煤层自封闭性对深层煤岩气的富集与改造意义  

Implications of coal reservoir self-sealing for the enrichment and stimulation of deep coalrock gas

作　　者：郗兆栋 唐书恒[1,2] 杨文府 杨雄雄 张迁 王凯峰 吕建伟 XI Zhaodong;TANG Shuheng;YANG Wenfu;YANG Xiongxiong;ZHANG Qian;WANG Kaifeng;LYU Jianwei(School of Energy Resource,China University of Geosciences(Beijing),Beijing,100083,China;Shanxi Center of Technology Innovation for Coal Measure Mineral Resources Comprehensive Exploration,Taiyuan,Shanxi 030000,China;Shanxi Coal Geology Investigation and Research Institute Co.,Ltd.,Taiyuan,Shanxi 030031,China)

机构地区：[1]中国地质大学(北京)能源学院,北京市100083 [2]山西省煤系矿产综合勘查技术创新中心 [3]山西省煤炭地质勘查研究院有限公司

出　　处：《天然气工业》2024年第10期105-112,共8页Natural Gas Industry

基　　金：国家自然科学基金项目“煤系页岩储层可改造性的微观控制机理研究”(编号:42302203)。

摘　　要：近年来,煤岩气勘探开发成功突破“深度禁区”,将中国煤岩气产业带入了一个新的发展阶段。深层煤岩气富集规律以及“千方砂,万方液”的超大规模储层压裂改造工艺无不与中、浅层煤岩气的富集规律和勘探开发技术形成鲜明对比,进一步彰显了深层煤岩气成藏、富集及开采的特殊性。为进一步明确有利于深层煤岩气富集、储层改造的地质-工程甜点纵向分布,推动实现深层煤岩气地质-工程一体化发展,以华北地区深层煤岩气为研究对象,基于土力学中超固结比的概念定量表征了煤储层的自封闭性,评价了深层煤岩气的富集条件和煤储层的可改造性。研究结果表明:①超固结比能够反映煤储层自封闭性的动态演化特征,与煤层埋藏深度具有耦合关系;②埋深越大,煤层超固结比越小,煤储层自封闭性越强,有利于煤岩气的富集,但煤储层压裂改造难度增大;埋深越浅,煤层超固结比越大,煤储层自封闭性越弱,不利于煤岩气的保存,但煤储层相对易于压裂改造;③基于煤层超固结比与埋深的耦合关系揭示了既有利于煤岩气富集又利于煤储层改造的深度范围,该深度带是深层煤岩气地质-工程甜点区带。结论认为,基于超固结比确定的地质-工程甜点深度界限可为相似地质背景条件下的深层煤岩气地质-工程一体化实施提供参考和借鉴,有助于煤岩气产业的高质量发展。In recent years,the exploration and development of coal-rock gas has successfully broken through the"deep forbidden zone",which has brought China's coal-rock gas industry into a new development stage.The enrichment laws of deep coal-rock gas and the ultra large scale reservoir fracturing with"one thousand cubic meters of sand,ten thousand cubic meters of fracturing fluid"are in sharp contrast to the enrichment laws and exploration and development technologies of middle and shallow coal-rock gas,highlighting the special characteristics of deep coal-rock gas in accumulation,enrichment and exploitation.In order to further determine the vertical distribution of the geology-engineering sweet spots favorable for the enrichment and reservoir stimulation of deep coal-rock gas and promote the geology-engineering integration development of deep coal-rock gas,this paper takes the deep coal-rock gas in North China as the research object to quantitatively characterize the self-sealing property of coal reservoirs based on the concept of over consolidation ratio(OCR)in rock mechanics and evaluate the enrichment conditions of deep coal-rock gas and the fracability of coal reservoirs.Tthe following results are obtained.First,the OCR can reflect the dynamic evolution characteristics of the self-sealing property of coal reservoir,and it is in a coupling relationship with the burial depth of coal reservoir.Second,the greater the burial depth,the smaller the OCR of coal reservoir,and the stronger the self-sealing ability of coal reservoir,which is beneficial to the enrichment of coal-rock gas,but increases the difficulty in the fracturing stimulation of coal reservoir.Otherwise,the smaller the burial depth,the greater the OCR of coal reservoir,and the weaker the self-sealing ability of coal reservoir,which is not conducive to the preservation of coal-rock gas,but facilitates the fracturing stimulation of coal reservoir.Third,the coupling relationship between OCR and burial depth of coal reservoir reveals a depth range that is benefic

关 键 词：深层煤岩气 成藏 保存条件 力学性质 可改造性 超固结比 地质-工程一体化 

分 类 号：TE132.2[石油与天然气工程—油气勘探]