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The vertical bearing capacity of circular surface foundations is the key to calculating that of suction caissons, and the latter is generally expressed as a multiple of the former. In the existing research, the soil around shallow foundations is considered homogeneous, and the sand friction angle is constant. In fact, the friction angle is affected by the compactness and stress level. For sand with a certain relative density, the friction angle varies with the soil depth. Therefore, a method, considering the effect of compactness and stress level on the friction angle, is proposed to calculate the vertical bearing capacity of circular surface foundations. Compactness and stress level are characterized by relative density and soil depth, respectively. The main innovation of this method is that the relationship between the friction angle, relative density, and soil depth is obtained, and the friction angle is expressed as a function of relative density and soil depth. This varying friction angle, after proper handling, can be used for vertical bearing capacity calculations. Combined with an example, the applicability of this method is verified. The research shows that the calculated results are in good agreement with the test results when the appropriate basic parameters are determined. • An innovative method for bearing capacity of flat foundations. • Sand friction angle depending on compactness and stress level. • Average friction angle within the depth range affected by the load. [ABSTRACT FROM AUTHOR]

Rigid piles are common foundations for offshore wind turbines. Scour around piles leads to the loss of surrounding soil, which seriously threatens the safe operation of offshore wind turbines. However, most of the existing experimental studies on the scour effects on marine foundations are carried out in the test box without a hydraulic environment, resulting in deviations between the test results and the actual ocean engineering. Therefore, a test method to study scour effects on the lateral response of rigid piles is proposed. The key to this test method lies in the design of four types of parameters: pile, soil, hydraulic (wave and current), and load. Considering the characteristics of scour tests and scour effects tests, the design method of the four types of parameters is proposed. Combined with an example, the test method is described in detail. Subsequently, the defects of this test method are discussed. The research shows that this test method is a good attempt to study the loss of lateral ultimate capacity and the increase of cyclic cumulative deformation of rigid piles under real scour conditions. • How to study the scour effect in a flume tank? • Four types of parameters are designed. • The dual properties of hydraulic parameters are considered. • The actual load characteristics of rigid piles are considered. [ABSTRACT FROM AUTHOR]

[Display omitted] • Impacts of granule properties on reactors performing partial nitritation/anammox. • Big anammox-enriched granules inoculated for high TN removal & low N 2 O production. • Optimum boundary layer thickness increased with decreasing diffusivity in granules. This work studied the impacts of key granule properties on the granular reactor performing partial nitritation/anammox from the modeling perspective. The results could guide not only future reliable modeling but also practical startup/operation of the reactor. To achieve high total nitrogen (TN) removal whilst avoiding significant N 2 O production, inoculated granules should be big and anammox-enriched. The optimum boundary layer thickness for maximum TN removal increased with the decreasing diffusivity of soluble components in the granule structure. Even though a thick boundary layer could protect anammox bacteria from elevated dissolved oxygen (DO) (e.g., 0.5 g-O 2 /m3) and obtain high TN removal (>90.0%) and low N 2 O production (<1.8%), even complete removal of the boundary layer would fail to provide sufficient substrate for anammox and therefore couldn't increase TN removal to 90.0% and decrease N 2 O production to <2.4% at insufficient DO (e.g., 0.3 g-O 2 /m3 in the presence of lifted influent NH 4 + concentration). [ABSTRACT FROM AUTHOR]

• Scour tests and lateral static load tests were conducted. • A three-dimensional scour hole model under steady current and its analytical expression is proposed. • The scour effect is positively related to the scour depth, and has nothing to do with the load eccentricity. • A formula for evaluating the ultimate lateral capacity of rigid piles after scour is presented. The rigid pile with a large diameter and a small slenderness ratio is the most widely used foundation for offshore wind turbines. Scour around piles seriously threatens the safe operation of offshore wind turbines, so its effects on rigid piles need to be studied urgently. In this paper, scour tests under steady current and static lateral load tests after scour are conducted. According to the results of scour tests, a three-dimensional scour hole model suitable for engineering reality and its analytical expression are proposed. Then, the results of load tests indicate that scour reduces the ultimate lateral capacity of foundations, and the percentage of reduction is related to the current direction, whereas does not change with load eccentricity. Finally, a preliminary formula for evaluating the ultimate lateral capacity of rigid piles after scour is presented, which can easily and quickly determine the upper and lower limits of scour effects. [ABSTRACT FROM AUTHOR]

Abstract: Dendritic cells (DCs) play a critical role in generating anti-tumor immunity. DC functional defect has been related to the growth and progression of various human cancers. In esophageal squamous cell carcinoma (ESCC), the examination of DCs using immunohistochemistry (IHC) with anti-S100 antibody has demonstrated an increased infiltration of DCs into the tumor mass, however, the distribution patterns of DCs at different maturation states in ESCC are not fully evaluated. In this study, we immunohistochemically analyzed the DC maturation status by examining the S100-positive DCs, CD1α-positive immature DCs (iDCs), and CD208-positive mature DCs (mDCs) and their distribution patterns in 45 ESCCs and 10 control tissues. The IHC analysis showed that the number of S100-positive DCs was increased in both the cancer epithelium and tumor stroma. Further phenotypic analyses revealed that intraepithelial DCs in the cancer mass were predominantly CD1α-positive iDCs. Whereas DCs presented in the tumor stroma were exclusively CD208-positive mDCs, CD208-positive mDCs were particularly dense in the margin of cancerous lesions and formed clusters with CD3-positive lymphocytes. The number of CD208-positive mDCs in the tumor mass was significantly lower than the number of CD1α-positive iDCs. The current results suggest that ESCC tissue comprises a high frequency of iDCs in the cancerous epithelium and a low density of mDCs in the tumor stroma. Such a distinct distribution pattern may reflect the ongoing DC tracking in ESCCs. [Copyright &y& Elsevier]

Abstract: The aims of this study were (1) to evaluate the effect of high-dose erythropoietin (EPO; 5000U/kg) on expression of inducible nitric oxide synthase (iNOS) in the facial nucleus after facial nerve transection; and (2) to explore whether this effect is relevant to facial motor neuron survival. Forty-two Wistar rats (250–300g) of both sexes were used in this study. The right facial nerves of 40 rats were transected at the level of the stylomastoid foramen, with the left sides left untreated. The rats were randomly divided into 2 groups: (1) EPO group (treated with EPO twice per week at a dose of 5000U/kg bodyweight); (2) saline group (treated with saline). The 2 rats that did not undergo axotomy served as the control group. After axotomy, expression of iNOS in the facial nucleus was detected by iNOS immunohistochemistry at various time points, and the number of surviving motor neurons was counted in coronal paraffin sections of the facial nucleus. In both the EPO and saline groups, axotomy caused a significant increase in iNOS expression in the facial nucleus at 1, 2, 3, and 4weeks after axotomy. iNOS expression was lower in the EPO group than in the saline group. At 2, 3 and 4weeks after axotomy, a significantly greater proportion of facial motor neurons survived in the EPO group than in the saline group. These results indicate that a high dose of EPO attenuates the increase in iNOS expression in the facial nucleus after facial nerve transection, and thus may enhance the survival of facial motor neurons. [Copyright &y& Elsevier]

• Enrichment of comammox Nitrospira in a mainstream SBR in the step-feeding mode. • Candidatus Nitrospira nitrosa was the dominant (∼95 %) comammox species enriched. • Identification of K NH4 -N and K O2 for enriched comammox bacteria-dominant sludge. • Floccular sludge enriched with comammox Nitrospira possessed low N 2 O and NO yields. The discovery of complete ammonium oxidation (comammox) has subverted the traditional perception of two-step nitrification, which plays a key role in achieving biological nitrogen removal from wastewater. Floccular sludge-based treatment technologies are being applied at the majority of wastewater treatment plants in service where detection of various abundances and activities of comammox bacteria have been reported. However, limited efforts have been made to enrich and subsequently characterize comammox bacteria in floccular sludge. To this end, a lab-scale sequencing batch reactor (SBR) in the step-feeding mode was applied in this work to enrich comammox bacteria through controlling appropriate operational conditions (dissolved oxygen of 0.5 ± 0.1 g-O 2 /m3, influent ammonium of 40 g-N/m3 and uncontrolled longer sludge retention time). After 215-d operation, comammox bacteria gradually gained competitive advantages over counterparts in the SBR with a stable nitrification efficiency of 92.2 ± 2.2 %: the relative abundance of Nitrospira reached 42.9 ± 1.3 %, which was 13 times higher than that of Nitrosomonas , and the amoA gene level of comammox bacteria increased to 7.7 ± 2.1 × 106 copies/g-biomass, nearly 50 times higher than that of conventional ammonium-oxidizing bacteria. The enrichment of comammox bacteria, especially Clade A Candidatus Nitrospira nitrosa , in the floccular sludge led to (i) apparent affinity constants for ammonium and oxygen of 3.296 ± 0.989 g-N/m3 and 0.110 ± 0.004 g-O 2 /m3, respectively, and (ii) significantly low N 2 O and NO production, with emission factors being 0.136 ± 0.026 % and 0.023 ± 0.013 %, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]

• Adding PAC or PAM to the plume can enhance particle settling. • The optimal types and dosage of flocculants to enhance settling have been revealed. • The settling velocity of particles with or without the flocculants was analyzed. • Flocculation enhances settling by increasing particle size. The sediment plumes produced by deep-sea mining operations have been observed to cause detrimental effects on the ecological environment. However, there is currently no effective measure available to counteract these plumes. In this study, we propose a potential solution to this problem by utilizing flocculants to expedite the settling of particles. Through several experiments investigating the impact of various types and concentrations of flocculants on plumes prepared from sediment samples in potential mining regions, we found that the slow settling velocity of single clay particles leads to the formation of a relatively thick plume suspension layer on a spatial scale, which fails to decay for a considerable period of time, causing turbidity in the water. However, when suitable flocculants are employed, micron-scale sediment particles can be flocculated into centimeter-scale flocs, which significantly increases the settling velocity of the suspended matter. We have identified the appropriate flocculant types and dosages that exhibit optimal efficacy in facilitating the sedimentation of deep-sea sediment particles. Furthermore, our experimental findings have led to the identification of the flocculation mechanism that takes place between deep-sea sediment particles and flocculants. We conducted a comparative analysis of the settling velocity of deep-sea sediment particles both with and without flocculants, which provided additional insight into the promotion of sedimentation by flocculation. [ABSTRACT FROM AUTHOR]

The design and synthesis of dual aromatase inhibitors/selective estrogen receptor modulators (AI/SERMs) is an attractive strategy for the discovery of new breast cancer therapeutic agents. Previous efforts led to the preparation of norendoxifen ( 4 ) derivatives with dual aromatase inhibitory activity and estrogen receptor binding activity. In the present study, some of the structural features of the potent AI letrozole were incorporated into the lead compound (norendoxifen) to afford a series of new dual AI/SERM agents based on a symmetrical diphenylmethylene substructure that eliminates the problem of E , Z isomerization encountered with norendoxifen-based AI/SERMs. Compound 12d had good aromatase inhibitory activity (IC 50 = 62.2 nM) while also exhibiting good binding activity to both ER-α (EC 50 = 72.1 nM) and ER-β (EC 50 = 70.8 nM). In addition, a new synthesis was devised for the preparation of norendoxifen and its analogues through a bis-Suzuki coupling strategy. [ABSTRACT FROM AUTHOR]

• Reactions in natural and artificially simulated kerogen are similar at low maturity. • The activation energy is more susceptible to the maturity compared to TOC. • Activation energy increases sequentially for retained oil, shale and kerogen. • Aromatic functional groups coincide with reduction of aliphatic functional groups. Shale oil is a significant alternative energy, and in-situ conversion technology can achieve large-scale yield. The objective is to investigate the activation energy characteristics of kerogen at different maturities and total organic carbon contents. The study compared the activation energy of shale, kerogen and retained oil. The correlation between organic matter structure and in-situ conversion mechanism were also studied. In order to achieve the above objectives, the Chang 7 Formation in the Ordos Basin was used as an example. The methods include open and semi-open hydrocarbon generation thermal simulation experiment, Fourier transform infrared spectroscopy, solid-state nuclear magnetic resonance and other tests. The results indicate that the hydrocarbon generation in natural and artificially simulated kerogen samples are similar at low maturity. The proportions of low and main activation energy groups decrease with maturity, while those of high activation energy groups increase. TOC has an impact on activation energy but is not the primary factor. The proportion of low activation energy groups at different maturity stages is greater in shale than in kerogen. The activation energy of retained oil is smaller than that of shale. The activation energy increases sequentially for retained oil, shale and kerogen. The area of aliphatic carbon is significantly greater than that of aromatic carbon at low maturity. With increasing maturity, the areas of both gradually converge, and aromatic carbon surpasses aliphatic carbon by Ro around 1.1 %. Aromatic carbon and hydroxy/carboxylic carbon are mainly derived from the consumption and transformation of aliphatic carbon. The aliphatic carbon structure is mainly composed of methylene carbon, and aromatic structure coexists as single and multiple rings. There is no significant aromatic ring condensation in the maturity Ro = 0.5 ∼ 1.1 %. Different maturities affect the structure of kerogen, with TOC having a small impact. As the thermal maturity increases, the increase in the aromatic component leads to a gradual increase in the proportion of average and high activation energy groups. HI, H/C and f ali exhibit a decreasing trend with maturity, indicating a reduction in the hydrocarbon generation potential. The study conducted novel experiments, which can provide a scientific basis for the in-situ conversion process of shale. [ABSTRACT FROM AUTHOR]

The cracking and stability of liquid oil is of critical importance in the exploration of deep petroleum accumulations. Numerous studies have been conducted on oils to investigate the cracking process. However, limited research has been directed to the cracking of oil with different maturities. Here, gold tube pyrolysis experiments were conducted on lower maturity normal oil (LMO) and higher maturity condensates (HMC) samples to investigate the compositions of pyrolysis products and to estimate the stability of oil during continuous deep burial. The results indicated that oil cracking can be generally divided into two stages, namely light oil generation stage and gas generation, with a maturity boundary approximately Easy R o ∼1.5%. Most of oil cracking gas was generated at EasyRo ∼2.4 %, with maximum mass yield of C 1-5 is 553.8 mg/g and 609.4 mg/g for LMO and HMC, respectively. The difference in gas yields between HMC and LMO indicates the higher gas potential during the cracking of light oil components. An obvious increase in the C 19 /C 23 tricyclic parameters was observed with enhanced thermal maturity, which indicates the interpretation of tricyclic parameters of high mature oils should be made with caution. Although high maturity also influenced the ratios of gammacerane/αβ C 30 hopane (G/H) and 4-methylsteranes/C 29 steranes (4MSI), the altered corresponding values still fall within the suggested discriminating zones for the Dongying and Shahejie Formation source rocks. Thus, the G/H and 4MSI parameters can be utilized to characterize the high mature oil with R o <1.3% in the Bohai Bay Basin (BBB) or other basins. The calculated activation energy of C 1-5 generation for LMO displays a more discrete and lower distribution compared to the HMC, which may indicate relatively lower stability heavy hydrocarbons in LMO. Based on previous studies of petroleum charge, the kinetics of C 1-5 generation of LMO were extrapolated to geological conditions, yielding a maximum depth of 5750 m for the occurrence of liquid oil in the BBB. This study underscores the high thermal stability of light oil fractions, which indicates that deep high mature oils may represent the preservation of directly charged light oil or the transformation by in-reservoir cracking of normal oil associated with continuous burial. • Compositions and yields of products during thermal cracking of oils with different maturities were examined. • The C 1-5 yield for high mature oil is higher than that of normal mature oil. • The validity of some source-related biomarkers was estimated. • Light oil displays higher thermal stability than normal oil. [ABSTRACT FROM AUTHOR]

Highlights: [•] Pyrolysis of type II kerogens with and without oil expulsion was performed. [•] Generated gas and oil and residual solids in the pyrolysis were characterized. [•] Oil expulsion strongly impacts the amount and composition of oil and gas. [•] Oil expulsion causes residual solids, oil and gas to be more enriched in 13C. [•] Oil expulsion influences data pattern in genesis crossplots. [ABSTRACT FROM AUTHOR]

Abstract: Three sets of pyrolysis experiments were performed for oil alone, pyrobitumen alone and oil plus pyrobitumen at two heating rates of 2°C/h and 20°C/h in confined systems (gold capsules). The results of these experiments demonstrated that pyrobitumen significantly promoted the generation of methane while not only inhibiting the generation, but also accelerating the cracking of wet gases during oil cracking experiments in confined systems. Furthermore, the cracking rate of wet gases increases with pyrobitumen/oil ratios. As a result, C1/ΣC1–5 ratio is significantly higher in the experiment of oil plus pyrobitumen than oil alone at the same temperature conditions. Although the amount of methane increased, the weight of the total gaseous hydrocarbons decreased and the volume of the total gaseous hydrocarbons remained unchanged with the addition of pyrobitumen. This result can be ascribed to some oil and wet gas components being combined with the pyrobitumen phase and released later mainly as methane at higher temperatures and maturities. The activation energies for the generation and cracking of wet gases decrease with the carbon number and are relatively lower in the experiments of oil plus pyrobitumen than oil alone. The distribution ranges of the activation energies for the generation of wet gases also decrease with the carbon number. [Copyright &y& Elsevier]

Abstract: The aim of this work was to assess the ability of four representative fractions (saturated, aromatic, polar and asphaltene) of crude oils to participate in thermochemical sulfate reduction (TSR) and thus to evaluate their pyrolysis behaviors, which is of great relevance to the stability of reservoir hydrocarbons. Experiments simulating reactions between oil fractions and magnesium sulfates (anhydrous MgSO4 and hydrated MgSO4·7H2O) at a constant temperature of 420°C and under a pressure of 50MPa were conducted over a period of 24h using a gold tube confined system. The yields of non-hydrocarbon and hydrocarbon gases and their δ13C values were measured and compared in order to reveal the main control factors on TSR under practical geological conditions. In pure blank pyrolysis experiments with oil fractions cracking without TSR, different pyrolysis rates were seen for the four petroleum fractions with a sequence of saturated>asphaltene>polar≫aromatic. Minimal yields of C1–C5 hydrocarbons in the aromatic fraction can mainly be attributed to the greater thermal stability of aromatic compounds, which was also reflected by their positive δ13C signatures. Upon addition of anhydrous MgSO4 to the saturated fraction, a small quantity of H2S was generated, indicating that only a weak TSR occurred in this series. Upon addition of hydrated MgSO4·7H2O to the four petroleum fractions, high yields of H2S were generated, indicating that water plays an important role in the occurrence of TSR. The presence of nitrogen and/or oxygen containing heteroatomic compounds in the polar fraction decreases the yields of H2S when subjected to MgSO4 TSR. Similar yields of H2S from the saturated, aromatic and asphaltene fractions revealed that TSR occurring in the aromatic fractions is unlikely to be associated with the opening of benzene rings but closely related to availability of hydrogen atom in the alkyl moiety. The addition of MgSO4·7H2O, TSR can significantly enhance the yield of methane, also reflected in an increase in its δ13C value. Besides methane, the other gaseous hydrocarbons (C2,C3) in the MgSO4·7H2O series also showed some less negative δ13C values relative to the blank series, irrespective of the fraction type. Relative to the other fractions (saturated, polar and asphaltene), low yields of C1–C5 gaseous hydrocarbons derived from the aromatic fraction could be attributed to the greater stability of the benzene ring and indicate that paraffinic oils may be more susceptible to thermal or thermochemical alterations than aromatic oils under the conditions of real subsurface reservoirs. [Copyright &y& Elsevier]

Abstract: Three sets of pyrolysis experiments were performed for oil alone, oil plus montmorillonite and oil plus calcite at two heating rates of 2°C/h and 20°C/h in confined systems (gold capsules). The main observations can be listed as follows: (1) the ratios of i-C4/n-C4, i-C5/n-C5 and the amount of butanes (n-butane+ i-butane) are significantly higher in the experiment for oil plus montmorillonite than oil alone and oil plus calcite, indicating the acidic catalysis by montmorillonite; (2) at low conversion values (<0.5 for methane generation), the formation rates of methane and total hydrocarbon gases in all the three experiments are very similar, demonstrating that neither montmorillonite nor calcite significantly influence the primary cracking of oil components (C6+) into gaseous hydrocarbons (C1–C5), while at high conversion values (>0.5 for methane generation), the formation rates of methane and the total hydrocarbon gases in the oil plus calcite experiment are relatively lower than the other two experiments, demonstrating that calcite hindered the secondary cracking of wet gases (C2–C5) into methane; (3) both montmorillonite and calcite greatly reduce the carbon isotope fractionation during methane formation from oil cracking, resulting in substantially higher methane δ13C values in the oil plus montmorillonite or calcite experiments than for oil alone. Based on the kinetic parameters determined from the oil cracking experiments, the predicted temperatures and vitrinite reflectance values (% Easy R o) for the formation of methane and the total gaseous hydrocarbons at 10% conversion are 190–192°C and 184–187°C, and 1.90–1.93% and 1.80–1.86%, respectively at the heating rate 1°C/my, demonstrating that oils are very thermally stable in sedimentary basins. [Copyright &y& Elsevier]

Even though modeling has been frequently used to understand the autotrophic deammonification-based membrane-aerated biofilm reactor (MABR), the relationships between system-specific biofilm property settings and model predicted N 2 O production have yet to be clarified. To this end, this study investigated the impacts of 4 key biofilm property settings (i.e., biofilm thickness/compactness, boundary layer thickness, diffusivity of soluble components in the biofilm structure, and biofilm discretization) on one-dimensional modeling of the MABR, with the focus on its N 2 O production. The results showed that biofilm thickness/compactness (200–1000 μm), diffusivity of soluble components in the biofilm structure (reduction factor of diffusivity: 0.2–0.9), and biofilm discretization (12–28 grid points) significantly influenced the simulated N 2 O production, while boundary layer thickness (0–300 μm) only played a marginal role. In the studied ranges of biofilm property settings, distinct upper and lower bounds of N 2 O production factor (i.e., the percentage ratio of N 2 O formed to NH 4 + removed, 5.5% versus 2.3%) could be predicted. In addition to the microbial community structure, the N 2 O production pathway contribution differentiation was also subject to changes in biofilm property settings. Therefore, biofilm properties need to be quantified experimentally or set properly to model N 2 O production from the MABR correctly. As a good practice for one-dimensional modeling of N 2 O production from biofilm-based reactors, especially the MABR performing autotrophic deammonification, the essential information about those influential biofilm property settings identified in this study should be disclosed and clearly documented, thus ensuring both the reproducibility of modeling results and the reliable applications of N 2 O models. [Display omitted] • Impacts of 4 key biofilm properties on modeling N 2 O production from MABR. • Distinct upper and lower bounds of modeled N 2 O production factor (5.5% vs 2.3%). • Disclosure of quantified/set biofilm properties as a good modeling practice. [ABSTRACT FROM AUTHOR]

Improved understanding of the hydrogen sulfide (H 2 S) origins is of significant importance for petroleum exploration, exploitation and refinement due to it being highly toxic and corrosive. H 2 S was discovered from the Qianjiang Formation (Eq) in the northern area and Xinggouzui Formation (Ex) in the southern area of the Qianjiang Depression, Jianghan Basin, China. The sulfur isotopic compositions of H 2 S, water-dissolved sulfates and oils and chemical compositions of volatile organic sulfur compounds (VOSCs) in natural gas as well as molecular and stable carbon isotopic compositions of oil and gas samples were measured to decipher the specific generation pathways of H 2 S. The conventional wisdom relays on bacteria sulfate reduction (BSR) for producing H 2 S because of the current low thermal regime (<80 °C). Crude oils, H 2 S and water-dissolved sulfates are progressively enriched in 34S. The δ 34S values of H 2 S are around 12.0–32.0‰ lower relative to that of the dissolved sulfates and 0.8–24.0‰ greater relative to that of crude oils. This indicates that the current major contribution of H 2 S is actually related to BSR according to the S isotopic fractionation levels in BSR. The secondary contribution of H 2 S is attributed to be thermogenic mainly by thermal cracking alteration of organic matters (TCA). This clue is provided by the distribution patterns of VOSCs in natural gas rather than S isotope of crude oils, H 2 S and water-dissolved sulfates due to the limited input of TCA-associated H 2 S. The Eq TCA-associated gases are significantly enriched in thiols, sulfides, and alklyated thiophenes, the Ex BSR-associated gases contain mainly thiols and a little bit sulfides and alkylated thiophenes. The relevant early-matured Eq oils are also rich in labile organosulfur compounds, favoring the generation of VOSCs by TCA. VOSCs detected on the artificially pyrolyzed gaseous products of Eq rock and oil both show the identical distribution patterns as those of Eq natural gas samples, supporting the occurrence of TCA-associated H 2 S in the Eq reservoirs. The positive correlation between i -C 4 / n -C 4 and H 2 S concentration for Eq gases indicates the catalytic effects of clays, promoting the generation by non-biological processes within the low thermal regimes. This study presents a novel method to clarify the origins of H 2 S by VOSCs in natural gas and improves our understanding of H 2 S generation pathways within low-temperature regime in nature. • The origins of H 2 S in the Qianjiang Depression investigated. • Bacteria sulfate reduction (BSR) makes the major contribution. • Thermal cracking alteration of organic matters (TCA) has the minor contribution. • BSR-associated gases are depleted in volatile organic sulfur compounds. • TCA-associated gases are enriched in volatile organic sulfur compounds. [ABSTRACT FROM AUTHOR]

• Confined pyrolysis was performed on seven coals. • Kinetic parameters for oil and HC gas generation were determined for these coals. • Total oil and HC gas yields contribute 38–53% of S1 + S2 at EASY%Ro 1.19–1.50. • A major portion of the HC gas is generated from these coals at EASY%Ro >2.19. Confined pyrolysis experiments (gold capsules) were performed to determine the yields and kinetic features for petroleum formation for seven coal samples with hydrogen index (HI) ranging from 57 to 278 mg HC/g TOC and maturities of 0.58–0.74 %Ro from coal pits within Triassic–Jurassic strata in the Kuqa Depression, China. Gases and liquid yields were measured at regular intervals as the sealed tubes were heated at 2 and 20 °C/h and total thermal stress calculated as a vitrinte reflectance equivalent (%Re) using Easy%Ro. The total confined pyrolysate yields of oil and gaseous hydrocarbons at 1.19–1.50 %Re only account for a portion (38–53%) of the releasable moieties in measured by Rock-Eval (open) pyrolysis, suggesting that a substantial portion of (47–62%) of these moieties was rearranged and incorporated into polyaromatic residual solids. At maturities >1.87 %Re, the solid residues of the seven coals have very similar gas generative potentials (ΣC 1–5), which are substantially higher than their quality index (QI = (S1 + S2)/TOC) with differences ranging from 20 to 40 mg/g TOC. This result can be mainly ascribed to the differences both in methane formation mechanisms and final thermal stress levels between open (2.25 %Re) and confined pyrolysis (4.44 %Re). Only a minor portion of gaseous hydrocarbons (∼32% and 44% for the Jurassic and Triassic coals, respectively) was generated up to 2.19 %Re while the major portion was generated at higher maturities. Under a heating rate of 5 °C/My, the Jurassic and Triassic coals are modeled to become effective gas source rocks with gas yield (ΣC 1–5) > 20 mg/g TOC at maturities of >1.76 %Re and 1.59 %Re, respectively. The abundant gaseous hydrocarbons found in the Kuqa Depression can be mainly ascribed to the high maturities of coal source rocks (>2.0 %Ro), in combination with excellent seal of thick salt and gypsum for the gas reservoirs. [ABSTRACT FROM AUTHOR]

Highlights • The thermal stability of thiadiamondoids was investigated. • Thiadiamondoids can be severely degraded at %Ro ≥ 2.0. • Thiadiamondoids are far less stable than diamondoids and gaseous hydrocarbons. • C 0–1 dibenzothiophenes are more stable than thiadiamondoids. • The extent of TSR may be underestimated using thiadiamondoids. Abstract The abundance of 2-thiadiamondoids is currently utilized to assess the extent of thermochemical sulfate reduction (TSR). However, these compounds are ultimately degraded to small molecules with increasing temperature in deep hot reservoirs, resulting in uncertainty in their use as a proxy to evaluate the extent of TSR. In this study, the thermal stability of 2-thiadiamondoids was determined from variations in their abundance upon pyrolysis at different temperatures using an oil enriched in thiadiamondoids. The results demonstrated that these compounds were generally stable at Easy%Ro ≤ 1.0, followed by partial destruction at Easy%Ro = 1.3–2.0 and intensive decomposition at Easy%Ro ≥ 2.0–2.3, suggesting the potential underestimation of the TSR extent at the highly mature to over mature stages. The thermal stability of 2-thiadiamondoids and diamondoids strongly depended on their cage numbers, which presented an increasing trend with higher cage numbers. However, diamondoids were far more stable than 2-thiadiamondoids and were still thermally stable even up to Easy%Ro = 1.8–2.3. The thermal stability of dibenzothiophenes (DBTs) showed a decreasing trend with increases in alkyl substituted carbon numbers. They were thermally stable at Easy%Ro ≤ 1.0–1.8 and can be seriously cracked at Easy%Ro ≥ 1.8–3.0. The C 0 -DBT and C 1 -DBTs were more stable than thiadiamondoids, but C 3 -DBTs showed the opposite trend. The thermal stability of gasoline range hydrocarbons showed a trend of CH 4 > C 2 H 6 > C 3 H 8 > C 4–5. CH 4 and C 2 H 6 were much more stable than diamondoids, while C 3–5 hydrocarbons were only thermally stable at Easy%Ro ≤ 1.8–2.3 and severely degraded at Easy%Ro ≥ 2.6–3.0. The C 3 H 8 and 2-cage diamantanes, C 4–5 compounds and 1-cage adamantanes had a similar thermal stability. Therefore, to accurately assess the TSR extent should be made using thiadiamondoids, diamondoids and C 0–1 -DBTs, even gasoline range hydrocarbons, rather than thiadiamondoids alone, if gases are well preserved within petroleum reservoirs in the subsurface. [ABSTRACT FROM AUTHOR]

Abstract Subduction is a key process for linking the carbon cycle between the Earth’s surface and its interior. Knowing the carbonation and decarbonation processes in the subduction zone is essential for understanding the global deep carbon cycle. In particular, the potential role of hydrocarbon fluids in subduction zones is not well understood and has long been debated. Here we report graphite and light hydrocarbon-bearing inclusions in the carbonated eclogite from the Southwest (S.W.) Tianshan subduction zone, which is estimated to have originated at a depth of at least 80 kilometers. The formation of graphite and light hydrocarbon likely results from the reduction of carbonate under low oxygen fugacity (∼FMQ - 2.5 log units). To better understand the origin of light hydrocarbons, we also investigated the reaction between iron-bearing carbonate and water under conditions relevant to subduction zone environments using large-volume high-pressure apparatus. Our high-pressure experiments provide additional constraints on the formation of abiotic hydrocarbons and graphite/diamond from carbonate-water reduction. In the experimental products, the speciation and concentration of the light hydrocarbons including methane (CH 4), ethane (C 2 H 6), and propane (C 3 H 8) were unambiguously determined using gas chromatograph techniques. The formation of these hydrocarbons is accompanied by the formation of graphite and oxidized iron in the form of magnetite (Fe 3 O 4). We observed the identical mineral assemblage (iron-bearing dolomite, magnetite, and graphite) associated with the formation of the hydrocarbons in both naturally carbonated eclogite and the experimental run products, pointing toward the same formation mechanism. The reduction of the carbonates under low oxygen fugacity is, thus, an important mechanism in forming abiotic hydrocarbons and graphite/diamond in the subduction zone settings. [ABSTRACT FROM AUTHOR]

The differences between the Rock-Eval pyrolysis results of powder and grain samples have attracted wide attentions. Grain samples show lower hydrocarbon yield and different composition of the products. However, the effect of grain size on hydrocarbon generation and expulsion has not yet been quantitatively evaluated. In this study, we prepared each grain into a regular column with precise geometric parameters such as diameter, height, surface area, and volume, which is defined as an independent unit of hydrocarbon generation and expulsion. For comparison, a powder sample corresponding to each grain sample is collected simultaneously during the preparation process. The grain samples are used to simulate the mass of hydrocarbons expelled, while the powder samples are used to simulate the total mass of hydrocarbon generated. Our results show significant differences between the grain samples and the powder samples. All powder samples have a higher expulsion of free hydrocarbons (S1) than grain samples, and almost all grain samples have a higher expulsion of pyrolysis hydrocarbons (S2) than powder samples when the diameter of the grains is smaller than 3 mm. Temperature controls hydrocarbon generation, but grain size retards hydrocarbon expulsion. The influences of the "carry-over" phenomenon, oil adsorption and nanopore confinement are enhanced by grain size, which retards and inhibits hydrocarbon expulsion. Some free hydrocarbons (S1) cannot be expelled from the grain samples at 300 °C. Parts of the retained free hydrocarbons (S1) further cracked into small molecules, which can be expelled and detected as pyrolysis hydrocarbons (S2) at 300–650 °C. Four new parameters were proposed to quantify these influences, namely the S1 retained , the S2 extra expulsion , the HI difference parameter, and the TOC difference parameter. Diameter is more closely related to hydrocarbon expulsion rather than height. For grain samples, HI increases and TOC decreases with increasing diameter. Activation energies for hydrocarbon generation ranges from 43 to 67 kcal/mol for powder samples, while activation energies for grain samples are almost concentrated in 54–55 kcal/mol, indicating a high expulsion threshold for grain samples. As the grain diameter increases from 1.74 to 5.24 mm, the transformation ratio decreases and the generation rate increases, indicating that the grain size delays the expulsion of hydrocarbon. This laboratory simulation provides some new results to better understand the hydrocarbon generation and expulsion of shale rock under natural conditions. • The effect of shale grain size on hydrocarbon generation and expulsion was studied using Rock-Eval and kinetics. • With diameter increasing,the results of grain size and powder samples based on Rock-Eval pyrolysis show regular differences. • Grain size enhances the "carry-over" phenomenon, oil adsorption, and nanopore confinement. • Larger grain size samples have lower transformation ratios and generation rates due to the high expulsion threshold. [ABSTRACT FROM AUTHOR]

Improved understanding of the reservoir mineral effects on the occurrence of thermochemical sulfate reduction (TSR) and possible mechanisms is critical for petroleum exploration and production. A series of hydrous pyrolysis experiments were conducted with and without the presence of montmorillonite, illite and quartz (silicates), calcite and dolomite (carbonates) at 360 °C and 50 MPa for 12 h, 48 h and 312 h. Gaseous compounds, C 7–8 light hydrocarbons, n -C 9 + and organic sulfur compounds as well as compound-specific δ 34 S analysis were conducted subsequently. The results show that with the heating time increasing or TSR advancing, n –C 9 + decrease gradually accompanied by the increases of TSR products, H 2 S, alkylbenzenes, benzothiophenes (BTs) and dibenzothiophenes (DBTs). The δ 34 S values of BTs and DBTs progressively approached that of MgSO 4 and the difference in their average δ 34 S values (Δ 34 S BT-DBT ) decreased. Compared to experiments with the absence of minerals, the experiments with silicates, in particular montmorillonite, are depleted in n –C 9 + and enriched in H 2 S, light monoaromatics and organosulfur compounds and smaller Δ 34 S BT-DBT . Experiments with carbonates demonstrated the opposite trend. This indicates that silicates, in particular montmorillonite, accelerated TSR rates while carbonates reduced them. Under the experimental conditions, the exchange cations within montmorillonite and on the surface of clays and talc precipitation can increase the concentrations of H + and hence HSO 4 − and then catalyze the generation of isoalkanes, which are prone to be oxidized in TSR. This can reduce the activation energy required for the occurrence of TSR. It might therefore be possible for TSR to occur at relatively low temperatures in silicate reservoirs and source rocks in natural environments. Carbonate dissolution can reduce the concentrations of H + and HSO 4 − , and hence reduce the TSR rates. This study demonstrates the importance of minerals in regulating the TSR occurrence and suggests that TSR can occur in siliciclasitic as well as carbonate formations in nature. Therefore, the significance of minerals should be considered in the evaluation of TSR and sour gas risk in TSR-altered hydrocarbon accumulations in different geological contexts. [ABSTRACT FROM AUTHOR]

• Extracted bitumen and solid bitumen were characterized simultaneously. • Characterization was carried out at lamina scale and lithofacies scale. • Biomarkers reveal greater thermal maturity in source rocks than reservoirs. • Raman spectroscopy reveals greater thermal maturity in reservoirs than source rocks. • Organic–inorganic interactions increase the aromaticity of solid bitumen. Organic solvent extracted bitumen (EB) and microscopically observed solid bitumen (SB) carry many geological implications in unconventional source-rock reservoirs. EB is a commonly used term in organic geochemistry, and SB is normally used in organic petrology. Although both EB and SB are secondary organic matter initially formed from kerogen degradation and partially describe the same components, they are defined by different physical and chemical criteria and have specific applications, and thus are rarely comparatively investigated. In this study, by taking the shale of the seventh member of the Upper Triassic Yanchang Formation in the Ordos Basin, China, as a case study, we performed an integrated characterization on the two types of bitumen. The characterization was carried out on source rocks and reservoir assemblages at two scales: lamina-scale (organic-rich lamina and silty lamina) and lithofacies-scale (shale and sandstone). Programmed temperature pyrolysis (Rock-Eval 7 pyrolysis), gas chromatography–mass spectrometry (GC–MS), and Raman spectroscopy were used in this study. The samples are distributed within a 12 m interval and therefore should have experienced the same degree of thermal stress. However, maturity parameters derived from GC–MS for EB and Raman spectroscopy for SB exhibit a different inferred thermal maturity between source rocks and reservoirs at both lithofacies- and lamina-scales. The side-chain scission reactions related (non-)biomarker parameters such as Ts/C 30 H, Σ n C 21− /Σ n C 22+ alkanes, relative C 21 + C 22 sterane content and TA(I)/TA(I + II) suggest higher thermal maturity in source rocks (shale and organic-rich lamina) than the corresponding reservoirs (sandstone and silty lamina), while Raman-derived parameters RBS and G-FWHM indicate higher maturity in reservoirs than the corresponding source rocks. It is speculated that the EB measured by GC–MS comprises saturated and aromatic components corresponding to relatively mobile hydrocarbons. The maturation of the source rock exerts greater control over this component than that of the reservoir. In comparison, the SB measured using Raman spectroscopy mainly consists of solid residue left behind after migration and/or decomposition of a once-liquid oil phase that is less readily able to move. It is more intensely altered by the organic–inorganic interactions (mineral dissolution–precipitation processes) in the reservoir than that in the source rock, resulting in a consolidated SB with higher aromaticity. The storage ability of silty lamina in shale may complicate the data interpretation of geochemical differences in EB- and SB-derived parameters. On a practical note, when assessing thermal maturity, taking into the account the lithology or rock texture, which affects the organic–inorganic interactions, as well as specific components detected by different techniques may provide helpful clues to explain some contradictory results. [ABSTRACT FROM AUTHOR]

The stability and persistence of organic matter (OM) in source rocks are of great significance for hydrocarbon generation and the global carbon cycle. Clay-OM associations commonly occur in sedimentation and diagenesis processes and can influence the pyrolytic behaviors of OM. In this study, clay-OM complexes, i.e., interlayer clay-OM complexes and clay-OM mixture, were prepared and exposed to high-pressure pyrolysis conditions in confined gold capsule reactors to assess variations in OM pyrolysis products in the presence of clay minerals. Three model organic compounds, octadecanoic acid (OA), octadecy trimethyl ammonium bromide (OTAB), and octadecylamine (ODA), were employed and montmorillonite (Mt) was selected as the representative clay mineral. The solid acidity of Mt plays a key role in affecting the amount and composition of the pyrolysis gases generated by the clay-OM complexes. The Brønsted acid sites significantly promote the cracking of hydrocarbons through a carbocation mechanism and the isomerization of normal hydrocarbons. The Lewis acid sites are primarily involved in the decarboxylation reaction during pyrolysis and are responsible for CO 2 generation. Mt exhibits either a catalysis effect or pyrolysis-inhibiting during pyrolysis of a given OM depending on the nature of the model organic compound and the nature of the clay-OM complexation. The amounts of C 1–5 hydrocarbons and CO 2 that are released from the Mt-OA and Mt-ODA complexes were higher than those of the parent OA and ODA, respectively, indicating a catalysis effect of Mt. In contrast, the amount of C 1–5 hydrocarbons produced from the pyrolysis of Mt-OTAB complexes was lower than that of OTAB, which we attribute to an inhibiting effect of Mt. This pyrolysis-inhibiting effect works through the Hoffmann elimination that is promoted by the catalysis of the Brønsted acid sites of Mt, therefore releasing smaller amounts of gas hydrocarbons than the nucleophilic reaction that is induced by the halide ions in OTAB. In particular, the interlayer space of Mt acts as an ‘amplifier’ that magnifies the above-mentioned catalysis or pyrolysis-inhibiting effect, due to the greater number of Brønsted acid sites with high acidity in the interlayer space. These findings are potentially important for understanding the storage and transfer mechanisms of natural OM in sedimentation and diagenesis processes. [ABSTRACT FROM AUTHOR]

• Ketones, alcohols, thiols and thiadiamondoids were generated from diamondoids by TSR. • Thiadiamondoids can be generated from C 0 alkylated diamondoids species by TSR. • Diamondoidyl ketones may be reaction intermediates for thiadiamondoids. • Formation of thiadiamondoids is dominated by the free sulfur radical mechanism. High concentrations of thiadiamondoids together with elevated H 2 S 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 MgSO 4 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 H 2 S 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 C 0 -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 H 2 S 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. [ABSTRACT FROM AUTHOR]

Evaluating the composition of organic reactants initially involved in thermochemical sulfate reduction (TSR) reaction and better understanding the chemical and isotopic compositions of gases are helpful to minimize the risks involved in exploration of natural sour gas reservoirs. Variations in the chemical and carbon isotopic compositions of the gas produced during high pressure (50Mpa), isothermal (360 °C) hydro-pyrolysis experiments of the TSR reaction and thermal cracking involving n-pentane (n -C 5) and condensate were investigated using a high-pressure gold tube system. The results show that the yields of CH 4 , CO 2 and H 2 S increased with reaction time, and that the yields of C 2 –C 4 firstly increased and then decreased. The δ13C value of alkane gases increased with reaction time. The δ13C value of CO 2 produced from the TSR reaction involving n -C 5 became less negative. The yields of alkane gas, CO 2 and H 2 S from the TSR reaction of n -C 5 were up to two times higher than that those from the TSR reaction of condensate. This indicates that lighter liquid hydrocarbons with higher hydrogen content produce more hydrocarbon and non-hydrocarbon gases. The relationship between the dryness, δ13C values of alkane gases and sourness could help to estimate whether the organic reactant was liquid or gaseous hydrocarbons. The value of ln(C 2 /C 3) at the early stage of TSR reaction can be used to roughly estimate the composition of the liquid hydrocarbons involved in the TSR reaction. Our analysis also shows that the value of ln(C 2 /C 3) firstly increased and then decreased with increasing gas dryness during the TSR reaction, which could be an effective index to assess the TSR reaction extent and provide new clues for identifying gas origin. The δ13C values of methane and ethane produced in the TSR reaction involving n -C 5 reversed to δ13C 1 > δ13C 2 during the 48–60h period, which could be related to the oxidation of alkanes by HSO 4 −. This could help explain the δ13C 1 > δ13C 2 in TSR influenced gas reservoirs with low H 2 S content. • During TSR reaction, lighter hydrocarbons with higher hydrogen content produce more hydrocarbon gases and H 2 S. • δ13C 1 > δ13C 2 from early stage of TSR reaction involving nC 5 might occur in reservoirs with low H 2 S content. • With increasing TSR extent, the δ13C 2 －δ13C 3 became negative or positive, depending on the organic reactant. • δ13CO 2 in the TSR group of nC 5 became less negative with increasing TSR extent. • For H 2 S-bearing dry gas reservoirs, the value of ln(C 2 /C 3) firstly increased then decreased with increasing TSR extent. [ABSTRACT FROM AUTHOR]

The sulfur isotopic fractionation associated with the formation of organic sulfur compounds (OSCs) during thermochemical sulfate reduction (TSR) was studied using gold-tube pyrolysis experiments to simulate TSR. The reactants used included n -hexadecane ( n -C 16 ) as a model organic compound with sulfate, sulfite, or elemental sulfur as the sulfur source. At the end of each experiment, the S-isotopic composition and concentration of remaining sulfate, H 2 S, benzothiophene, dibenzothiophene, and 2-phenylthiophene (PT) were measured. The observed S-isotopic fractionations between sulfate and BT, DBT, and H 2 S in experimental simulations of TSR correlate well with a multi-stage model of the overall TSR process. Large kinetic isotope fractionations occur during the first, uncatalyzed stage of TSR, 12.4‰ for H 2 S and as much as 22.2‰ for BT. The fractionations decrease as the H 2 S concentration increases and the reaction enters the second, catalyzed stage. Once all of the oxidizable hydrocarbons have been consumed, sulfate reduction ceases and equilibrium partitioning then dictates the fractionation between H 2 S and sulfate (∼17‰). Experiments involving sparingly soluble CaSO 4 show that during the second catalytic phase of TSR the rate of sulfate reduction exceeds that of sulfate dissolution. In this case, there is no apparent isotopic fractionation between source sulfate and generated H 2 S, as all of the available sulfate is effectively reduced at all reaction times. When CaSO 4 is replaced with fully soluble Na 2 SO 4 , sulfate dissolution is no longer rate limiting and significant S-isotopic fractionation is observed. This supports the notion that CaSO 4 dissolution can lead to the apparent lack of fractionation between H 2 S and sulfate produced by TSR in nature. The S-isotopic composition of individual OSCs record information related to geochemical reactions that cannot be discerned from the δ 34 S values obtained from bulk phases such as H 2 S, oil, and sulfate minerals, and provide important mechanistic details about the overall TSR process. [ABSTRACT FROM AUTHOR]

The Junggar Basin is a major oil producing province in China. Most of the oil originated from Permian lacustrine oil-prone source rocks in the basin. Kinetic parameters for oil and gas generation were obtained from confined pyrolysis experiments using gold capsules at heating rates of 20 °C/h and 2 °C/h on kerogen samples from two Permian lacustrine oil-prone source rocks (J23S3 and SS1S3) having hydrogen indices of 663 and 698 mg HC/g TOC, respectively. The kinetic properties for oil and gas generation vary substantially between these two source rocks. Assuming a burial heating rate of 5 °C/My, the temperature for 50% transformation ratio to oil is 132 °C for J23S3 and 168 °C for SS1S3. The maximum oil yields are about 604 and 770 mg/g TOC, while the maximum yields of total gaseous hydrocarbons are about 306 and 348 mg/g TOC for J23S3 and SS1S3, respectively. Gaseous hydrocarbons from the confined pyrolysis experiments include primary cracking components from kerogen and secondary cracking components from the generated oil. The secondary cracking gaseous hydrocarbons comprise up to 84.9% and 95.1% of the total, respectively, for the two source rocks in the highest temperature experiments. A practical method estimates the amount of gaseous hydrocarbons generated from these source rocks under geological conditions based on: (1) kinetic parameters for gas generation obtained from kerogen confined pyrolysis experiments in the present study, (2) the maximum yield of gaseous hydrocarbons from oil confined pyrolysis experiments from previous studies, and (3) the maximum amount of expelled oil. The maximum amounts of expelled oil range from 509–588 and 724–750 mg/g TOC with oil expulsion efficiencies in the ranges 84.3–97.4% and 94.0–97.4% for J23S3 and SS1S3, respectively, assuming that the amounts of retained oil range from 30–160 and 50–110 mg/g TOC for the two source rocks after oil expulsion based on the amounts of extracted bitumen. Consequently, the maximum yields of total gaseous hydrocarbons could be in the ranges 53.1–87.0 and 25.5–36.8 mg/g TOC, respectively, for J23S3 and SS1S3 in nature. Using the kinetic parameters for these two source rocks determined from pyrolysis experiments, oil and gas generation and expulsion were modeled for source rocks within the Lower Permian Fengcheng (P 1f ) and Middle Permian Lower Wuerhe formations (P 2w ) in the central area of the Mahu Depression, the source kitchen for most oilfields in the basin. [ABSTRACT FROM AUTHOR]

Isothermal confined (gold capsule) pyrolysis experiments were performed for coal alone, oil alone and coal plus oil with oil/coal ratios ranging from 0.006 to 0.171 at 315 °C, 345 °C and 375 °C, respectively and 50 MPa for 72 h. In the experiment for coal plus oil, the amounts and compositions of hydrocarbon gases are substantially different from those predicted from the results in the experiments for oil alone and coal alone. The results of these experiments demonstrate that kerogen and oil do not crack separately in the experiments of coal plus oil. The interaction between kerogen and oil components leads to the generation of hydrocarbon gases. With oil/coal ratio increasing, the amounts of individual and total hydrocarbon gases decrease at first, and then increase rapidly up to several times those calculated from the yields of these components in the experiments for oil alone and coal alone. The C 1 /ΣC 1–5 ratios of hydrocarbon gases decrease and are increasingly lower than those calculated from the yields of hydrocarbon gases in the experiments for oil alone and coal alone. The amount and carbon isotopes of individual n -alkane demonstrate that the free liquid n -alkanes were incorporated into kerogen and replaced the bound liquid n -alkanes (covalently bonded alkyl groups in kerogen). Carbon isotopes of hydrocarbon gases further suggest that the bound liquid n -alkanes in kerogen preferentially crack into hydrocarbon gases. [ABSTRACT FROM AUTHOR]

• Insensitive TN removal to longitudinal heterogeneity at non-excessive CH 4 supply. • Longitudinal gradient in liquid phase affected biomass stratification/CH 4 utilization. • Recommended plug flow operation for MBfR with co-current flow of wastewater and CH 4. Integrating anammox with denitrifying anaerobic methane oxidation (DAMO) in the membrane biofilm reactor (MBfR) is a promising technology capable of achieving complete nitrogen removal from wastewater. However, it remains unknown whether reactor configurations featuring longitudinal gradients parallel to the membrane surface would affect the performance of the CH 4 -driven MBfR. To this end, this work aims to study the impacts of longitudinal heterogeneity potentially present in the gas and liquid phases on a representative CH 4 -driven MBfR performing anammox/DAMO by applying the reported modified compartmental modeling approach. Through comparing the modeling results of different reactor configurations, this work not only offered important guidance for better design, operation and monitoring of the CH 4 -driven MBfR, but also revealed important implications for prospective related modeling research. The total nitrogen removal efficiency of the MBfR at non-excessive CH 4 supply (e.g., surface loading of ≤0.064 g-COD m−2 d−1 in this work) was found to be insensitive to both longitudinal gradients in the liquid and gas phases. Comparatively, the longitudinal gradient in the liquid phase led to distinct longitudinal biomass stratification and therefore played an influential role in the effective CH 4 utilization efficiency, which was also related to the extent of reactor compartmentation considered in modeling. When supplied with non-excessive CH 4 , the MBfR is recommended to be designed/operated with both the biofilm reactor and the membrane lumen as plug flow reactors (PFRs) with co-current flow of wastewater and CH 4 , which could mitigate dissolved CH 4 discharge in the effluent. For the reactor configurations with the biofilm reactor designed/operated as a PFR, multi-spot sampling in the longitudinal direction is needed to obtain a correct representation of the microbial composition of the MBfR. Graphical abstract [Display omitted]. [ABSTRACT FROM AUTHOR]

The exploration history of Bohai Sea reveals that Liaodong Bay is relatively rich in natural gas, which is mainly gas condensate; however, the source rocks in Liaodong Bay share a medium maturity level with values of %Ro being generally < 1.3. This study was undertaken to better understand gas potential of Paleogene oil-prone source rocks (II) in Liaodong Bay, Bohai Sea. Three immature Paleogene source rocks were selected to complete gold tube pyrolysis experiments. The experiment results reveal that the secondary gas from oil cracking can be neglected until the cumulative yields of C 6 –C 14 compounds reach the maximum (corresponding to %Ro ∼ 1.3). Above %Ro ∼ 1.3%, oil starts to crack to wet gases substantially. Based on comparative analysis of pyrolysis results and source rock geochemical parameters, we constructed a hydrocarbon generation model, especially for hydrocarbon gas, and validated the calculated %Ro values for pyrolysis conditions. The C 1 –C 5 yields for source rocks at ∼1.3 %Ro in gold tube pyrolysis approximate the maximum gas yield for source rock in open system pyrolysis, indicating the majority of primary gas from kerogen cracking has been generated at ∼1.3 %Ro, with its yields being 156 ml/g TOC, 100 ml/g TOC and 117 ml/g TOC for Ed 3 , Es 1 and Es 3 source rocks, respectively. This suggests that source rocks with %Ro < 1.3 are of good primary gas generation potential. The extrapolation of kinetic parameters of C 1 –C 5 shows that source rocks are generally at the stage of primary gas in Liaodong Bay, where proved gases are primary gas with estimated values of %Ro < 1.3. [ABSTRACT FROM AUTHOR]