Geoenergy Science and Engineering最新文献_第3页

Harnessing the power of machine learning for the optimization of CO2 sequestration in saline aquifers: Applied on the tensleep formation at teapot dome in Wyoming 利用机器学习的力量优化含盐含水层中的二氧化碳封存：应用于怀俄明州茶壶穹顶的天眠地层

0 ENERGY & FUELS

Geoenergy Science and Engineering

Pub Date : 2024-11-19 DOI: 10.1016/j.geoen.2024.213522

Hussein B. Abdulkhaleq , Ibraheem K. Ibraheem , Watheq J. Al-Mudhafar , Zeena T. Mohammed , Mohamed S. Abd

The sequestration of carbon dioxide in deep saline aquifers offers a highly promising approach to mitigate CO₂ emissions resulting from the fossil fuels industry. The practicality of this solution is mostly dependent upon the CO₂ trapping efficiency, which governs the capacity of the aquifer for CO₂ storage. Generally, the compositional reservoir simulation is employed to evaluate the trapping efficiency, but is computationally expensive, particularly when adjusting parameters necessitates hundreds of simulations. In this paper, A machine learning (ML) proxy model was used to address these difficulties for fast evaluation and optimization of the residual and dissolution trapping mechanisms in the Tensleep sandstone formation in the Teapot Dome Field, located in Wyoming, USA. The initial CO₂ storage capacity of the aquifer was calculated to be 17.7 thousand tons. In the simulation model, several injection wells were placed in the high porosity regions and CO₂ injection was simulated over duration of 10 years, followed by a 90-year post-injection period. The injection rates were optimized to maximize the overall trapping efficiency, which takes into account both residual and solubility indices. In order to construct a dataset for machine learning-based proxy models, the Latin hypercube sampling technique was adopted to generate 100 simulation runs that varied operating constraints: maximum injection rate, maximum injection pressure, and number of injection wells. The Radial Basis Function-Artificial Neural Network (RBF-ANN) was specifically trained to accurately determine the most appropriate injection rates by identifying complex and non-linear correlations within the data. The total CO₂ trapping effectiveness by the RBF-ANN model was enhanced from 75% to 83%, accompanied by an insignificant increase in the leakage index from 0.64% to 1.3%. The results indicated that machine learning proxy modeling offers a rapid and accurate approach to optimize the storage of CO₂ in saline aquifers. Through the reduction of CO₂ emissions, this method significantly improves the viability of large-scale sequestration projects, so making a valuable contribution to climate change mitigation.

在深层含盐含水层中封存二氧化碳为减少化石燃料工业产生的二氧化碳排放提供了一种极具前景的方法。这一解决方案的实用性主要取决于二氧化碳的封存效率，它决定了含水层封存二氧化碳的能力。一般情况下，采用成分储层模拟来评估捕集效率，但计算成本高昂，尤其是在调整参数需要进行数百次模拟的情况下。本文采用机器学习（ML）代理模型来解决这些困难，以快速评估和优化位于美国怀俄明州 Teapot Dome 油田 Tensleep 砂岩层的残留和溶解捕集机制。经计算，含水层的初始二氧化碳封存能力为 1.77 万吨。在模拟模型中，在高孔隙度区域放置了几口注入井，并模拟了 10 年的二氧化碳注入期和 90 年的后注入期。对注入率进行了优化，以最大限度地提高整体捕集效率，其中考虑到了残余指数和溶解度指数。为了构建基于机器学习的代理模型数据集，采用了拉丁超立方采样技术，生成了 100 次模拟运行，这些运行改变了运行限制条件：最大注入率、最大注入压力和注入井数量。对径向基函数-人工神经网络（RBF-ANN）进行了专门训练，以通过识别数据中复杂的非线性相关性来准确确定最合适的注入率。RBF-ANN 模型的二氧化碳总捕获率从 75% 提高到 83%，同时泄漏指数从 0.64% 微增至 1.3%。结果表明，机器学习代理建模为优化含盐蓄水层中的二氧化碳封存提供了一种快速、准确的方法。通过减少二氧化碳排放，该方法显著提高了大规模封存项目的可行性，从而为减缓气候变化做出了宝贵贡献。

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引用次数: 0

Effect of amygdala on the pore-crack structure and mechanical properties of Permian tuff and breccia during hydration 杏仁核对二叠纪凝灰岩和角砾岩水化过程孔裂结构及力学性能的影响

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Geoenergy Science and Engineering

Pub Date : 2024-11-19 DOI: 10.1016/j.geoen.2024.213534

Xiangyu Fan , Liang He , Kerui Li , Qiangui Zhang , Chao Cheng , Pengfei Zhao , Yufei Chen , Jin Li

The Permian volcanic rocks in the Sichuan Basin are rich in oil and gas resources. However, during volcanic rock exploitation, the working fluid fully contacts with the volcanic rocks, and hydration reaction will occur, which destroys the pore structure of the rock, makes the rock layer loose and fragile, increases the risk of wellbore collapse, and causes the loss of volcanic rock production. However, the reasons for the change of pore structure of volcanic rocks after hydration and the understanding of the hydration mechanism of volcanic rocks are not clear. Therefore, this paper uses microscopic and mechanical experimental testing methods combined with digital core technology to study the changes of pore-crack structure, amygdale structure and mechanical characteristics of Permian tuff and breccia in Sichuan Basin before and after hydration. The research results show that during the hydration process of volcanic rocks, pores, cracks, and amygdales are transformed into each other. The hydration process of the volcanic rocks is characterized by the disappearance of isolated pores, the generation of small cracks, and the generation and transformation of new pores into amygdales. Amygdales also have an important impact on the mechanical properties and hydration of volcanic rocks. When the content of amygdales in volcanic rocks is high, the rocks are more prone to breakage. In addition, amygdales promote the hydration reaction of volcanic rocks, and the size and number of amygdales determine the strength of volcanic rock hydration ability. When the content of amygdales in the rock is higher, the rock is more prone to hydration reactions. Therefore, in the process of gas reservoir development, understanding the distribution and characteristics of amygdale is helpful to optimize the composition of the working fluid and enhance drilling technology. It aims to maximize the productivity gas wells.

四川盆地二叠系火山岩具有丰富的油气资源。但在火山岩开采过程中，工作流体与火山岩充分接触，会发生水化反应，破坏岩石孔隙结构，使岩层松散脆弱，增加井筒坍塌风险，造成火山岩产量损失。然而，对火山岩水化后孔隙结构变化的原因及火山岩水化机理的认识尚不清楚。因此，本文采用显微力学实验测试方法，结合数字岩心技术，研究四川盆地二叠系凝灰岩和角砾岩水化前后孔隙-裂缝结构、杏仁核结构及力学特征的变化。研究结果表明，在火山岩水化过程中，孔隙、裂缝和杏仁核相互转化。火山岩水化过程的特点是孤立孔隙消失，小裂缝生成，新孔隙生成并转化为杏仁核。杏仁核对火山岩的力学性质和水化作用也有重要影响。当火山岩中杏仁核含量高时，岩石更容易破碎。此外，杏仁核促进了火山岩的水化反应，杏仁核的大小和数量决定了火山岩水化能力的强弱。岩石中杏仁核含量越高，岩石越容易发生水化反应。因此，在气藏开发过程中，了解杏仁核的分布和特征，有助于优化工作流体的组成，提高钻井技术。其目标是使气井的产能最大化。

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引用次数: 0

Research on CO2 injection for water control and enhanced nature gas recovery in heterogeneous carbonate reservoirs 在异质碳酸盐岩储层中注入二氧化碳以控制水和提高天然气采收率的研究

0 ENERGY & FUELS

Geoenergy Science and Engineering

Pub Date : 2024-11-19 DOI: 10.1016/j.geoen.2024.213506

Jie Wei , Daqian Zeng , Zhaojie Song , Yuchun You , Haochen Ren , Zhiliang Shi , Changxiao Cao , Rui Zhang , Jiaqi Wang , Peiyu Li , Kai Cheng , Yunfei Zhang , Yilei Song , Jiatong Jiang , Xiao Han

During the development of edge-water driven carbonate gas reservoirs, the impact of the heterogeneity of carbonate rocks on water invasion in production wells remains unclear. This study utilizes parallel core experimental models and heterogeneous reservoir numerical simulation models to investigate the water invasion in heterogeneous carbonate rocks and the potential of using CO₂ injection as a water control solution after water flooding in production wells. Based on this, it explores the influence of factors such as injection pressure, permeability ratio, and injection location on water control effectiveness. The study focuses on the impact of various sensitivity parameters of CO₂ injection on edge water production and natural gas increment, and elucidates the mechanism of these sensitivity parameters on water control and production efficiency in heterogeneous formations. The results show that: 1) Due to the larger seepage channels, high-permeability cores experience a greater increase in the degree of water invasion compared to low-permeability cores, resulting in a shorter water-free gas production period; 2) After CO₂ injection, CO₂ can mobilize more water-locked gas in high-permeability cores, achieving better water control and production enhancement effects; 3) When the core pressure recovery from CO₂ injection increases from 60% to 100%, the recovery increases from 9.56% to 35.42%, and the cumulative water reduction increases from 3 ml to 10 ml. This pushes the edge water further back, slows down the flow of edge water in the core in the form of slugs, and extends the time before water invasion; 4) When the permeability ratio of the core is changed, the higher the permeability of the parallel core combination, the higher the production of water-locked gas, the better the water control effect, with a maximum recovery increment of 53.13% and a maximum cumulative water reduction of 15 ml; 5) Near-water end wells, being closer to the edge water, achieve better water control and production enhancement effects after CO₂ injection compared to far-water end wells. These findings are crucial for optimizing the recovery rate of edge-water gas reservoirs and provide guidance for the application of CO₂ injection for water control and CO₂ sequestration in carbonate gas reservoirs.

在边缘水驱碳酸盐岩气藏的开发过程中，碳酸盐岩的异质性对生产井水侵的影响仍不清楚。本研究利用平行岩心实验模型和异质储层数值模拟模型，研究了异质碳酸盐岩的水侵情况，以及在生产井水淹后使用二氧化碳注入作为水控制解决方案的潜力。在此基础上，探讨了注入压力、渗透率和注入位置等因素对控水效果的影响。研究重点关注注入二氧化碳的各种敏感性参数对边缘水产量和天然气增量的影响，并阐明了这些敏感性参数对异质地层控水和生产效率的影响机理。结果表明1）由于渗流通道较大，高渗透岩心与低渗透岩心相比，水侵程度增加较大，导致无水产气期缩短；2）注入CO2后，CO2在高渗透岩心中能调动更多的锁水气，达到更好的控水增产效果；3）当注入CO2的岩心压力采收率从60%提高到100%时，采收率从9.56%提高到35.42%，累计减水量从3 ml提高到10 ml。这将边缘水进一步向后推，减缓了边缘水在岩心中以蛞蝓形式流动，延长了水入侵前的时间；4）当岩心渗透率比发生变化时，平行岩心组合的渗透率越高，锁水气产量越高，控水效果越好，最大采收率增量为 53.13%，最大累计减水15 ml；5）与远水端井相比，近水端井更接近边水，注入CO2后的控水增产效果更好。这些发现对于优化边缘水气藏的采收率至关重要，并为碳酸盐岩气藏应用注入二氧化碳进行控水和二氧化碳封存提供了指导。

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引用次数: 0

Evaluating flue gas geo-sequestration and EOR in fractured reservoirs through simulated synergistic reservoir characteristics and injection kinetics 通过模拟协同储层特征和注入动力学评估裂缝储层中的烟气地质封存和 EOR

0 ENERGY & FUELS

Geoenergy Science and Engineering

Pub Date : 2024-11-19 DOI: 10.1016/j.geoen.2024.213521

Mehdi Nassabeh , Zhenjiang You , Alireza Keshavarz , Stefan Iglauer

The global reliance on hydrocarbon resources and fossil fuels has resulted in a significant surge in carbon dioxide emissions, necessitating urgent measures to mitigate greenhouse gas emissions. Integrating CO₂ storage with enhanced oil recovery (EOR) presents a promising solution for reducing emissions and enhancing oil recovery by sequestering CO₂ within oil reservoirs, especially in fractured carbonate reservoirs. The research utilized the Eclipse simulator to model different gas injection scenarios in a crude oil reservoir, focusing on assessing the effectiveness of CO₂ and flue gas geo-sequestration and EOR, performing sensitivity analyses on reservoir characteristics, and evaluating the impact of varying injection rates on gas storage capacity and oil recovery factor. The findings demonstrated a superior capacity to store flue gas (150 MMSCF) in comparison to CO₂ (85 MMSCF) and flue gas injection demonstrated better reservoir pressure maintenance than CO₂ injection, while CO₂ injection resulted in a higher oil recovery factor of 52% compared to flue gas injection at 36%. Additionally, analysis of reservoir characteristics in gas storage revealed that, an augmentation in reservoir porosity, permeability, and injection rate substantiated an increase in gas storage capacity for both CO₂ and flue gas injection. Except for CO₂ storage, which displayed a normal distribution trend in the permeability analysis. Additionally, it was elucidated that higher reservoir pressure and temperature in flue gas injection resulted in a reduction of gas storage capacity, while these variables exhibited relative stability in the context of CO₂ injection. The scrutiny of gas storage in reservoir characteristics unveiled substantial alterations in porosity and injection rate, signifying their pivotal roles in influencing gas storage capacity. In the EOR study, heightened reservoir pressure, temperature, permeability, and injection rate collectively contributed to an amplified oil recovery for both flue gas and CO₂, except CO₂ injection demonstrated a normal distribution trend in oil recovery within the permeability analysis. Conversely, higher porosity was associated with a decrease in oil recovery. The findings of this research provide valuable insights into the feasibility and effectiveness of employing flue gas geo-sequestration and EOR in fractured carbonate reservoirs.

全球对碳氢化合物资源和化石燃料的依赖导致二氧化碳排放量激增，因此必须采取紧急措施减少温室气体排放。将二氧化碳封存与提高石油采收率（EOR）相结合，是通过在油藏（尤其是裂缝碳酸盐岩油藏）中封存二氧化碳来减少排放和提高石油采收率的一种前景广阔的解决方案。研究利用 Eclipse 模拟器对原油储层中的不同注气方案进行建模，重点评估二氧化碳和烟道气地质封存与 EOR 的有效性，对储层特征进行敏感性分析，并评估不同注入率对气体封存能力和石油采收率的影响。研究结果表明，与二氧化碳（85 兆立方英尺）相比，烟道气（150 兆立方英尺）的存储能力更强；与二氧化碳注入相比，烟道气注入能更好地保持储层压力；与烟道气注入相比，二氧化碳注入的石油采收率为 52%，而烟道气注入的石油采收率为 36%。此外，对储气库储层特征的分析表明，储层孔隙度、渗透率和注入率的增加证实了二氧化碳和烟道气注入储气库储气能力的提高。但二氧化碳储层除外，其渗透率分析显示出正态分布趋势。此外，研究还发现，在注入烟道气时，较高的储层压力和温度会导致储气能力下降，而在注入二氧化碳时，这些变量则表现出相对稳定。对储层储气特性的研究揭示了孔隙度和注入率的重大变化，表明它们在影响储气能力方面起着关键作用。在 EOR 研究中，储层压力、温度、渗透率和注入率的提高共同导致了烟道气和二氧化碳采油率的提高，但在渗透率分析中，二氧化碳注入的采油率呈现正态分布趋势。相反，孔隙度越高，采油率越低。这项研究的结果为在裂缝碳酸盐岩储层中采用烟气地质封存和 EOR 的可行性和有效性提供了宝贵的见解。

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引用次数: 0

Study on multiphase flow modeling and parameter optimization design for bullheading 牛头掘进多相流建模与参数优化设计研究

0 ENERGY & FUELS

Geoenergy Science and Engineering

Pub Date : 2024-11-18 DOI: 10.1016/j.geoen.2024.213519

Xi Wang , Hui Liu , Min Zhao , Shikun Tong , Zhiyuan Wang , Yaxin Liu , FeiFei Zhang , Wenqiang Lou

Deepwater and deepwell oil and gas drilling face complex environmental challenges. The limitations of conventional well control methods make it difficult to ensure the safety of wellbore pressure control. Bullheading is an efficient and simple well control technique for resolving complex kick problems, but the success rate of a single bullheading operation is low due to the inadequacy of well control parameter design. In this study, we first address critical challenges in designing critical bullheading displacement, calculating loss pressure, and characterizing reverse flow characteristics. We then propose a transient multiphase flow model and solution method for bullheading that comprehensively considers gas-liquid counterflow, formation loss, energy transfer, and PVT characteristics. By comparing simulation results with full-scale test wells and field construction parameters, the simulation errors were found to be less than 5% and 10%, respectively, verifying the accuracy of the model and method. Sensitivity analysis of bullheading parameters was conducted using the model, revealing that wellbore pressure is extremely sensitive to bullheading displacement and formation parameters. The combination of bullheading parameters within a safe range is constrained by the downward gas flow, the pressure limit of the blowout preventer, and the formation fracture pressure conditions. Based on the simulation results, we propose a bullheading parameter optimization design process. This work provides a comprehensive description of the response characteristics of wellbore flow parameters during bullheading and offers a theoretical basis for the optimization and control of bullheading parameters, helping to improve the safety of wellbore pressure control.

深水和深井油气钻探面临着复杂的环境挑战。传统井控方法的局限性使得井筒压力控制的安全性难以保证。顶牛是一种高效、简单的井控技术，可以解决复杂的井眼问题，但由于井控参数设计的不足，单次顶牛作业的成功率较低。在本研究中，我们首先解决了设计关键牛头位移、计算损失压力和表征反向流动特性等方面的关键难题。然后，我们提出了一种全面考虑气液逆流、地层损失、能量传递和 PVT 特性的瞬态多相流模型和牛头效应求解方法。通过将模拟结果与全尺寸试井和油田施工参数进行对比，发现模拟误差分别小于 5%和 10%，验证了模型和方法的准确性。利用该模型对掘进参数进行了敏感性分析，发现井筒压力对掘进位移和地层参数极为敏感。在安全范围内的牛头参数组合受制于下行气流、防喷器压力极限和地层裂缝压力条件。根据模拟结果，我们提出了一种牛头参数优化设计流程。这项工作全面描述了井筒流动参数在井喷过程中的响应特征，为井喷参数的优化和控制提供了理论依据，有助于提高井筒压力控制的安全性。

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引用次数: 0

Multi-component waxy model oil design to mimic rheologically complex gas condensate liquids 设计多组分蜡状模型油，模拟流变复杂的天然气凝析油液

0 ENERGY & FUELS

Geoenergy Science and Engineering

Pub Date : 2024-11-18 DOI: 10.1016/j.geoen.2024.213516

Jonathan J. Wylde , Ahmad A.A. Majid

This paper provides a detailed case study on the construction of two model oils with the purpose of being used during the DEFINE phase flow assurance strategy development process for a greenfield gas-condensate project. Details on the characterization methods used on the scarcely available well-test samples are given along with instructions on constructing the model oils. These fluids were unique with an abnormally high paraffin content, unusual (cyclic) alkane content, low wax appearance temperature, resulting in a complex rheological behavior. The real field fluids were severely volume-limited and non-destructive techniques were used as much as possible to characterize the oil. Classical methods such as High-Temperature Gas Chromatography (HTGC) and Differential Scanning Calorimetry (DSC) were used to elucidate the paraffinic species and SARA the remaining non-paraffinic species. Additionally, Nuclear Magnetic Resonance (NMR) and (Fourier-Transform Infrared Spectroscopy) FTIR were used to further speciate the crude oil components providing further clarification on composition. The characterization methods showed that the additional methods provided a better understanding of gas-condensate composition and behavior. The presence of alicyclic, aromatic, and carbonyl compounds were poorly detected with classic methods. These components can have a profound influence on the rheology of the oil and, therefore too, on gelation and/or waxing potential. NMR and FTIR are shown to be essential in this regard and offer a quantification method for drilling mud contamination. Construction of the model oils had to not just include n-paraffinic components but also iso-paraffins, alicyclics, and aromatics. Rheology results show the step by step addition of these components to the model oils and the individual influence they have on rheology and gelation behavior compared to the real field fluids. In conclusion, two prototype model oils are presented that enabled further assessment of the paraffin-related flow assurance risks to the development project including chemical selection. This is the first time such complex model oils have been constructed and reported. With the advent of more gas-condensate fields and the expense (and therefore scarcity) of obtaining liquid samples for flow assurance studies the methodology described here offers an alternative to costly sampling pre-production sampling campaigns.

本文提供了关于构建两种模型油的详细案例研究，目的是在一个新建天然气凝析油项目的 DEFINE 阶段流量保证策略开发过程中使用这两种模型油。本文详细介绍了用于稀缺油井测试样本的表征方法，以及构建模型油的说明。这些油液非常独特，石蜡含量异常高，烷烃含量异常（环状），蜡外观温度低，导致流变行为复杂。真实的油田流体受到严重的体积限制，因此尽可能使用非破坏性技术来表征油品。高温气相色谱法（HTGC）和差示扫描量热法（DSC）等经典方法用于阐明石蜡种类，并对剩余的非石蜡种类进行 SARA 分析。此外，还使用核磁共振（NMR）和傅立叶变换红外光谱（FTIR）来进一步确定原油成分，从而进一步澄清成分。表征方法表明，采用其他方法可以更好地了解气体冷凝物的成分和行为。传统方法很难检测到脂环族、芳香族和羰基化合物的存在。这些成分会对油的流变性产生深远的影响，因此也会影响凝胶化和/或打蜡的可能性。核磁共振和傅立叶变换红外光谱在这方面非常重要，并提供了钻井泥浆污染的量化方法。模型油的构建不仅包括正石蜡成分，还包括异链烷烃、脂环族和芳烃。流变学结果显示了模型油中逐步添加的这些成分，以及与实际现场流体相比，这些成分对流变学和凝胶行为的影响。最后，介绍了两种原型模型油，从而能够进一步评估开发项目中与石蜡相关的流动保证风险，包括化学品的选择。这是首次构建和报告如此复杂的模型油。随着更多天然气凝析气田的出现，以及为流量保证研究获取液体样本的费用（因此也很稀缺），本文介绍的方法为昂贵的生产前取样活动提供了一种替代方法。

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引用次数: 0

CO2 geological storage in subsurface aquifers as a function of brine salinity: A field-scale numerical investigation 地下含水层中的二氧化碳地质封存与盐水盐度的关系：实地数值研究

0 ENERGY & FUELS

Geoenergy Science and Engineering

Pub Date : 2024-11-17 DOI: 10.1016/j.geoen.2024.213505

Haiyang Zhang , Yihuai Zhang , Muhammad Arif

Subsurface aquifers demonstrate a broad range of salinities and salt compositions, affecting the physicochemical characteristics of the CO₂/brine/rock systems, which in turn, influence the CO₂ trapping of the aquifer formation. Available simulation studies generally focus on single NaCl systems and do not adequately account for the variations in salt types. In this study, the impact of salinity and salt type on several key parameters, including wettability, interfacial tension, brine properties, diffusion, and capillary pressure, were considered within the context of underground CO₂ storage. We conducted pore network modeling to assess the impact of salinity (i.e., pure water, 1 M (molality), 3 M, and 5 M) and salt type (i.e., NaCl, CaCl₂, and MgCl₂) on the residual trapping behaviors. Subsequently, these findings were utilized in field-scale simulations to assess the influence of various salinities and salt types on the CO₂ trapping capacity in a single salt brine system. The pore network modeling results showed that residual CO₂ saturation decreases in higher salinity conditions, with the lowest value in MgCl₂ brine system. In field-scale simulations incorporating residual trapping alone, the residual trapping capacity decreases in higher salinity NaCl brine systems. However, in high salinity MgCl₂ brine, increased viscosity and density lead to a widespread CO₂ plume, leading to an increased residual trapping capacity. This plume spread difference also influences the amount of dissolved CO₂ in scenarios considering dissolution trapping alone. When considering both trapping mechanisms, our observations indicate that a decrease in dissolution trapping under high salinity and divalent cations conditions leads to enhanced residual trapping (e.g., ∼51.56% for 5 M MgCl₂) - suggesting an interplay or codependency between these two mechanisms. The influences of diffusion and capillary pressure on the CO₂ geo-storage trapping capacity are also investigated. Overall, an aquifer containing lower salinity brine composed of monovalent ions exhibits lower residual trapping, greater dissolution trapping, and lower mobile CO₂. Especially, the pure water system exhibits the lowest percentage of mobile CO₂ (∼13.72%). We also highlight that this impact is not governed by the corresponding wettability shift alone; rather, the physical properties of native brine (i.e., viscosity and density) play a part too. The findings help evaluate the CO₂ storage potential of aquifers and thus assist in de-risking large-scale storage projects.

地下含水层的盐度和盐分组成范围很广，会影响二氧化碳/卤水/岩石系统的物理化学特性，进而影响含水层的二氧化碳捕集能力。现有的模拟研究一般侧重于单一的氯化钠系统，没有充分考虑盐类的变化。本研究以地下二氧化碳封存为背景，考虑了盐度和盐类型对几个关键参数的影响，包括润湿性、界面张力、盐水特性、扩散和毛细管压力。我们进行了孔隙网络建模，以评估盐度（即纯水、1 M（摩尔）、3 M 和 5 M）和盐类型（即 NaCl、CaCl2 和 MgCl2）对残留捕集行为的影响。随后，利用这些发现进行了实地模拟，以评估不同盐度和盐类型对单一盐卤系统中二氧化碳捕集能力的影响。孔隙网络建模结果表明，残余二氧化碳饱和度在盐度较高的条件下会降低，在氯化镁盐水系统中最低。在仅考虑残留捕集的实地规模模拟中，残留捕集能力在盐度较高的氯化钠盐水系统中降低。然而，在高盐度的氯化镁盐水中，粘度和密度的增加会导致二氧化碳羽流的扩散，从而提高残留捕集能力。在仅考虑溶解捕集的情况下，这种羽流扩散差异也会影响溶解的二氧化碳量。当同时考虑两种捕集机制时，我们的观察结果表明，在高盐度和二价阳离子条件下，溶解捕集的减少会导致剩余捕集能力的增强（例如，5 M MgCl2 时为 51.56%）--这表明这两种机制之间存在相互作用或相互依存关系。此外，还研究了扩散和毛细管压力对二氧化碳地质封存捕集能力的影响。总的来说，含盐量较低的盐水（由单价离子组成）含水层的残留捕集能力较低，溶解捕集能力较强，二氧化碳的流动性较低。特别是，纯水系统的移动 CO2 百分比最低（13.72%）。我们还强调，这种影响并不仅仅受制于相应的润湿性变化；相反，原生盐水的物理性质（即粘度和密度）也起到了一定的作用。这些发现有助于评估含水层的二氧化碳封存潜力，从而帮助降低大规模封存项目的风险。

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引用次数: 0

Permeability shifts in chalk core during produced water reinjection 白垩岩芯在采出水回注过程中的渗透性变化

0 ENERGY & FUELS

Geoenergy Science and Engineering

Pub Date : 2024-11-17 DOI: 10.1016/j.geoen.2024.213471

Maksim Kurbasov, Karen L. Feilberg

<div><div>Chalk reservoirs, due to their high porosity and very low permeability, represent one of the most interesting cases for engineering studies of carbonates. They exhibit complex fluid-rock interactions because of their reactive surfaces and dense porous medium. The reinjection of produced water is an attractive strategy for managing wastewater flow from oil wells. However, the complex composition of produced water, the reactive nature of carbonate rocks, and their low permeability create challenges related to permeability loss.</div><div>This study examines the stages of permeability change during core flooding experiments up to the point of complete clogging. A distinctive feature of this study is the presence of residual oil in the core samples, which simulates real reservoir conditions during produced water reinjection. The presence of residual oil is an additional factor influencing the change in core permeability, but there is no clear consensus in the research community on its impact on permeability during produced water injection.</div><div>All experiments were conducted in a core flooding system simulating well conditions in terms of pressure (170 bar) and temperature (70 °C). Produced water samples from the Dan field were used to replicate the chemical and thermodynamic processes occurring in a real well. The experiments identified three stages of permeability change: an initial increase in permeability (+12%), a period of pressure stabilization, and a subsequent decrease in permeability (−8%) due to the formation of inorganic precipitates within the core channels.</div><div>The primary objective of the experiments is to investigate the relationship between permeability changes and the stages of reinjection, with a focus on the effects of residual oil. The study focuses on identifying the processes occurring up to the point of complete clogging, considering the impact of residual oil saturation in the chalk core samples. Image analysis using scanning electron microscopy, particle size measurement with a zeta-potential meter, and thermodynamic scale formation modeling with ScaleCERE software were employed to explain these processes.</div><div>Three stages of permeability change were identified during the injection of 200 pore volumes of produced water: increased permeability (+12%), pressure stabilization, and decreased permeability (−8%). The positive influence of residual oil saturation on the filtration and storage properties of the reservoir was established, due to the mobilization of chalk core particles. Additionally, the theory of core channel clogging during the reinjection of formation water by the formation of inorganic precipitates within the channels was confirmed.</div><div>Understanding the causes of permeability reduction that occurred during the stage of permeability decrease enables the development of water purification methods specifically targeted at the causes of rock clogging. Predicting the process of injecti

白垩储层具有高孔隙度和极低的渗透率，是碳酸盐岩工程研究中最有趣的案例之一。由于白垩岩具有活性表面和致密的多孔介质，它们表现出复杂的流体-岩石相互作用。回注采出水是管理油井废水流的一种有吸引力的策略。然而，采出水的复杂成分、碳酸盐岩的反应性及其低渗透率给渗透率损失带来了挑战。本研究考察了岩心充水实验过程中渗透率变化的各个阶段，直至完全堵塞。本研究的一个显著特点是岩心样本中存在残余油，这模拟了采出水回注过程中的真实储层条件。残余油的存在是影响岩心渗透率变化的另一个因素，但研究界对残余油在采出水注入过程中对渗透率的影响还没有达成明确的共识。丹油田的采出水样本被用来复制真实油井中发生的化学和热力学过程。实验确定了渗透率变化的三个阶段：渗透率最初增加（+12%）、压力稳定期以及随后由于岩心通道内无机沉淀物的形成而导致的渗透率下降（-8%）。考虑到白垩岩芯样本中残余油饱和度的影响，研究重点是确定直至完全堵塞前的过程。为解释这些过程，采用了扫描电子显微镜进行图像分析，使用 zeta 电位计测量颗粒大小，并使用 ScaleCERE 软件进行热力学尺度地层建模。在注入 200 孔隙体积的采出水期间，确定了渗透率变化的三个阶段：渗透率增加（+12%）、压力稳定和渗透率降低（-8%）。由于白垩岩芯颗粒的移动，确定了剩余油饱和度对储层过滤和储存特性的积极影响。此外，岩心通道内无机沉淀物的形成也证实了地层水回注过程中岩心通道堵塞的理论。了解渗透率下降阶段渗透率降低的原因，就能开发出专门针对岩石堵塞原因的净水方法。预测注入采出水和海水混合物的过程将有助于在向注水井注入地层水的处理作业中解释数据，并有助于选择有效措施以减轻对储层的影响。

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引用次数: 0

Experimental and modeling study on the acid-etching and conductivity of hydraulic fractures in carbonate rocks: A critical review 碳酸盐岩水力裂缝酸蚀与传导性的实验和模型研究：重要综述

0 ENERGY & FUELS

Geoenergy Science and Engineering

Pub Date : 2024-11-17 DOI: 10.1016/j.geoen.2024.213517

Bo Gou , Zihao Liu , Jianping Zhou , Ke Xu , Bin Xiao , Kun Pu , Jianchun Guo

Acid fracturing is a pivotal technique for the exploitation of deep carbonate oil and gas, geothermal resources, and also an important injection technology for carbon capture, utilization and storage. The essence of acid fracturing lies in the process where acid non-uniformly etches hydraulic fracture to generate conductivity. Laboratory experiments and numerical simulations are two crucial means to replicate in-situ environment of acid fracturing, understand acid-rock reaction mechanism, and innovate on-site technologies. However, due to complex geological environment of ultra-deep carbonate formations and diverse on-site acid fracturing technologies, existing experimental methods and numerical simulation methods have struggled to fully characterize the emerging acid fracturing technology. Therefore, it is imperative to systematically review research progress on acid-etching and conductivity of acid-etched fractures while identifying gaps between experimental methods, numerical simulations, and on-site technologies, which holds immense significance in advancing theoretical research and technical development related to acid fracturing. Detailed reviews are provided on experimental equipment, models employed for acid etching analysis, as well as testing methods utilized for assessing both etching characteristics and conductivity. The current limitations of existing experimental techniques and numerical simulations are also presented. The proposed acid fracturing experiment and model researches, in conjunction with the engineering geological characteristics of deep and ultra-deep carbonate reservoirs over 10,000 m, not only offer valuable insights for future investigations into acid-etched fracture conductivity but also provide essential support for the advancement of acid fracturing engineering technology. Moreover, these findings can be applied to all the study on flow and reaction processes of reactive fluids within narrow channels.

酸性压裂是开采深层碳酸盐岩油气和地热资源的关键技术，也是碳捕集、利用和封存的重要注入技术。酸性压裂的本质在于酸性物质非均匀地蚀刻水力裂缝以产生传导性的过程。实验室实验和数值模拟是复制酸性压裂现场环境、了解酸岩反应机理、创新现场技术的两种重要手段。然而，由于超深碳酸盐岩层地质环境复杂，现场酸压裂技术多样，现有的实验方法和数值模拟方法难以全面描述新兴的酸压裂技术。因此，有必要系统回顾酸蚀和酸蚀裂缝电导率的研究进展，同时找出实验方法、数值模拟和现场技术之间的差距，这对推动酸压裂相关理论研究和技术发展具有重要意义。本研究对实验设备、酸蚀分析模型以及用于评估蚀刻特性和导电性的测试方法进行了详细评述。此外，还介绍了现有实验技术和数值模拟的局限性。结合 10,000 米以上深层和超深层碳酸盐岩储层的工程地质特征，所提出的酸压裂实验和模型研究不仅为今后研究酸蚀裂缝传导性提供了宝贵的见解，也为酸压裂工程技术的进步提供了重要支持。此外，这些发现还可应用于所有关于反应流体在狭窄通道内的流动和反应过程的研究。

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引用次数: 0

Spatial deterioration responses of coals under the thermo-mechanical effects from liquid CO2 interaction 液态二氧化碳相互作用的热机械效应下煤炭的空间劣化响应

0 ENERGY & FUELS

Geoenergy Science and Engineering

Pub Date : 2024-11-17 DOI: 10.1016/j.geoen.2024.213511

Jizhao Xu , Sheng Qian , Cheng Zhai , P.G. Ranjith , Guanhua Ni , Yong Sun , Xu Yu , Ting Liu

The technology of CO₂ fracturing and enhanced coalbed methane recovery has garnered significant attention worldwide because of its potentials of CH₄ resource exploitation and geological sequestration. The Joule-Thomson effect during the liquid CO₂ injection process along the borehole induces rapid changes in temperature and pressure, which might have some impacts on the mechanical responses of coals. However, these effects have not been visualized through physical experiments. This paper focused on the thermo-mechanical impacts of cyclic liquid CO₂ injection on the deterioration behaviors of coals, by unsealing and sealing borehole, respectively, under the conditions of different confining pressure. Several non-contacting monitoring technologies were employed to document the spatial deterioration and fracturing behaviors of coals during the liquid CO₂ injection process. When the unsealed samples were subjected to cyclical cryogenic CO₂, the temperature inner borehole steadily decreased and remained at a low-temperature of −22 °C, only beginning to rise when the injection was completed. The acoustic emission (AE) events initially manifested at the bottom of borehole and subsequently dispersed along the borehole axial direction within the cyclical CO₂ injection. The presence of repeatability and multiple steps in AE events indicated that the thermal fractures were generated under the effects of alternative changes of negative/positive temperatures. Compared to the straightforward crack morphology observed in the free-pressured sample, a higher number of cracks were produced in the samples subjected to the confining stress, and these cracks had greater toughness and good fractal characteristics. The crack density, crack number and fragments had positive relations with the fractal dimension, respectively. The confining stress and physical features of coals jointly affected the crack spatial distribution, and the reduction of ultrasonic velocity reflected that matrix had the anisotropy of the mechanical responses. Finally, a cracking initiation model was established considering the thermal cycling, damage accumulation and expansion pressure by phase-transition. The experimental results might have some theoretical significances on the field application.

二氧化碳压裂和煤层气强化回收技术因其在甲烷资源开发和地质封存方面的潜力而备受全球关注。在液态二氧化碳沿井眼注入的过程中，焦耳-汤姆逊效应会引起温度和压力的快速变化，这可能会对煤的机械响应产生一些影响。然而，这些影响尚未通过物理实验得到直观体现。本文重点研究了在不同封闭压力条件下，通过解封和封堵井眼，循环注入液态二氧化碳对煤炭劣化行为的热力学影响。采用了多种非接触式监测技术来记录液态二氧化碳注入过程中煤炭的空间劣化和破裂行为。当未密封样品受到循环低温二氧化碳作用时，井眼内部的温度稳步下降，并保持在-22 °C的低温状态，直到注入完成后才开始上升。声发射（AE）事件最初出现在钻孔底部，随后在循环二氧化碳注入过程中沿钻孔轴向扩散。声发射事件的重复性和多级性表明，热裂缝是在负/正温度交替变化的影响下产生的。与在自由加压样品中观察到的直接裂纹形态相比，在受到约束应力的样品中产生了更多的裂纹，这些裂纹具有更大的韧性和良好的分形特征。裂纹密度、裂纹数量和碎片分别与分形维度呈正相关。约束应力和煤的物理特征共同影响了裂纹的空间分布，超声波速度的降低反映了基体具有力学响应的各向异性。最后，考虑到热循环、损伤累积和相变膨胀压力，建立了裂纹起始模型。实验结果可能对现场应用具有一定的理论意义。

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