石油与天然气地质 ›› 2024, Vol. 45 ›› Issue (6): 1577-1589.doi: 10.11743/ogg20240606

• 油气地质 • 上一篇    下一篇

鄂尔多斯盆地中、东部石炭系本溪组煤储层纵向非均质性特征及成因

牛小兵1,2(), 张辉1,3, 王怀厂1,3, 虎建玲1,3, 吴陈君4, 赵伟波1,3(), 潘博1,3   

  1. 1.低渗透油气田勘探开发国家工程实验室,陕西 西安 710018
    2.中国石油 长庆油田分公司,陕西 西安 710018
    3.中国石油 长庆油田公司 勘探开发研究院,陕西 西安 710018
    4.长江大学 资源与环境学院,湖北 武汉 430100
  • 收稿日期:2024-09-15 修回日期:2024-10-20 出版日期:2024-12-30 发布日期:2024-12-31
  • 通讯作者: 赵伟波 E-mail:nxb_cq@petrochina.com.cn;zhaowb_cq@petrochina.com.cn
  • 第一作者简介:牛小兵(1978—),男,教授级高级工程师,油气勘探管理与科研。E-mail:nxb_cq@petrochina.com.cn
  • 基金项目:
    中国石油攻关性应用性科技专项(2023ZZ18-02)

Characteristics and genesis of vertical heterogeneity in a coal seam of the Carboniferous Benxi Formation, eastern Ordos Basin: A case study of well M172

Xiaobing NIU1,2(), Hui ZHANG1,3, Huaichang WANG1,3, Jianling HU1,3, Chenjun WU4, Weibo ZHAO1,3(), Bo PAN1,3   

  1. 1.National Engineering Laboratory for Exploration and Development of Low-Permeability Oil & Gas Fields,Xi’an,Shaanxi 710018,China
    2.Changqing Oilfield Company,PetroChina,Xi’an,Shaanxi 710018,China
    3.Research Institute of Exploration and Development,Changqing Oilfield Company,PetroChina,Xi’an,Shaanxi 710018,China
    4.College of Resources and Environment,Yangtze University,Wuhan,Hubei 430100,China
  • Received:2024-09-15 Revised:2024-10-20 Online:2024-12-30 Published:2024-12-31
  • Contact: Weibo ZHAO E-mail:nxb_cq@petrochina.com.cn;zhaowb_cq@petrochina.com.cn

摘要:

鄂尔多斯盆地石炭系本溪组8#煤储层厚度大、分布范围广、发育稳定,是该区深层煤岩气有利勘探层段。通过对盆地中、东部重点井煤岩样品开展宏观煤岩特征、煤岩性质、储层特征以及煤岩含气性等方面的测试分析,研究了本溪组8#煤储层非均质性特征及成因。研究表明:①煤岩性质纵向发育存在明显的非均质性特征,下段主要发育半亮煤,灰分产率高,惰质组相对较发育,表明该段煤储层形成于偏氧化的成煤环境。中、上段发育光亮煤和半亮煤,灰分产率低,镜质组含量较高,反映了陆源输入较少的还原性成煤环境;②本溪组8#煤储层煤岩沉积环境变化控制了煤岩性质和储层发育特征。储层非均质性受到陆源矿物输入充填原生孔隙以及高含量镜质组生烃阶段产生大量气孔的双重影响。③上段由于沉积环境稳定,成煤条件好,灰分产率较低,煤储层孔隙和裂隙受碎屑矿物充填影响较小,煤岩储集物性更好,有利于气体的吸附和保存。中、上段镜质组含量高、生气能力强,具有更好的煤岩气物质条件,使得煤岩含气量更高,是鄂尔多斯盆地本溪组8#煤储层天然气勘探开发的有利层段。

关键词: 工业组分, 成煤环境, 储层非均质性, 煤岩气, 本溪组, 石炭系, 鄂尔多斯盆地

Abstract:

The No. 8 coal seam of the Carboniferous Benxi Formation in the Ordos Basin exhibits great thickness and extensive, continuous distribution, establishing itself as a favorable interval for the exploration of deep coal-rock gas in this region. In this study, we examine the characteristics and genesis of the vertical heterogeneity in the No. 8 coal seam by conducting tests and analysis of the macroscopic characteristics, properties, reservoir characteristics, and gas content of coal samples collected from key well M172 in the eastern Ordos Basin. The results indicate that the No. 8 coal seam exhibits pronounced vertical heterogeneity with dominated semi-bright coals, high ash content and high inertinite content in the lower section, indicating a slightly oxidizing coal-forming environment. In contrast, its middle and upper parts contain bright and semi-bright coals and feature low ash content and high vitrinite content, reflecting a reducing coal-forming environment with limited terrestrial input. The coal rock properties and reservoir development characteristics of the No. 8 coal seam are controlled by changes in the sedimentary environment. The reservoir heterogeneity, to be specific, is influenced by both the input of terrigenous minerals to fill primary pores and the formation of abundant pores during hydrocarbon generation with high vitrinite content. For the sake of the stable sedimentary environment, the upper section of the No. 8 coal seam exhibits favorable coal-forming conditions and low ash content. Furthermore, the pores and fractures of the coal reservoirs in this part are minimally filled with detrital minerals, resulting in improvement in reservoir properties and gas adsorption and preservation. In contrast, the middle and upper sections demonstrate high vitrinite content and a significant gas generation capacity, providing more favorable material conditions for the generation of coal-rock gas and resulting in higher coal-rock gas content. Therefore, the middle and upper sections of the No. 8 coal seam represent favorable intervals for natural gas exploration and production in the Ordos Basin.

Key words: proximate analysis-derived coal elemental composition, coal-forming environment, reservoir heterogeneity, coal-rock gas, Benxi Formation, Carboniferous, Ordos Basin

中图分类号: