High H2S Research Articles

Effect of increased temperature and leachate recirculation on biogas production and settlement of municipal solid waste.

This study evaluated the effects of increased temperature and leachate recirculation on volatile solids (VS), biogas, hydrogen sulphide (H2S) leachate quality (pH and chemical oxygen demand) and the settlement of municipal solid waste (MSW). Three large-scale tests were conducted with no leachate recirculation at 21°C, weekly leachate recirculation at 20°C and weekly leachate recirculation at 50°C. Leachate recirculation and increased temperature accelerated biodegradation and pushed forward the onset time (from 27 to 8 days). The increase of biodegradation activity was reflected in the change of biogas production, VS and settlement. Compressibility index , increased from 0.71 and 0.77 at 21°C to 0.83 when the temperature was 50°C. In addition, leachate recirculation and high temperature reduced H2S concentration levels by inhibiting the growth of sulphate-reducing bacteria and leachate recirculation lowered H2S production by dissolving the high H2S presence. The results showed that MSW can have significantly changed mechanical and biochemical behaviour under different temperatures and saturations. The results help understand the processes in landfills for more effective short-term and long-term design and management.

Causes of variation in the concentration and distribution of H2S in carbonate reservoirs of the Feixianguan Formation, Lower Triassic in the eastern Sichuan Basin

Hydrogen sulfide (H2S) has been encountered in many oil and gas fields worldwide, causing potentially various health and safety issues; thus, it is crucial to assess its concentration before drilling. Natural gas from the Feixianguan carbonates in the Jiannan gas field is predominantly composed of methane with various H2S concentrations varying from very minor to 3.71%. However, the H2S concentrations display obvious difference, ranging from 0.18% to 0.81% in the southern zone and 0.21–3.71% in the northern zone, with high concentrations (>1%) occurring selectively in dolomitized reservoirs in the northern zone. Based on petrographic and geochemical data and reactive transport numerical modeling, the H2S origin and sulfate sources were analyzed for understanding factors controlling the H2S concentration and distribution.In the northern zone containing high H2S concentrations, there is a common mineral assemblage of pyrobitumens, burial calcite cements, pyrite, and hemispherical elemental sulfur in dolomite reservoirs. Burial calcite cements, often coated by pyrobitumens, have higher precipitation temperatures (>106 °C), and lighter δ13C ratios than host dolostones, suggesting the incorporation of organic carbon into the precipitation of these high-temperature burial calcites supplied by thermochemical sulfate reduction (TSR). Numerical modeling indicates the SO42− concentrations of pore waters would increase significantly in dolomitized domains during seawater-involved dolomitization, consisting with the fact of the higher SO42− concentrations of pore waters in the northern zone. The dolomitizing fluids delivered sulfates into reservoirs which were inevitably reduced by hydrocarbons, once the reaction temperature was reached. Comparatively, in the southern zone where carbonates were not subjected to intensive dolomitization and the SO42− concentrations of pore waters were low, the H2S originated only from the thermal decomposition of oil and organic matter (<1%). This study implies that hydrocarbon exploration in dolomitized reservoirs should be given greater caution because of the more favorable conditions for H2S generation.

Performance and Characterization of Bi-Metal Compound on Activated Carbon for Hydrogen Sulfide Removal in Biogas.

This study reports on the synthesis of bi-metal compound (BMC) adsorbents based on commercial coconut activated carbon (CAC), surface-modified with metal acetate (ZnAc2), metal oxide (ZnO), and the basic compounds potassium hydroxide (KOH) and sodium hydroxide (NaOH). The adsorbents were then characterized by scanning electron microscopy and elemental analysis, microporosity analysis through Brunauer-Emmett-Teller (BET) analysis, and thermal stability via thermogravimetric analysis. Adsorption-desorption test was conducted to determine the adsorption capacity of H2S via 1 L adsorber and 1000 ppm H2S balanced 49.95% for N2 and CO2. Characterization results revealed that the impregnated solution homogeneously covered the adsorbent surface, morphology, and properties. The adsorption test result reveals that the ZnAc2/ZnO/CAC_B had a higher H2S breakthrough adsorption capacity and performed at larger than 90% capability compared with a single modified adsorbent (ZnAc2/CAC). Therefore, the synthesized BMC adsorbents have a high H2S loading, and the abundance and low cost of CAC may lead to favorable adsorbents in H2S captured.

Biomethane production kinetics during the anaerobic co-digestion of Sargassum spp. and food waste using batch and fed-batch systems in Punta Cana, Dominican Republic

Collecting Sargassum spp. biomass and using it for the generation of renewable energy is a sustainable approach to mitigate the costs associated to this weed management. The biomethanation of this algal biomass with other organic waste to produce biogas promotes the integrated sustainable management of these materials while generating gaseous fuel for the tourism industry. The purpose of this work is to determine the percentage Sargassum spp. biomass during the anaerobic co-digestion of this brown algae with food waste that results in the best biogas composition, methane yield, production kinetics, and digestate. The biomethanation was conducted in 1200 L fed-batch and bench scale batch biodigestors and the kinetic parameters were estimated using the modified Gompertz model. The methane yield of Sargassum spp. and food waste combinations in 0.58 OLR at fed batch and 15 g/L organic load at batch were comparable. The methane yield produced in the 100% Sargassum spp. fed-batch anaerobic biodigester was 101.3 ± 23.6 N. L CH4/kg, but up to 615.5 ± 78.4 N. L CH4/kg in the 45% Sargassum spp. / 55% food waste biodigestor. The anaerobic co-digestion of Sargassum spp. and food waste in the batch system showed methane production rates as high as 14.6 ± 0.3 N.L CH4/kg.day. Higher H2S were detected in the biogas of the biodigesters fed with larger percentages of the Sargassum spp. with more than 5000 ppm during mono-digestion. Our results suggest that 55% Sargassum spp. and 45% food waste are the most promising feed combination under the studied conditions for the anaerobic co-digestion of these feedstock at larger scale.

Sodium hydrosulfide alleviates aluminum toxicity in Brassica napus through maintaining H2S, ROS homeostasis and enhancing aluminum exclusion

Hydrogen sulfide (H2S) is a gaseous mediator that plays versatile roles in plant growth and stress responses. However, the regulatory functions of H2S in plant responses to aluminum (Al) stress remain elusive. We observed that application of 20 μM of NaHS (H2S donor) or 0.2 mM of hypotaurine (HT, H2S scavenger) significantly mitigated the inhibition of rapeseed root growth caused by Al stress (150 μM). Exposure to Al for 6 h induced significant H2S accumulation and high levels were maintained thereafter, owing to the elevation of cysteine (83.73 %), L-cysteine desulfhydrase (LCD, 92.32 %), and cyanoalanine synthase (CAS, 11.23 %), and the inhibition of O-Acetyl-l-serine (thiol) lyase (OAS-TL, 15.13 %). Addition of HT significantly scavenged the prolonged H2S accumulation caused by Al stress. Exogenous NaHS maintained the H2S homeostasis through increasing OAS-TL activity (34.99 %) and inhibiting LCD activity (25.72 %), and cysteine level (39.53 %). Moreover, exogenous NaHS mitigated oxidative damage by enhancing antioxidant enzyme activity (SOD 26.27 %, POD 28.62 %, CAT 400.5 % and APX 92.68 %) and proline content (19.85 %). It also decreased root cell wall Al accumulation (20.52 %) by decreasing PME activity (24.64 %) and facilitating pectin methylation (16.74 %). Similar alleviative effects were observed when HT was added. These results suggest that H2S functions differential roles in Al stress response in rapeseed seedlings, depending on its local concentration and duration. Prolonged high H2S emissions might contribute to Al toxicity, while moderate exogenous H2S improves Al tolerance through controlling H2S and ROS accumulation and enhancing Al exclusion through replenishing antioxidant reservoirs and facilitating pectin methylation. It is therefore important that further study investigates how to orchestrate endogenous H2S levels and improve plant stress tolerance.

Experimental investigation on the phase behaviour for gas hydrates in CO2 rich gas mixtures & multiphase system

Almost 40% of undiscovered hydrocarbon reserves have high CO2 and H2S concentrations around the globe. So it is crucial to understand these hydrocarbon systems’ thermophysical properties for the excellent design of production facilities. An experimental investigation is conducted in this study to understand and evaluate the thermodynamic conditions of gas hydrate formation in natural gas systems with high CO2 levels gas and dominant multiphase (high CO2 level gases, deionized water, and crude oil). Three gas mixtures were chosen in this study to simulate natural gas with high CO2 content. The experiments are conducted within the critical pressure of the selected gas to avoid any phase change due to pressure. The impact of high CO2 levels in gas systems on the thermodynamic conditions of the gas hydrates was first explored. Then, the effect of a multiphase system was investigated after the addition of the oil phase into the system. The thermodynamic equilibrium conditions obtained from experiments were used to construct the Hydrate liquid–vapour Equilibrium (HLVE) curves, and the phase behaviour was studied. The details about the temperature variance and enthalpy are also clearly discussed. It has been discovered that gas mixtures with a higher CO2 content tend to promote compared to the pure methane gas system but inhibit compared the pure CO2 system. But in the multiphase system, all the gases show an inhibition effect compared to their respective pure gas system results.

Experimental and kinetic study on laminar burning velocities of NH3/CH4/H2S/air flames

Recently, ammonia has been favored by scientists and engineers as a new type of carbon-free fuel for future carbon–neutral society. Before large-scale application, some existing drawbacks including extremely low reactivity need to be overcomed by enhancing combustion technology. Blending ammonia with sour gas, a type of natural gas resource containing amounts of H2S, can be a solution to enhance the combustion of ammonia as well as efficiently utilize natural gas resource. In this study, the laminar burning velocities of NH3/CH4/H2S/air flames were investigated using the Heat Flux method over a wide range of equivalence ratios and and mixing ratios. A kinetic model for NH3/CH4/H2S/air flames simulation was developed by integrating ammonia sub-mechanism with the mechanism of Han et al. and validated based on the experimental data. The experimental results show that the H2S addition has a negative effect on the flame speed, which reaches 13.36 % decrease at ϕ = 1.25 when the H2S mole fraction is 12 %. Kinetic analysis was performed for exploring the effect of H2S addition on the laminar flame propagation of NH3/CH4/H2S mixtures. The results show that the elevated H2S content significantly impacts the radicals pool in flame, where the mole fraction of H, OH radicals decreases while the S-containing species content increases obviously. Sensitivity analysis shows that the reactions involving S-containing species become important for laminar flame speed determination at high H2S content. Besides, the increament of NH3 ratio in the fuel significantly improves the concentration level of NH2 radical in the flame, leading to the increased importance of NH2 chemistry.

Estimation of sulfur fate and contribution to VSC emissions from lakes during algae decay

Algae decay is an important process influencing environmental variables and emissions of volatile sulfur compounds (VSCs) in eutrophic lakes. However, effects of algae decay on VSC emissions from eutrophic lakes as well as fate of algae-derived sulfur remain poorly understood. In this study, simulated algae-sediment systems were used to explore the flow and distribution of sulfur during algae decay. VSCs including hydrogen sulfide (H2S), methanethiol (CH3SH), carbon disulfide (CS2) and dimethyl sulfide ((CH3)2S) were detected during algae decay, which increased with algae biomass and eutrophic levels in lakes. During algae decay, the highest H2S, CH3SH and (CH3)2S emission rates of 10.45, 21.82 and 43.26 μg d−1 occurred in the first 1–2 days, respectively, while the highest CS2 emission rates were observed between days 8 and 11. The maximum emissions of H2S and CS2 from algae decay were estimated at 0.51 and 0.35 mg m−2 d−1 in Lake Taihu, accounting for 1.57% and 0.69% of the total H2S and CS2 emissions of in situ, respectively. Algae decay could significantly increase the contents of total sulfur and total carbon in sediments by 2.90%–21.11% and 4.23%–45.05%, respectively. The VSC emissions during algae decay could be predicted using the multiple regression models with the contents of total carbon, total nitrogen and sulfur-containing compounds in sediments. Partial least squares path modelling demonstrated that algae decay had a low direct effect on VSC emissions with a strength of 0.06, while it had a significant influence on environmental variables with a strength of 0.63, which could affect VSC emissions with a strength of 0.85, indicating VSC emissions from eutrophic lakes were affected by the environmental variables rather than the direct influence of algae decay. These findings illustrated the mechanisms of VSC emissions during algae decay and provided insights into VSC control and mitigation for eutrophic lakes.

ANALYSIS OF LIVER FUNCTION DISORDERS IN CRUMB RUBBER FACTORY WORKERS IN PALEMBANG CITY, SOUTH SUMATRA

Workers are required to receive Occupational Safety and Health protection. Work accidents can be influenced by physical, chemical, biological, ergonomic and psychological factors. Natural rubber factory is one of the industries that have risks to these factors. This study used a cross-sectional design. Data analysis used the CHAID (Chi-Square Automatic Interaction) method. P value &lt; 0.05 was considered statistically significant. The results of the study showed that the average concentration of H2S in the air and in solids was above the quality standard and the average concentration of H2S in water was still below the quality standard. The average concentration of NH3 in water and in solids is above the quality standard and the average concentration of NH3 in the air is still below the quality standard. The results of the CHAID method analysis showed that glucose levels were associated with impaired liver function (p = 0.000; chi square = 48.766) and the risk of H2S exposure in the air with impaired liver function (p = 0.007; chi square = 7.944). In addition, 3 segments of liver function disorders were also found, namely Segment 1: Workers with abnormal BBS levels, high air exposure H2S; segment 2: Workers with abnormal glucose levels, low air exposure H2S; segment 3: Workers with normal glucose levels. Based on this segment, it was also found that the percentage of risk of experiencing liver function disorders were workers in segment 2 (36.3%) and segment 1 (17.4%).

Durable superhydrophobic silica/epoxy resin coating for the enhanced corrosion protection of steel substrates in high salt and H2S environments

A superhydrophobic coating composed of epoxy on the bottom and siloxane-modified silica on the top was prepared by employing the scraping and spraying methods. The superhydrophobic coating possesses excellent mechanical properties, is superhydrophobic (water contact angle, WCA = 164.3°), and has low adhesion. The long-term corrosion resistance of the epoxy coating and the superhydrophobic coating in a 3.5 % NaCl solution and hydrogen sulfide environment was assessed using electrochemical impedance spectroscopy (EIS), polarization curve analysis, immersion testing, and X-ray diffraction (XRD). Test results indicate that the superhydrophobic coating has excellent anti-corrosion capability in an H2S environment for 50 days and in a 3.5 % NaCl solution for 60 days. This is of great significance for developing the potential applications of superhydrophobic coatings in H2S environments.

Horizontal and vertical heterogeneity of sediment microbial community in Site F cold seep, the South China Sea

Site F is the most vigorous cold seep known on the continental slope of the northern South China Sea. Up to now, the microbial community structures in sediments of Site F based on the high-throughput sequencing of the 16S rRNA genes have been studied extensively. However, few studies investigated the microbial community structures at fine vertical scales of Site F and control stations outside Site F. In this study, a comprehensive investigation of microbial communities in sediments of Site F along the depths varying from 0 to 24 cm below sea floor (cmbsf) of four sampling sites—SRS (Southern Reduced Sediment), NRS (Northern Reduced Sediment), Control 1 (close to Site F), and Control 2 (far from Site F)—was carried out. The high relative abundances of anaerobic methanotrophic archaea (ANME),Desulfobacterota[sulfate-reducing bacteria (SRB)], andCampylobacteria[sulfur-oxidizing bacteria (SOB)] in SRS and NRS indicated that these two sites were newborn cold seep sites compared with non-seep sites, Control 1, and Control 2. A positive correlation between ANME-1b, ANME-2, and SEEP-SRB and an enrichment ofSulfurovumandMethlomonadaceaewere found in the surface sediments of both SRS and NRS, indicating that the processes of anaerobic oxidation of methane (AOM), sulfur oxidation, and sulfate reduction might occur in seep sites. SRS was enriched with ANME-1b and SEEP-SRB2 with a proposed sulfate-methane transition zone (SMTZ) approximately located at 8 cmbsf. The high abundance of ANME in SRS may due to the high concentration of methane. NRS was enriched with ANME-2,Desulfatiglans,Sulfurovum, andMethanosarcinaceaewith a proposed SMTZ at about 10 cmbsf. According to the analyses of microbial community structure and environmental factors, NRS could be described as a notable cold seep reduced sediment site with low sulfate and high H2S that nourished abundant SEEP-SRB1, ANME-2,Methanosarcinales, andSulfurovum, which showed similar distribution pattern. Our study expands the current knowledge on the differences of microbial communities in cold seep sites and non-seep sites and sheds light on the horizontal and vertical heterogeneity of sediment microbial community in Site F.

Effect of feeding gas type and nitrogen: Sulfur ratio on a novel sulfide-driven denitrification methane oxidation (SDMO) system

To save treatment costs of nitrogen-polluted water, a novel sulfide-driven denitrification methane oxidation (SDMO) system, which integrated autotrophic denitrification (AD) and denitrification anaerobic methane oxidation (DAMO) to simultaneously realize wastewater denitrification and biogas utilization in situ, has been operated. In this work, nine groups V0—V8 were derived from a mature SDMO reactor which already enriched AD and DAMO microorganisms. Batch tests about them were proceeded to investigate the effect of feeding gas type and N/S ratio on kinetic performance, microorganism community structure, and functional genes. Results showed as N/S rising up from 2.3 to 23.3, the nitrate removal efficiency decreased from 100 % to 15.4 % but its contribution by DAMO/AD ratio increased from 0.5 to 2.2. Biogas serving as feeding gas enhanced nitrate removal efficiency to 100 % at most in group V3 (N/S = 2.3, H2S = 1.5 %) whereas DAMO and AD contribution for nitrate removal was 33.1 % and 65.6 % respectively. Low H2S content gave little effect on microorganism community structure but high hydrogen sulfide content decreased the abundance of DAMO bacteria Candidatus Methylomirabilis to ∼ 4 % and increase abundance of AD bacteria Thiobacillus to > 20 %. Comparing with V1 feeding with methane, nitrate reduction genes napA, narG, nirK, nirS, cnorB and sulfide oxidation gene soxB up-regulated to > 3.0 × 109 copies/g in HS groups (biogas with high H2S content > 1 %) while gene pmoA up-regulated to ∼ 1.0 × 109 copies/g in LS groups (biogas with low H2S content < 1 %). This study provided more comprehensive understanding for the effect of feeding gas type and N/S ratio on SDMO system.

Effects of operational variations of micro-oxygenation and pH shock on the competition between methane production and sulfate reduction in a UASB reactor

To investigate the effect of oxygen, pH shock, and H2S inhibition on the competition between sulfate-reducing bacteria (SRB) and methane-producing archaea (MPA), a UASB reactor treating wastewater containing sulfate, ethanol and acetate was operated for 360 days. With micro-oxygenation performed at a flow rate of 100 mL/min in the upper part of the up-flow anaerobic sludge blanket (UASB) reactor, the sulfate removal and total sulfide concentration increased to 68.6% and 500 mg S/L, while the methane production rate slightly reduced from 2.5 to 2.1 L/L/d. However, methane production was still the main reaction in the reactor. The pH shock and high H2S concentration finally changed the competition results between SRB and MPA. Sulfate reduction was not affected while methane production was completely inhibited at H2S concentration more than 200 mg/L. Complete sulfate reduction (99.0%) was maintained over the long term with a stable organic COD removal (70.4%). The experimental results proved that in the complete sulfate-reducing stage, ethanol was mainly utilized by incomplete-oxidizing SRB for sulfate reduction.

Spatial sulfur poisoning behavior associated with in‐plane electrochemical performance variation of solid oxide fuel cells

AbstractIn this study, sulfur poisoning behavior is investigated on a 5 × 5 cm2 anode‐supported cell as a function of H2S concentration, cell voltage, and in‐plane region. At a lower cell voltage, the 1st drop % in the current density decreases by promoting sulfur desorption while the 2nd drop % increases slightly. The outlet regions with poor performance show a lower drop % owing to the water vapor effect, while the inlet regions with superior performance show a higher drop %, especially at high H2S concentrations. Ni oxidation in the inlet regions is caused by the substantial 2nd drop under the combined conditions of high current density and H2S concentration, whereas that in the outlet region is caused by the high H2O concentration. The results indicate that in‐plane performance variation may aggravate sulfur poisoning in the inlet regions, whereas it may lead to Ni oxidation in the outlet regions.

Gold Nanoparticles Decorated Copper Oxide Nanosheets Sensor for Hydrogen Sulfide Gas Sensing at Room Temperature

This study exhibits a highly H2S-selective gas sensor based on copper oxide nanosheets (CuO-NSs) material. CuO-NSs are fabricated by a simple and economical method. CuO-NSs are decorated by gold nanoparticles (AuNPs) and used to detect H2S at room temperature. The AuNPs decorated CuO sensor has responses of 36.55% to 69.67% at 0.1 to 0.5 ppm of H2S while the pure sensor has responses from 4.77% to 13.37%. It can be seen that AuNPs can enhance H2S sensing responses five to nine times higher than pure one. The sensor also shows high H2S selectivity against NH3, SO2 and volatile organic compounds (VOCs). The beneficial effect of AuNPs allow the H2S detection of CuO material down to ppb and even lower level, which make it possible to be applied in environmental applications and portable devices.

Probabilistic Assessment of Biodeterioration Effects on Reinforced Concrete Sewers

The worldwide current practice of the structural design of sewers is based on procedures which usually include the effects caused by chemical and biological deterioration. However, in the last few decades, many sewer pipes have been designed using reinforced concrete which have succinctly considered such deterioration promoters. Indeed, knowledge related to reinforced concrete deterioration processes has become an important issue when forecasting the expected or remaining lifespan of sewers. Within these processes, thickness and strength losses and porosity augments have been found to be the result of the vital activity of sulfur-oxidizing bacteria and some types of fungus. This paper presents a rational methodology that uses biodeterioration measurements to describe how biodeterioration effects can affect the probability of failure during the lifetime of sewers. The probability of failure was obtained using Monte Carlo simulations based on numerical sampling from lognormal and uniform distributions. The concrete and reinforcement strength, geometric properties, H2S concentration in the headspace, and load values were considered as the main sources of uncertainty. The results indicate that the expected service lifespan can vary between 55 and 37 years for low and high H2S concentrations, respectively.

Exploring covalent organic frameworks for H2S+CO2 separation from natural gas using efficient computational approaches

Covalent organic frameworks (COFs) are emerged as strong adsorbent candidates for industrial gas separation applications due to their highly porous structures. In this work, we explored H2S+CO2 capture potentials of synthesized and computer-generated COFs from a natural gas mixture using an efficient, multi-level computational screening approach. We computed the adsorption data of a six-component natural gas mixture, CH4/C2H6/CO2/C3H8/H2S/H2O, for 580 synthesized COFs by performing Grand Canonical Monte Carlo (GCMC) simulations under industrially relevant conditions. H2S+CO2 selectivities and working capacities of COFs were computed to be 0.4–12.4 (0.2–8.5) and 0.01–5.36 (0.04–2.5) mol/kg at pressure-swing adsorption (vacuum-swing adsorption) condition. NPN-3 was identified as the best performing COF due to the competitive adsorption of H2S+CO2 over C2H6 and C3H8 as revealed by density functional theory (DFT) calculations. Structural (pore sizes, porosities, and topologies) and chemical properties (linker units and heats of gas adsorption) of the best-performing synthesized COFs were used to efficiently screen the very large number of hypothetical COFs (hypoCOFs). Results showed that isosteric heats of adsorption can be used to discover high performing hypoCOFs for H2S+CO2 separation from natural gas. Finally, we compared COFs, hypoCOFs, zeolites, carbon nanotubes, metal organic frameworks (MOFs) and concluded that several synthesized and computer-generated COFs can outperform traditional adsorbents in terms of H2S+CO2 selectivities. Our results provide molecular-level insights about the potential of COFs for natural gas purification and direct the design and development of new COF materials with high H2S+CO2 selectivities.

Hydrothermal activity and associated subsurface processes at Niuatahi rear-arc volcano, North East Lau Basin, SW Pacific: Implications from trace elements and stable isotope systematics in vent fluids

Hydrothermal activity is abundant in the area between the North Eastern Lau Spreading Center and the Tofua intra-oceanic island arc with multiple active sites in the rear-arc at the Mata and Niuatahi volcanoes. We report geochemical data for high-temperature vent fluids sampled from within the caldera of Niuatahi volcano. Hydrothermal fluids were sampled from three vent sites: South Central, Southwestern Cone and Northern Cone located in water depths between 1607 and 1699 m. Maximum temperatures of 334 °C were measured and pH values were as low as 2.8. The vent fluids were characterized by depletions in Mg, SO4 and U as well as an enrichment of (trace) metals (e.g., Fe, Mn, K, Li) and dissolved gases (e.g., H2S, CO2, H2) relative to seawater. Water-rock ratios calculated based on concentrations (K, Li, Rb, Cs, REE) and isotope ratios (δ7Li, δ11B, 87Sr/86Sr) suggest fluid-rock interactions under rock-dominated conditions at all three vent sites.The South Central vents lie closest to the site of most recent volcanic activity in the Niuatahi caldera. Vent fluids are characterized by relatively low Cl concentrations (as low as 292 mmol/kg) that are indicative of sub-critical phase separation. These fluids also had the lowest pH values (2.8–3.1), highest H2S and lowest H2, CH4 and CO2 concentrations of the three sites. The δD and δ18O values suggest that H2O and CO2 were added in small amounts by subduction-related volcanic vapors. However, there was no evidence for magmatic SO2 input in the vent fluids at the time of sampling in 2018. Vent fluids from the Northern and Southwestern Cone sites on the caldera ring fault had a similar chemical composition, despite being situated at opposite sides of the caldera. Fluids from these sites had lower Fe/Mn ratios (<1) and H2S concentrations than those from South Central suggesting that they were affected by subsurface cooling and sulfide precipitation. This study indicates variations of the Niuatahi hydrothermal vent sites depending on the location within the caldera with variable effects of fluid-rock interaction and magmatic input on fluid compositions in agreement with previous work on fluid S isotopes and sulfides.

Hydrogen Sulfide Measurement of Degraded Corrosion Inhibitor with Glass Tube Detector in Oil &amp; Gas Industry

Introduction: Corrosion inhibitor (CI) is injected as carbon steel pipe corrosion protection with sulfur-containing substances in the product. One type of them is thioglycolic acid (TGA). Besides having benefits in maintaining pipe integrity, TGA can be decomposed to HS (hydrogen sulfide) due to changes in ambient temperature during storage, such as direct sunlight exposure on the field. This irritant gas can pose a risk to the health of chemical workers. Therefore, this study aims to measure the concentration of H2S in a CI product containing TGA. Method: The data were collected from an oil and gas company measurement report on 12 CI drums with 1-3%w of TGA content by using a glass tube detector. Measurements were performed by varying the measurement distance (0 and 10 cm from the mouth of the drum), observing the condition of the inflated drum surface, and determining the existence of internal pressure. Results: All samples were contained H2S, and the inflated drums had higher H2S content than those that were not inflated up to more than 200 ppm in the drum bore. At this concentration, workers can experience pulmonary edema significantly prolonged exposure. Biological monitoring can be done by analyzing thiosulfate content in urine and blood after exposure or routine examination at the end of the work shift. Conclusion: CI with TGA content has the potential of high H2S concentration, and it requires risk control such as engineering control, administration control, and PPE application to minimize the health impact of H2S exposure to the workers.

Links of Hydrogen Sulfide Content With Fluid Components and Physical Properties of Carbonate Gas Reservoirs: A Case Study of the Right Bank of Amu Darya, Turkmenistan

Hydrogen sulfide (H2S) in carbonate gas reservoirs shows strong relevance with the natural gas components and has an obvious impact on reservoir types and their petrophysical properties. In this work, core and fluid samples were collected from the Right Bank of Amu Darya reservoirs, Turkmenistan. Then, fluid composition analysis and flash evaporation experiments were performed to investigate the components of reservoir fluid. Petrophysical properties, that is, porosity and permeability, and micropore structures of cores were determined by permeameter–porosimeter and scanning electron microscope (SEM) analysis, respectively. Results in this work indicate that the H2S content shows obvious relevance to fluid components in carbonate gas reservoirs. With the increase of H2S content, the total heavy hydrocarbons and potential condensate content decrease, while the condensate density increases. In addition, at higher H2S content, larger pore and vug porosity was observed. However, in reservoirs with lower H2S content, the matrix pores are relatively tight and prone to develop fractures. Furthermore, sulfate thermochemical reduction (TSR) is found to be the dominant contributor to high H2S content in carbonate reservoirs through material and thermodynamic condition analysis. The Gibbs free energy and normalized hydrocarbon content show that the consumption of heavy hydrocarbons generally increases with carbon numbers during TSR, but reaches a minimum at the components of C7 to C9. Finally, the relationship between TSR and rock petrophysical properties was discussed, indicating that pore volume enlargement and the dissolution effect of acidic gases are the main mechanisms for TSR to improve carbonate reservoir property. Results in this study present comprehensive analyses of the links between H2S content and fluid components and petrophysical properties in carbonate gas reservoirs.