石油与天然气地质 ›› 2024, Vol. 45 ›› Issue (6): 1555-1566.doi: 10.11743/ogg20240604

• 油气地质 • 上一篇    下一篇

鄂尔多斯盆地大牛地气田深层中煤阶煤层气勘探实践及产能新突破

李亚辉()   

  1. 中国石油化工集团有限公司 华北油气分公司,河南 郑州 450000
  • 收稿日期:2024-10-14 修回日期:2024-11-19 出版日期:2024-12-30 发布日期:2024-12-31
  • 第一作者简介:李亚辉(1970—),男,博士、教授级高级工程师,油气地质学、构造地质学。E-mail: liyahui.hbsj@sinopec.com
  • 基金项目:
    中国石油化工股份有限公司重点科技项目(P23204)

Exploration practices of and recent production breakthroughs in deep middle-rank coalbed methane in the Daniudi gas field,Ordos Basin

Yahui LI()   

  1. North China Petroleum Bureau,SINOPEC,Zhengzhou,Henan 450000,China
  • Received:2024-10-14 Revised:2024-11-19 Online:2024-12-30 Published:2024-12-31

摘要:

鄂尔多斯盆地在大牛地气田2 800 m以深的中煤阶深层煤层气勘探开发中取得了重大突破,其中阳煤1HF井单井最高日产气量超10.4×104 m3,稳产时间已超过1年,平均稳产气量6.3×104 m3/d,累计产气量超2 300.0×104 m3。通过对该区深部中煤阶煤及煤层气地质特征的分析,提出了“区带优选、层段控制、规模压裂、精细排采”建产思路并实践应用。根据含气量、煤层厚度与特征、顶板条件和热演化程度对榆阳目标区进行了优选评价,研究表明:研究区以原生结构半亮煤为主,含气量主要分布在16.50 ~ 26.00 m3/t,游离气占总含气量的20 % ~ 25 %,平均孔隙度为4.68 %,平均渗透率为0.24×10-3 μm2,割理/裂隙发育,部分被方解石充填。光亮煤和半亮煤的总厚度大及高含气量是高产的基础,大排量和大规模改造是高产的关键。规模压裂时,要基于“饱和加砂、控近扩远、有效支撑”的工作思路,以“多簇密切割+大排量+高强度加砂”为有效技术手段。合理控制降压速率是深层煤层气井稳产、高产的关键,采用“控砂不控粉”排采理念,在排液和快速上产阶段采用光套管生产,在自喷生产阶段下入生产管柱采用控压连续、稳定排采,阳煤1HF井的控压生产实践已证实这些措施效果良好。

关键词: 勘探潜力, 富集特征, 成藏条件, 深层煤层气, 大牛地气田, 鄂尔多斯盆地

Abstract:

Breakthroughs have been achieved in the exploration and production of middle-rank coalbed methane (CBM) at a depth of 2 800 m and even deeper in the Daniudi gas field within the Ordos Basin. Notably, well YM-1HF exhibits a maximum single-well production of over 104 000 m3/d, an average stable production of 63 000 × 104 m3/d over one consecutive year, and an accumulative gas production exceeding 23 million m3. By analyzing the geological characteristics of deep middle-rank coals and CBM in the Daniudi gas field, we propose and practically apply a production capacity improvement approach that integrates play selection, interval-based drilling, volume fracturing, and fine coalbed gas production. For play selection, we assess the Yuyang area from the perspectives of gas content, coal seam thicknesses and characteristics, roof conditions, and thermal maturity. The results indicate that coals in the Yuyang area are dominated by semi-bright coals with primary texture, exhibiting gas content ranging from 16.50 to 26.00 m3/t, free gas accounts for 25 % to 30 % of the total gas content, an average porosity of 4.68 %, and an average permeability of 0.24 × 10-3 μm2. Cleats and fissures are well-developed in the coals and are partly filled with calcite. The substantial total thickness of bright and semi-bright coals and high gas content provide the foundation for high gas production, while high injection rates of fracturing fluids and large-scale hydraulic-fracture stimulation are critical to high gas production. To achieve volume fracturing, it is recommended to employ effective technical approaches including multi-cluster closely spaced perforation, high injection rates of fracturing fluids, and high-intensity proppant injection based on a work philosophy that integrates saturated proppant injection, fracturing fluid control for creating large-scale primary fractures near wellbores and more secondary fractures far away from wellbores, and effective propping of induced fractures. In addition, proper control of the depressurization rate is vital for stable, high production of deep CBM wells, and the production concept of preventing proppant production while promoting coal fines is adopted. Bare casing should be utilized in the fluid drainage and rapid production stage, and in the flowing production stage, it is necessary to employ production strings to achieve continuous and stable production under pressure control. This production concept has proven effective in the pressure-controlled production of well YM-1HF.

Key words: exploration potential, enrichment characteristics, accumulation condition, deep coalbed methane (CBM), Daniudi gas field, Ordos Basin

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