桑树勋,郑司建,易同生,等. 煤系叠合型气藏及其勘探开发技术模式[J]. 煤田地质与勘探,2022,50(9):13−21. DOI: 10.12363/issn.1001-1986.22.02.0109
引用本文: 桑树勋,郑司建,易同生,等. 煤系叠合型气藏及其勘探开发技术模式[J]. 煤田地质与勘探,2022,50(9):13−21. DOI: 10.12363/issn.1001-1986.22.02.0109
SANG Shuxun,ZHENG Sijian,YI Tongsheng,et al. Coal measures superimposed gas reservoir and its exploration and development technology modes[J]. Coal Geology & Exploration,2022,50(9):13−21. DOI: 10.12363/issn.1001-1986.22.02.0109
Citation: SANG Shuxun,ZHENG Sijian,YI Tongsheng,et al. Coal measures superimposed gas reservoir and its exploration and development technology modes[J]. Coal Geology & Exploration,2022,50(9):13−21. DOI: 10.12363/issn.1001-1986.22.02.0109

煤系叠合型气藏及其勘探开发技术模式

Coal measures superimposed gas reservoir and its exploration and development technology modes

  • 摘要: 煤系叠合型气藏是含煤地层煤系气特有的关键成藏类型,煤系叠合型气藏的发现、勘探开发实践与研究探索为我国煤系非常规天然气勘探开发提供了新领域和新思路。提出并阐述煤系叠合型气藏的概念、主要类型、发育特征和赋存分布,探讨煤系叠合型气藏的形成条件、成藏过程、成藏模式,揭示其形成机理,重点讨论2种主要类型煤系叠合型气藏的地质适配性勘探开发技术模式,分析前瞻了煤系叠合型气藏在煤系气勘探开发中的应用。研究表明:我国发育(分流)河道砂体与煤层接触型(华北型)、煤层−砂岩–泥岩互层型(华南型)、煤层–砂岩–泥岩互层夹砂砾岩型(东北型)3类煤系叠合型气藏,分布赋存分别以华北地区山西组、华南地区龙潭组和东北地区城子河组为代表;沉积作用是煤系叠合型气藏的关键主控地质因素,三角洲沉积体系的泥炭沼泽、分流河道、支流间湾的沉积微相组合为煤系叠合型气藏的有利沉积相序组合;煤层为主的叠置复合储层结构和岩性圈闭是煤系叠合型气藏的重要特征,统一的含气系统和压力梯度一致是其本质特征;含煤段煤层/砂岩/页岩不同类型储层间发生能量物质传递和平衡、煤层气/致密砂岩气/页岩气间运移和相态转化是煤系叠合型气藏形成的主要机理,喜马拉雅期是华北地区山西组煤系叠合型气藏成藏关键期;高分辨率地震岩相解释识别气藏与虚拟产气层合层开发是华北型煤系叠合型气藏勘探开发技术模式的关键特征,“层段优选、小层射孔、分段压裂、投球分压、合层排采”构成华南型煤系叠合型气藏勘探开发技术模式的核心内涵。这些技术模式已得到应用并将为我国煤系气共探共采和深层煤层气高效开发提供重要支持。

     

    Abstract: Coal measures superimposed gas reservoir is a key reservoir type of coal-measure gas in coal bearing formation. The discovery, exploration and development practice of coal measures superimposed gas reservoirs in China have opened up a new chapter for the coal-measure gas exploration. In this study, the concept, main types, development characteristics and occurrence distribution of coal measures superimposed gas reservoir are proposed and expounded. The formation prerequisite, accumulation process and reservoir forming mechanism of coal measure superimposed gas reservoir are analyzed. Specifically, the geological suitability exploration and development technology modes of two typical coal measures superimposed gas reservoirs are emphatically discussed, and the application of coal measure superimposed gas reservoir exploration and exploitation technologies in coal-measure gas reservoirs is prospected. At present, three types of coal measure superimposed gas reservoirs have been found in China, which are: (distributary) channel sandstone-coal syntagmatic relation type, developed in the Shanxi Formation of north China (denoted as the North China type); coal-sandstone-mudstone interbedding type, developed in the Longtan Formation of south China (denoted as the South China type); coal-sandstone-mudstone interbedded conglomerate type, developed in the Chenghe Formation of northeast China (denoted as the Northeast China type). As a crucial controlling geological factor, sedimentary microfacies combination of mire, distributary channel and interdistributary bay in delta depositional system is favorable to form the coal measure superimposed gas reservoir. The superimposed composite reservoir structure and lithologic trap are the important characteristics of coal measure superimposed gas reservoir and the unified gas-bearing system and pressure gradient account for its essential characteristics. Furthermore, the critical formation mechanism of coal measure superimposed gas reservoir involves the transfer and balance of matter and energy among coal seams, sandstones, and shales, the migration and phase transformation among coalbed methane, tight sandstone gas, and shale gas. Himalayan orogeny is the key period for the coal measure superimposed gas reservoir formation in Shanxi formation in north China. On a technical level, high-resolution seismic lithofacies interpretation for gas reservoir identification and virtual gas-producing bedding development have been proven to be powerful means in the exploration and development of North China type coal measure superimposed gas reservoirs. Techniques such as interval optimization, small-layer perforation, staged fracturing, ball-drop pressure separation and combined layer drainage corporately contribute to the adaptive development of Longtan Formation coal measures superimposed reservoir in south China. These technical modes have made breakthroughs in the co-exploration and co-production of coal measures gas, and predictably, they will continually provide strong backing for the high efficiency development of deep buried coalbed methane in China.

     

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