《石油学报》：深部煤层气主题双语文章推荐

作为中国天然气规模性增储上产的重要接续领域，深部煤层气的高效勘探开发，是破解能源供需矛盾、保障能源安全的关键抓手。相较于中浅层煤层气，深部煤层气因赋存环境复杂、地质条件特殊，其成藏规律、解吸特征与开发技术均存在显著差异，相关研究长期面临理论突破与工程实践的双重挑战。

本期为大家推荐发表于《石油学报》的5篇深部煤层气研究相关双语文章，既有对我国深部煤层气地质研究20余年进展的系统梳理，也有针对鄂尔多斯盆地东缘等典型区块的深度剖析；既阐释了 “深度效应”“高渗窗” 等关键地质理论，又揭示了游离气与吸附气的耦合赋存规律、多要素耦合控制机理；更创新性地构建了基于大数据分析算法的煤层气地质—工程一体化智能决策系统。诚邀广大能源领域科研工作者、工程技术人员研读借鉴，共同推动我国深部煤层气产业迈向高质量发展新阶段。

01

中国深部煤层气地质研究进展

Progress on geological research of deep coalbed methane in China

【摘要】深部煤层气是中国未来天然气规模性增储上产的重要领域，回顾深部煤层气地质研究历史与进展，评述面临问题和探索方向，可为发展适应性勘探开发技术提供借鉴。分析表明，中国在20余年的深部煤层气地质研究中主要取得3方面进展。第一，界定了深部煤层气基本概念及其科学内涵，发现深部煤层吸附气含量存在临界深度，这一深度主要取决于地温梯度和地应力梯度两者的耦合关系，其他地质因素对临界深度具有调整作用；吸附气含量降低可能导致游离气含量随之增高，结果是形成煤层气在深度序列上的有序聚集，在深部形成富含游离气的高饱和—超饱和煤层气藏。第二，对深部煤层地质属性的研究进展显著，认识到深部煤层吸附性减弱及游离气含量增高是地层压力正效应与地层温度负效应之间动态平衡的结果；发现在深度剖面上地应力状态转折带附近存在煤层“高渗窗”，与深部煤层可改造性相关的地层温度、压力指标可能具有“门限”性质，温度补偿效应和变孔隙压缩系数效应可能使得深部煤层渗透率衰减速率显著降低。第三，对深部煤层气成藏作用与地质评价的研究逐渐深入，对成藏作用原理的探讨聚焦在由埋深变化引起的煤层含气性、渗透率垂向分布及其地质控制等5个方面，初步揭示了煤层气成藏“深度效应”。对现场案例进行的剖析经历了由盆地到有利区、由有利区到“甜点”、由控藏到控产的认识深化过程。分析认为，基础地质（成藏作用）、勘查地质（评价优选）、开发地质（动态过程）3方面有机衔接和深度耦合，是面向深部煤层气勘探开发地质—工程一体化所需探索的关键方向，建议未来研究应聚焦“深度效应”，包括深部煤层气藏特征的系统描述和气藏工程对地质条件响应的刻画。

【Abstract】Deep coalbed methane (CBM) will become an important field for China to increase the large-scale natural gas reserves and production in the future. It is of great significance to review the history and progress of the geological research on deep CBM propose and evaluate the existing problems and exploration directions, which can provide a reference for developing applicable exploration and development technologies. Analyses reveal that China has made three major advances in the geological research of deep CBM in the past 20 years. First, the basic concept and its scientific connotation of deep CBM have been defined. It is found that there is a critical depth for the absorbed gas content of deep coalbeds, which mainly depends on the coupling relationship between geothermal gradient and geo-stress gradient, and other geological factors can adjust the critical depth. A decrease in the adsorbed gas content may lead to an increase in free gas content, resulting in the orderly accumulation of CBM in the depth sequence and the formation of highly to super saturated reservoirs with abundant free gas in the deep coal. Second, remarkable progress has been made in research of the geological properties of deep coal reservoirs, and it has been recognized that the weakening adsorption of deep coal reservoirs and the increase of free gas content are resulted from the dynamic equilibrium between the positive effect of pressure and the negative effect of temperature. Moreover, it has been found that there is a “highly permeability window” of coal reservoirs near the transition zone of geo-stress state on the depth profile, and the formation temperature and pressure indices related to the reconstruction of deep coal reservoirs may have a threshold property, and the temperature compensation and variable pore compressibility effects may significantly lower the decay rate of permeability for deep coal reservoirs. Third, an in-depth research is gradually implemented on the accumulation and geological evaluation of deep CBM reservoirs, and the exploration on accumulation mechanism focuses on CBM gas-bearing property formed by buried depth changes, vertical permeability distribution and its geological control, thus initially revealing the “depth effect” for CBM reservoir formation. Through on-site case analysis, the relevant understandings have been deepened and expanded from basin to favorable zone, then to sweet spot and from reservoir control to production control. The analyses suggest that the organic connection and deep coupling of basic geology (reservoir-forming process), exploration geology (evaluation optimization) and development geology (dynamic process) are key directions for the geological-engineering integration in deep CBM exploration and development. Therefore, it is suggested future research should focus on “depth effect”, including the systematic description of deep CBM reservoir and the characterization of gas reservoir engineering responses to geological conditions.

02

深部煤层气多要素耦合控制机理、解吸规律与开发效果剖析

Analysis of multi-factor coupling control mechanism, desorption law and development effect of deep coalbed methane

【摘要】深部煤层气（埋深大于2 000 m）是煤层气勘探开发的重要领域，不同于以吸附气为主的中—浅部煤层气，其赋存状态以游离气与吸附气共存为特征。目前，深部煤层气的解吸规律尚不明确，游离气与解吸气的转换时机、开发效果差异的原因尚不清楚。以鄂尔多斯盆地东缘大宁—吉县区块为例，由于其关键地质参数的分布规律与构造趋势具有一致性，根据微构造形态可将该区块划分为负向微构造区、构造平缓区、正向微构造区和构造抬升区4个开发单元，并明确其地质特征。提出决定深部煤层气开发效果的关键要素可归纳为“五大必要条件”和“一个程度”，并对这些关键要素在深部煤层气开发中的耦合控制机理进行了剖析。“五大必要条件”包括保存条件、资源条件、解吸条件、渗流条件、可改造条件，是地质基础；“一个程度”指压裂改造程度，在开发过程中需要根据“五大必要条件”对其进行差异化调整。基于“五大必要条件”（25项地质参数），系统归纳了4个开发单元的煤层气开发评价结果、综合生产特征和典型生产曲线，并给出了相应的工程技术对策建议。以煤层气评价中一直被忽视的解吸条件为研究内容，通过等温吸附实验，明确了影响深部煤层气等温吸附特征的主控因素。深部煤岩的吸附能力随着温度、灰分含量和水分含量的升高而减弱，随着有机质热演化程度的升高而增加，同时，Langmuir压力会随着水分含量的升高而增加；当煤岩中灰分含量变化较大时，煤岩的吸附能力与煤岩热演化程度的相关性不明显，灰分含量成为影响解吸的主控因素；从构造平缓区至正向微构造区，煤岩的等温吸附曲线形态由陡变缓，Langmuir体积下降10.7%，但Langmuir压力增高36.8%。结合实验结果与基础理论方法进一步明确了深部煤层气在不同构造开发单元的解吸规律，对比分析了解吸特征的差异。深部煤层气的生产过程可划分为4个阶段：（1）低效解吸阶段+游离气主导阶段（阶段Ⅰ）、（2）缓慢解吸阶段（阶段Ⅱ）、（3）高效解吸阶段（阶段Ⅲ）、（4）敏感解吸阶段（阶段Ⅳ）。大宁—吉县区块深部煤层气的解吸启动压力为9.05～9.30 MPa、解吸转折压力约为6.00 MPa、解吸敏感压力为2.30～2.70 MPa，在深部煤层气井的生产中，从以游离气产出为主到以吸附气产出为主的转换是一个过程，主要取决于缓慢解吸阶段时间的长短及解吸关键压力点（解吸启动压力、转折压力）的大小、压力降幅和解吸曲线特征。最后，结合地质规律和认识，具体剖析了构造平缓区和正向微构造区煤层气井开发效果差异的原因，以期为推动深部煤层气高效开发所面临的地质精细评价与单元划分、开发规律预测、采气设备优选及排采制度制定等提供科学指导。

【Abstract】Deep coalbed methane (CBM) with a buried depth of greater than 2 000 m is an important field of CBM exploration and development. Different from the middle-shallow CBM that mainly consists of adsorbed gas, the occurrence state of deep CBM is characterized by the coexistence of free gas and adsorbed gas. At present, the desorption law of deep CBM, the opportunity for conversion between free gas and desorbed gas and the reasons for the difference in development effect are still unclear. This paper is a case study of Daning-Jixian block in the eastern margin of Ordos Basin. Since the distribution law of its key geological parameters is consistent with the tectonic trend, the block can be divided into four development areas based on the microstructural morphology, including negative microtectonic area, gentle tectonic area, positive microtectonic area and tectonic uplift area, of which the geological characteristics have been determined. The key factors that impact the development effect of deep CBM can be summarized as “five essential conditions” and “one degree”. Moreover, an analysis is performed on the coupling control mechanism of these key factors in deep CBM development. The “five essential conditions” include the preservation condition, resource condition, desorption condition, seepage condition, and reservoir stimulation condition, which are the geological foundation; the “one degree” refers to the degree of fracturing reformation, which needs to be differentially adjusted according to the “five essential conditions” in the hydrocarbon development process. Based on the “five essential conditions” (25 geological parameters), the paper systematically summarizes the evaluation results, comprehensive production characteristics, and typical production curves of coalbed methane development in 4 development areas, and further proposes corresponding engineering countermeasures. Based on the desorption condition that has been neglected in the evaluation of CBM, the main controlling factors affecting the isothermal adsorption characteristics of deep CBM were identified through isothermal adsorption experiments. The adsorption capacity of deep coal rock is weakened with the increase of temperature, ash content, and moisture content, and increased with the increasing level of the thermal evolution of organic matter. Meanwhile, Langmuir pressure keeps increasing with the increase of moisture content; when the ash content in coal rock varies greatly, the adsorption capacity of coal rock is not significantly correlated with the thermal evolution level of coal rock, and the ash content becomes the main controlling factor for desorption; from the gentle tectonic area to positive microtectonic area, the isothermal adsorption curve of coal rock is varied from steep to gentle, the Langmuir volume is decreased by 10.7%, and the Langmuir pressure is increased by 36.8%. In combination with the experimental results from basic theoretical methods, the paper further determines the desorption laws of deep CBM in different tectonic development areas, and compares and analyzes the differences in desorption characteristics. The production process of deep CBM can be divided into four stages: (1) low efficiency desorption stage + free gas dominant stage (stage Ⅰ), (2) slow desorption stage (stage Ⅱ), (3) high efficiency desorption stage (stage Ⅲ), and (4) sensitive desorption stage (stage Ⅳ). The starting pressure for the desorption of deep CBM in Daning-Jixian block is 9.05 MPa to 9.30 MPa, the desorption turning pressure is about 6.00 MPa, and the desorption-sensitive pressure is 2.30 MPa to 2.70 MPa. In the production of deep CBM wells, the transition from dominant free gas production to dominant adsorbed gas production is a process that mainly depends on the duration of the slow desorption stage, the size of key desorption pressure points (desorption starting pressure and turning pressure), pressure drop, and the characteristics of desorption curve. Finally, based on geological laws and relevant understandings, the reasons for the difference in the development effect of CBM wells in the gentle tectonic area and positive microtectonic area have been analyzed in detail, which aims to provide scientific guidance for the fine geological evaluation and units division, prediction of development laws, optimization of gas production equipment, and formulation of drainage and production system in promoting the efficient development of deep CBM.

03

深部煤层气地质特征与开发对策

Geological characteristics and development countermeasures of deep coalbed methane

【摘要】深部煤层气勘探与开发先导试验取得的重要突破展示了良好的勘探开发前景。但深部煤层气埋藏较深、非均质强，影响开发效果的地质、工程因素众多，合理的开发对策尚不明确。通过分析鄂尔多斯盆地8号煤层的成藏规律与开发地质特征表明：8号煤层有机质成熟度高，全盆地稳定分布，生烃潜力巨大；深部煤岩储层微孔、介孔、宏孔和微裂缝体积平均占比分别为78.0%、6.8%、2.1%和13.1%，为典型的多重孔-裂隙系统，储集条件复杂；深部煤层气通常位于临界深度以下，构造抬升幅度更小，埋藏深，储层相对致密，断裂不发育，水动力较弱，保存条件更好；深部煤层气含气量高且吸附气与游离气共存，煤体结构发育相对完整，更有利于压裂改造，气井排采早期产气量便快速提升，具有早期产量高、递减快的特征，按照解吸规律可划分为游离气采出、稳产和递减3个开发阶段。针对深部煤层气的开发难点，结合致密气与页岩气的开发经验，提出坚持三维地震先行、建立储层地质力学模型、工厂化大井丛建产模式、坚持先导试验4点针对性建议。以大宁—吉县区块为例，总结了先导试验取得的规律认识，以期为深部煤层气进一步开发提供借鉴。

【Abstract】Significant breakthroughs have been made in precursor experiments for the exploration and development of deep coalbed methane, showing good prospect for development. However, deep coalbed methane has relatively high buried depth with strong heterogeneity. Lots of geological and engineering factors may affect the development results, and reasonable development countermeasures are still not determined. This paper is a case study of No.8 coal seam in Ordos Basin, and analyzes its accumulation laws and development characteristics. The results show that No. 8 coal seam has high maturity, stable distribution in the whole basin, and huge hydrocarbon generation potential; the average volume proportions of micropores, mesopores, macropores, and microfractures in deep coal reservoirs are 78.0%, 6.8%, 2.1% and 13.1%, respectively, as being a typical multiple pore-fracture system with superior hydrocarbon accumulation conditions; deep coalbed methane is located below the critical depth, characterized with a smallscale structural uplift, relatively tight reservoirs, undeveloped faults, weak hydrodynamic forces, and better preservation conditions. There is a high content of deep coalbed methane in the study area, which coexists with adsorbed gas and free gas. The coal structure is generally well developed, which is more conducive to reservoir stimulation by hydraulic fracturing. The production of gas wells quickly increases at early stag, characterized with high early production and rapid decline; according to desorption laws, the whole process can be divided into three development stages: free gas production, stable production, and decline. To address the challenges faced in the exploitation of deep coalbed methane, based on the experiences obtained during the development of tight gas and shale gas, four targeted suggestions are proposed: (1) initially applying 3D seismic technique; (2) establishing a reservoir geomechanical model; (3) building an industrialized large-scale well cluster construction mode; (4) keep doing precursor experiments. Finally, taking the Daning-Jixian block as an example, the understandings obtained from the precursor experiments have been summarized, and will provide reference for further development of deep coalbed methane.

04

基于大数据分析算法的深部煤层气地质—工程一体化智能决策技术

Integrated intelligent decision-making technology for deep coalbed methane geology and engineering based on big data analysis algorithms

【摘要】煤层气勘探开发形势日趋复杂、资源品质劣化程度加剧。明确煤层气高产主控因素与作用机理、建立地质—工程综合甜点评价方法、提高煤层气动态预测精确度和工程决策有效性，成为亟待解决的技术挑战。以区域数据湖及气藏精细描述研究成果为基础，运用人工智能技术对煤层气藏综合数据进行深度挖掘，构建了基于大数据分析算法的煤层气地质—工程一体化智能决策系统，实现了煤层气地质—气藏—工程一体化数据的集成和管理、大数据驱动下的煤层气单井产量快速预测及主控因素分析、融合地质及工程因素各参数的煤层气储层综合甜点分析、基于煤层气井压后产量主控因素分析的压裂参数优化等关键技术。该系统在鄂尔多斯东缘深部煤层气大宁—吉县区块进行了试点，推广应用结果显示，系统显著提升了气藏研究的效率与工程决策的有效性，为全面了解和掌握气藏的资源潜力、全力推进智能化在科研生产中的深度应用提供了有力的支撑。

【Abstract】The exploration and development of coalbed methane are facing increasingly complex challenges, accompanied by a worsening of the quality of resources. It is imperative to address the technical challenges of identifying the primary control factors and mechanisms for high coalbed methane production, establishing a reliable integrated geological-engineering evaluation method, enhancing the accuracy of dynamic coalbed methane prediction, and improving the effectiveness of engineering decisions. Building upon research achievements related to regional data repositories and detailed descriptions of gas reservoirs, and leveraging artificial intelligence technology, a comprehensive data mining effort was conducted on coalbed methane reservoirs. This innovative approach led to the development of an integrated intelligent decision-making system for coalbed methane geological and engineering activities, based on big data analysis algorithms. This system integrates and manages data related to coalbed methane geological, gas reservoir, and engineering aspects, offers rapid predictions of single-well gas production under big data-driven conditions, analyzes the primary control factors, conducts comprehensive analyses of coalbed methane reservoir parameters by incorporating geological and engineering factors, and optimizes fracturing parameters based on post-fracturing production analysis. The system was piloted in the Daning-Jixian block in the eastern margin of Hubei, and its subsequent widespread application significantly improved the efficiency of gas reservoir research and the effectiveness of engineering decisions. It provided strong support for gaining a comprehensive understanding of the resource potential of gas reservoirs and advancing the deep application of intelligent technology in research and production.

05

鄂尔多斯盆地东缘深部煤层气成藏演化规律与勘探开发实践

Evolution law of deep coalbed methane reservoir formation and exploration and development practice in the eastern margin of Ordos Basin

【摘要】中国深部煤层气（埋深>1 500 m）资源丰富，具有吸附气与游离气共存的赋存特征，其赋存状态、成藏特征和开发规律与中—浅部煤层气存在显著差异，成藏演化规律尚不清晰制约了其高效勘探与开发。以鄂尔多斯盆地东缘大宁—吉县区块深部8号煤层为例，通过精细刻画深部煤层气的成藏特征，模拟深部煤层的埋藏演化史、热演化史、生烃演化史，完善了深部煤层气的富集成藏规律和成藏模式，并提出了针对性勘探开发对策。研究结果表明，大宁—吉县区块深部8号煤层全区发育、有机质热演化程度高、干酪根类型为Ⅲ型、生烃潜力大，总生烃强度为（20.2～34.7）×108m3/km2；深部煤储层发育割理、裂隙、组织孔、胞腔孔、气孔、晶间孔和溶蚀孔等储集空间，为深部游离态煤层气提供了良好的储集条件；构造-岩性-水动力耦合封闭利于深部煤层气保存。研究区深部煤层的成藏演化可以划分为初始生烃阶段（阶段Ⅰ，306～251 Ma）、第1次热成因生烃阶段（阶段Ⅱ，251～203 Ma）、有机质热演化作用减缓阶段（阶段Ⅲ，203～145 Ma）、生烃高峰阶段（阶段Ⅳ，145～130 Ma）和成藏状态定型阶段（阶段Ⅴ，130 Ma至今）5个阶段。研究区深部煤层气表现为游离态与吸附态共存，提出了深部煤层气“广覆式生烃、箱式封闭、微构造调整、自生自储、毯式成藏”的富集成藏规律，建立了微幅褶皱与物性耦合控藏（Ⅰ型）、微幅单斜与水动力耦合控藏（Ⅱ型）、物性与水动力耦合控藏（Ⅲ型）3类深部煤层气成藏模式。研究认识有效指导了大宁—吉县区块深部煤层气勘探有利区的优选，建立了深部煤储层有利区评价指标体系，针对不同成藏模式发育区，提出了差异化开发方案，助力研究区实现了深部煤层气真正意义上的效益开发。研究认识对于中国其他区块开展深部煤层气勘探与开发具有重要参考与借鉴意义。

【Abstract】China's deep coalbed methane (CBM) resources, with the burial depths exceeding 1 500 m, are abundant and coexist with adsorbed and free gases. The occurrence state, accumulation characteristics, and development laws of deep CBM differ significantly from those of mid-shallow CBM, and the unclear evolution patterns have restricted its efficient exploration and development. Taking the No.8 deep coal seam in Daning-Jixian block on the eastern margin of Ordos Basin for example, this study finely characterizes the accumulation characteristics of deep CBM and simulates the burial evolution history, thermal evolution history, and hydrocarbon generation history of deep coal seams, thus improving the deep CBM enrichment and accumulation laws and patterns; moreover, the targeted exploration and development strategies are proposed. The results show that the No. 8 deep coal seam is widespread in Daning-Jixian block, with high organic matter thermal maturity and Type III kerogen. This indicates significant hydrocarbon generation potential, with the total hydrocarbon intensity of (20.2–34.7) × 108 m3/km2. The deep coal reservoir develops cleats, fractures, texture pores, cell pores, gas pores, intergranular pores, and dissolution pores, providing favorable conditions for the accumulation of deep free-state CBM. The structural-lithologic-hydrodynamic coupling closure is favorable for the preservation of deep CBM. The evolution stages of hydrocarbon accumulation in deep coal seams in the study area include the initial hydrocarbon generation stage (Stage I, 306–251 Ma), the first thermal hydrocarbon generation stage (Stage II, 251–203 Ma), the decreasing stage of organic matter thermal evolution (Stage III, 203–145 Ma), the hydrocarbon generation peak stage (Stage IV, 145–130 Ma), and the final formation stage of the oil/gas accumulation pattern (Stage V, 130 Ma to present). The deep CBM under free and adsorbed states coexist in the study area. On this basis, the paper proposes the hydrocarbon enrichment and accumulation pattern of “wide covering hydrocarbon generation, box-type closure, microstructure adjustment, self-generation and self-storage, and blanket-type accumulation”, and establishes three types of deep CBM accumulation models: microfold and physical property coupling control (Type I), microfault monocline and hydrodynamic force coupling control (Type II), and physical property and hydrodynamic force coupling control (Type III) on reservoir accumulation. These understandings can effectively guide the selection of favorable areas for deep CBM exploration in Daning-Jixian block, establish an evaluation index system for favorable areas in deep coal reservoirs, propose differentiated development plans for exploration areas with different accumulation models, and help achieve the truly efficient and low-cost development of deep CBM in the study area. The research findings have important reference significance for carrying out deep CBM exploration and development in other blocks in China.

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《石油学报》（ACTA PETROLEI SINICA）是由中国科学技术协会主管、中国石油学会主办的综合性高级学术刊物，创刊于1980年，是中国自然科学核心期刊之一，在中国石油学术界具有较高的权威性和较大的影响力。 近年来，《石油学报》注重报道中国石油和天然气领域具有原创性的基础研究及应用研究成果，反映重大课题研究的最新进展，推广新技术和新方法，促进国内外石油科技学术交流。

《石油学报》主要刊登内容包括：石油天然气地质及地球物理、油气田开发技术与工艺、石油与天然气钻井、海洋油气工程、油气储运、石油矿场机械设备等方面的学术论文。 读者对象主要是从事石油与天然气及其相关领域的中、高级科技工作者和高校师生。

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