Gas Production Method Research Articles

The Mechanism of Sodium Sulfate Coupled with Anaerobic Methane Oxidation Mitigating Methane Production in Beef Cattle.

The aim of this experiment is to explore the effect of sodium sulfate (Na2SO4) on methane reduction in the rumen, and its impact on anaerobic methane-oxidizing archaea (ANME). Using mixed rumen fluid from four Angus cattle fistulas, this study conducted an in vitro fermentation. Adding Na2SO4 to the fermentation substrate resulted in sulfur concentrations in the substrate of 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, and 2.4%. The gas production rate and methane yield were measured using an in vitro gas production method. Subsequently, the fermentation fluid was collected to determine the fermentation parameters. The presence of ANME in the fermentation broth, as well as the relationship between the number of bacteria, archaea, sulfate reducing bacteria (SRB), ANME, and the amount of Na2SO4 added to the substrate, were measured using qPCR. The results showed that: (1) the addition of Na2SO4 could significantly reduce CH4 production and was negatively correlated with CO2 production; (2) ANME-1 and ANME-2c did exist in the fermentation broth; (3) the total number of archaea, SRB, ANME-1, and ANME-2c increased with the elevation of Na2SO4. The above results indicated that Na2SO4 could mitigate methane production via sulfate-dependent anaerobic methane oxidation (S-DAMO) in the rumen. In the future management of beef cattle, including sodium sulfate in their diet can stimulate S-DAMO activity, thereby promoting a reduction in methane emissions.

Effect of Agro-Industrial by Products Derived from Volatile Fatty Acids on Ruminant Feed In Vitro Digestibility.

The growing demand for sustainable ruminant feed alternatives has motivated the application of bioconversion approaches for the valorization of agro-food byproducts (AFB) into feed additives and supplements. The present study thoroughly investigated substituting volatile fatty acids (VFAs) obtained from acidogenic fermentation (AF) of AFB as an energy source in ruminant feed. Rumen in vitro digestibility assays were conducted utilizing the gas production method, wherein the VFAs obtained from AF of apple pomace and potato protein liquor was substituted with partial silage and concentrate energy at levels of 10%, 20%, and 30%. The results indicate that substituting 20% of the concentrate's energy with VFA mixture significantly reduced methane production and had no adverse effect on the production and accumulation of VFAs in the simulated rumen media. Conversely, replacing 10% of the silage energy with VFAs led to a decrease in methane production and further enhanced the production of VFAs. Readily digestible VFAs in ruminant feed have the potential to enhance energy availability and sustainability in ruminant farming practices, aligning with the principles of circular economy and waste valorization.

Achieving decarbonization considering green hydrogen production: Case study of Oman

Life Cycle Assessment (LCA) method is employed to study and mitigate negative environmental impacts using various approaches via OpenLCA software. This paper investigates the LCA of green hydrogen gas production from produced water in Oman, using the Activated Sludge Method (ASM) and Fluidized-Bed Bioreactor (FBB), as treatment technologies. Different scenarios were considered, utilizing the ReCiPe midpoint impact method over 100 years, to evaluate global warming potential (GWP100), fossil depletion potential (FDP), and water depletion (WDP). The objective is to compare and evaluate the sustainability of Dark Fermentation (DF) and Electrolysis methods for hydrogen gas production from both treatment technologies to achieve Oman's Vision 2040. The DF method involves utilizing sludge from both primary and secondary treatment stages, while the Electrolysis method uses the tertiary treatment stage. Results show that using 50 % (15,000 m³/day) of the flow for hydrogen production, the DF yields 60,000 kg of H2/day, while the electrolysis method produces 833,333 kg of H2/day. This difference arises because the DF method depends on sludge production, impacting hydrogen gas production, whereas, the electrolysis method relies entirely on treated water. Both processes significantly impact GWP100. Incorporating solar power for ASM and FBB, as a green energy source, reduces CO2 emissions by 7560.28 kg CO2-eq for DF and 8245.18 kg CO2-eq for electrolysis. This study provides a novelty application, which contributes to advancing sustainability practices through evaluating the environmental impacts of using produced water for green hydrogen production in waste-to-energy and advocates for energy policy making regarding recent climate change commitments.

Effects of orthogonal cleat structures on hydraulic fracture evolution behavior

Hydraulic fracturing operation as an effective enhancing coalbed gas production method is widely used in ultra-low permeability coal seam. However, complex geo-stresses and high heterogeneity between natural cleats structure lead to difficulty predicting hydraulic fracture patterns. Fracture evolution behavior for fracturing operation in coal seams requires a better understanding. In this study, a 2D model of hydraulic fracture propagation was built based on the cohesive zone model of finite element method. The effect of orthogonal cleat system, in-situ stress, dig angle and construction parameters on fracture geometries were main investigated. The main conclusions were as follows: (1) According to the interaction types between hydraulic fracture and cleat system, ladder-shaped fracture and H-shaped fracture geometry was summarized. The difference between them was whether there were continuous and small pressure fluctuation stages. (2) When the horizontal stress difference coefficient was lower and larger than 3/12, fracture geometry was prone to present Η shape and ladder shape respectively. Besides, the dimensionless fracture length and the dimensionless fracture extension aspect ratio of fracture were increasing with larger horizontal stress difference coefficient. (3) The favorable condition for fracture extension was that the dig angle was 45°. Hydraulic fracture tended to propagate along face cleats direction. (4) Larger fracture fluid displacement was beneficial to form more balanced hydraulic fracture geometry and promote large extension scale. As fracture fluid viscosity increased, the fracture geometries transformed from ladder shape to H shape.

Wood Chipper Design for Biofuel Production in a Global Catastrophic Loss of Infrastructure Scenario

A variety of events such as high-altitude electromagnetic pulses, extreme solar storms, and coordinated cyber attacks could result in a catastrophic loss of infrastructure on a continental or global scale. The lengthy repair of critical infrastructure creates a need for alternative fuels such as wood gas. Wood gas is produced by heating wood in a low-oxygen environment and can be used to power combustion engines. This work investigates a novel wood chipper, designed as an energy-efficient tool for producing wood gas stock, wood chips, aiming to speed up the transition to alternative fuel. A prototype is built and tested to determine the energy efficiency and production rate of the device. The results suggest that the wood chipper could produce one cord of wood chips, 3.6 m3, in less than a day and is a viable alternative to other manual wood-processing methods. In addition, the global scaling up of production of the wood chipper is considered, indicating that the mass production of the wood chipper could accelerate the transition of wood gas production methods from manual to machine-driven immediately after a catastrophic event.

An in vitro evaluation of partial energy replacement in a total mixed ration with volatile fatty acids derived from agro-industrial residues

AbstractThe scientific interest in volatile fatty acids (VFAs) as an energy source and chemical precursor in ruminant diets has been longstanding, as it has significant implications for animal physiology and well-being. The present study explores the substitution of volatile fatty acids (VFAs) derived from agro-food residues via acidogenic fermentation as an alternative energy source in ruminant feed. Utilizing the gas production method, rumen digestibility assays were conducted, wherein the recovered VFA effluent from the acidogenic fermentation of apple pomace and potato protein liquor was substituted for 10%, 20%, and 30% of the total mixed ration (TMR) energy. Various parameters such as gas, VFA yield and composition, VFA peak intervals, changes in pH, and ammonium nitrogen content were investigated. Based on the results obtained, provision of 20% and 30% of the energy with VFAs did not increase methane production or did not cause significant pH alternations. Nevertheless, such supplementation resulted in increased production and accumulation of VFAs in the rumen media. The bioconversion of agro-food side streams into VFAs opens a new path in sustainable nutrient recovery and feed production from low value agro-industrial residues. Graphical Abstract

Microbial biomass, apparent and true degradability, and Undegradable Dietary Protein (UDP) values of concentrated rations containing white Kabesak Leaf (Acacia leucophloea) In vitro

The objective of this study was to evaluate the effect of using white kabesak leaves in the concentrate on biomass production, apparent and true degradability, and undegraded protein of rations In Vitro. This study used the In Vitro gas production method, designed using a group randomized experimental design. The proportion of grass forage and concentrate in the diet was 60:40. The treatment of the use of white kabesak leaves is R0: without white kabesak leaves (0%), R1: 10%, R2 20%, R3 30% and R4 40%. The results showed that the treatment had a very significant effect (P<0.01) on microbial biomass production, Apparent and True Degradability, and a considerable impact (P<0.05) on undegraded dietary protein rations. Biomass production decreased from 77.30 mg/500 mg DM in R0 to 43.6 mg/500 mg DM in R4. Apparent degradability from 287.25 mg/500 mg DM in R0 to 268.42 mg/500 mg DM in R4, and True degradability from 364.87 mg/500 mg DM in R0 to 312 mg/500 mg DM in R4. Undegraded dietary protein increased from 8.65% in R0 to 13.93% in R3. It was concluded that the use of white kabesak leaves in concentrates In Vitro produced a positive effect by decreasing feed protein degradation and increasing undegraded protein, making it more available post-rumen. The use of 20% white kabesak leaves in concentrate is the ideal level for In Vitro nutrient acceptance.

Net-zero produced water strategy on gas production in marine gas hydrate bearing sediment

Gas hydrates, commonly found in deep marine sediments, have been considered a potential long-term energy source. Recent field trials demonstrated that well depressurisation, converting solid gas hydrates into fluid in situ, is the most efficient method for gas production. However, this process involves continuously pumping a large volume of water from the ocean that cannot be simply disposed of due to environmental concerns. The produced water, with temperature, salinity and residues different from those of shallower seawater, could impact marine species, habitats and ecosystems if directly discharged into the sea. Storing or transporting this water for treatment is economically impractical. Furthermore, as hydrate dissociation increases sediment permeability, water production rates rise over time. Therefore, re-injecting produced water into gas hydrate reservoirs emerges as a promising net-zero produced water strategy. This study investigates the effects of produced water re-injection on gas productivity and sediment deformation through coupled thermo-hydro-chemo-mechanical numerical analysis. The results indicate that re-injecting the water could improve gas productivity but may cause heave and differential displacement near the injection well. This highlights the importance of considering thermo-hydro-chemo-mechanical processes in comprehensively evaluating energy production strategies and suggests that further studies are necessary for future commercial gas production from gas hydrate reservoirs.

Field-scale numerical investigation of a hybrid gas production method from the oceanic hydrate accumulation at site NGHP-02-09 in the Krishna-Godavari Basin, and the associated geomechanical responses

The objectives of this study are to investigate (a) the technical feasibility of gas production from a gas hydrate accumulation at Site NGHP-02-09 in the Krishna-Godavari Basin, India Ocean using a hybrid production method involving a combination of depressurization and thermal stimulation, as well as (b) the associated geomechanical system response when considering both a simplified and a full geomechanical model. This is an extension of the earlier numerical study of Moridis et al. (2019a) of the site using cylindrical (single-well) 2D systems, which indicated (a) the main source of the produced gas to be CH4 dissolved in the water rather than CH4 from hydrate dissociation because of the presence of a high-permeability water-bearing zone that short-circuits the depressurization process and (b) the possibility of adverse geomechanical issues caused by significant displacements that could not be adequately investigated and resolved by the one-way coupling scheme invoked in that study. The proposed hybrid production plan involves two vertical wells in a 3D Cartesian domain: an injection well of warm ocean (saline) water and a production well at an appropriate distance, with the expectation that the hydrate dissociation caused by the depressurization at the production well can be augmented by the thermal effect of the injected warm water (as well as by its salinity), thus mitigating the effects of the high-permeability water zone. The results of this study that uses high-resolution 3D grids indicate that (a) the hybrid production scheme does not appear to offer any advantage over the simple single-well depressurization method of the earlier study, (b) the majority of the produced gas originates from CH4 exsolution from the water rather from hydrate dissociation, and (c) consideration of full geomechanics leads to generally slightly higher dissociation and fluid production because of the evolution of lower porosities and permeabilities, but also to the disappearance of the gas phase after 62 days of production, after which time CH4 from hydrate dissociation is fully dissolved in the water before production. Thus, the hybrid scheme investigated here appears ineffectual in enhancing hydrate dissociation and gas production, and the hydrate deposits at the Site NGHP-02-09 do not appear to be a promising production target under the conditions in this study, in agreement with the earlier conclusion of Moridis et al. (2019a).

Development of Oil and Gas Condensate Fields

In the world, with the development of science, brand new technologies are being created to generate energy resources (e.g., hydrogen energy, electric car, etc.). These inventions will reduce the consumption and cost of hydrocarbon resources. This leaves oil and gas resource producers with only one option – accelerated development of oil and gas fields with low capital investment. This monograph is devoted to the development of oil and gas fields in a short period of time with a reduction in the volume of drilling operations and well quality by at least 50%. The developed technology of simultaneous split operation will give an impetus to volumetric production of hydrocarbons, accelerated field development and reduction of capital investments, as well as lead to the production of all recoverable and non-recoverable reserves from the subsoil. This monograph also delves into the technological aspects of operating wells in the Altyguyi gas condensate field. The scientific work examines the operational and technological aspects of hydrodynamic and thermohydrodynamic studies. To support this research, patents for invention No. 643 and 644, dated January 6, 2015, were obtained (application numbers 14/101317 and 15/101320). These patents cover the “Simultaneous method of separate and joint operation of several productive horizons by one chink and device for its realization” and the “Method of dual oil and gas production from one well in a multizone”. Based on the findings of the conducted analyses, studies, and calculations, the implementation of the intensification of the gas condensate field using the oil and gas DC method by one well is justified. This approach represents a first in global practice and aims to reduce capital investments and accelerate development.

Progress in Cobalt Complexes for Enabling Asymmetric Hydrogenation, H2 Production Catalysis and Alkene/Alkyne Hydro‐functionalization: A Review

AbstractThe use of hydrogen as an alternate clean fuel over conventional fuels, in addition to its role in chemical industries giving rise to useful products like hydrocarbons, has been the subject of research for many years. The need for hydrogen gas production methods has ever since been in demand. This review offers a comprehensive exploration of applications of cobalt complexes in asymmetric hydrogenation, H2 production catalysis and the hydro‐functionalization of alkenes and alkynes. Cobalt metal stands out, particularly due to its distinctive involvement in potential single‐electron processes. The main objective of this review is to provide an insight into the role of cobalt‐based coordination complexes as catalysts in hydrogenation reactions. It delves into models for enantio‐induction and extensively investigates the role of cobalt complexes in hydrogen evolution and associated reactions. Cobalt selection as the central metal is attributed to its beneficial (II)/(III) redox couple state, which proves valuable in hydride transfer reactions. While the review is structured based on substrate types, its core focus lies in the mechanism‐driven exploration of catalytic systems. These catalytic systems exhibit versatility in facilitating the hydrogenation and hydro‐functionalization of various types of double bonds through the utilization of tridentate ligands.

Potential feeding value, feed quality, microbial protein production, and antimethanogenic properties of tree leaves admixed with Italian ryegrass at different ratios using <i>in vitro</i> gas production

The purpose of this study was to use the in vitro gas production (IVGP) method to assess the relative feeding value, feed quality, and anti- methanogenic capabilities of tree leaves added to Italian ryegrass forage at various proportions. With the addition of 2% and 4% willow leaf (Salix alba), 2% and 4% vine leaf (Vitis vinifera), 2% and 4% plane leaf (Platanus orientalis), and a control group devoid of these supplements, a total of 21 forage samples were created. The data were subjected to analysis of variance after nutritional composition, energy content, feeding value, and feed quality were determined using the in vitro gas generation method. The effect of the addition of tree leaves to forage on crude ash, IVGP, methane, metabolizable energy, net energy lactation, organic matter digestion, true digestible dry matter, partitioning factor, microbial protein, microbial protein synthesising efficiency, degree of true digestion, NDF digestion, total digestible nutrients, and relative feed quality was substantial. With the addition of 2% willow leaves, the digestibility, metabolic energy, net energy lactation value, organic matter digestion, microbial protein value, and relative feed quality all improved. The findings showed that tree leaves can be utilized as an alternate feed source for ruminants. Tannin content should be taken into account when preparing rations utilizing tannin-containing tree leaves.

An efficient data-driven global sensitivity analysis method of shale gas production through convolutional neural network

The shale gas development process is complex in terms of its flow mechanisms and the accuracy of the production forecasting is influenced by geological parameters and engineering parameters. Therefore, to quantitatively evaluate the relative importance of model parameters on the production forecasting performance, sensitivity analysis of parameters is required. The parameters are ranked according to the sensitivity coefficients for the subsequent optimization scheme design. A data-driven global sensitivity analysis (GSA) method using convolutional neural networks (CNN) is proposed to identify the influencing parameters in shale gas production. The CNN is trained on a large dataset, validated against numerical simulations, and utilized as a surrogate model for efficient sensitivity analysis. Our approach integrates CNN with the Sobol' global sensitivity analysis method, presenting three key scenarios for sensitivity analysis: analysis of the production stage as a whole, analysis by fixed time intervals, and analysis by declining rate. The findings underscore the predominant influence of reservoir thickness and well length on shale gas production. Furthermore, the temporal sensitivity analysis reveals the dynamic shifts in parameter importance across the distinct production stages.

Effect of Nutmeg Meal on Microbial Abundance of Biohydrogenation Process, and Fatty Acid Profile of Goat Rumen Fluid In Vitro

This study aimed to evaluate the effect of nutmeg meal as a source of phenol on the abundance of dominant microbes in the biohydrogenation process and the fatty acid profile of goat rumen fluid in vitro. This study used a randomized complete block design with four treatments and three replicates of in vitro batches, each replicate in duplicate. The dietary treatments consisted of elephant grass (40%), soybean meal (10%), with varying proportion of wheat pollard, canola oil and nutmeg meal hence, treatment P0 (40:10:45:5:0); P1 (40:10:40:5:5); P2 (40:10:35:5:15); P3 (40:10:30:5:10). Fermentation using the in vitro gas production method described by Menke and Steinggas with an incubation period of 48 hours. Parameters observed included microbial abundance and fatty acid profile of goat rumen fluid. The statistical analysis showed that adding nutmeg meal starting at the 5% level decreased the abundance of the main biohydrogenation process bacteria anaerovibrio, butyrivibrio fibrisolvens, and pseudobutyrivibrio. Total saturated fatty acid and stearate fatty acid concentrations decreased (P<0.05), while total unsaturated fatty acid, linoleic and oleic acid concentrations increased (P<0.05).

A comprehensive review on hydrogen production, storage, and applications.

The transformation from combustion-based to renewable energy technologies is of paramount importance due to the rapid depletion of fossil fuels and the dramatic increase in atmospheric CO2 levels resulting from growing global energy demands. To achieve the Paris Agreement's long-term goal of carbon neutrality by 2050, the full implementation of clean and sustainable energy sources is essential. Consequently, there is an urgent demand for zero or low-carbon fuels with high energy density that can produce electricity and heat, power vehicles, and support global trade. This review presents the global motivation to reduce carbon dioxide by utilizing hydrogen technology, which is key to meeting future energy demands. It discusses the basic properties of hydrogen and its application in both prototype and large-scale efficient technologies. Hydrogen is a clean fuel and a versatile energy carrier; when used in fuel cells or combustion devices, the final product is water vapor. Hydrogen gas production methods are reviewed across renewable and non-renewable sources, with reaction processes categorized as green, blue, grey, black, pink, and turquoise, depending on the reaction pathway and CO2 emissions management. This review covers the applications of hydrogen technology in petroleum refining, chemical and metrological production, hydrogen fuel cell electric vehicles (HFCEVs), backup power generation, and its use in transportation, space, and aeronautics. It assesses physical and material-based hydrogen storage methods, evaluating their feasibility, performance, and safety, and comparing HFCEVs with battery and gasoline vehicles from environmental and economic perspectives. Finally, the prospects and challenges associated with hydrogen production, handling, storage, transportation, and safety are also discussed.

3D printing of titanium dioxide and polyaniline-based photocatalytic composites

Photocatalysis has emerged as a promising method for wastewater treatment, organic removal, and hydrogen gas production. Titanium dioxide (TiO2) is a popular photocatalyst due to its ability to absorb ultraviolet light, its electronic structure, and its optical and chemical stability. The photocatalytic capacity of TiO2 is influenced by its crystal structure (anatase, rutile, and brookite), particle size, and surface area, which can be optimized. Moreover, TiO2 can be coated onto substrates such as ceramics or polymers. This research aims to investigate the application of 3D printing techniques to fabricate composites between TiO2 and polyaniline (PANI) under controlled processing conditions. The 3D photocatalyst was characterized using XRD, SEM, XAS, FTIR, and UV-VIS techniques. The results of this research could pave the way for more efficient and effective photocatalysts fabricated by 3D printing technique, with potential benefits for environmental sustainability and energy production.

In vitro protein fractionation methods for ruminant feeds

Estimating protein fractions and their degradation rate are vital to ensure optimum protein supply and degradation in the digestive system of ruminants. This study investigated the possibility of using the ANKOM gas production system and preserved rumen fluid to estimate the protein fractions and in vitro degradability of protein-rich feeds. Three in vitro methods: (1) gas production method (2) Cornell Net Carbohydrate and Protein System (CNCPS), and (3) the unavailable nitrogen assay of Ross (uNRoss) were used to quantify protein fractions of four feeds (lupin meal, vetch grain, Desmanthus hay, and soybean meal). Rumen fluid mixed with 5% dimethyl sulfoxide and frozen at −20 °C was also compared against fresh rumen fluid in the gas production and uNRoss methods. All three methods ranked the feeds identically in the proportions of available (degradable or ‘a + b’) protein fractions as vetch grain, soybean meal, lupin meal, and Desmanthus hay in decreasing order. The use of fresh rumen fluid produced greater available protein fractions than preserved rumen fluid in all feeds. However, there was no difference between total gas production from lupin meal and vetch grain fermented for 16 h in either rumen fluid source. The in vitro degradable CP (IVDP) was higher for vetch grain (46 and 70%) at the 4th and 8th hours of incubation than other feeds, whereas soybean meal (85%) exceeded the other feeds after the 16th hour of incubation (P < 0.001). The greatest ammonia-N concentration was from soybean meal (1.27 mg/g) and lupin meal (0.87 mg/g) fermented for four hours using fresh rumen fluid. The proportion of fraction 'b' for soybean (82.1% CP) and lupin meals (39.4% CP) from the CNCPS method were not different (P = 0.001) from the fraction 'b' estimation of the gas production method for the same feeds (r = 0.99). Regardless of the methods, a greater water-soluble protein fraction was found from vetch grain (39.6–46.6% CP), and the proportion of fraction ‘c’ or unavailable protein in Desmanthus hay (39.1–41.5% CP) exceeded other substrates (P < 0.001). The strong positive correlation between fractions across different methods and identical ranking of feeds suggests the possibility of using ANKOM gas production apparatus for protein fractionation.

Evaluation of legumes for fermentability and protein fractions using in vitro rumen fermentation

Diversifying feed with non-traditional options could minimize the dependency on traditional sources, maintain the feed supply throughout the year, and potentially reduce the cost of raising animals. A total of eight forage legumes including Peltophorum pterocarpum, Neptunia monosperma, Vachellia sutherlandii (Corkwood), Gliricidia sepium, Bauhinia hookeri and three Desmanthus species (JCU4, JCU5 and JCU9) were collected to assess their in vitro fermentability, degradable and undegradable protein fractions using in vitro gas production method. Soybean meal and lucerne hay were used as control. The total gas production ranged from 12.8 mL/g in P. pterocarpum to 127.3 mL/g in soybean meal. The total volatile fatty acid (VFA) concentration from G. sepium (117.7 mM/L) and V. sutherlandii (111.3 mM/L) were larger than other legumes except for soybean meal (157.1 mM/L) and lucerne hay (130.4 mM/L), P < 0.001. The methane gas produced from B. hookeri and P. pterocarpum (0.39 and 0.32 mL/g) was lower than other feeds, P < 0.001. The V. sutherlandii (720 g/kg crude protein (CP)) and G. sepium (745 g/kg CP) had the greatest effective CP degradation (EPD) than other legume species examined, P < 0.001, which was approaching that measured in the control samples. The amount of protein fraction ‘a’ (rapidly degradable) was larger in JCU9 (551 g/kg CP), and G. sepium (472 g/kg CP), and lower in B. hookeri (10.9 g/kg CP) and P. pterocarpum (14.8 g/kg CP), P < 0.001. The V. sutherlandii (386 g/kg CP) and G. sepium (272 g/kg CP) exceeded other legumes in the proportion of fraction ‘b’ (slowly degradable), P < 0.001, but not the controls. The undegradable fraction increased with increasing phenolic content and reached more than 940 g/kg CP for both B. hookeri and P. pterocarpum. The Desmanthus cultivars showed intermediate values among the tested legumes in fermentation characteristics and shows potential to provide slowly degradable protein while reducing methane. The findings indicate the possibility of using V. sutherlandii and G. sepium to substitute other forages for their greater slowly degradable protein content. Moreover, B. hookeri and P. pterocarpum plants emerged as candidates to assist protein protection in the rumen and reduce methane emissions. However, these legumes need to be evaluated in vivo before promoting for further use to confirm the variability reported here.

Numerical Simulation of Optimized Step-Wise Depressurization for Enhanced Natural Gas Hydrate Production in the Nankai Trough of Japan

The utilization of natural gas hydrates as an alternative energy source has garnered significant attention due to their proven potential. Despite the successful offshore natural gas hydrate production tests, commercial exploitation has not been achieved. This study aims to enhance the understanding of gas production behavior through simulations from a single vertical well in the Nankai Trough and assess the effectiveness of the step-wise depressurization method for gas production using TOUGH + HYDRATE. The simulation results showed that the effective permeability for the water phase decreased as the hydrates were decomposed, and the invasion of the pore water from the underburden eliminated this effect. Compared with the direct depressurization method, the step-wise depressurization method significantly increased the cumulative gas production by more than 10% and mitigated the rapid generation of gas and water production during the moment of depressurization. The results also indicated that the depressurization gradient was more sensitive to the cumulative gas production than the maintenance time of depressurization. In view of the gas and water production characteristics coupled with the challenges in carrying out the step-wise depressurization method, it is suggested that a depressurization gradient of 1 MPa and a maintenance time of 1 day should be employed.

A novel prediction method of gas and water production in tight gas wells on the Eastern margin of Ordos Basin

In order to address the limitations of traditional methods for predicting gas production of tight gas wells in the Linxing area, such as a single data type, simplified mathematical models, and insufficient accuracy. A novel approach is proposed that relies on comprehensive geological and engineering data from gas wells in the field. Data from 48 gas wells in the field were collected and pre-processed to obtain 129 geological and engineering influencing factors, and the correlation coefficients of each factor were calculated, ranked and chipped, and finally 39 main controlling factors for gas well production were screened out. Three models of multiple regression, support vector machine and Bayesian ridge regression were developed and evaluated, and the highest R 2 of the multiple regression model was 0.97. Relatively regression equations for daily gas and water production distribution were fitted and evaluated for their adequacy. The results demonstrated that the types of major control factors were consistent, and gas production was more sensitive than water production. Therefore, optimizing water control in gas wells with sufficient water production and adjusting the intensity of water control based on gas production adequacy is a feasible approach.