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In this work, an integrated system for hydrogen energy utilization system (HUS) in oil and gas fields was constructed focusing on two scenarios: hydrogen fuel cell bus and industrial combustion. The energy consumption, environmental, economic, and energy efficiency were assessed for the various HUS technological pathways associated with produced water treatment, hydrogen production, transport and storage, refueling, and utilization. The entropy weight-TOPSIS method was utilized to assess the optimal pathway. The results indicate that the pathway of alkaline water electrolysis for hydrogen production and pipeline transportation to gas-hydrogen refueling stations for hydrogen fuel cell bus shows excellent comprehensive indicators, which has an energy consumption of 197.15 MJ/kgH 2 , the levelized cost of hydrogen (LCOH) of 6.70 USD/kgH 2 , a system energy efficiency of 30.43%. For industrial combustion, the best pathway is alkaline water electrolysis for hydrogen production and pure H 2 pipeline transportation. Sensitivity analyses were conducted to explore the impact of different factors on LCOH. As the electricity price decreases to 0.014 USD/kWh, LCOH will reduce by 2.50 USD/kgH 2. The reduction in electricity prices will further increase the feasibility of hydrogen energy in the future. • The Hydrogen utilization system (HUS) in oil and gas fields was proposed. • The technical-economic and environmental performance of HUS were analyzed. • The entropy-weighted TOPSIS method is used to select the optimal pathway. • Alkaline water electrolysis and pipeline transportation are the best pathways. • Electricity prices are the most sensitive factor to LCOH. [ABSTRACT FROM AUTHOR]

Lithology identification assumes an absolutely crucial role in the realm of reservoir delineation, functioning as a fundamental prerequisite for accurately determining porosity, oil saturation, and sundry other parameters. The precise identification of lithology effectively forms a foundation for ensuring the effective exploration and development of oil and gas fields in the subsequent stages. Traditional logging lithology identification methods have many limitations, and therefore many challenges. Therefore rapid and accurate lithology identification is a matter of significant concern and importance. This study identified the initial lithology using a cross-plot approach, capitalizing on the distinctive characteristics of the lithology logging response. Subsequently, a rapid lithology identification method was developed for marine carbonate rocks by integrating artificial neural networks and the logging curves. To evaluate its accuracy and precision, the outcomes were compared with the core data and the lithology scanning logging techniques. The neural network–based method proposed in this paper can enable swift and accurate identification of lithologies, encompassing even transitional lithologies such as silty limestone and limy dolomite. Therefore, it provides novel theoretical and technical support that is of tremendous significance for subsequent research and applications. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Oilfield Development in Daqing is the property of Editorial Department of Petroleum Geology & Oilfield Development in Daqing 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.)

The development of infill wells have gained significant traction in enhancing shale gas recovery in the Sichuan Basin. During the development of infill wells, the production of the parent wells leads to changes in in-situ stress, which in turn affects the fracture morphology of the infill well, resulting in frac-hits. These frac-hits are commonly considered a potential hazard to the adjacent infill well production and wellbore. In this study, a comprehensive flow-geomechanics coupling model has been developed to address this challenge. The model incorporates the processes of parent well fracturing and production, evolution of in-situ stress after production, and infill well fracturing and production. This study discusses four cases in the Sichuan Basin, each highlighting intriguing field phenomena. The first case focuses on an infill well situated in the same layer, while the second case pertains to a three-layers infill wells pad. The third case delves into the phenomenon of frac-hits in deep shale gas reservoirs (3800 m), while the final case explores the effect of high-steep structures in the fracturing process. By utilizing this integrated model and field data, the mechanisms underlying these phenomena are observed. The results indicate that: (i) The 'microseismic events barrier' (MSEB) effect caused by stress shadow has been reported and the main reasons have been analyzed. (ii) The range of stress shadow is critical to the deployment of multi-layers infill well pattern, the influence range in both horizontal and vertical directions is related to the size of hydraulic fractures. (iii) In deep shale gas reservoir, high stress and the development of natural fracture zones are the main reasons of frac-hit and the fracturing sequence can exacerbate this phenomenon. (iv) The high formation dip in the high-steep structural zone will restrict the propagation of hydraulic fractures in the horizontal direction. Through this research, valuable insights into the behavior of infill wells in the Sichuan Basin have been obtained, shedding light on the challenges and opportunities associated with maximizing shale gas recovery in this region. Highlights: In this study, a comprehensive flow-geomechanics coupling model has been developed to address the stress evolution caused by the depletion of parent well and then hydraulic fracturing of infill wells can be simulated based on the updated stress. Based on this method, we have conducted a large number of infill well case studies on shale gas fields across Sichuan Basin. The four case studies reported in this paper belong to different shale gas fields and have their own highlights and uniqueness. The 'microseismic events barrier' effect (MSEB effect) was reported in the first case which explained the reason for the sharp decrease in the number of microseismic (MS) events when the MS were close to the boundary of the parent well. Besides the phenomenon of parent well pressure regained through the enhanced permeable channel. The second case pertains to a three-layers infill wells pad which the infill wells were drilled both in upper, middle, and bottom layers. The stress influenced range in both horizontal and vertical directions analyzed. The third case delves into the inter-well interference in deep shale gas reservoirs. For the severe frac-hits having a negative effect on production and stimulation treatment, the influencing factors and types of frac-hits were summarized. The final case explores the effect of high-steep structures on the fracture propagation and explains why the hydraulic fracturing treatment in this area did not meet expectations [ABSTRACT FROM AUTHOR]

With the increase in production of sour oil and gas fields, mitigation of production-related failures due to H2S corrosion of mild steel is a key challenge. In H2S environments, most failures occur due to localized corrosion originating from the galvanic coupling between mild steel and conductive iron sulfide corrosion products. However, the mechanism of the galvanic coupling between mild steel and iron sulfides and the effect of influential parameters, have not been studied yet. Here, we provide a systematic experimental investigation on the galvanic corrosion between mild steel and iron sulfides by examining the effect of the critical factors: iron sulfide type, cathode to anode surface area ratio, and salt concentration. Specifically, we focus on pyrite and pyrrhotite as the main corrosion products found in localized corrosion of mild steel in H2S environments. Our results show that the cathodic current obtained on pyrrhotite was an order of magnitude higher than that obtained on pyrite, leading to a higher galvanic current for coupled mild steel-pyrrhotite compared to coupled mild steel-pyrite. Moreover, our study reveals that the increase of cathode to anode surface area ratio and, to some extent, the increase of salt concentration, enhance the galvanic current for the coupled materials. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience 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.)

• A model was developed to simulate hydrate formation in porous media. • The model was validated using experimental data. • Injection of cold CO 2 into depleted gas fields was simulated. • The impact of water evaporation on hydrate formation was studied. The reduction of temperature caused by Joule-Thomson effect during injection of CO 2 in low pressure reservoirs combined with presence of water can lead to formation of hydrates, which in turn reduces rock permeability and hence CO 2 injectivity. This paper introduces an empirical model to evaluate impact of hydrate formation on injectivity of CO 2 injection wells. Experiments were also conducted to validate the model. The model was then used to simulate injection of CO 2 into a multi-layered depleted gas field. The results indicate that operational parameters, particularly CO 2 injection rate and temperature, have a large influence on hydrate formation. This is because a higher CO 2 injection rate leads to a greater pressure drop within the injection well, potentially triggering conditions conducive to hydrate formation. It is also shown that the dynamics of the competition between the dry-out and temperature fronts play an important role in the final saturation of the hydrate within porous media. For large evaporation rates, the evaporation of water reduces water saturation near wellbore and hence formation of hydrates is limited. [ABSTRACT FROM AUTHOR]

The fan delta front deposit is a notable reservoir type in the basin margin and typically exhibits high heterogeneity in reservoir architecture. With the deepening of exploration and development of oil and gas fields, the study of lower-order depositional architectures is relatively weak, and their implication on remaining oil distribution and enrichment are poorly understood. Field outcrops of the fan delta front deposit exhibit first-hand data of lithofacies, association, and depositional architectures, effectively providing insights for underground reservoir research to guide the development of oil fields, such as high water–cut oil fields in the late development period. Herein, we considered the fan delta front outcrops of the Sangyuan section as an object to reveal the depositional architectures located in the Luanping Basin, northeast China. Using meticulous artificial fieldwork and unmanned aerial vehicle observation, we focused on the 4th-order (single sandbody) and 3rd-order (composite laminaset groups) architectural units. Based on field observations, quantitative statistics, and model matching and guidance, architectural models of the fan delta front in the Sangyuan section were established in response to the high-frequency lake-level. In addition, genetic types of remaining oil controlled by architectural features in Wenchang B oil field during the high water–cut stage were further discussed, and suitable strategies and measures are proposed to produce different types of remaining oil. Results indicate that there are twelve basic types of lithofacies and three types of a single sandbody developed in the Sangyuan section, and evidently, the dimensions and spatial stacking patterns of 4th-order architectural units are closely related to high-frequency lake-level fluctuation, that is, with the rise of lake-level, the thickness and width of a single sandbody gradually decrease, whereas the width–thickness ratio gradually increases. Meanwhile, the spatial stacking patterns of sandbody gradually evolution from the downcut type to the superposition or butted type and finally to the isolated type. A single sandbody is divided into one or more composite laminate groups by the interfaces of 3rd-order architectural elements, which are identified according to the flow regime and sedimentary structures. Different orders of architectural units have different controlling effects over remaining oil distribution and enrichment, and the corresponding technical measures are proposed to enhance the remaining oil recovery. The above mentioned analyses can provide a valuable reference for oil and gas production in the late stage of an oil field with a similar depositional environment. • Representative lithofacies types, sedimentary structures, and lithofacies association of fan delta front deposits were examined and identified. • Single sandbody and their internal component units of fan delta front deposits are identified and characterized in detail. • The controlling effect of high-frequency lake level fluctuation on architecture features was determined. • Architectural model helps solve the production problems and enhance the remaining oil recovery during the high water cut stage of oil field development with a similar depositional environment. [ABSTRACT FROM AUTHOR]