes and degassed at 110, 200, and 300 °C for 3 and 12 h, respectively. Our results indicate that degassing duration has a minimal influence on pore-character interpretations from LPGA experiments, while the degassing temperature shows a strong influence on the pore attributes. For both shales, reliable porosity estimates were obtained when the samples were degassed at 110 °C. When the degassing temperature was increased to 200 and further to 300 °C, distinct changes in adsorption isotherms and other pore structural features were observed. For the mesoporous low-mature shale (collected from a lignite mine) when the degassing temperature was kept at 200 °C, a macroporous character was induced with a manifold increase in pore diameter. Results from thermogravimetry and Rock-Eval indicate abundance of reactive kerogen, which undergoes alteration when degassed at higher temperatures. When the degassing temperature was kept at 300 °C, the organic matter underwent further alteration and showed an isotherm similar to the shales degassed at 110 °C. Similarly, for the oil-window mature shale sample, a transition towards macroporous structure was observed when the sample was degassed at 200 and 300 °C, compared to a mesoporous structure observed when degassed at 110 °C. The results from fractal dimensions also support the above inferences, indicating the presence of simpler structures at higher degassing temperatures. Reduction in pore volume (110–200 °C) and its further rise (200–300 °C) are also evident in the micropore domain, more distinctly in the oil window mature shale. Our results strongly indicate that degassing temperature should be kept at around 110 °C for reliable shale pore character estimation.
The Rock-Eval pyrolysis-stage derived parameters such as free hydrocarbons (S1), heavier pyrolysis-hydrocarbons (S2), pyrolyzable carbon (PC) and pyrolysis Tmax (from S2 curve) have received ...considerable interest for source-rock screening and thermal maturity assessment. On the other hand, the Rock-Eval oxidation-stage S4CO2 curve, which gives the amount of residual carbon (RC), only recently has received some interest. While the pyrolysis-stage S2 temperature-peak (Tmax) is conventionally used as a maturity proxy, in this work we show that the temperature-peak of S4CO2 curve (S4Tmax) can also be used as a thermal maturity proxy for shales. For overmature and low-TOC shale samples, showing asymmetric S2 shape and concomitantly producing doubtful Tmax, the S4 curves showed symmetric nature and consequently the S4Tmax was observed to be a reliable thermal maturity estimate. While the S4Tmax clearly resolved immature and overmature shales, for the early mature and peak mature shales the S4Tmax showed overlapping values. S4Tmax of pre-pyrolyzed and pyrolyzed masses showed good positive correlation with differential scanning calorimetry temperature-peak (DSCTpeak), and consequently indicated its applicability as a thermal maturity proxy. When early mature pre-pyrolyzed samples were directly analyzed using the Rock-Eval oxidation stage, the S4 curves showed formation of two sub-peaks, and consequently the Tmax was observed to decrease. It is recommended that analysts and interpreters should thoroughly cross-check S2 curves before reporting data, and in case of asymmetric or unreliable S2 curves, the S4Tmax can be used as a maturity proxy.
•Importance of Rock-Eval oxidation stage.•S4Tpeak as a thermal maturity proxy for shales.•Critical monitoring of Rock-Eval S2 curves.
Over the past four decades Rock-Eval pyrolysis has become a common means to type organic matter. The modified van Krevelen diagram, using the hydrogen and oxygen indices, has become a commonly used ...tool for organic matter classification. It assumes that the components used to calculate the two indices are representative of the indigenous organic matter, which is especially the case for the oxygen index. This study provides a series of experimental results that further characterize the impact of siderite on the hydrogen and oxygen index values, which decrease and increase, respectively, with increasing mineral content. This work suggests that the changes in hydrogen index values are a result of the interaction between the mineral phase and the generated hydrocarbons, where hydrocarbons may be adsorbed on to the mineral surfaces and not fully released. The increase in the oxygen index appears to be a result of mineral decomposition and the release of CO2. The oxygen index was found to be particularly sensitive to the presence of siderite in the sample. Siderite decomposition was found to occur at temperatures below often published decomposition temperatures and at or below the S3 peak trapping temperature (390 °C). Thus, the impact of organic carbon content and mineral interaction need to be taken into consideration when characterizing organic matter, especially when siderite and to a lesser extent other carbonate minerals are present. At lower organic carbon levels, organic matter will appear more gas-prone and would suggest that the organic matter has been strongly oxidized. Although corrections have been proposed in the literature they reduce the value of the Rock-Eval “quick” screen by adding additional analyses or data treatment. It is further suggested that the effect may be sensitive to the early diagenetic environment as well as cation substitution.
•Importance of Rock-Eval S3 and S3′ curves to the correct kerogen classification.•Stronger influence of siderite on the S3 peak and OI values than originally suggested.•OI was found to significantly increase with increasing siderite, and to a lesser extent with limestone content.•An associated reduction in the HI appears due to interaction with the minerals.
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•Permian shales of India show distinctive oil and gas generation potential.•Shale reactivity is closely linked to kerogen type and thermal maturity.•Multi-heating-rate pyrolysis with ...kerogen petrography explain kinetic variations.•Contact metamorphism of organic-rich shales lowers their residual reactivity.•A substantial range of shale reactivity is associated with different kerogen types.
Reconstructing hydrocarbon generation history for predicting the onset of oil/gas generation is an important step for petroleum system modeling, and for the purpose, source rock kinetic analysis is required. For evaluating the controlling factors that influence shale rock kinetics, Lower Permian Barren Measures Formation shales from two Damodar Valley sub-basins, India are evaluated in terms of their source rock properties and kinetics. Rock-Eval open-system programmed-pyrolysis is applied at heating-rates of 5, 15 and 25 °C/min to determine the shales’ reaction kinetics. The results substantiate the importance of petrographic composition in controlling the shale source rock potentiality and reaction kinetics. North Karanpura Basin shales are shown to have liquid hydrocarbon generation potential, owing to their richness in type I-II kerogen. In contrast, the Raniganj Basin shales are richer in type III-IV kerogen and gas prone. The shales are grouped in distinct clusters on an E versus LnA (activation energy versus pre-exponential factor) kinetic distribution. The type I-II kerogen-bearing samples display the highest reactivity, while the type III-IV kerogen-bearing shales, and those with higher thermal maturity levels, display lower reactivity. The least reactivity is associated with a heat-altered shale from the Raniganj Basin, which also displays the highest Rock-Eval S2 Tmax, S4 Tpeak, and lowest HI (hydrogen index) value. This indicates the significant impact of igneous intrusions by removing hydrocarbons from shales and lowering their residual reactivity. The dominance of type I-II kerogen and presence of framboidal pyrite in the North Karanpura Basin shales also indicates some marine influence during their deposition.
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