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This article estimates the potential of using depleted offshore gas fields in Brazil for hydrogen storage and the effects this may have in terms of energy security. Brazil is starting to invest in producing green hydrogen associated with offshore wind energy generation. This initiative has stimulated the search for suitable locations to store hydrogen, including in depleted offshore gas reservoirs. The methodology used in this paper allows for identifying which of the 85 assessed depleted offshore gas fields are the most suitable for hydrogen storage and evaluating the storage capacity of the selected fields. In addition, a wind speed analysis is made to investigate possible locations for prospective wind energy generation projects that can accommodate green hydrogen production. As our main result, we find that the selected depleted offshore gas fields have the potential to store around 5483 TWh worth of hydrogen. This amount is equivalent to about 10 times the total annual electricity consumption in Brazil. Hence, Brazil can comfortably leverage its offshore wind potential in connection with hydrogen production to enhance the energy security of its electricity supply. Considering that to date primarily natural gas has been used as the main source of energy security in Brazil and that its share in the electricity sector has significantly increased over the last decade, the combination of hydrogen storage and renewable energy such as offshore wind power has the potential to provide a resilient and decarbonised electricity system in the country. Furthermore, hydrogen stored in offshore reservoirs in Brazil can become an important resource in the international energy market and constitute a possible key to energy security for countries to which Brazil may export hydrogen. We end our paper by providing comments on the challenges, opportunities, and prospects of offshore hydrogen storage in Brazil. • Offshore natural gas fields in Brazil are suitable for hydrogen storage. • Depleted offshore gas fields can store around 5483 TWh worth of hydrogen. • Two main offshore storage clusters exist in the Southeast and Northeast of Brazil. • Fossil fuel dependence in Brazil can be reduced through hydrogen use and storage. • Large-scale hydrogen storage can contribute to Brazil's energy security. [ABSTRACT FROM AUTHOR]

The analysis of amplitude spectra from a thin polystyrene-based scintillation counter on muon-enriched and hadron beams of channel 18 of the U-70 accelerator complex in Protvino has been presented. On the basis of statistics of 150 million events on the Hyperon-M setup, the contribution of the -fragmentation processes are highlighted and the cross sections of these processes on hadron and pion beams with a momentum of 7 GeV/c have been measured. In the future, the obtained result may be of interest for the method of analyzing the age of gas fields based on the concentration of helium in natural gas, the formation of which is possible in the reaction of fragmentation of carbon nuclei in interactions induced by high-energy cosmic muons. [ABSTRACT FROM AUTHOR]

LNG floating production storage and offloading (FPSO) unit is a new type of floating production unit developed for offshore natural gas fields. It performs the functions of natural gas extraction, pretreatment, liquefaction, and storage. In this study, the heat transfer characteristics of a spiral-wound heat exchanger were studied using numerical simulations, which provides a basis for equipment selection and structural optimization of spiral-wound heat exchangers. The main research contents and conclusions are as follows. Under land-based simulation conditions, the heat transfer coefficient of the shell side of the spiral-wound heat exchanger decreases with an increase in the winding angle of the heat exchange tube, decreases with an increase in the spacing of the heat exchange tube, and increases with an increase in the outer diameter of the heat exchange tube. When the winding angle increased from 5° to 8°, the heat transfer coefficient decreased by 6.70%. The heat transfer coefficient of the shell side decreased by 13.21% when the heat exchange tube spacing increased from 14 to 17 mm. The heat transfer coefficient of the shell side increased by 22.89% when the outer diameter of the heat exchange tube increased from 9 to 12 mm. When the sloshing angle is constant, the heat transfer coefficient of the spiral-wound heat exchanger decreases with an increase in the winding angle and spacing of the heat exchange tubes, and increases with an increase in the outer diameter of the heat exchange tubes. When the structural parameters of the heat exchanger are constant, the heat transfer coefficient decreases as the sloshing angle increases. When the sloshing angle was less than 3°, the sloshing promoted heat transfer on the shell side. When the sloshing angle was higher than 7°, the heat transfer effect of the shell side deteriorated considerably, which weakened the heat transfer performance of the heat exchanger. When the sloshing period is constant, the heat transfer coefficient of the wound heat exchanger decreases with an increase in the winding angle and spacing of the heat exchange tubes, and increases with an increase in the outer diameter of the heat exchange tubes. When the structural parameters of the heat exchanger are constant, the heat transfer coefficient increases with sloshing period. When the sloshing period was greater than 15 s, the influence of sloshing on the heat transfer on the shell side of the heat exchanger was relatively weak. [ABSTRACT FROM AUTHOR]

Constructivists in the field of International Relations assume that states not only seek to ensure their physical security but also try to secure their identities by maintaining durable behavioral patterns in their relations with other actors. The dominant identity of the Israeli state is associated with policies characterized by resoluteness and decisiveness. This article argues that this state identity also manifests itself in the domestic sphere and presents case studies of two such manifestations. The first pertains to the development of Israeli offshore gas fields in the Eastern Mediterranean while the second deals with the country's COVID-19 pandemic containment strategy. The two cases are similar in the decisive and extraordinary character of the measures that the government attempted to use. At the same time, in the first case study this attempt was mostly unsuccessful and only in the second case the decisive stance was effectively implemented. [ABSTRACT FROM AUTHOR]

The hydrocarbon accumulation modes and differences in the Tethyan realm serve as a hot research topic in the petroleum geology community at home and abroad. Both the Persian Gulf Basin in the Middle East and the Sichuan Basin in China, situated on the southern and northern sides of the Tethyan realm, respectively, record the whole geological process of the opening and closure of the Prototethys, the Paleotethys, and the Neotethys sequentially, exhibiting anomalous hydrocarbon enrichment Based on the analysis of the plate tectonic evolution in the Tethyan realm, this study dissects the structures and hydrocarbon accumulation conditions of both basins. Followed by a systematic comparative analysis of the factors controlling hydrocarbon enrichment in the process of plate breakup and convergence in the Tethyan realm, this study proposes petroleum exploration targets in the realm. The results are as follows: (1) Since the Meso-Neoproterozoic, the Persian Gulf Basin and the Sichuan Basin have undergone similar tectonic evolution in the early stage but different in the late stage. Under the influence of the formation and evolution of the Prototethys, Paleotethys, and Neotethys oceans, both basins experienced multi-stage development and modification, forming two major extension-convergence cycles. Consequently, both basins are characterized by the vertical orderly superimposition of various basin prototypes in the order of rift-intracratonic basin (passive continental margin)-foreland. (2) The fact that the Tethyan realm was long located at medium-low latitudes and the local anoxic environment formed in the process of plate breakup and convergence played a vital role in the formation of extensive source rocks. The source rocks are predominantly distributed in underfilled rifts and deep depressions that were connected to the ocean in the unidirectional continental breakup process; basin-slopes and intra-shelf basins on passive continental margins; basinal lows within intracratonic basins, and underfilled foredeeps in foreland basins. The favorable areas for the formation of carbonate reservoirs include platform margins, submarine highs and paleo-uplifts within platforms, and fault zones. The evaporite cap rocks, intimately associated with the basin evolutionary stages and global dry-hot events, are critical for large-scale hydrocarbon preservation. (3) Under the influence of Tethyan evolution, the Persian Gulf Basin and the Sichuan Basin share similar primary factors controlling hydrocarbon enrichment. The moderate tectono-sedimentary differentiation and structural modification in the process of prototype basin superimposition, as well as the spatio-temporal matching of elements critical for hydrocarbon accumulation, are beneficial for the development of large oil and gas fields. The macroscopic hydrocarbon distribution is dictated by source rock-cap rock assemblages, while the local hydrocarbon distribution is governed by trap-reservoir assemblages. The critical factors determining the differential hydrocarbon enrichment in the Persian Gulf Basin and the Sichuan Basin include plate size and position, basement stability, eustatic movement, paleoclimate, and tectonic transformation. Besides, different tectonic modification intensities are closely related to the type, enrichment degree, and distribution of hydrocarbon reservoirs. [ABSTRACT FROM AUTHOR]

The evaluation of remaining reserves is crucial for assessing the developmental effect and further enhancing the recovery of a gas field. In this research, with the Changning shale gas field in the southern Sichuan Basin as the center of study, a comprehensive analysis was conducted on reservoir distribution, remaining reserves, and strategies to enhance recovery through the utilization of diverse methodologies, including organic geochemical testing, triaxial rock mechanics experiments, and numerical simulations. The results show that, in the study area, the recovery percentage of the well-controlled reserves ranges from 45% to 70%, with the average remaining reserves of wells falling within the (50-150) × 106 m3 range, alongside the potential for additional development in specific local areas. The Changning shale gas field exhibits three distinct types of undeveloped reserves, identified in areas where no wells have been drilled, inadequately fractured zones, and vertically undeveloped areas, respectively. In the areas where the average remaining reserves of wells are exceeding 100 × 106 m3, wells for repeated fracturing are selected depending on the coupling of geological, engineering, and development. In the case of well infilling, areas characterized by developed reticular fractures and existing well spacing >500 m are prioritized, taking into account the surface wellsite conditions. Through an extensive analysis, which include reservoir assessments, rock mechanics evaluations, and numerical modeling, sublayer? is identified as the optimal target in the upper gas interval, with a vertical distance of more than 20 m from sublayer? in the lower gas interval. Zones with well-developed reticular natural fractures, a pressure coefficient >1.2, and a continuous thickness of Class I reservoirs in the upper gas interval >10 m, are selected for staggered tridimensional development with an expected increase in the platform-level recovery percent by 30%. These findings can provide valuable references and guidance for the deployment of well patterns in shale gas blocks. [ABSTRACT FROM AUTHOR]

The largest Precambrian gas field (Anyue Gasfield) in China has been discovered in the central Sichuan Basin. However, the deep ancient Ediacaran dolomite presents a substantial challenge due to their tightness and heterogeneity, rather than assumed large-area stratified reservoirs controlled by mound-shoal microfacies. This complicates the characterization of "sweet spot" reservoirs crucial for efficient gas exploitation. By analyzing compiled geological, geophysical and production data, this study investigates the impact of strike-slip fault on the development and distribution of high-quality "sweet spot" (fracture-vuggy) reservoirs in the Ediacaran dolomite of the Anyue Gasfield. The dolomite matrix reservoir exhibits low porosity (less than 4%) and low permeability (less than 0.5×10–3 μm2). Contrarily, fractures and their dissolution processes along strike-slip fault zone significantly enhance matrix permeability by more than one order of magnitude and matrix porosity by more than one time. Widespread "sweet spot" fracture-vuggy reservoirs are found along the strike-slip fault zone, formed at the end of the Ediacaran. These fractured reservoirs are controlled by the coupling mechanisms of sedimentary microfacies, fracturing and karstification. Karstification prevails at the platform margin, while both fracturing and karstification control high-quality reservoirs in the intraplatform, resulting in reservoir diversity in terms of scale, assemblage and type. The architecture of the strike-slip fault zone governed the differential distribution of fracture zones and the fault-controlled "sweet spot" reservoirs, leading to wide fractured-vuggy reservoirs across the strike-slip fault zone. In conclusion, the intracratonic weak strike-slip fault can play a crucial role in improving tight carbonate reservoir, and the strike-slip fault-related "sweet spot" reservoir emerges as a unique and promising target for the efficient development of deep hydrocarbon resources. Tailored development strategies need to be implemented for these reservoirs, considering the diverse and differential impacts exerted by strike-slip faults on the reservoirs. [ABSTRACT FROM AUTHOR]

Logs are valuable information for oil and gas fields as they help to determine the lithology of the formations surrounding the borehole and the location and reserves of subsurface oil and gas reservoirs. However, important logs are often missing in horizontal or old wells, which poses a challenge in field applications. To address this issue, conventional methods involve supplementing the missing logs by either combining geological experience and referring data from nearby boreholes or reconstructing them directly using the remaining logs in the same borehole. Nevertheless, there is currently no quantitative evaluation for the quality and rationality of the constructed log. In this paper, we utilize data from the 2020 machine learning competition of the Society of Petrophysicists and Logging Analysts (SPWLA), which aims to predict the missing compressional wave slowness (DTC) and shear wave slowness (DTS) logs using other logs in the same borehole. We employ the natural gradient boosting (NGBoost) algorithm to construct an Ensemble Learning model that can predicate the results as well as their uncertainty. Furthermore, we combine the SHAP (SHapley Additive exPlanations) method to investigate the interpretability of the machine learning model. We compare the performance of the NGBosst model with four other commonly used Ensemble Learning methods, including Random Forest, GBDT, XGBoost, LightGBM. The results show that the NGBoost model performs well in the testing set and can provide a probability distribution for the prediction results. This distribution allows petrophysicists to quantitatively analyze the confidence interval of the constructed log. In addition, the variance of the probability distribution of the predicted log can be used to justify the quality of the constructed log. Using the SHAP explainable machine learning model, we calculate the importance of each input log to the predicted results as well as the coupling relationship among input logs. Our findings reveal that the NGBoost model tends to provide greater slowness prediction results when the neutron porosity (CNC) and gamma ray (GR) are large, which is consistent with the cognition of petrophysical models. Furthermore, the machine learning model can capture the influence of the changing borehole caliper on slowness, where the influence of borehole caliper on slowness is complex and not easy to establish a direct relationship. These findings are in line with the physical principle of borehole acoustics. Finally, by using the explainable machine learning model, we observe that although we did not correct the effect of borehole caliper on the neutron porosity log through preprocessing, the machine learning model assigned a greater importance to the influence of the caliper, achieving the same effect as caliper correction. [ABSTRACT FROM AUTHOR]

The petroleum industry produces a large amount of wastewater, known as produced water (PW), during oil production and processing. This PW contains hazardous organic and inorganic components that can harm the environment. Conventional treatment methods have been used to purify PW, but they do not meet environmental regulations, especially when the goal is to reuse the water. Therefore, further research is needed to find an effective technology for managing PW. This review focuses on the characteristics and management of PW originating from oil and gas fields. Firstly, we provide a detailed overview of PW production scenarios worldwide and in the US with detailed quantities and chemical compositions of organic, inorganic, and physicochemical characteristics. Secondly, challenges and environmental concerns associated with treating PW are discussed. Thirdly, all relevant treatment technologies for PW are systematically explored. In addition, this review highlights the management of PW and suggests treatment options and best practices for the industry, and finally, future research needs and opportunities for sustainable water treatment and effective reuse technologies are addressed. Because PW contains a variety of severe contaminants, single methods have not been effective in converting it to a reusable form or fulfilling disposal criteria. As a result, integrated technologies may provide a potential approach that not only meets regulatory standards but also provides chances to employ PW as a non-conventional water supply. Advances in PW management are critical and demand a defined framework and risk-based approach to determine and build the most efficient plan. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract—A solution to the problem of compiling decision rules for determining possible oil and gas fields in the territory of Western Siberia by the method of monotonic functions is proposed. The method is based on a model in which the decision rule is sought in the class of monotonic functions on the feature space. This method was applied first to solving the binary classification problem when choosing the type of operation for patients with prostate cancer. In this paper, an example of applying the method to the classification problem in geosciences is considered. The results of the method showed quite high estimates of the probability of identifying possible deposits, with fairly low error probabilities. [ABSTRACT FROM AUTHOR]

Understanding the factors affecting reservoir quality and producing wells requires an in-depth knowledge of petrophysical analysis. The study employed wireline log data from three wells (TT-1, TT-6, and TT-11) to analyze the petrophysical properties of a giant gas field in Bangladesh. In TT-1 and TT-6 wells, the gamma ray log, resistivity log, and porosity log were used to calculate the petrophysical properties. Along with these logs, a caliper log was also used for the TT-11 well. "Sedlog 3.1" was used in this study to identify and show the lithology of the TT-1, TT-6, and TT-11 wells. Using the log reading, the average effective porosity in TT-1, TT-6, and TT-11 ranges from 1.83 to 28.5% at different ranges of depth (600 to 3400 m) of the three wells, where the porosity was 7.73–69.06%. The gas saturation of the sandstone zone ranges from 0 to 49.2%, and the maximum gas saturation was found at depths of 2650 to 2800 m at well TT-11. The shale volumes of the sand zones were calculated by Schlumberger Clavier and Atlas formulas, which show that the shale volumes of TT-1, TT-6, and TT-11 were 7.88–38.31%, 10.20–26.02%, and 5–38.3%, respectively. Analyzing the petrophysical properties, it is summarized that TT-1 and TT-6 have two hydrocarbon-bearing potential zones, and TT-11 has the one most effective hydrocarbon potential zone. This data can be used by the national gas field developer to reevaluate the giant gas field's reserve. [ABSTRACT FROM AUTHOR]

The current situation of the energy conservation standard system in the oil and gas industry and the actual needs of the energy consumption quota standard system are analyzed, which include the hierarchical division of the energy consumption quota index system and the energy consumption quota index. The energy consumption quota index system for oil and gas field production is established. The formulation methods mainly include the actual measurement method, the technical calculation method and the statistical analysis method, which are compared and analyzed. The energy consumption quota indicator system and quota formulation method for oil and gas field production can provide scientific support for the formulation of energy consumption quota for oil and gas fields, so as to promoting the improvement of quality and efficiency of oil and gas field enterprises. [ABSTRACT FROM AUTHOR]

Despite the efforts to transition to a low carbon economy, greenhouse gas emissions are surging to critical levels. Carbon dioxide removals (CDR) methods, such as direct air capture (DAC), have been gaining substantial public attention in the last few years. DAC is essential in curbing CO2 concentrations and achieving climate targets. It is said that DAC can be deployed at anywhere, but a throughout life cycle assessment (LCA) is imperative to prove its viability. Therefore, this paper aims to explore the feasibility of constructing a 1 MT CO 2 plant in Ireland, using Kinsale and Corrib gas fields as storage points. The results showed that the country is an ideal candidate for scaling up this emerging industry. The efficiency is primarily influenced by the construction of the pipeline section, given a reliable sources of heat and electricity. The study highlights the significant impact of distances to the storage points on feasibility, favouring counties near of the gas fields. In conclusion, Ireland has the potential to establish its own DAC industry. [ABSTRACT FROM AUTHOR]

In order to solve the problem of external corrosion of deep well casing in oil and gas fields, a new type of high-temperature-resistant zinc alloy sacrificial anode material was used. The temperature and corrosion resistance of the new anode material and TP140 casing were investigated by simulating the high-temperature working conditions of a deep well in an oil field using high-temperature and high-pressure corrosion tests and electrochemical tests. The results showed that at 100–120 °C, the corrosion rate of TP140 protected by a sacrificial anode was only one-tenth of that under unprotected conditions, and the minimum corrosion rate of TP140 protected by a sacrificial anode at 100 °C was 0.0089 mm/a. The results of the dynamic potential polarization curve showed that the corresponding corrosion current density of TP140 first increased and then decreased with the increase in temperature. The self-corrosion potential in sacrificial anode materials first increased and then decreased with the increase in temperature, and the potential difference with TP140 gradually decreased. [ABSTRACT FROM AUTHOR]

A simulation study was carried out to investigate the temporal evolution of H2S in the Huangcaoxia underground gas storage (UGS), which is converted from a depleted sulfur-containing gas field. Based on the rock and fluid properties of the Huangcaoxia gas field, a multilayered model was built. The upper layer Jia-2 contains a high concentration of H2S (27.2 g/m3), and the lower layer Jia-1 contains a low concentration of H2S (14.0 mg/m3). There is also a low-permeability interlayer between Jia-1 and Jia-2. The multi-component fluid characterizations for Jia-1 and Jia-2 were implemented separately using the Peng-Robinson equation of state in order to perform the compositional simulation. The H2S concentration gradually increased in a single cycle and peaked at the end of the production season. The peak H2S concentration in each cycle showed a decreasing trend when the recovery factor (RF) of the gas field was lower than 70%. When the RF was above 70%, the peak H2S concentration increased first and then decreased. A higher reservoir RF, a higher maximum working pressure, and a higher working gas ratio will lead to a higher H2S removal efficiency. Similar to developing multi-layered petroleum fields, the operation of multilayered gas storage can also be divided into multi-layer commingled operation and independent operation for different layers. When the two layers are combined to build the storage, the sweet gas produced from Jia-1 can spontaneously mix with the sour gas produced from Jia-2 within the wellbore, which can significantly reduce the overall H2S concentration in the wellstream. When the working gas volume is set constant, the allocation ratio between the two layers has little effect on the H2S removal. After nine cycles, the produced gas's H2S concentration can be lowered to 20 mg/m3. Our study recommends combining the Jia-2 and Jia-1 layers to build the Huangcaoxia underground gas storage. This plan can quickly reduce the H2S concentration of the produced gas to 20 mg/m3, thus meeting the gas export standards as well as the HSE (Health, Safety, and Environment) requirements in the field. This study helps the engineers understand the H2S removal for sulfur-containing UGS as well as provides technical guidelines for converting other multilayered sour gas fields into underground storage sites. [ABSTRACT FROM AUTHOR]

In this study, the effects of vane channel parameters on the flow field and separator performance are investigated based on a vane type gas-water separator for a PEMFC (proton exchange membrane fuel cell) system. The Eulerian-Eulerian model combines with the Multi-Fluid VOF (volume of fluid) modeling approach is used to comprehensively investigate the gas-liquid two-phase flow field and performance indexes in the separator, and the sensitivity analysis of the structural parameters is carried out. The results show that the pressure drop of the separator gradually increases with the increase of the vane contraction ratio, while the separation efficiency has a tendency to increase and then decrease with the increase of the vane incidence angle. For the separation efficiency, the most beneficial structural variant results in an increase of 11.63%, while for the pressure drop, almost all structural variants result in a reduction of the pressure drop from the standard structure with a maximum reduction of 36.58%. By analyzing the phase distribution, pressure field and velocity distribution of different structures, it can be obtained that the main factors affecting the performance of the separator are the extreme values of tangential velocity inside the separator and the symmetry of velocity distribution in the internal flow field. The results presented in this study can provide a reference for the PEMFC gas-water separator. [Display omitted] • A numerical simulation coupling Eulerian method with Multi-Fluid VOF model is applied. • A new gas-water separator structure for PEMFC system is investigated in detail. • Vane incidence angle and vane contraction ratio have a large effect on separator performance. • Sensitivity analysis of vane structural parameters to find out their priorities. [ABSTRACT FROM AUTHOR]

The Rio Muni Basin is a hotspot for deep-water oil exploration in West Africa. The discovery of thirteen oil and gas fields, including Ceiba, Akom 1, and Oveng, proves the basin's excellent exploration prospects, but only limited research has thus far been carried out there. The recent new drilling indicates that there are organic matter-rich fine-grained sedimentary rocks in the Albian and Cenomanian–Turonian stages of the Cretaceous strata. However, the depositional models of organic-rich, fine-grained sedimentary rocks are not clear. The main objectives of this study are as follows: (1) to identify the lithofacies characteristics of fine-grained sedimentary rocks in the Albian–Turonian stages of the Rio Muni Basin; and (2) to establish a depositional model for organic-rich fine-grained sediments. In this study, the mineralogical characteristics of Albian–Turonian fine-grained were determined by means of X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and thin section analysis. In addition, the integration of mineralogical features with the total organic carbon (TOC) content allows for the recognition of three distinct lithofacies: (1) siliceous-clayey rock, (2) terrigenous clastic mixed fine-grained rock, and (3) lime-mixed fine-grained rock. Based on the evolutionary history of the passive continental margin basins in West Africa and the lithofacies characteristics, the deposition mode of organic-rich fine-grained sedimentary rocks in the Albian–Turonian stages was reconstructed by combining geochemical features with the characteristics of framboidal pyrite. The depositional models for the Albian stage are "continental margin–restricted sea–marine algae–source rocks" with the development of organic-rich fine-grained sedimentary rocks. The depositional models for the Cenomanian–Turonian stage are "continental margin–semiopen sea–mixed-source rocks". The Albian and Cenomanian–Turonian organic-rich fine-grained sedimentary rocks represent two different deposition modes with restricted sea and semiopen sea conditions. The sedimentary characteristics in the study area during the two periods were both inherited and notably different. [ABSTRACT FROM AUTHOR]

In the process of natural gas production using foam to lift liquid, there exists obvious difference in the requirements of foam stability between wellbores and gathering & transportation systems. To ensure the effect foam dewatering of gas wells and highly efficient defoaming and gas-water separation on surface, it is meaningful to investigate the influencing factors of foam stability comprehensively. In this paper, a tight gas block in China which adopted foam for liquid lifting was taken as an example. It was researched that the key influencing factors and changing rules of foam stability through static and dynamic experiments on foam stability, chemical defoaming experimets and field tests. The results showed that the concentration of foaming agent used in the field, namely UT-11C, had the most significant effect on the foam stability followed by the salinity, temperature and PH value. Foam stability was also can be improved with higher pressure. Results of chemical defoaming experiments showed that even under the optimal defoaming concentration, mamely 1%, it also took about 20 minutes to completely eliminate the foam. Combined with the laboratory results and the statistical analysis of the water production in field, the optimal injection amount of foaming agent was calculated, which makes the dosage reducing by 40%. And the effective was validated by field test. This work not only ensures the high production of gas wells, but also takes the economy into account, having a strong guidance for the production of natural gas fields. [ABSTRACT FROM AUTHOR]

Temporary plugging and diverting fracturing technology is of utmost importance in stimulating fractured reservoirs. However, studies investigating the mechanisms of new fracture initiation and propagation during far-field temporary plugging and diverting fracturing have been scarce, and the optimal technique parameters are still unknown. To address this issue, a two-dimensional fracturing model is developed via the finite element method in this work, which simulates the temporary plugging effect using the equivalent viscosity temporary blockage method and the unrestrained growth of hydraulic fractures by globally embedding the cohesive element of zero-thickness. Then, some key parameters for far-field temporary plugging and diverting fracturing in fractured reservoirs are discussed and some interesting insights are given. Firstly, a lower-permeability plugging zone expedites the pressure increase within the fracture, thereby boosting the probability of achieving temporary plugging and diverting fracturing. The size of the plugging zone significantly impacts the pressure increase within the fracture. Secondly, the plugging position should be determined considering the density and arrangement of natural fractures in the layer, and the temporary plugging construction should be performed after maximizing the elongation of initial hydraulic fracture. Thirdly, an increase in fluid viscosity and injection displacement promotes the pressure rise inside the fracture. Nonetheless, the impact of injection displacement on temporary plugging and diverting fracturing surpasses that of fluid viscosity. Overall, the established model can inform the design of temporary plugging and diverting fracturing in fractured reservoirs. [ABSTRACT FROM AUTHOR]

Corrosion perforation of wet gas pipelines occurs frequently, threatening the safe production on gas fields and bringing huge economic losses. Therefore, wet gas pipelines need to use a suitable corrosion prediction model to predict the corrosion rate along the pipeline and anticipate the corrosion risk. However, current corrosion prediction models have problems such as large errors and inaccurate predictions. This paper compares four common corrosion prediction models and combines these four models with OLGA multiphase flow simulation calculations to predict the corrosion condition of the same pipeline under three different conditions. Finally, it compares the model predictions with the actual corrosion internal detection data. The predicted value of the De Waard 95 model was closer to the corrosion internal detection data, but the error result still reached 82.03%. To further improve the accuracy of the corrosion prediction model for wet gas pipelines, the De Waard 95 model was optimized using the linear fitting method to obtain a new corrosion prediction model, W22. And the corrosion prediction experiment was conducted for the multiphase flow corrosion loop using the W22 model, and the error between the prediction results and the experimental results was only 6.8%. Compared with the De Waard 95 model, the average error of the W22 model was reduced by 81.32%. Therefore, the W22 model has high accuracy in predicting wet gas pipeline corrosion, which lays the foundation for improving the essential safety of wet gas pipeline operation. [ABSTRACT FROM AUTHOR]

The purpose of this review is to highlight the applications of carboxymethyl cellulose (CMC) in oil and gas industries. CMC is one of the most promising cellulose derivatives and the most widely used in the drilling sector. Owing to its multifunctionality, facile, inexpensive, raw material abundance, availability, compatibility, distinctive surface property and many other disparate aspects, it is now widely used in many fields for a variety of applications, including the oil and gas industry, pharmaceuticals, food, textiles, wastewater treatment, and energy production/storage. Despite CMC's wide applications in many fields, very few studies report its role in oil and gas operations such as drilling and completion, hydraulic fracturing, corrosion inhibition and cementing applications. As a result, this review points some of CMC's relevance in the oil and gas industry now and in future. [ABSTRACT FROM AUTHOR]

This paper reviews the research background and significance of foam drainage agents, foaming and foam stability mechanisms, and analyzes the advantages and drawbacks of conventional foam drainage agents. With the development of natural gas applications, the exploitation of gas fields becomes more stringent. A new type of foam drainage agent characterized by a wide applicability should be developed based on the particular needs of gas wells. A new foam drainage agent not only resolves the deficiency of conventional foam drainage agents, but also deals with the problem of high costs. It has a higher foam stability and provides a standard for the further design of special conventional and unconventional foam drainage agents for gas fields. Moreover, the polymer addition dramatically improves the performance of foam drainage agents. A Gemini surfactant opens up a new possibility for foam drainage agents. The use of nanoparticles provides the further enhancement of the foam stability for different types of gas reservoirs. The future application trends for foam drainage agents are also discussed. A low-cost and environmentally friendly natural gas promoting a low-carbon green energy, should be developed and used. Highly efficient, environmentally-friendly and recyclable low-cost foam drainage agents would become a hotly debated research point. [ABSTRACT FROM AUTHOR]

Although improving the recovery of water-invaded gas reservoirs has been extensively studied in the natural gas industry, the nature of the efficiency of water-invaded gas recovery remains uncertain. Low-field nuclear magnetic resonance (NMR) can be used to clearly identify changes in water saturation in the core during high-pressure water-invasion gas. Here, we provide four types of water-invasion gas experiments (spontaneous imbibition, atmospheric pressure, high-pressure approximate equilibrium, and depletion development water-invasion gas) to reveal the impact of the water-invasion gas efficiency on the recovery of water-invasion gas reservoirs. NMR suggested that imbibition mainly occurs in medium to large pores and that residual gas remains mainly in large pores. The amount of gas driven out from the large pores by imbibition was much greater than that driven out from the small pores. Our findings indicate that the initial gas saturation, contact surface, and permeability are the main factors controlling the residual gas saturation, suggesting that a reasonable initial water saturation should be established before the water-invasion gas experiments. Additionally, the water-invasion gas efficiency at high pressures can be more reliably obtained than that at normal pressures. After the high-pressure approximate equilibrium water invasion for gas displacement, a large amount of residual gas remains in the relatively larger pores of the core, with a residual gas saturation of 42%. In contrast to conventional experiments, the residual gas saturation and water displacement efficiency of the high-pressure approximate equilibrium water invasion for gas displacement did not exhibit a favorable linear relationship with the permeability. The residual gas saturation ranged from 34 to 43% (avg. 38%), while the water displacement efficiency ranged from 32 to 45% (avg. 40%) in the high-pressure approximate equilibrium water invasion for gas displacement. The residual gas saturation in the depletion development water-invasion gas experiment was 26–40% (average: 33%), with an efficiency ranging from 45 to 50% (average: 48%), indicating that the depletion development experiment is closer to the actual development process of gas reservoirs. Our findings provide novel insights into water-invasion gas efficiency, providing robust estimates of the recovery of water-invasion gas reservoirs. [ABSTRACT FROM AUTHOR]

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Taking the Zhongqiu 1 Gas Field in the Tarim Basin as an example, the heterogeneity of large-scale mono-block gas fields and their primary controlling factors have been analyzed. Based on drilling core data, well log data, scanning electron microscopy, thin-section analysis, and mercury injection experiments, combining sedimentological interpretation, research on the reservoir characteristics and variability was carried out. The results showed that: (1) The lithologic characteristics showed obvious variations among wells in the Zhongqiu 1 gas field. Specifically, the main lithology developed in the Zhongqiu 1 well is feldspar lithic sandstone, while the remaining wells predominantly consist of lithic feldspar sandstone. These differences in rock composition maturity reveal that a higher proportion of stable mineral components leads to poorer reservoir properties; (2) the main factors controlling oil and gas productivity include the variations in petrology, mineralogy, and diagenetic process characteristics. The high content of unstable mineral components and constructive diagenesis could increase reservoir porosity together. (3) Sedimentary facies of the Bashijiqike Formation in the Zhongqiu 1 Gas Field played a dominant role in the reservoir distribution. The division of sedimentary facies zones reflects variations in material composition and grain size, serving as the main material basis for reservoirs. Differences in mineral composition reflect the sedimentary environment of the reservoir. Additionally, mineral composition indicates the relationship between diagenetic processes and reservoir evolution. The high feldspar content in well ZQ1 corresponded to relatively favorable reservoir properties. The dominant feldspar type was plagioclase, suggesting that early-stage chemical weathering had undergone significant alteration. The above conclusions provided a microscopic perspective to explain the differences in oil and gas production capacity of large delta-front gas fields, serving as a geological basis for the exploration and exploitation of similar fields. [ABSTRACT FROM AUTHOR]

A multi-disciplinary approach was employed to study a set of marginal marine sandstone reservoirs within Ekpeti oil field onshore Niger Delta to define discrete facies and their connection with reservoir property trends. Nine wells with accompanying biostratigraphic data were used to build a sequence stratigraphic model while petrophysical and machine learning tools were incorporated to evaluate the reservoirs' potential and establish depositional facies distribution, respectively. This work revealed three fourth-order depositional sequences bounded by erosional surfaces. A total of nine stratal surfaces were delineated which include sequence boundaries (SBs) 13.1 Ma through 21.8 Ma and maximum flooding surfaces (MFSs) 15.9 Ma through 20.7 Ma. The classic three systems tract model (Highstand Systems Tract (HST), Lowstand Systems Tract (LST) and Transgressive Systems Tract (TST)) was adopted in subdividing the depositional sequences into genetically related strata. Incorporating well log facies analysis, results showed the predominant depositional systems within the field general span across the littoral to outer neritic bathymetric zones. A self-organizing map (SOM) algorithm with an added hierarchical clustering technique was used to produce and group nodes that were interpreted as four distinct facies, which correspond to sand, shaly sand, shale and coaly facies. Evaluating the LST and TST marginal marine sandstones revealed very good porosities, low clay volume, high net-to-gross values and significant hydrocarbon accumulations. These results show that depositional facies influence reservoir quality significantly and accurate facies classification can improve the knowledge of the reservoir architecture and help produce more realistic geological models.. [ABSTRACT FROM AUTHOR]

Natural gas liquids are a by-product of natural gas preparation, one of the most common and environmentally friendly energy sources. In natural gas fields located in remote areas, there is no resource-efficient way to use natural gas liquids. However, natural gas liquids are a valuable hydrocarbon feedstock for the production of motor fuels, in particular motor gasolines. The aim of this work is to develop a method for obtaining motor gasolines by processing natural gas liquids on a zeolite catalyst, taking into account the influence of the particle size of the zeolite catalyst, the technological parameters of the process, and the composition of the feedstock. As part of the work, for the first time, regularities of the influence of zeolite catalyst particle size, technological parameters of the process and the composition of feedstock on the composition and characteristics of the resulting processed products were revealed. A database about the composition and characteristics of natural gas liquids, obtained from various gas fields in Western Siberia of the Russian Federation, has been accumulated. During the study, it was found that the optimal particle size of the zeolite catalyst is 0.50–1.00 mm; optimal technological parameters are a temperature of 375 °C, pressure 2.5 atm. and the feedstock space velocity 2 h−1. It is shown that the processing of natural gas liquids of various compositions on a zeolite catalyst, on average, makes it possible to increase their detonation resistance by more than 16 points. The results obtained indicate the prospects of using the process for the production of motor gasoline. The paper presents a number of blending recipes for obtaining fuels, both within the framework of production at the fields and at processing plants. [ABSTRACT FROM AUTHOR]

As the cleanest fossil fuel, natural gas plays a key role in the path towards renewables. Considering the increasing gas demand, rich CO2 and H2S gas reserves, in the past considered economically unviable, are becoming fruitful. However, the non‐conventional nature of this kind of gases, in addition to the potentially higher production cost, raises the need of new strategies for their monetization, bypassing the conventional approaches. Starting from the huge number of novel large‐scale projects for the exploitation of rich‐H2S gas fields, this paper overviews the current tendencies in sour and ultra‐sour natural gas production, focusing on the removal of sulfur‐based compounds, together with H2S and CO2. At first, available technologies for ultra‐sour gas treatment are discussed. Then, simulations of the absorption processes based on a real case‐study are carried out, in order to verify the effectiveness of the proposed alternatives for the removal of mercaptans, as well as CO2 and H2S. Results are critically analyzed, in view of providing a practical guide of industrial interest for the selection of the most suitable method. [ABSTRACT FROM AUTHOR]

In recent years, oil and gas field surface engineering construction projects tend to be large in scale, large in quantity, and short in cycle. The task of surface construction management has increased significantly. In the process of project construction, corresponding standards and specifications are required to provide sufficient technical guidance and support for design, construction, and management personnel to ensure project management and control towards compliance, safety, and quality. However, the oil and gas field engineering standards are numerous and specialized, involving different levels of national standards, enterprise standards, and industry standards, which leads to the inefficiency of the actual use of standards and specifications. To solve them, this paper uses knowledge graph technology, OCR recognition, and natural language processing technology to conduct systematic research on the knowledge classification mechanism, data extraction, database construction mechanism, data structuring, and intelligent retrieval matching of oil-gas field surface engineering construction standards. In this study, the structured identification, storage, and information warehousing of standards are realized, and a highly sharable library of standards and specifications is formed, which realizes the intelligent retrieval and pushing of technical standards for surface engineering construction. This paper creates conditions for the realization of intelligent push and benchmarking management of standards and specifications, providing support for digital transformation and intelligent development of oil–gas fields. [ABSTRACT FROM AUTHOR]