Author
Listed:
- Wei Zhang
(Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, Ministry of Education of China, China University of Mining and Technology, Xuzhou 221116, China
China United Coalbed Methane National Engineering Research Center Co., Ltd., Beijing 100095, China
PetroChina Coalbed Methane Company Limited, Beijing 100028, China)
- Zheng Zhang
(Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, Ministry of Education of China, China University of Mining and Technology, Xuzhou 221116, China)
- Liheng Bian
(China United Coalbed Methane National Engineering Research Center Co., Ltd., Beijing 100095, China
PetroChina Coalbed Methane Company Limited, Beijing 100028, China)
- Rui Shi
(Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, Ministry of Education of China, China University of Mining and Technology, Xuzhou 221116, China)
- Hewei Zhang
(Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, Ministry of Education of China, China University of Mining and Technology, Xuzhou 221116, China)
- Jian Shen
(Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process, Ministry of Education of China, China University of Mining and Technology, Xuzhou 221116, China)
Abstract
Deep coalbed methane (CBM) demonstrates significant production potential, and a fervent exploration and development boom is currently underway in China. The permeability of coal reservoirs is heavily influenced by pore–fracture structure heterogeneity. Some researches have been conducted on deep coals’ pore–fracture structure; however, these studies mostly consider coal as a homogeneous material, neglecting the heterogeneity of the macrolithotypes within the coal. In this study, 33 deep coals with burial depths of more than 2000 m were obtained from the Daning-Jixian block of the Ordos Basin, covering all macrolithotypes: bright coal (BC), semi-bright coal (SBC), semi-dull coal (SDC), and dull coal (DC). These samples were subjected to three sets of NMR tests in dry, fully saturated, and irreducible water conditions, with the pore–fracture structure characteristics being analyzed. The results demonstrate that the sampled deep coals’ pore–fracture structure is highly heterogeneous, with transitional pores being dominant, followed by mesopores, “macropores and fractures”, and micropores. The NMR T 2C ranges from 0.61 to 2.44 ms, with an average of 1.19 ms; a higher T 2C value indicates more developed micropores. The ranges for producible water porosity ( φ pr ) and producible water saturation ( S pr ) are 0.31–7.24% (avg. 2.42%) and 6.97–71.47% (avg. 31.06%), respectively. Both of them exhibit a high positive correlation with the total volumes of “macropores and fractures” and mesopores. Compared to SDC and DC, the BC and SBC, especially the former, overall contain more “macropores and fractures” and mesopores, fewer transitional pores and micropores, and higher φ pr and S pr . These findings suggest that regions with abundant BC and SBC should be prioritized during deep CBM exploration and production due to the inherently superior permeability and gas extraction potential of BC and SBC, and these coals are likely to require less intensive stimulation to achieve higher recovery rates and could provide more sustainable gas production over time.
Suggested Citation
Wei Zhang & Zheng Zhang & Liheng Bian & Rui Shi & Hewei Zhang & Jian Shen, 2024.
"NMR-Based Investigation of Pore–Fracture Structure Heterogeneity in Deep Coals of Different Macrolithotypes in the Daning-Jixian Block, Ordos Basin,"
Energies, MDPI, vol. 17(23), pages 1-16, December.
Handle:
RePEc:gam:jeners:v:17:y:2024:i:23:p:6081-:d:1535533
Download full text from publisher
Corrections
All material on this site has been provided by the respective publishers and authors. You can help correct errors and omissions. When requesting a correction, please mention this item's handle: RePEc:gam:jeners:v:17:y:2024:i:23:p:6081-:d:1535533. See general information about how to correct material in RePEc.
If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.
We have no bibliographic references for this item. You can help adding them by using this form .
If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your RePEc Author Service profile, as there may be some citations waiting for confirmation.
For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: MDPI Indexing Manager (email available below). General contact details of provider: https://www.mdpi.com .
Please note that corrections may take a couple of weeks to filter through
the various RePEc services.