新疆石油地质

新疆石油地质 ›› 2025, Vol. 46 ›› Issue (5): 531-543.doi: 10.7657/XJPG20250502

• 油气勘探 • 上一篇    下一篇

深层煤岩储集层孔隙结构和储集性能——以鄂尔多斯盆地西南部山西组深层5号煤岩为例

罗京1(), 张雷1, 张建伍1, 潘星1, 曹茜1, 李磊1, 严婷1, 李腾2()   

  1. 1.中国石油 长庆油田分公司 a.勘探开发研究院; b.低渗透油气田勘探开发国家工程实验室，西安 710018
    2.西安石油大学 石油工程学院，西安 710065
  • 收稿日期:2025-01-07 修回日期:2025-01-21 出版日期:2025-10-01 发布日期:2025-09-30
  • 通讯作者: 李腾（1989-），男，河南洛阳人，副教授，博士，非常规油气地质，（Tel）13689288702（Email）liteng2052@163.com
  • 作者简介:罗京（1993-），男，陕西宝鸡人，工程师，博士，天然气地质勘探，（Tel）15129486041（Email）luojing_cq@petrochina.com.cn
  • 基金资助:
    国家重点研发计划(2024YFC2909400);陕西省自然科学基础研究计划-面上项目(2024JC-YBMS-256);油气藏地质及开发工程全国重点实验室开放基金(PLN2023-21)

Pore Structure and Reservoir Properties of Deep Coals: A Case Study of No.5 Coal Rock of Shanxi Formation in Southwestern Ordos Basin

LUO Jing1(), ZHANG Lei1, ZHANG Jianwu1, PAN Xing1, CAO Qian1, LI Lei1, YAN Ting1, LI Teng2()   

  1. 1. PetroChina Changqing Oilfield Company, a.Research Institute of Exploration and Development; b.National Engineering Laboratory for Exploration and Development of Low-Permeability Oil & Gas Fields, Xi'an, Shaanxi 710018, China
    2. College of Petroleum Engineering, Xi'an Shiyou University, Xi'an, Shaanxi 710065, China
  • Received:2025-01-07 Revised:2025-01-21 Online:2025-10-01 Published:2025-09-30

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摘要：

为了明确深层煤岩成煤期成煤环境及其对煤岩微观孔隙结构和储集性能的控制作用，以鄂尔多斯盆地西南部山西组深层5号煤岩为研究对象，开展宏观煤岩观察、煤岩煤质测试、电镜扫描、气体吸附等相关测试，对深层煤岩成煤期煤相特征、煤岩微观孔隙结构特征及储集性能进行了研究。结果表明，山西组深层5号煤岩煤质整体表现为特低水分产率、中灰分产率、特低挥发分产率和中—高固定碳，煤岩平均镜质体反射率为2.38%；煤岩中镜质组含量为42.09%~72.49%，平均为60.60%，惰质组平均含量为27.34%，未见壳质组；基质镜质体、均质镜质体和半丝质体是煤岩主要有机亚显微组分，成煤期成煤环境以潮湿森林沼泽相为主，覆水深度较大、水动力微弱；层理缝、气孔和植物组织胞腔孔是主要的储集空间类型，另有少量的粒间孔和黏土矿物晶间孔；微孔和孔隙半径小于22 nm的介孔为山西组深层5号煤岩储集空间，较大尺寸介孔孔隙结构非均质性更为显著；强覆水、弱流动成煤环境利于镜质组的发育，即微孔是山西组深层5号煤岩的主要储集空间；高凝胶化作用下，煤岩有机质对陆源碎屑的吸附、粘连作用使得较大尺寸介孔的非均质性强。

关键词: 鄂尔多斯盆地, 山西组, 深层煤岩, 煤层气, 孔隙结构, 储集性能, 影响因素

Abstract:

In order to clarify the deep coal-forming environment and its controls on the microsopic pore structure and reservoir properties of coal rocks, the deep No.5 coal rock of Shanxi formation in southwestern Ordos Basin was selected for investigating the facies, pore structure and reservoir properties of deep coal rocks through macroscopic observations, coal quality measurements, scanning electron microscope (SEM), and gas adsorption tests. The results show that the No.5 coal rock features extra-low water yield, moderate ash yield, extra-low volatile yield, and moderate-high fixed carbon content, with the average vitrinite reflectance up to 2.38%. The content of vitrinite ranges from 42.09% to 72.49%, with an average of 60.60%, and the content of inertinite reaches 27.34% averagely, while exinite is rare in the coal. Desmocollinite, telocollinite and semifusinite are the dominant sub-macerals of the coal samples. The coal-forming environment was dominated by moist forest-swamp facies, with large overlying water depth and weak hydrodynamic force. The bedding fractures, gas pores and plant tissue pores serve as the dominant reservoir space types, and a small amount of intergranular pores and clay mineral intercrystalline pores are also observed. Micropores and mesopores with pore sizes less than 22 nm are the reservoir space, and the heterogeneity of pore structure containing larger mesopores is more significant. The coal-forming environment with strong water overburden and weak flow is conducive to the development of vitrinite, which also determines that micropores are the main reservoir space of the deep coal. Under the action of gelation, the adsorption and adhesion of terrigenous detritus by coal organic matters led to strong heterogeneity of pore structure containing larger mesopores.

Key words: Ordos Basin, Shanxi formation, deep coal rock, coalbed methane, pore structure, reservoir property, influence factor

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