Gas Production Process Research Articles

Two-phase reactive transport modeling of heterogeneous gas production in a low- and intermediate-level radioactive waste repository

Deep geological disposal is a widely proposed approach for safe storage of low- and intermediate-level radioactive waste (L/ILW) for tens to hundreds of thousands of years. Although the use of cement materials will maintain a high pH environment that is favorable for radionuclide retention, slows down metal corrosion, and suppresses microbial activity, different gases may still be produced by chemical reactions, such as pH-dependent anoxic corrosion of metals, and the degradation of organic matter as well. Both reactions consume water and may lead to the formation of a free gas phase within and around the repository.In order to investigate the controlling factors of this gas production processes, a coupled reactive transport model of component-based two-phase flow in the OpenGeoSys framework is adopted here. Building on the previous work by Huang et al. (2021), this work extends the geometric configuration of the model from a single drum to the scale of a waste container (12 drums) in order to more realistically model the water and gas fluxes. The geochemical evolution of a container filled with cemented steel drums and surrounded by mortar and host rock is simulated in a two-dimensional setup over 500 years. The relative humidity in the pore space as measure of water availability determines the chemical reactivity.We have conducted a sensitivity study for the influence of mortar capillarity and permeability on gas production over time in the waste drums. As expected, the amount of gas produced within the first several years depends primarily on the initial water content within the waste drum and the amount of fast degradable waste stored in a drum. Later, this feedback system is forced into a new equilibrium, where the water transport has to match the water consumption rate at the waste package. Both, the mortar capillarity and permeability control the point in time when the equilibrium is reached and the subsequent rate of gas production.This study shows how reactive transport models are capable to help with the understanding of couplings between chemical and transport processes that control gas generation in L/ILW waste repositories, especially in barrier systems with different material properties. Future studies could benefit from more accurate parameterization of the chemical reactions, depending on the availability of new experimental data and/or more realistic process-based model approaches.

Natural gas production process fault localization based on direct transfer entropy with adaptive lag

Abstract Natural gas production equipment has complex structures, numerous monitoring parameters, and intricate correlation relationships, making it challenging to trace the source of faults for abnormal events. This paper proposes a fault localization method for natural gas production processes based on direct transfer entropy with adaptive lag (AL-DTE). Firstly, a variable set is screened based on the contribution plot. To enhance the adaptability to multiple operating conditions and reduce the reliance on experience, this paper integrates the adaptively to DTE and proposed AL-DTE. A causal analysis is then constructed and the causality graph is utilized to visualize the abnormal propagation path and identify the root cause of the fault. The proposed method can locate abnormal and faulty sub-equipment without relying on historical experience, enabling rapid localization of unknown faults. The effectiveness of the method is verified through simulation data and real faults of a triethylene glycol (TEG) dehydration equipment.

Data-Model Fusion-Driven Method for Fault Quantitative Diagnosis of Heat Exchanger

Heat exchangers play essential roles in the oil and gas production process for convective heat transfer and heat conduction. The health management of heat exchangers stays in the direct monitoring of performance parameters. Aiming at the difficulty of precise fault identification and quantification for heat exchangers in multiple unknown failure modes, a data-model fusion-driven fault quantitative diagnosis method is proposed. Firstly, based on the monitoring data such as temperature, pressure and flow rate, the secondary parameters characterizing the heat exchanger running state are constructed combined with structural physical parameters. Then, by analyzing the correlation among parameter variation, failure modes and deterioration degree, a qualitative inference model of heat exchanger is formed for fault identification, where weights of parameters are introduced based on their sensitivity for different failure modes. After the fault mode is identified, to achieve quantitative analysis of the failure degree, an index-integrated mechanism equation is constructed using monitoring data and secondary parameters, where the index is dynamically modified by online data. Finally, a heat exchanger experiment is carried out to demonstrate the robustness and accuracy of the proposed method.

Research on resistivity characteristics of grain-coating and pore-filling hydrates in different sediment packings based on voxelated 3D models

Natural gas hydrate is a clean energy resource with abundant reserves. Before conducting large-scale exploitation, understanding its physical properties, such as electrical properties, is crucial for gas reserve evaluation and production process monitoring. Due to the complexity of the pore space geometry and different hydrate growth morphology, electrical resistivity may vary for different samples at the same hydrate saturation. This study considered three packings of unconsolidated marine sediment grains (simple cubic, body-centered cubic, and face-centered cubic) and two end distribution patterns of hydrates in pores (grain-coating and pore-filling). The original 3D geometries of hydrate-bearing models were replaced with voxelated meshes to achieve better stability and versatility. The resistivities of models were calculated using the finite element method and compared with the results from Archie's law. The simulation results show that the resistivity curve's shape is jointly affected by the hydrate distribution pattern and the initial pore space geometry. A rational function can be used to fit the saturation exponent curves to give critical brine saturations. The grain-coating hydrate prefers blocking the throats and has a critical brine saturation above 0. In contrast, the pore-filling hydrate has resistivities lower than the Maxwell-Garnett equation's lower boundary due to a bypassing effect, which partially compensates for the conductivity loss of the pore fluid and is more remarkable for models distributed by bigger hydrate particles, and has a critical brine saturation equal to 0. The findings are helpful in understanding the non-Archie phenomenon of hydrate-bearing sediments.

Black powder and mineral deposits in the LPG production and processing line: Analytical study and formation mechanisms

The accumulation of mineral deposits such as black powder causes severe impacts throughout the gas production and transport process. The phenomenon takes place from gas wells to LNG/LPG treatment plants and terminals. The complexity lies in understanding the mechanisms by which these materials are formed in random quantities, as well as their varied nature. The aim of this study is to monitor black powder and other mineral deposits formation in a chain of gas production and processing situated in the south of Algeria and unravel their root causes. To that extent, an analytical study was carried out on four samples of both mineral deposits and black powder taken from an LPG processing and production unit. The adopted analytical approach included an exploration of the textural and structural properties. It also involves a composition characterizations related to the content of metallic elements, moisture, organic and mineral matter. The particle distribution is also determined. The analytical study was conducted using gravimetric determination, XRD, XRF, SEM/EDX and Raman spectroscopy. Particle distribution was given by Laser granulometry technique. The results of the DRX/FRX and EDX characterization primarily revealed that the samples contain a variety of mineral components such as iron oxides; magnetite Fe3O4 and hematite Fe2O3, iron oxy-hydroxide FeO(OH), iron sulphide FeS2, calcite CaCO3, SiO2 and halite NaCl. The presence distribution of these components depends on the location of the sample in gas line. Granulometry study shows that black powder contamination can be spread over a wide spectrum of particle sizes ranging from 1.51 µm to 678.50 µm. This study has allowed to elucidate the nature and distribution of particles deposited at different positions in the LPG production chain and to propose probable mechanisms for their formation.

Effects of operational parameters on fuel gas production from DC-transferred arc plasma processing of sewage sludge

ABSTRACT In this work, a DC-transferred arc plasma reactor was used to investigate the influence of operating parameters on the process of gas production from sewage sludge treatment. By varying the operating temperature, feedstock feed rate and exhaust gas flow, the study aims to elucidate the physicochemical mechanisms during plasma treatment. The sewage sludge from the municipal wastewater treatment plant has an ash content of 40.5%, consisting mainly of Si, Al, Fe and Ca (>75%), and a complex organic fraction containing carbonyls, amines and amides. At a constant mass of feedstock (without feed rate), the gas produced by the plasma treatment was obtained with a maximum syngas fraction of 86% and a heating value of 10,000 kJ/m3, while the process operated at a constant sludge feed rate of 300 g/min increased the volumetric fraction of the syngas to 95% and the heating value to 12,000 kJ/m3.

МҰНАЙ ЖӘНЕ ГАЗ КЕНОРЫНДАРЫНЫҢ ӨНІМДЕРІН ӨНДІРУДЕ ҚАЗІРГІ ЗАМАНҒЫ ЦИФРЛЫ ЖӘНЕ ЗИЯТКЕРЛІ ТЕХНОЛОГИЯЛАРДЫ ҚОЛДАНУ АСПЕКТІЛЕРІ

Most oil fields cover thousands of square kilometers, and some have reserves in difficult local conditions (heat, permafrost, desert, deep water) or difficult to recover. Due to these factors and a number of other problems related to technological safety, there are difficulties in the development of oil fields (with a steady increase in demand for oil and gas). Therefore, oil companies still need a highly reliable digital infrastructure that provides high productivity and security and manages many of the devices used in the oil and gas business throughout the field. Therefore, in recent years, oil companies around the world are increasingly managing their oil fields using "smart" technologies. They have proven to be a powerful tool for ensuring the safety of oil fields and increasing labor productivity, as well as economic efficiency. The technologies used include the improvement of all stages of the work process through the rapid acquisition of production data associated with advanced analytics, which contributes to a more complete and efficient development of the oil field. With experience in the implementation of "intelligent" technologies, it already shows high efficiency and very reliable results (both in terms of the oil production process itself and in terms of reducing the cost of individual operations). The use of modern digital and intelligent technologies in the production process in the oil and gas sector plays an important role in order to increase efficiency, ensure safety and reduce environmental impact. Application of digital technologies-data collection and analysis: IoT sensors (Internet of Things) allow you to collect data from deposits in real time and send it to analytical platforms. Field modeling: Using digital Twin technology, virtual field models are created that allow you to predict and optimize production processes. Automation: The automated systems and robotics used help to increase productivity in the management of the oil and gas production process.

Miscibility Evaluation for Reinjection of CO2 Flooding Associated Gas in Jilin Oilfield

Abstract In view of large amounts of associated gas produced in the late stage of CO2 flooding in Jilin Oilfield, the production characteristics of CO2 flooding associated gas are divided into three stages (i.e. before injected gas breakthrough, during injected gas breakthrough and after injected gas breakthrough). Taking the formation pressure as miscibility evaluation criteria, the miscibility effect of the produced CO2 flooding associated gas from different stages is evaluated. According to different gas production stages, the reinjection method of mixing the associated gas with pure CO2 under different proportions is proposed to elevate the utilization degree of the produced associated gas. The results indicate that at the very beginning of gas production process, produced gas is mainly composed of CH4 (58%) and C2~C3 (29%) with small amounts of N2 and C4~C6. During this stage, the associated gas can not reach miscibility with the oil by direct reinjection. It needs to be mixed with pure CO2, also the blending ratio of the associated gas should not exceed 6%. In the second stage, the compositions of the produced gas are mainly CH4 (34%) and CO2 (40%). During this stage, the blending ratio should not exceed 11%. At the final stage, the main composition of the produced gas is CO2 (94%). The associated gas can be directly reinjected into the reservoir during this stage.

Exploring the potential of cobalt-based catalysts in the methane dry reforming for sustainable energy applications

Cobalt-based powder catalysts with different Co loadings were synthesized via wet impregnation using MgAl2O4 spinel as support. The catalytic properties of the solids were evaluated in the dry-reforming methane at different reaction temperatures and two CH4:CO2 ratios. The catalyst with higher cobalt content (13 %) presented superior performance due to increased Co0 species availability, confirmed by XPS analysis. Besides, this catalyst displayed remarkable resistance to carbon deposition at 550 °C and CH4:CO2 1: 1 ratio. In-situ DRIFT measurements demonstrated the formation and transformation of carbonate and hydrogen carbonate species during the DRM reaction, highlighting efficient CO2 and CH4 activation on the catalyst surface. Based on this data, a structured catalyst was deposited on top of the FeCrAlloy monolith, which was active, stable, selective for H2, and resistant against on/off cycles. Compared with the powder catalyst, the structured system displayed higher catalytic activity, possibly due to higher reducibility of metal species and improved heat transfer provided by the FeCrAlloy substrate. The results highlight the potential of Co-based structured catalysts for H2 or synthesis gas production processes.

Development and Evaluation of Insulation Materials for Deepwater Cementing.

Marine oil and gas resources are abundant in deepwater regions, where the shallow seabed harbors natural gas hydrate layers due to the cold temperature and high-pressure environment. Hydrates are prone to thermal decomposition, which can compromise the integrity of cement sealing and even lead to accidents like blowouts. While current low-hydrated heat cement systems mitigate hydrate decomposition from cement hydration heat during the waiting period for cementing, they do not address heat transfer from deep strata to shallow hydrate layers through fluid circulation in the tubing during deep oil and gas development. Rather than utilizing costly pipe insulation technology, adjusting the thermal conductivity of well cement emerges as a cost-effective approach to prevent heat loss in the wellbore to the hydrate layer and thus inhibit hydrate decomposition. The critical aspect lies in utilizing insulation functional materials. This study delves into the functional and structural design of insulation materials suitable for cement slurry systems in well cementing, outlining the preparation methods and processes for two insulation materials (SDBW and SDBW-II) tailored for deepwater well cementing. SDBW and SDBW-II are both nuclear shell structural materials. The core is made of high-strength hollow microspheres, produced by using a reverse suspension polymerization method to form spheres followed by high-temperature sintering. The shell consists of a wear-resistant BPA epoxy resin layer, with the surface of SDBW-II also containing highly reflective glass microspheres. Incorporating 20% of material SDBW into the cement reduces the thermal conductivity of the cement stone from 0.8 to 0.31 W·(m·K)-1 while achieving a compressive strength of 6 MPa after 24 h at 20 °C. Material SDBW-II offers both thermal resistance and reflection functions, increasing reflectivity (R) from 0.3 to 0.5. By adding 20% of this material to the cement, under the same conditions, although the compressive strength decreases to 4.2 MPa, the thermal conductivity can be reduced to 0.27 W·(m·K)-1. Furthermore, there is no significant change within 180 days, demonstrating long-term thermal insulation stability. These developed insulation materials can effectively improve the thermal insulation performance of the cement sheath, thereby maintaining the stability of the upper natural gas hydrate layer in the oil and gas production process of deepwater wells, providing an innovative solution for the long-term operation of deepwater oil and gas wells.

Experimental investigation of online solving for critical valve opening for eliminating severe slugging in pipeline-riser systems

In an offshore pipeline-riser system, the critical opening of choke valve, i.e., the maximum permanent opening to eradicate severe slugging, plays an important role in both pipeline design and offshore oil and gas production processes. However, solving critical opening online in an offshore oil field is very difficult because only topside measurements are available and system information such as inlet gas–liquid flow rates and transfer functions are unavailable or far from precise. In order to cope with this problem, manually traversal experiments were first conducted in a large-scale experimental system consists of a 114-m horizontal pipeline, an 18.7-m downward-inclined pipeline with an inclination angle of −5˚ and a 16.3-m riser. Based on the results, a new process variable characterizing cut-off ratio of outflow and a new valve parameter describing the influence of valve on flow were derived. An approximate linear relation between these two parameters was found, with which critical openings can be calculated by processing real-time data. Finally, a control scheme was designed to overcome the calculation errors and solve for critical openings on line. The performance was validated by automatic control experiments.

Analysis of deformation and failure of sediment particle-surrounding rock structure of salt cavern gas storage under the coupled action of temperature and pressure

When gas is injected or produced in the gas storage of salt cavern, the different effects of thermal stress, gas pressure, sediment particles and brine pressure on the cavity wall of salt cavern may cause large deformation and damage in the surrounding rock, which threatens the safe and stable operation of the gas storage of salt cavern. Therefore, based on FLAC3D-PFC3D coupling method, a numerical model of salt cavern gas storage with sediment particles in consideration of temperature was constructed, and the influence of injection-production time effect, sediment particle size and initial porosity on the deformation and failure of sediment-surrounding rock structure is studied. The results show that the tensile contact force chain of sediment is sensitive to the particle size of sediment, but insensitive to the initial porosity of sediment and injection-production conditions; during gas production, the larger the particle size and initial porosity of sediment particles, the greater the vertical displacement of shallow sediment particles, and the opposite results are obtained during gas injection. With the progress of gas production and gas injection, the absolute value of vertical displacement of the roof of the salt cavern increases gradually, and the plastic failure range of surrounding rock expands; for gas production process, the larger the particle size and initial porosity of sediment, the smaller the algebraic value of vertical displacement of surrounding rock at the top of cavity and the smaller the plastic failure range of surrounding rock. For the gas injection process, the larger the particle size and initial porosity of the sediment, the larger the algebraic value of the vertical displacement of the surrounding rock at the top of the cavity and the larger the plastic failure range of the surrounding rock. The results can provide reference for the reasonable setting of injection-production operation parameters of salt cavern gas storage and ensure the safe and stable operation of underground salt cavern gas storage (USCGS).

Development and prototyping of a concentrated ethanol gas monitoring system based on the MQ-3 sensor using the KAVi machine calibrator for environmental safety

This research outlines the development of a device for measuring concentrated ethanol gas concentrations using the MQ-3 sensor. The device is engineered utilizing an Arduino Uno microcontroller and an LCD as the output interface. The MQ-3 sensor has demonstrated optimal sensitivity and a linear response to ethanol gas. The range of ethanol gas concentrations tested, from 10% to 70%, was selected to match the capabilities of the KAVi machine in generating ethanol gas. The testing process of the sensor was conducted to generate data that were subsequently calibrated to ensure measurement accuracy. Validation results indicate that the MQ-3 sensor can measure ethanol gas concentrations with high accuracy and good linearity within this range. However, discrepancies between the sensor measurements and the calibrator values were observed and need attention. The development of this device provides improvements in the accuracy and linearity of the MQ-3 sensor compared to previous studies. It is important to note that the KAVi machine has limitations in producing ethanol gas concentrations above 70%, which should be considered in the practical applications of this device. Overall, this device shows great potential in applications for monitoring ethanol gas concentrations, with a note to consider the limitations of the ethanol gas production process from the KAVi machine for more optimal results.

Pressure Source Model of the Production Process of Natural Gas from Unconventional Reservoirs

This work is focused on developing a computational model to predict the production rate and pressure evolution of natural gas from unconventional reservoirs, particularly shale gas deposits. The model is based on the principle of conservation of mechanical energy and was developed from the transient solution of Bernoulli’s equation. This solution was obtained by computing the pressure evolution in the well resulting from the combined action of extracting the free gas and of gasification from kerogen. The transient behavior of gas production by hydraulic fracturing was calculated by numerically integrating Bernoulli’s equation. The curves representing gas flow evolution were considered as a series of stepwise steady states under a constant gas flow rate, similar to the pressure–time curves. These time steps were connected by instantaneous drops in pressure or gas flow rates. On the other hand, the delayed release of the adsorbed and dissolved gas in the kerogen was accurately calculated by introducing a semi-empirical gas pressure source term into the gas well pressure equation. The effect of this source is to gradually increase the gas pressure in the reservoir, emulating the gas release mechanisms from the organic matter. Model validation was based on production data from the unconventional reservoirs Eagle Ford, U.S.A., and Burgos basin, México. The initial measured gas production rate was used to determine a global friction factor of the gas flowing out from soil cracks and ducts. Additionally, measured production rate data were used to determine the coefficients of the source term function. Pearson correlation coefficients of 0.97 and 0.96 were obtained for Eagle Ford and Burgos basins data, respectively. In contrast, the corresponding coefficients calculated from the traditional Arps’ model were 0.89 and 0.5, respectively. The present pressure source model (PSM) represents a new approach to characterize the process of gas production from unconventional reservoirs, proving to be accurate in forecasting both the gas flow rate and pressure evolution during gas production. The postulated pressure source term was shown to mimic the desorption and diffusion kinetics, which release free gas from the kerogen.

Rhamnolipids Enhance Bioremediation of Petroleum-Contaminated Soil

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 215952, “Enhancing Bioremediation of Petroleum-Contaminated Soil Using Rhamnolipids: A Combined Laboratory and Field Study,” by Pan Ni, Lehigh University; Yonglin Ren, SPE, Stepan Oilfield Solutions; and Derick G. Brown, Lehigh University, et al. The paper has not been peer reviewed. _ Hydrocarbon spills can occur at various stages of the oil and gas exploration and production process. Treating these spills onsite to avoid more-expensive excavation and incineration processes would be beneficial. The study outlined in the complete paper aims to optimize the use of rhamnolipid biosurfactants for enhancing the bioremediation of hydrocarbon-contaminated soil. The goal of this work was to explore the effects of rhamnolipid application on hydrocarbon degradation rate under both laboratory and field conditions and to examine the effects of this treatment on the indigenous soil microorganism population. Introduction The authors write that, to the best of their knowledge, previous research studies on rhamnolipid-based soil remediation focused on either laboratory or field tests and that comparison between laboratory-scale and field-scale tests is overlooked but necessary for practical applications. Materials and Methods Materials and Chemicals. The soil used for this work (23 kg for the laboratory test, 10 metric tons for the field test) was obtained from a contaminated site in Longford Mills, Canada. The soil properties are presented in Table 1 of the complete paper. The rhamnolipid stock solution featured 9.8 wt% rhamnolipid blends in deionized water. Another commercial remediation agent (enzyme-based) was used in the field test to compare with the performance of rhamnolipid. Ammonium chloride (NH4Cl) and potassium hydrogen phosphate (K2HPO4) also were used along with sodium hydroxide (NaOH). Experimental Setup. Both laboratory and field tests were ex-situ tests using simulated soil piles. The laboratory test was conducted for 193 days. For the laboratory experiments, an aerobic/anaerobic respirometer system equipped with a low-temperature incubator was used to monitor the in-situ oxygen uptake inside eight reactors (Fig. 1). Each reactor contained 250 g of soil with rhamnolipid doses of 0, 0.1, 0.5, and 1 g/kg. The temperature was set to 25°C. Inside each reactor was placed 10 mL of 4-M NaOH in a 20-mL glass beaker to adsorb the produced CO2. A parallel set of eight reactors was prepared and operated under the same conditions. The nutrients of nitrogen and phosphorous (NH4Cl and K2HPO4) were added at specific times based on the oxygen uptake rate monitored by the respirometer. To avoid the possible inhibition of the microbes in the soil as a result of high ionic strength (greater than 160 mM) in the soil pore water, NH4Cl and K2HPO4 were added so that the molar concentration in the soil pore water did not exceed 100 mM. The field test is being conducted in Longford Mills, Ontario, Canada, and is ongoing at the time of writing. For the field test, 10 metric tons of soil were mixed to achieve homogeneity before the preparation of the soil piles. Five different treatment conditions were examined using duplicate soil piles (10 piles total), with each consisting of 1 metric ton of soil. Nutrient addition was similar to that used in the laboratory tests. Temperature and moisture were monitored every few days at five points in each soil pile, and the pH was monitored once every month at five points.

Modulation Excitation Spectroscopy: A Powerful Tool to Elucidate Active Species and Sites in Catalytic Reactions.

ConspectusA rational design of catalysts requires a knowledge of the active species and sites. Often, catalyst surfaces are dominated by spectators, which do not participate in the reaction, while the catalytically active species and sites are hidden. Modulation-excitation spectroscopy (MES) allows discrimination between active and spectator species by applying a concentration modulation, which is translated into the active (that is, actively responding) species by phase-sensitive detection (PSD).While MES has been known for a while, its combination with infrared spectroscopy (IR-MES) has been applied to the detailed mechanistic analysis of a wide range of supported metal and metal oxide catalysts only recently, used for catalytic reactions such as CO2 hydrogenation, water-gas shift, and CO and selective oxidation. The applicability of IR-MES is not limited to catalysis but has started to expand into other areas of research (e.g., gas sensing).In the context of renewable energy, CO2 hydrogenation has been a matter of intense mechanistic debate, despite its great importance for synthesis gas production and further processing to fuels and chemicals. Applying IR-MES to supported Cu and Au catalysts enabled us to discriminate between redox and associative mechanisms. While CO2 hydrogenation to CO and water follows an associative pathway with sequential H2 activation via hydrides and formation of carbon- and oxygen-containing intermediates, such as carbonates and formates, the reverse reaction, that is, the water-gas shift reaction, was shown to proceed via a redox mechanism including oxygen vacancy formation followed by reoxidation of the catalyst by CO2.Recent IR-MES studies on (supported) metal oxides have provided direct spectroscopic insight into the catalytically active sites during the selective oxidation of alkanes and alcohols. By further expanding the potential of IR-MES by transient isotopic exchange experiments, we were able to resolve the nuclearity-dependent vanadium and adsorbate dynamics of supported vanadia catalysts during oxidative dehydrogenation, highlighting the intimate interplay between the surface vanadia species and the support. The strong influence of the support material (ceria and titania) on the sequence of reaction steps provides an explanation for the different catalytic performance. Based on these mechanistic insights, the rational design of improved catalysts has been possible.Expanding the application of IR-MES to the area of gas sensing, as recently demonstrated for doped SnO2, provides access to enhanced mechanistic insight, including previously undetected surface species. Methodical challenges arising from background features associated with semiconductor metal oxides have been successfully tackled, supporting further expansion of IR-MES in the gas sensing community. Mechanistically, the application of IR-MES allows identification of the actively participating OH groups and adsorbed species (e.g., alkoxy, CO, carbonate) and monitoring of reaction sequences based on their temporal behavior, providing a level of understanding typically not accessible by steady-state methods.As outlined above, the combination of MES/PSD with IR spectroscopy constitutes a powerful approach for the identification of catalytically active species and sites, which is essential for a profound mechanistic understanding of surface reactions, greatly facilitating the rational design of catalysts and other functional materials.

A Review of the Utilization of CO2 as a Cushion Gas in Underground Natural Gas Storage

A cushion gas is an indispensable and the most expensive part of underground natural gas storage. Using CO2 injection to provide a cushion gas, not only can the investment in natural gas storage construction be reduced but the greenhouse effect can also be reduced. Currently, the related research about the mechanism and laws of CO2 as a cushion gas in gas storage is not sufficient. Consequently, the difference in the physical properties of CO2 and CH4, and the mixing factors between CO2 and natural gas, including the geological conditions and injection–production parameters, are comprehensively discussed. Additionally, the impact of CO2 as a cushion gas on the reservoir stability and gas storage capacity is also analyzed by comparing the current research findings. The difference in the viscosity, density, and compressibility factor between CO2 and CH4 ensures a low degree of mixing between CO2 and natural gas underground, thereby improving the recovery of CH4 in the operation process of gas storage. In the pressure range of 5 MPa–13 MPa and temperature range of 303.15 K–323.15 K, the density of CO2 increases five to eight times, while the density of natural gas only increases two to three times, and the viscosity of CO2 is more than 10 times that of CH4. The operation temperature and pressure in gas storage should be higher than the temperature and pressure in the supercritical conditions of CO2 because the diffusion ability between the gas molecules is increased in these conditions. However, the temperature and pressure have little effect on the mixing degree of CO2 and CH4 when the pressure is over the limited pressure of supercritical CO2. The CO2, with higher compressibility, can quickly replenish the energy of the gas storage facility and provide sufficient elastic energy during the natural gas production process. In addition, the physical properties of the reservoir also have a significant impact on the mixing and production of gases in gas storage facilities. The higher porosity reduces the migration speed of CO2 and CH4. However, the higher permeability promotes diffusion between gases, resulting in a higher degree of gas mixing. For a large inclination angle or thick reservoir structure, the mixed zone width of CO2 and CH4 is small under the action of gravity. An increase in the injection–production rate intensifies the mixing of CO2 and CH4. The injection of CO2 into reservoirs also induces the CO2–water–rock reactions, which improves the porosity and is beneficial in increasing the storage capacity of natural gas.

Sistem Kontrol Dan Monitoring Hidrogen - Oksigen (HHO) Generator Berbasis Internet Of Things (IoT)

Electrolysis is a way to separate water (H2O) into hydrogen (H2) and oxygen (O2) gas by using an electric current through the water. The aim of this research is to create an Internet of Things (IoT) based prototype system that can monitor and control the hydrogen gas (H2) production process using the water electrolysis method. This research was carried out in several stages starting with a technology survey, then continuing with prototype design (including hardware design, software design, and circuit schematic design). This monitoring system device is designed with 3 sensors, namely: MQ-8 gas sensor, ACS712 current sensor, and BME280 pressure-temperature sensor. The MQ-8 sensor is set with a reading scale of 200-1000 ppm (parts per million) with an RMSE value obtained of 0.0288%. The ACS712 current sensor has an accuracy of 88.35% with a reading scale of 0-3.3 amperes, and the BME280 sensor has an accuracy of 94.47% for temperature and 99.37% for pressure with an ambient air reading scale. The results of water electrolysis testing of the entire system show that the system can work well in measuring parameters in accordance with the data sheet provisions, as well as providing flexibility in monitoring for users via smartphone.

Novel CNN-based transformer integrating Boruta algorithm for production prediction modeling and energy saving of industrial processes

Industrial process data collected by sensors have characteristics of high dimensionality, non-linearity and dynamics. Consequently, the selection extraction is regarded as a critical part for reducing the dimension of the data and removing irrelevant variables of constructing the production prediction model of industrial processes. Therefore, a novel production prediction model using the Boruta algorithm integrating the convolutional neural network-based Transformer (BCT) is proposed in this paper. Primarily, the Boruta algorithm maps nonlinear high-dimensional data to a low-dimensional space to select features that are meaningful to the yield of the industrial process. Then, the features are extracted adaptively using a convolutional neural network (CNN), which is encoded based on the transformer layer to learn relevant information about the different representation spaces. Furthermore, a linear layer with highway connections is employed to obtain prediction results. Finally, the BCT method is applied to establish a realistic production prediction model of actual liquefied petroleum gas plants for energy saving. Compared with back propagation neural networks, the radial basis function, the extreme learning machine, and the transformer based on the CNN, the BCT method achieves a state-of-the-art level. Furthermore, the BCT method provides the operation guidance on the actual liquefied petroleum gas (LPG) production process with increasing the LPG yield by 17.21%, which can improve production efficiency and reducing energy consumption.

Vibration characteristics and safety analysis of production string in high temperature, high pressure gas wells

During the production of high-temperature, high-pressure (HPHT) gas wells, the gas entering the production tubing column induces vibration, which in turn leads to changes in the mechanical properties and safety of the tubing column. A dynamic model of the production string in an HPHT gas well was established to study the dynamic characteristics of its production string. The additional axial force caused by the transient temperature change and the nonlinear contact collision between the production string and the casing were considered. The Newmark-β method was used to solve the problem by analyzing and comparing the flow-induced vibration characteristics of the production pipe string. In this study, a gas well in the southwest Sichuan Basin was used as the research object to study the effects of gas production, packer setting position, and string wall thickness on the dynamic characteristics of the string. The results show that in the gas production process, intense vibrations are generated in the transverse and longitudinal directions of the tubular column. After high-velocity gas flows through the production tubing column, the vibrations at the wellbore inclination and the top of the tubing column are more intense. With the rise of production and the downward movement of the packer setting position, the vibration displacement and frequency of the tubing column increase. In addition, as the column's wall thickness increases, the column's stiffness rises, which, in turn, reduces the vibration of the column. When the gas production increases from 60 × 104 m3/d to 150 × 104 m3/d, the maximum transverse vibration displacement of the production string will increase by 22.2%–39.3%, while the frequency will increase by 15.3%–54.3%. When the wall thickness of the pipe column reaches 9.53 mm and 10.92 mm, it can be employed to enhance the safety factor of the string and extend the fatigue life of the string. This study provides a theoretical framework for field string protection and production guidance.