石油与天然气地质 ›› 2024, Vol. 45 ›› Issue (6): 1605-1616.doi: 10.11743/ogg20240608

• 油气地质 • 上一篇    下一篇

鄂尔多斯盆地纳林河地区煤岩气成藏地质特征

侯雨庭1(), 周国晓2,3(), 黄道军2,3, 王彦卿2,3, 焦鹏帅2,3   

  1. 1.中国石油 长庆油田分公司，陕西 西安 710018
    2.低渗透油气田勘探开发国家工程实验室，陕西 西安 710018
    3.中国石油 长庆油田分公司 勘探开发研究院，陕西 西安 710018
  • 收稿日期:2024-09-02 修回日期:2024-10-30 出版日期:2024-12-30 发布日期:2024-12-31
  • 通讯作者: 周国晓 E-mail:hyt_cq@petrochina.com.cn;zhougx_cq@petrochina.com.cn
  • 第一作者简介:侯雨庭（1971—），男，教授级高级工程师，油气勘探综合地质研究与勘探管理。E-mail： hyt_cq@petrochina.com.cn。
  • 基金项目:
    中国石油天然气股份有限公司攻关性应用性科技专项(2023ZZ18)

Geological characteristics of coal-rock gas accumulation in the Nalinhe area， Ordos Basin

Yuting HOU1(), Guoxiao ZHOU2,3(), Daojun HUANG2,3, Yanqing WANG2,3, Pengshuai JIAO2,3   

  1. 1.Changqing Oilfield Company，PetroChina，Xi’an，Shaanxi 710018，China
    2.National Engineering Laboratory for Exploration and Development of Low Permeability Oil & Gas Fields，Xi’an，Shaanxi 710018，China
    3.Research Institute of Exploration and Development，Changqing Oilfield Company，PetroChina，Xi’an，Shaanxi 710018，China
  • Received:2024-09-02 Revised:2024-10-30 Online:2024-12-30 Published:2024-12-31
  • Contact: Guoxiao ZHOU E-mail:hyt_cq@petrochina.com.cn;zhougx_cq@petrochina.com.cn

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摘要：

鄂尔多斯盆地纳林河地区8#煤层埋深大于3 000 m，储层温度和压力场与中、浅层区别较大，研究其煤岩气成藏特征对深层煤岩气勘探具有重要的意义。系统解剖了纳林河地区深层煤岩气成藏地质要素，研究了煤岩煤质、储层特征、温-压场、含气性和保存条件等。对排采时间较长的M1H井进行了排采特征分析和产能预测。研究结果表明，相比埋深小于1 500 m的低压、低孔、低渗和含气量以欠饱和状态吸附气为主的浅层煤层气，埋深大于3 000 m的纳林河地区8#煤层煤岩气特征有显著差异：①纳林河地区本溪组8#煤层厚度大，以半亮煤为主，处于中-高煤阶。②受压实作用与煤化作用影响，中-高煤阶煤岩储层孔隙以孔径小于2 nm的微孔为主，微孔占比高达79.8 %，微米级内生微裂隙发育，在深部原位应力场条件下微裂隙处于开启状态，基质渗透率可高达3.949 × 10-3 μm2。③鄂尔多斯盆地3 000 m深度以深的地层温度和压力分别高达97 ℃和32 MPa，压力对煤岩吸附性能的影响程度已经趋于稳定，煤岩的吸附性能主要取决于温度的负效应。煤岩吸附气处于过饱和状态，游离气含量占比约30 %。④研究区深层煤岩储层处于承压水区，煤层本身富水性弱，现产出的地层水为顶、底板残留的原始沉积水。⑤M1H井排采曲线特征与煤岩气地球化学特征跟踪结果一致，证实3 000 m深度以深的煤岩气稳产效果好，开发潜力大。

关键词: 排采, 成藏地质特征, 煤岩气, 纳林河地区, 鄂尔多斯盆地

Abstract:

The No. 8 coal seam in the Nalinhe area， Ordos Basin， with a burial depth exceeding 3 000 m， exhibits reservoir temperature and pressure fields significantly different from those of shallow to moderately coal-rock gas reservoirs. Investigating the coal-rock gas accumulation characteristics of this coal seam holds great significance for deep coal-rock gas exploration. This study systematically analyzes the geologic factors controlling deep coal-rock gas accumulation in the Nalinhe area， delves into the geological characteristics concerning coal quality， reservoir characteristics， temperature and pressure fields， gas-bearing properties， and coal-rock gas preservation conditions in the area. Using data from well M1H， which has undergone prolonged coal-rock gas production， we analyze the production characteristics and predict the coal-rock gas productivity of the Nalinhe area. The results indicate that the coal-rock gas reservoirs in the No. 8 coal seam at burial depths exceeding 3 000 m exhibit characteristics significantly different from shallow coal-rock gas reservoirs at burial depths less than 1 500 m， which feature low pressure， porosity， and permeability and gases dominated by undersaturated adsorbed gas. The specific characteristics of the No. 8 coal seam are as follows： （1） This coal seam is thick and mainly composed of semi-bright coals， and of the medium to high rank； （2） Under compaction and coalification， the medium to high-rank coal reservoirs are dominated by micropores smaller than 2 nm， which account for up to 79.8 % of the total pore volume. Additionally， micron-scale endogenetic microfractures， which remain open under deep in-situ stress field， are well-developed in these reservoirs， leading to a high matrix permeability of up to 3.949 × 10-3 μm2； （3） At burial depths exceeding 3 000 m in the Ordos Basin， the formation temperature and pressure reach up to 97 ℃ and 32 MPa， respectively. The formation pressure tends to exert stabilized impacts on the adsorption capacity of coals， which predominantly hinges on the negative effect of temperature. Consequently， the adsorbed gas in the coals is in supersaturation， with free gas accounting for approximately 30 %； （4） The deep coal reservoirs in the study area are situated in a confined aquifer zone， while the coal seam itself manifests a low water-yielding capacity. The formation water produced is identified as the primary depositional water remaining in the roof and floor of the coal seam； （5） The consistency between the production curve characteristics of well M1H and the traced coal-rock gas geochemical characteristics demonstrates the stable production and great exploitation potential of coal-rock gas in deep reservoirs at burial depths exceeding 3 000 m.

Key words: dewatering and production, accumulation-associated geological characteristics, coal-rock gas, Nalinhe area, Ordos Basin

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