摘要
鄂尔多斯盆地上古生界山西组5#煤作为该区煤岩(层)气勘探的重要目标层系,其储层沉积特征、物性条件及煤质特征在盆地尺度上尚缺乏系统性研究,制约了深部煤岩(层)气的高效勘探与开发。为此,本文综合运用测井解释、煤质分析(工业组分与热演化程度)、跨尺度孔隙结构表征(CO_(2)吸附、低温液氮吸附与高压压汞)以及含气量测试(实测含气量与甲烷等温吸附)等方法,系统揭示了5#煤在沉积环境、物性特征与煤质属性等方面的空间展布规律,进一步阐明了影响含气性差异的关键控制因素。研究结果表明:(1)5#煤层形成于海陆过渡相浅水三角洲沉积体系,煤层厚度总体呈现东北厚、西南薄的特征,顶底板以泥岩为主,局部发育砂岩或者砂泥岩;(2)煤的热演化程度自东北向西南逐渐增高,固定碳含量占主导,灰分与挥发分呈北高南低分布;(3)孔隙结构以微孔(<2 nm)为主,随热演化程度增高,自北向南微孔发育程度增强,吸附能力显著提升;(4)平面上,5#煤总含气量整体呈现南高北低的分布格局;(5)顶板封闭性、孔隙度与固定碳含量与含气量呈显著正相关,而灰分与挥发分含量则呈强负相关。本研究系统识别了影响5#煤含气性差异的关键地质因素,对鄂尔多斯盆地深部煤层气勘探部署与开发优化具有重要指导意义。
The No.5 coal seam of the Upper Paleozoic Shanxi Formation in the Ordos Basin is an important tar⁃get for coalbed methane(CBM)exploration in the region.However,systematic understanding of its reservoir depositional features,physical properties,and coal quality characteristics at the basin scale remains insuffi⁃cient,which constrains the efficient exploration and development of deep CBM.To address this issue,this study comprehensively applied well-log interpretation,coal quality analysis(proximate analysis and thermal maturity),multi-scale pore structure characterization(CO₂adsorption,low-temperature N_(2)adsorption,and high-pressure mercury intrusion),and gas content tests(measured gas content and methane isothermal adsorp⁃tion)to systematically reveal the spatial distribution patterns of the depositional environment,physical proper⁃ties,and coal quality attributes of the No.5 coal,and further clarify the key controlling factors influencing the differential gas-bearing properties.The results show that:(1)The No.5 coal was formed in a shallow-water delta sedimentary system within a marine-continental transitional facies,generally thickening toward the northeast and thinning toward the southwest,with roof s and floors dominated by mudstone and locally developed sandstone or sandy mudstone;(2)The thermal maturity of the coal gradually increases from northeast to southwest,fixed carbon content is dominant,and ash yield and volatile matter content are higher in the north and lower in the south;(3)The pore structure is dominated by micropores(<2 nm),and with increasing thermal maturity,the develop⁃ment of micropores enhances from north to south,significantly improving the gas adsorption capacity;(4)The total gas content of the No.5 coal generally exhibits a spatial distribution pattern of higher in the south and lower in the north;(5)Gas content shows a significant positive correlation with roof sealing,porosity,and fixed carbon content,and a strong negative correlation with ash yield and volatile matter content.This study systematically identifies the key geological factors controlling the differential gas-bearing properties of the No.5 coal,providing important guid⁃ance for the exploration and development planning of deep CBM in the Ordos Basin.
作者
黄道军
王康乐
陈宇航
潘博
梁晨
庄一鹏
王维斌
高星
张君莹
荆雪媛
HUANG Daojun;WANG Kangle;CHEN Yuhang;PAN Bo;LIANG Chen;ZHUANG Yipeng;WANG Weibin;GAO Xing;ZHANG Junying;JING Xueyuan(Research Institute of Petroleum Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an,Shaanxi 710018,China;Exploration Department,PetroChina Changqing Oilfield Company,Xi’an,Shaanxi 710018,China)
出处
《现代地质》
2025年第6期1595-1610,共16页
Geoscience
基金
国家重点研发计划项目“深部煤系流-固复合矿藏成矿规律与成藏机理”(2024YFC2909401)
中国石油长庆油田分公司勘探开发研究院项目“2024年盆地上古生界非主力层煤岩(层)气成藏地质条件与勘探潜力评价”(CQYTC⁃QKTY2024JS634)
中国石油长庆油田勘探事业部前期评价项目(202509)。
关键词
鄂尔多斯盆地
上古生界
山西组
深部煤层气
5号煤
孔隙结构
含气量
Ordos Basin
Upper Paleozoic
Shanxi Formation
deep coalbed methane
No.5 coal seam
pore structure
gas content
