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Direct power generation near gas fields offers numerous benefits, including optimized economic efficiency and reduced environmental impact. Moreover, building on-site greenhouses emerges as a promising approach to further minimize carbon emissions and residual heat, greatly promoting resource utilization. However, such power plants generally have access to a weak grid due to their remote locations, and they also contain nonlinear local loads, such as the grow lights in the greenhouses. Consequently, the generation system is susceptible to power quality issues, manifested in overvoltage and harmonics. To address these issues, a smart back-to-back converter is employed to interconnect the gas turbine generator and the utility grid. This smart converter not only enhances power quality but also offers potential ancillary services that contribute to the dynamics of the gas generation system, such as damping low-frequency oscillation among parallel-connected generators. In this paper, three control configurations for the back-to-back converter are developed, enabling the coordinated regulation of exported active power, AC voltage, and DC-link voltage in either a grid-following or grid-forming manner. Furthermore, comparative studies are conducted to provide guidelines for selecting an appropriate control strategy that ensures stable operation under various short circuit ratios. A practical gas cogeneration system is chosen to evaluate the performance of the back-to-back converter, and real-time simulations based on RT-LAB are carried out to validate the effectiveness of the methodology. [ABSTRACT FROM AUTHOR]

In the process of working face mining, the permeability of the coal seam and the crack evolution characteristics of overlying strata are very important for efficient gas drainage. In this study, the distribution characteristics of the stress field and crack field in the working face and their relations are analyzed mainly by 3DEC numerical simulation. Furthermore, combined with the on-site measurement of coal seam stress, gas pressure, and gas seepage in front of the working face and the gas seepage in overlying strata before and after mining, the coupling effect of stress field and gas field and the law of gas migration and distribution in the working face are deeply explored. The results show that the changing trend of gas seepage and gas pressure is controlled by the stress change of the working face, and with the increase of stress, gas pressure and gas seepage also increase. The peak position of gas pressure is the farthest from the coal wall, about 22.5~25 m, followed by the peak of stress and gas seepage. When the permeability of coal and rock mass increases, the gas seepage increases and the gas pressure decreases. The coal seam stress and gas seepage in the working face and gas seepage in the overlying strata fracture zone along the tailgate side are generally greater than those on the headgate side, but the gas pressure is the opposite. Mining cracks and strata separation provide a good channel and space for gas migration and accumulation. Along the strike and tendency of the working face, gas is mainly concentrated in the overlying strata crack space above the separation zone and the roof and overlying strata crack space on the side of the tailgate, respectively. Based on this, the directional borehole gas drainage technology and borehole layout scheme in the fractured zone are put forward, which effectively reduce the gas concentration in the working face by 30~36%. [ABSTRACT FROM AUTHOR]

The possibilities of using geothermal energy are slowly expanding to all areas of energy consumption, so the assessment of geothermal potential has become the backbone of energy policies in countries that have the potential. Countries and companies that have experience in the oil and gas industry are increasingly exploring the possibilities of first using the acquired knowledge, and then using the existing oil and gas infrastructure for the use of geothermal energy. For this reason, it is necessary to analyse the possibilities of using the existing infrastructure with all its limitations to maximise the energy potential of geothermal energy. The existing oil infrastructure, especially the wells, is in many cases not suitable for the production of brine and it is necessary to analyse the maximum impact of each well for the production of geothermal energy, with particular attention to the equipment installed in the well and the thickness of the geothermal reservoir in the oil and gas fields that would be suitable for the production of brine. [ABSTRACT FROM AUTHOR]

Numerical models reproducing the seismic evolution in gas fields can be utilized to study the characteristics of compaction‐induced seismicity during production and thus derive valuable information for the assessment of the seismic hazard. Here, we present a numerical approach for a Rotliegend gas field in Northern Germany ("reference field"), consisting of the simulation of poro‐elastic stresses within a 3D finite element model. Fault stability is controlled by Coulomb friction, whereas the post‐failure process is implemented using a slider‐block model. The model successfully computes seismic sequences, which reproduce the main characteristics of the observed seismicity in the reference field: the location, the temporal seismic evolution, including the retarded onset several years after the beginning of production, the high prevalence of moderate magnitudes, the observed maximum magnitude and cumulative seismic moment release. The numerical simulations reveal that seismicity‐driving stresses are restricted to the vicinity of fault intersections with the top and bottom of the reservoir, respectively. Slip frequently extends beyond the vertical boundaries of the reservoir, although the failure process is generally self‐arrested outside the reservoir boundaries. The magnitude frequency distribution of observed and simulated earthquakes deviates from the log‐linear behavior frequently assumed in seismic hazard assessments. Instead, the earthquake activity is consistent with a "characteristic earthquake" model, where a fault repeatedly hosts earthquakes with a specific maximum magnitude. Our analysis indicates that production‐induced seismicity is primarily controlled by poro‐elastic stress changes rather than by unknown details of subsurface conditions. This allows for a prognosis of future seismicity and associated hazard. Plain Language Summary: Seismicity induced by gas production in Northern Europe exhibits an unusual signature compared to seismicity associated with other subsurface technologies. Moderately strong earthquakes appear after several years of production, frequently without any smaller‐sized precursors. A so far unanswered question is whether the magnitude of the strongest earthquakes continues to increase during ongoing gas production or stays at a moderate magnitude level. We have developed a numerical model to simulate induced seismicity caused by gas production at a field in Northern Germany. Initially, we model the gas depletion and the associated changes in the stress conditions in the subsurface. Subsequently, we simulate earthquakes triggered by these stress changes with a block‐spring approach, where subsurface faults consist of a large number of undeformable but interconnected blocks. The strength of each earthquake at a certain time is mainly determined by the area of simultaneously activated blocks. The results of these simulations indicate that the maximum earthquake strength remains constant with ongoing gas production. The earthquake of maximum strength is subjective to each fault and may occur several times. This finding is crucial regarding the assessment of the seismic hazard for producing gas fields in Northern Europe. Key Points: A physics‐based model reproduces the most important characteristics of gas production‐induced seismicity in a field in Northern GermanyEarthquakes originate at the reservoir boundaries and may propagate into the surrounding rock, where the failure process is self‐arrestedSeismicity on each fault is characterized by a recurring maximum magnitude [ABSTRACT FROM AUTHOR]

Coal in a natural geological mass is typically heterogeneous, potentially containing widely distributed faults that affect gas migration and are closely associated with the occurrence of coal-gas outbursts. In this study, the permeabilities of intact and heterogeneous coals during the mining process were described using a dual-porosity model and modified transversely isotropic permeability model, respectively. Numerical simulations based on these models revealed a high gas pressure gradient in front of the working face largely owing to the blocking effect of a low-permeability zone along the fault that led to the formation of a high-pressure gas zone; field measurements confirmed that the gas content in this zone was 2–3 times that in ordinary coal. When close to the fault, a considerable quantity of gas was observed within the working face, then the gas emission increased by 2.4 times once the low-permeability zone along the fault was obliterated. Finally, the proposed model was employed to explain how concurrent increases in shear stress and gas pressure affect the stability of a fault and promote coal-gas outbursts. The proposed model can be applied to conduct theoretical assessments informing measures to prevent gas-related dynamic disasters in coal mines. [ABSTRACT FROM AUTHOR]

The ethylenediamine-N,N′-disuccinic acid (EDDS) was utilized to form Fe-EDDS complex to activate peroxymonosulfate (PMS) in the electrochemical (EC) co-catalytic system for effective oxidation of naphthenic acids (NAs) under neutral pH conditions. 1-adamantanecarboxylic acid (ACA) was used as a model compound to represent NAs, which are persistent pollutants that are abundantly present in oil and gas field wastewater. The ACA degradation rate was significantly enhanced in the EC/PMS/Fe(III)-EDDS system (96.6%) compared to that of the EC/PMS/Fe(III) system (65.4%). The addition of EDDS led to the formation of a stable complex of Fe-EDDS under neutral pH conditions, which effectively promoted the redox cycle of Fe(III)-EDDS/Fe(II)-EDDS to activate PMS to generate oxidative species for ACA degradation. The results of quenching and chemical probe experiments, as well as electron paramagnetic resonance (EPR) analysis, identified significant contributions of •OH, 1O2, and SO4•− in the removal of ACA. The ACA degradation pathways were revealed based on the results of high resolution mass spectrometry analysis and calculation of the Fukui index. The presence of anions, such as NO3−, Cl−, and HCO3−, as well as humic acids, induced nonsignificant influence on the ACA degradation, indicating the robustness of the current system for applications in authentic scenarios. Overall results indicated the EC/PMS/Fe(III)-EDDS system is a promising strategy for the practical treatment of NAs in oil and gas field wastewater. [ABSTRACT FROM AUTHOR]