Gold Tubes Research Articles

The Gas Generation Process and Modeling of the Source Rock from the Yacheng Formation in the Yanan Depression, South China Sea

The research on deepwater oil and gas exploration areas is relatively limited, and sample collection is difficult. A drilled coal sample from Yanan Depression was used to investigate the hydrocarbon generation process, and the potential, by a gold tube thermal simulation experiment. The results show that the total gas yield was much higher than the oil yield. According to an analysis of the gas pyrolysis data, as represented by ln(C1/C2) and ln(C2/C3), the gas generation process consisted of two forms, namely, primary gas with ~1.33% Ro and secondary gas that occurred at levels greater than 1.33% Ro. The primary gas from kerogen was generated at ~1.33% Ro, which coincided with the %Ro value of the maximum oil yield. The activation energy distribution of the C1–C5 generation processes ranged from 54 to 72 kcal/mol, with a frequency factor of 6.686 × 1014 s−1 for the coal sample. We constructed the history of gas generation on the basis of the process and kinetic parameters, combined with data on the sedimentary burial and thermal history. The extrapolation of the gas history revealed that the gas has been generated from 5 Ma to the present, with a maximum yield of 178.5 mg/gTOC. This history suggests that the coal has good primary gas generation potential and provides favorable gas source conditions for the formation of gas fields. This study provides a favorable basis for expanding the effective source rock areas.

Occurrence and maturation transformation of organic and inorganic nitrogen in the Lower Cambrian shelf–slope facies shale: Implications for overmature N2-rich shale reservoirs in Southern China

Thermogenic molecular nitrogen (N2) is one of the primary sources of high N2 content in overmature shale gas reservoirs. However, it remains uncertain whether N2 is released from organic or inorganic sources because the occurrence and thermal stability of different nitrogen species vary. This study investigates the Lower Cambrian shale samples from a well in southeastern Guizhou, China to determine the abundance, occurrence, and source of nitrogen in marine shale. A sealed gold tube pyrolysis experiment was further conducted on isolated kerogen and organic matter (OM)-ashed samples from one typical shale to explore the maturation transformation of organic nitrogen (Norg) and inorganic nitrogen (Ninorg). The results reveal that the studied shale exhibits a high nitrogen content, with the Norg content being less than that of Ninorg. The predominant functionality of Norg is pyrrolic-N, and Ninorg occurs primarily in silicates (NH4+-bearing illite and (NH4+, K, Ba)-feldspar). The structural characteristics of the different nitrogen functionalities cause them to vary in their thermal transformation behavior. The pyrolysis experiment results indicate that the nitrogen release of the shale increases rapidly when EqVRo >3.7%, and the N2 yields for typically shelf-slope facies shales are primarily 1–2 m3/t at EqVRo 4.0%–4.2%, to which the Ninorg has a dominant contribution. Further evidence that the high N2 shale gas reservoirs occur at EqVRo >3.5% is provided by compiled gas composition data from various risk wells. It is proposed that the Lower Cambrian shale gas exploration should address the considerably increased N2 risk in the shelf–slope facies area.

Generation of abnormal distributions of inter- and intramolecular δ13C compositions in hydrocarbons from gold tube pyrolysis of an Australian torbanite

Abnormal stable carbon isotopic (δ13C) compositions, deviating from the conventional order of δ13C1 < δ13C2 < δ13C3, are frequently observed in natural gas reservoirs. For thermogenic gas, these anomalies, such as δ13C1 < δ13C3 < δ13C2 or δ13C1 > δ13C2 > δ13C3, have multiple formation mechanisms including gas mixing in conventional systems and desorption processes of gaseous hydrocarbons in unconventional shale gas systems due to their inconsistency with Rayleigh fractionation processes. Considering distinct reaction pathways (e.g., C1 polymerized to C2), these aberrant δ13C signatures are often construed as intrinsic hallmarks of extensively evolved natural gas. However, on the basis of gas generation simulation, not all findings exhibit abnormal δ13C values, hinting at multifaceted and intricate mechanisms governing the isotopic fractionation of alkane gas components. This study conducted gold tube pyrolysis of an Australian torbanite, revealing four distinct types of δ13C anomalies in hydrocarbon classes. Polycyclic aromatic hydrocarbons (PAHs) exhibited δ13C values more negative than co-occurring n-alkanes. δ13C3 displayed a negative trend shift from EasyRo = 3.5 %, resulting in a partially δ13C-reversed gas (δ13C1 < δ13C3 < δ13C2) formed at EasyRo ≈ 4.1 %. Moreover, intramolecular δ13C3 (both terminal and central carbons, termed δ13Ca and δ13Cb, respectively) reversed alongside the overall δ13C3 trend. Additionally, the evolution of site preference in δ13C3 (termed ‰SP = δ13Ca – δ13Cb) transitioned from progressively negative to positive. The results of this study demonstrate that the potential conversion between saturated hydrocarbons, aromatic hydrocarbons, and alkane gases is at least partially responsible for δ13C anomalies, but also that gaseous hydrocarbons formed from other fractions at high maturity cannot be ruled out, such as kerogen and pyrobitumen.

The influence of asphaltene matrix on the thermal evolution of polycyclic aromatic hydrocarbons: Experimental evidence and geochemical implications

The thermal evolution of components trapped in matrix of asphaltenes is supposed to be retarded, as compared to the free ones. Studying the geochemical evolution of trapped polycyclic aromatic hydrocarbons (PAHs) may provide insight for the characterization of high-maturity organic matter. The discrepancies in the thermal evolution between free and trapped (asphaltene-adsorbed/occluded) PAHs (phenanthrene, chrysene, pyrene, and their methylated isomers) were studied by thermal maturation (gold tubes, 300 ∼ 400 °C) experiments on a low-maturity solid bitumen from the Sichuan Basin, southwestern China. The results show that the thermal evolution of asphaltene-adsorbed PAHs is retarded compared to that of free ones. This is attributed to slight differences in reaction kinetics due to steric hindrance by the asphaltene structure. The asphaltene matrix appears to act as a reaction inhibitor leading to a retardation of the thermal evolution of the methylphenanthrene index (MPI) in asphaltene-adsorbed hydrocarbons. This could provide a possibility for maturity assessment of high-maturity organic matter. The thermal evolution of asphaltene-occluded PAHs in the experiments resulted in thermodynamically controlled isomer distributions of occluded methylphenanthrenes and methylchrysenes. However, the occluded methylpyrene isomers were hardly affected by thermal stress. They probably retained their original distributions and may serve as source indicators.

Triple oxygen stable isotope analysis of nitrite measured using continuous flow isotope ratio mass spectrometry

Oxygen stable isotopes (i.e., 16O, 17O, 18O) of nitrite (NO2−) are useful for investigating chemical processes and sources contributing to this important environmental contaminant and nutrient. However, it remains difficult to quantify the oxygen isotope compositions of NO2− due to the lack of internationally recognized NO2− reference materials with a well-known Δ(17O) value. Here we have adopted a combination of methodologies to develop a technique for measuring Δ(17O) of NO2− by reducing nitrate (NO3−) materials with internationally recognized Δ(17O) values to NO2− using activated cadmium catalyzed by chloride in a basic solution while conserving Δ(17O). The NO3− reference materials reduced to NO2− and sample NO2− unknowns are converted to N2O using sodium azide/acetic acid reagent and decomposed to O2 by passing through a heated gold tube and introduced into a continuous flow isotope ratio mass spectrometer for analysis at m/z 32, 33, and 34 for Δ(17O) quantification.The adapted method involves the following main points:•NO3− reference materials with internationally recognized oxygen isotope composition are reduced to NO2− under high pH conditions that conserve Δ(17O) values.•The NO3− reference materials reduced to NO2− and sample NO2− with unknown Δ(17O) values are reduced to N2O using chemical methods involving sodium azide/acetic acid.•The product N2O is extracted, purified, decomposed to O2, and analyzed for its isotope composition using a continuous flow isotope ratio mass spectrometer for Δ(17O) quantification. The Δ(17O) of NO2− samples are calibrated with respect to the NO3− reference materials with known Δ(17O) values.

Generation, accumulation, and distribution of Upper Paleozoic tight sandstone gas in the northeastern margin of the Ordos Basin

Tight sandstone gas in the Upper Paleozoic strata of the northeastern margin of the Ordos Basin exhibits remarkable exploration potential. The objective of this study is to characterize the generation, accumulation, and distribution of Upper Paleozoic tight sandstone gas in the Linxing–Shenfu gas fields located on the northeastern margin of the Ordos Basin. This study uses the following approaches: (1) porosimetry and permeability testing; (2) stable carbon isotope analysis; (3) organic geochemical examination; (4) gold tube pyrolysis experiments; (5) basin modeling; (6) fluid inclusion analysis; and (7) drilling and seismic data analysis. Reservoirs are classified based on the distance between the sandstone traps and source rocks: in Type I reservoirs, the sandstone traps are interbedded with the source rocks; in Type II reservoirs, the sandstone traps immediately overlie the source rocks; and in Type III reservoirs, the sandstone traps are located far from the source rocks. The three types of gas-bearing reservoirs in the Linxing–Shenfu gas fields formed between 190 Ma and 96 Ma (Early Jurassic to Late Cretaceous), and gas accumulation in the three types of reservoirs occurred during the same period. A pressure differential was created between the source rocks and neighboring sandstones as a response to gas generation, and this was the primary mechanism of gas migration and accumulation in the Type I and Type II reservoirs. The initiation and growth of the vertical faults enabled the gas to migrate from the deep source rocks along faults, eventually accumulating in the Type III reservoirs; additionally, the gas migration and accumulation were primarily driven by buoyancy. Type I reservoirs with high gas saturation was mainly distributed in regions with gas expulsion intensities greater than 7 × 108 m3/km2 and located away from the faults. Type II reservoirs with high gas saturation were predominantly distributed in regions with gas expulsion intensities greater than 10 × 108 m3/km2. Type III reservoirs with gas production capacity primarily distributed in conventional sandstone units with high reservoir quality near the faults.

Experimental Characteristics of Hydrocarbon Generation from Scandinavian Alum Shale Carbonate Nodules: Implications for Hydrocarbon Generation from Majiagou Formation Marine Carbonates in China’s Ordos Basin

The hydrocarbon source rocks of the marine carbonates of the Ordovician Majiagou Formation in the Ordos Basin are generally in the high-overmature stage and are, therefore, not suitable for hydrocarbon thermal simulation experiments. Their hydrocarbon generation potential and hydrocarbon generation characteristics are not clearly understood. Meanwhile, Nordic Cambrian carbonates are similar in lithology, parent material type, and sedimentary age, and are in the low evolution stage, which is suitable for hydrocarbon thermal simulation experiments. Therefore, in this study, we selected the Nordic carbonates for the gold tube thermal simulation experiment to analyze the content and geochemical characteristics of the thermal simulation products. The experimental results are also compared and analyzed with the characteristics of thermal simulation products of Pingliang Formation mud shale (contemporaneous with the Majiagou Formation) and Shanxi Formation coal (in the upper part of the Majiagou Formation), which are similar to the Majiagou Formation in the Ordos Basin. The results showed that the Nordic carbonate has different hydrocarbon production characteristics from the mud shale of the Pingliang Formation of the same parent material type, and although the hydrocarbon production yields of the two are not very different, the carbonate still produces methane at 600 °C. The hydrocarbon production yield of the Nordic carbonates is almost equivalent to that of type-II2 kerogen, indicating that the hydrocarbon production yield is not related to lithology and only to the organic matter type; however, the Nordic carbonate can produce a large amount of H2S. The alkane carbon isotope changes are mainly controlled by the degree of thermal evolution, showing gradual heaviness with increasing temperature. No carbon isotope sequence reversal occurred during the thermal simulation, and its distribution range is roughly the same as that of the alkane carbon isotope composition of the mud shale of the Pingliang Formation. The ethane carbon isotope composition is as heavy as −21.2‰ at the high-temperature stage, showing similar coal-type gas characteristics. The addition of calcium sulphate (CaSO4) causes the TSR reaction to occur, which has a significant impact on the methane content under high maturity conditions, reducing its content by more than 50% at 600 °C. However, the addition of CaSO4 increases the yield of heavy hydrocarbon gases, such as ethane, and promotes the production of C6-14 hydrocarbons and C14+ hydrocarbons at high-temperature stages, and the addition of CaSO4 substantially increases the yield of H2, CO2, and H2S. The thermal simulation results have implications for the hydrocarbon formation mechanism of the early Paleozoic marine carbonate formation system in the stacked basins of the Ordos Basin and the Tarim Basin in China.

Petrological Characteristics and Hydrocarbon Generation of Carbonate Source Rocks of the Permian Taiyuan Formation in Central and Eastern Ordos Basin, China

In order to evaluate the hydrocarbon generation potential and effectiveness of the carbonate source rock from the Lower Permian Taiyuan Formation of the Upper Paleozoic gas reservoirs in the central and eastern Ordos Basin, 87 core samples from the formation were analyzed through the comprehensive application of core observation, thin section analysis, lithofacies division, and organic geochemistry experiments. The results show that the carbonate source rocks of the Taiyuan Formation comprise four lithofacies types with type I–II kerogen: laminar argillaceous micritic limestone, massive micrite, massive bioclastic micritic limestone, and massive algae-clotted limestone. Among them, laminar argillaceous micritic limestone and massive micrite are favorable lithofacies for high-quality source rocks, with a TOC distribution range of 0.99% to 6.07% (average 2.56%) and 0.24% to 8.27% (average 1.77%), respectively. Hydrous gold tube pyrolysis showed that the samples of laminar argillaceous micritic limestone and massive micrite attained a peak yield of nearly 115.0 mL/g TOC (heating rate 2 °C/h) and 101.4 mL/g TOC (heating rate 2 °C/h), respectively, for C1–5 compounds. Due to the higher maturity of the samples, the hydrocarbon gases were dominated by residual kerogen pyrolysis gases and lacked liquid hydrocarbon cracking gas. Furthermore, the carbonate source rocks had weak methane absorption ability, with a maximum adsorption capacity of only about 0.15 cm3/g. In addition, the hydrocarbon gas generation of carbonate source rocks of the Taiyuan Formation was far greater than 0.2 mL/g rock, which is the lower limit standard for effective gas source rock. Therefore, the carbonate source rocks of the Taiyuan Formation should be regarded as important gas source rocks in subsequent explorations of the central and eastern Ordos Basin.

Experimental Study about Shale Acceleration on Methane Cracking

The temperature or maturity limit of methane (CH4) cracking is very useful for the determination of the most depth or the highest maturity in natural gas exploration owing to the composition of over mature gas. In this work, three series of CH4 cracking experiments were conducted under different conditions of N2 + CH4, N2 + CH4 + montmorillonite and N2 + CH4 + shale, respectively, in a gold tube system. The experimental results show that some heavy gas with negative carbon isotope composition could be generated in the three series experiments and that shale has more intense catalysis for CH4 cracking than montmorillonite. The catalysis of metal elements distributed in the minerals of shale is attributed to CH4 cracking acceleration. The shale catalysis makes the maturity threshold of CH4 substantial cracking decrease from 6.0%Ro under no catalysis, to 4.5%Ro under a shale system in a geological setting. Nevertheless, we suggest not to lightly practice natural gas exploration in shale with the maturity range of 3.5–4.5%Ro, as the maturity threshold of gas generation from oil prone organic matter distributed extensively in shale is 3.5%Ro.

Effects of synthetic maturation on phenanthrenes and dibenzothiophenes over a maturity range of 0.6 to 4.7% EASY%Ro

As the exploration target of the shale gas industry is shifting to more deeply buried strata, it is of great application value to study the distribution of molecular maturity ratios in the late dry gas zone and the mechanisms behind them for a robust thermal maturity evaluation. This study investigates the continuous molecular evolution of parent and alkylated phenanthrenes (P, A-Ps), anthracenes (An, A-An), and dibenzothiophenes (DBT, A-DBTs) during the synthetic maturation (Gold tube hydrous pyrolysis) from 0.6% to 4.7% EASY%Ro of two marine shales. The two untreated samples show different elemental composition, bulk geochemistry, and molecular geochemistry characteristics. The distribution sequence of classes with different degrees of alkylation indicates that higher reaction energy is needed for the demethylation of compounds with a lower degree of alkylation. However, the occurrence of trimethyl- and dimethyl-classes of A-Ps and A-DBTs at 550 °C (EASY%Ro: 4.4%) and 600 °C (EASY%Ro: 4.7%) is proposed to result from the breakdown of pyrobitumen at high pyrolysis temperature. The inclusion of An with P when calculating maturity ratios has an influence on their correlation with EASY%Ro at very high maturity. Common molecular thermal ratios including MPI-1, MPI-3, MPDF, MPR, and DMPR were calculated and compared with previous works. All proxies show general trends of firstly increasing and then decreasing along with thermal evolution. The separate trends in the molecular thermal evolution of the two source rocks could be attributed to the difference in organic matter composition and sedimentary facies. Two new thermal molecular maturity ratios applicable in the late gas window, i.e. 2+3-MDBT/4-MDBT and (2,4,6-TMDBT + 1,4,6-TMDBT)/(3,4,6-TMDBT + 2,6,7-TMDBT) are proposed based on the sensitivity of 2+3-MDBT, 2,4,6-TMDBT and 1,4,6-TMDBT isomers towards high maturity.

Geocatalytically generated methane from low-maturity coal and shale source rocks at low temperatures (80–120 °C) over 52 months

Geocatalytic methanogenesis has been proposed to contribute to methane generation from low-maturity coal and shale source rocks. This study contributes further evidence for geocatalytic methanogenesis from low-maturity source rocks based on long-term experiments lasting up to 52 months. Samples from the Upper Devonian New Albany Shale (Ro 0.54 %) and Springfield Coal No. 2 (Pennsylvanian; Ro 0.54 %) were heated in glass tubes at 80, 100, and 120 °C for 52 months. Sample aliquots from the Upper Cretaceous Second White Specks Formation (Ro 0.42 %) were heated in gold tubes at 80 and 100 °C for 42 months at elevated hydrostatic pressures of 100 to 300 MPa. The product gases — methane (CH4) and carbon dioxide (CO2) — were collected and quantified, and gas yields were corrected for leakage from imperfectly closed pores in samples during heating. The results show that longer heating produced more CH4. The average CH4 yields from New Albany Shale and Springfield Coal No. 2 are 0.47 and 3.0 μmol CH4 per gram of total organic carbon (TOC) over 52 months of heating. Elevated hydrostatic pressure caused lower CH4 yields from the Second White Specks Formation (3.82 to 1.20 μmol g−1 TOC), suggesting that pressure can retard methanogenesis. Maceral type critically controls the methanogenesis potential of low-maturity coal and shale source rocks. Results of this study provide important insights to the origin of natural gas in low-maturity sedimentary basins.

Petroleum Generation Kinetics and Geological Implications for Jurassic Hydrocarbon Source Rocks, Hongqi Depression, Hailar Basin, Northeast China

AbstractA sample from the Jurassic Tamulangou Fm. and two comparison samples from the Cretaceous Fm. were used to document the hydrocarbon generation kinetics and phase behaviors at two heating rates using the confined gold tube system. The results show that the different heating rates affect the reaction rates, paths and levels of organic matter evolution. The average activation energy and dominant frequency activation energy of liquid hydrocarbon are significantly lower than those of gaseous. Moreover, igneous intrusion had a positive effect on the blooming, enrichment and preservation of organic matter, promoting a Ro increase of 0.09%–1.07% in the Jurassic Tamulangou Fm. Two models were used to simulate the normal and abnormal evolution caused by thermal events combined hydrocarbon generation kinetic parameters. Thermal simulation analysis shows that oil generation was initially slow and then increased rapidly until a burial depth of 1500 m was reached at ~128 Ma. The largest hydrocarbon expulsion began at ~120 Ma, corresponding to a burial depth of 2450 m. The maximum cumulative yield is 510 mg/g TOC, and it is still in the peak period of hydrocarbon generation, which demonstrates a favorable potential for hydrocarbon exploration.

Differential hydrocarbon generation and evolution of typical terrestrial gas-prone source rocks: An example from the Kuqa foreland basin, NW China

Terrestrial gas-prone source rocks are significant for hydrocarbon gas accumulations especially in central and western basins in China. The Kuqa foreland basin in the northern margin of the Tarim Basin, NW China is rich in natural gas with recent discoveries of several large to giant gas-producing fields (e.g., the Kela-2, Dibei, Dabei-1, and Zhongqiu-1 gas fields, etc.) and a proven 3 P gas reserve of over one trillion cubic meters (TCM). This proliferous petroleum province is powered by an effective and diverse gas-prone source rock series in the basin comprising mudstone, carbonaceous mudstone, and coal seams. To date, little systematic research work has been done on the petroleum generation potential of the source rocks. This has seriously restricted the assessment of petroleum resources and further exploration in the frontier areas of the basin. A sealed gold tube pyrolysis approach was employed to simulate the oil and gas generation and cracking yields for the aforementioned three types of source rock. Compared with typical Type I and II1 kerogens, the three types of source rocks in the Kuqa foreland basin are characterized by (1) far less hydrocarbon yield (150 mg/g TOC) with comparatively larger amounts of CO2 (310 mg/g TOC), (2) a limited capacity and narrower window (0.5%–1.08% Ro) for oil generation, and (3) a much earlier secondary cracking for bulk oil to light oil and gases (>0.86% Ro for mudstone and >1.08% Ro for both carbonaceous mudstone and coal). All the source rocks are gas-prone, and significant amount of gas can still be generated during an over-mature stage. The kinetic parameters obtained allow us to model hydrocarbon generation in the Kuqa foreland basin more realistically. It is concluded that (1) two episodes of hydrocarbon generation occurred with hydrocarbon gases being mainly generated during the later stage (12–3 Ma); and (2) the depocenter of the basin is capable of supplying massive high-mature gases as late as in the Quaternary, which is crucial for the formation of giant gas fields. The findings provide new insight on the reconstruction of oil and gas accumulation processes and further hydrocarbon exploration in the basin.

Fuel compression in the magnetized cylindrical implosion driven by a gold tube heated by heavy ion beams

A magnetized cylindrical target composed of a gold tube filled with deuterium-tritium fuel plasma at low density is studied numerically in the present paper. A shock wave is produced when a heavy ion beam heats the gold along the direction of the magnetic field. The density peak of the shock wave increases with the increase in time and it propagates in the −r direction in the cylindrical tube. It seems that this wave is the supermagnetosonic wave. It is found that the Mach number M is between 6.96 and 19.19. The density peak of the shock wave increases as the intensity of the heavy ion beam increases. Furthermore, the density peak of the shock wave increases as the external magnetic field increases.

Characteristics of light hydrocarbons under the superimposed influence of biodegradation and subsequent thermal maturation

Recently, several large light oil and condensate reservoirs were discovered in the Tarim and Junggar basins (China). In these superimposed petroliferous basins, the early formed palaeo-oil reservoirs experienced complex tectonic movements, resulting in complex secondary alterations (e.g., biodegradation and water washing), known to alter the chemical composition of crude oils. Thus, crude oils previously modified by biodegradation exhibit significantly different generation potential, chemical composition, and timing of generation (in terms of light oils/condensates), during subsequent thermal alteration. To elucidate the influence of biodegradation on crude oil cracking (to form light hydrocarbons), we artificially matured four crude oils of the same origin (with varying degrees of biodegradation) to various maturity levels, using programmed-temperature gold tube closed-system pyrolysis. The yields, molecular parameters, and stable carbon isotope ratios of the light hydrocarbon products derived from the matured oils were analysed and compared. The preferential removal of n-alkanes and branched alkanes during biodegradation significantly reduced the generation potential of light hydrocarbons. Under the superimposed influence of biodegradation and subsequent thermal alteration, referred to as superimposed secondary alteration (SSA), a few hydrocarbon ratios used for oil–oil correlations were severely modified. Most maturity-related light hydrocarbon parameters of the pyrolysis products derived from the biodegraded oils achieved maximum values at a lower maturity (Easy%Ro) than that observed for non-biodegraded crude oil. At 0.5–1.4 Easy%Ro, SSA caused the depletion of 13C in most light hydrocarbons, due to an increased sourcing from the biodegradation-resistant fractions of the oil. Such carbon isotopic differences decreased with increasing maturity.

The evolution characteristics of diamondoids in coal measures and their potential application in maturity evaluation

In this study, gold tube thermal simulation experiments were carried out on the soluble components (extracts) and insoluble components (extracted coal-measure mudstones) of coal-measure mudstones, and diamondoid compounds in the pyrolysis products were quantitatively analyzed. The results showed that diamondoid compounds in the extracts and the extracted coal-measure mudstones had undergone the process of formation and decomposition during thermal evolution. Based on the quantitative composition of the extracts and the extracted coal-measure mudstones, the calculated evolution characteristics of the diamondoid compounds in the coal-measure mudstones were mainly consistent with the results of thermal simulation experiments, indicating that the formation of diamondoid compounds was primarily controlled by the original material source. Some diamondoid maturity parameters (MAI, EAI, TMAI-1) in coal-measure mudstones were consistent with the parameters of the evolution characteristics in marine shale. Therefore, the relationship between these parameters and vitrinite reflectance can be established, to calculate the maturity of marine source rocks. In addition, the evolution characteristics and some diamondoid maturity parameters in the extracts and the extracted coal- measure mudstones showed a good linear relationship, but the specific characteristics were different, which may enable the identification of kerogen cracking and secondary cracking of crude oil.

Formation mechanism of thiadiamondoids: evidence from thermochemical sulfate reduction simulation experiments with model compounds

High concentrations of thiadiamondoids together with elevated H2S are indicative of the occurrence and extent of thermochemical sulfate reduction (TSR). However, the obscure formation mechanism and accumulation timing of thiadiamondoids restricts their application in TSR evaluation. In this study, TSR simulation experiments with MgSO4 and three model compounds, namely adamantane, 1-methyladamantane, and diamantane, were performed in gold tubes in high pressure reactors. The gaseous hydrocarbons and liquid products generated from the model compounds by TSR were identified and quantified. According to the H2S yields from the three model compounds, the susceptibility to TSR of three model compounds is 1-meththyladamantane > adamantane > diamantane. Four types of compound groups with diamondoid structure were detected in the liquid products: from high to low abundance these are diamondoidyl ketones, diamondoidyl alcohols, diamondoidthiols and thiadiamondoids, respectively. Thiadiamondoids can be generated from C0-alkylated diamondoid species by TSR. During the TSR process, the concentrations of both diamondoidyl alcohols and diamondoidthiols first increased within the maturity range 0.89–1.09 Easy%Ro and then decreased at maturity > 1.09 Easy%Ro. The rapid decrease in concentration of diamondoidthiols does not correspond to increasing thiadiamondoids, suggesting that diamondoidthiols may not be reaction intermediates for thiadiamondoids in laboratory experiment conditions. In the TSR simulation experiments, slowly increasing concentrations of diamondoidyl ketones correspond to slowly increasing concentrations of thiadiamondoids. For the synthesis mechanism of thiaadamantanes derived from thiaadaamantane-4,8-dione, we propose that the diamondoidyl ketones could be reaction intermediates in thiadiamondoid formation. The thiadiamondoids in petroleum could have two different formation mechanisms: (1) low-temperature cationic carbon ion rearrangement in diagenesis to early catagenesis stages, in which thiadiamondoids are derived from the diagenetic products of polycyclic thiols in the source rock; and (2) a free sulfur radical mechanism that occurs in the TSR process at high temperature in the middle catagenesis to metagenesis stages. During the TSR process, free sulfur radicals attack the diamondoidyl ketones generated in the first stage of TSR and open the cage structure. Then the carbonyl carbon atom is replaced by a sulfur atom, followed by cyclization to form thiadiamondoids. Based on the H2S yields in the TSR simulation experiments with diamondoid model compounds, most thiadiamondoids formed in the second stage of the autocatalyzed TSR process within the maturity range of 1.09–1.21 Easy%Ro.

Extensive characterization of Marshak waves observed at the LIL laser facility

We detail results of an experiment performed at the Ligne d'Intégration Laser facility aimed at studying supersonic and diffusive radiation front propagation in low-density SiO2 aerogel (20 and 40 mg/cm3) enclosed in a gold tube, driven by thermal emission from a laser-heated spherical gold cavity. The evolution of the front is studied continuously by measuring its self-emission with a 1D (one-dimensional) time-resolved soft x-ray imager. Measurement is performed along (through a 200-μm-wide observation slit) and at the exit of the tube giving access to the dynamics and the curvature of the front. Experimental results are then compared successfully to results from the 3D (three-dimensional) radiation hydrodynamics code TROLL, which shows that if continuous tracking of the front position is accessible with this experimental scheme, measurement of its maximum radiation temperature is on the contrary affected by radiation closure of the observation slit. 3D simulations also indicate that this effect can even be worsened if one includes pointing errors of the x-ray imager. Radiation temperature along the tube was then inferred by combining results from the imager to a wall shock breakout time measurement using a velocity interferometer system for any reflector and results from a broadband x-ray spectrometer used to determine the temperature at the exit of the tube. A decrease in the radiation temperature along the tube is observed, the decrease being more important for the higher SiO2 aerogel density.

PENGARUH FLUKTUASI HARGA EMAS DAN PROMOSI TERHADAP MINAT NASABAH PADA PRODUK TABUNGAN EMAS DI PEGADAIAN SYARIAH JELUTUNG

This study aims to determine the effect of gold price fluctuations and promotions on customer interest in gold savings products at the Jelutung Sharia Pawnshop. This study uses descriptive quantitative research methods. The research was conducted at the Office of PT. Pegadaian (Persero) Syariah which is located at Jl. DI Panjaitan No.30,Kebun Handil, Kec. Jelutung, Jambi City, Jambi. This study uses multiple regression analysis tools. This study uses a population of 2,151 customers of the gold tube of Pegadaian Syariah Jelutung Branch with sampling using the slovin formula which produces a sample of 100 customers. The results of this study are partially positive and significant effect of Price Fluctuations on Customer Interest in gold savings products at Pegadaian Syariah Jelutung. Promotion has an effect on customer interest in gold savings products at the Jelutung Sharia Pawnshop. Simultaneously, price fluctuations and promotions have an effect on customer interest in gold savings products at the Jelutung Sharia Pawnshop

Evaluation of Hydrocarbon Generation Potential of Laiyang Formation Source Rocks in Ri-Qing-Wei Basin, Eastern Shandong

The Ri-Qing-Wei Basin is a newly discovered Late Mesozoic rift basin on the eastern Shandong coast in recent years. Thick, continuous deposited source rocks are found in the Lingshan Island scientific drilling project. Therefore, it is necessary to evaluate the distribution and hydrocarbon generation potential of source rocks in this area. Organic geochemical experiments were carried out on samples from the core of LK-1 and outcrops in the Lingshan Island, the Laoshan area, and the Jimo Zhougezhuang area to evaluate the maturity, abundance, and type of organic matter in source rocks. The results show that the cumulative thickness of the source rocks in the study area is more than 500 m, and the TOC content is generally greater than 1.0%. The organic matter type is good (mainly type II1 and type II2 kerogen) and the Ro value is more than 2.0. The thermal evolution degree of the organic matter is high with natural gas predominantly generated. We carried out Rock-Eval, PY-GC and gold tube experiments on low-maturity samples of Laikong 2 and established a chemical kinetic model to quantitatively evaluate the study area in combination with sedimentary burial history and thermal history data. The results show that the total resources of the five sags in the study area are about 476 billion cubic meters, and the average resource intensity is about 82.2 million cubic meters/km2. Among them, the resource intensities of the Lingshan Island Sag and Laoshan Sag are 112.6 million cubic meters/km2 and 98.8 million cubic meters/km2, respectively. Studied sites are “small and fertile” and may be used as favorable exploration prospect areas.