Experimental Study of Nitrogen Throughput for Decongestion of Low Permeability Coal Seams
DOI:
https://doi.org/10.54097/gre2p895Keywords:
When Low Permeability Coal Seam, Coal Bed Methane, Unblocking, Nitrogen Injection PressureAbstract
China's underground coal seam geology is relatively old, and most of the reservoirs have low porosity, low permeability and low pressure. When a CBM well has been in production for a long period of time, the water production, gas production and formation pressure decrease over time. In order to achieve stable production or even increase production, multiple "nitrogen injection - pressure holding - release" operations can be implemented to achieve efficient development of CBM. In this paper, anthracite coal from coal seam 3# and coal seam 15# in Mabidong District was selected as the test sample for nitrogen throughput unblocking test to obtain the characteristics of permeability change after multiple throughput tests on coal rock samples. The test results show that: (1) in the process of nitrogen throughput, when the nitrogen injection pressure and holding time are fixed, the change in permeability is less related to the number of throughput repetitions, and the focus is on the increase in pressure and the selection of holding time; (2) with the holding time fixed, the permeability gradually increases with the increase in nitrogen injection pressure and the number of throughputs, and there is a large increase in permeability when the nitrogen injection pressure reaches 12.6 MPa and above high pressure; (3) Under the condition of lower nitrogen injection pressure, extending the holding time and increasing the number of throughputs, the permeability has a slow increase until 36h of holding pressure, and after 36h, the permeability shows a significant decrease and is smaller than the original permeability; (4) Increase the nitrogen injection pressure and holding time at the same time, the overall increase of permeability is larger, the reservoir nitrogen injection pressure is 12.6~13.6MPa, and the holding time is 36~48h, not only the overall increase in permeability is larger by increasing the nitrogen injection pressure and holding time simultaneously.
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[1] Wang Mingfeng. Multi-scale Digital Core Characterization of Coal Reservoirs in the Mabidong Block [D]. China University of Geosciences (Beijing), 2020.
[2] Sun Qinping, Zhao Qun, Jiang Xinchun, Mu Fuyuan, Kang Lixia, Wang Meizhu, Yang Qing, Zhao Yang. Prospects and Countermeasures for CBM Exploration and Development in China under the New Situation [J/OL]. Journal of China Coal Society: 1-13 [2021-01-19].
[3] Zhu Ruijing, Mu Mangeng, Jing Libo, Shi Jiangtao. Current Situation and Prospect of CBM Development in China [J]. Energy and Environment, 2020(04): 24+45.
[4] Li Jingming, Chao Haiyan, Li Xiaojun, Liu Honglin. Resource Characteristics and Development Strategies of CBM in China [J]. Natural Gas Industry, 2009, 29(04): 9-13+129-129.
[5] Zheng Han, Liu Kaide, Li Xiaolong, Li Shujia. Research Progress on Pore-Fracture Structure and Permeability of Coal Reservoirs Based on NMR and CT [J]. Science and Technology Innovation, 2020(34): 64-67.
[6] Meng Zhaoping, Tian Yongdong, Li Guofu. Theory and Methods of Coalbed Methane Development Geology [M]. Beijing: Science Press, 2010.
[7] Luo Peipei. Experimental Study on N₂ Soaking for Permeability Enhancement: A Case Study of Lu’an Mining Area [D]. Beijing: China University of Mining and Technology (Beijing), 2014.
[8] Gao Yuan. Research on Nitrogen Injection Stimulation Technology for Coalbed Methane [D]. China University of Petroleum (Beijing), 2018.
[9] Pang Feng, Zhang Jin, Zhou Jinhui, et al. Experimental Study on Influence of Nitrogen Soaking on Permeability of High-Rank Coal [J]. Coal Science and Technology, 2019, 47(2): 101-106.
[10] Cao Yunxing, Shi Bin, Zhou Dan, et al. Technology and Application of High-Pressure Nitrogen Soaking for Stimulation Reconstruction of Low-Production CBM Wells [J]. Journal of China Coal Society, 2019, 44(8): 2556-2565.
[11] Chen Zhenhong, Chen Yanpeng, Yang Jiaosheng, et al. Dynamic Permeability Characteristics of High-Rank CBM Reservoirs and Their Influence on CBM Production [J]. Acta Petrolei Sinica, 2010, 31(6): 966-974.
[12] Wang Caifeng. Permeability Variation Law and Its Influence on Production during CBM Development [D]. Qinhuangdao: Yanshan University, Oil and Gas Field Development Engineering, 2013.
[13] Tan Shifu, Li Xiaoliang. Influence of Adsorption on Permeability Characteristics of Raw Coal [J]. China Mining Magazine, 2012, 21(3): 92-95.
[14] Wei Jianping, Wei Le, Wang Dengke. Experimental Study on Influence of Adsorbed Gas on Seepage Characteristics of Gas-Bearing Coal under Load [J]. Journal of Henan Polytechnic University (Natural Science), 2013, 32(6): 653-657.
[15] Gu Dasheng, Xian Xuefu, Zhou Junping, et al. Analysis of Effective Stress and Different Gases on Coal Permeability [J]. Chinese Journal of Underground Space and Engineering, 2012, 8(6): 1296-1300.
[16] Chen Defei, Kang Yili, Meng Xiangjuan, et al. Influence of Gas Adsorption on Coal Rock Seepage Characteristics under Variable Stress [J]. Petroleum Geology and Recovery Efficiency, 2016, 23(1): 107-112.
[17] Long Qingming. Influence of Coal Adsorption on Gas Permeability Characteristics [D]. Chongqing: Chongqing Research Institute of China Coal Technology & Engineering Group, Prevention and Control of Coal and Gas Disasters, 2008.
[18] Wang Chen, Xian Xuefu, Zhou Junping, et al. Experimental Study on Full Stress-Strain Permeability Characteristics of Coal Rocks Containing Different Gases [J]. Chinese Journal of Underground Space and Engineering, 2013, 9(3): 492-495.
[19] Zhang Jie, Lin Shanshan, Qu Yonglin, et al. Experimental Study on CBM Flooding, Adsorption and Desorption Laws [J]. Special Oil & Gas Reservoirs, 2012, 19(6): 122-125.
[20] Wang Liguo. Experiment on Gas Injection Displacing CH₄ in Deep Coal Seams and Research on Characteristic Traces after Displacement [D]. Xuzhou: China University of Mining and Technology, Coal Safety Technology and Engineering, 2008.
[21] Deng Linsheng, Xue Dongjie, Zhou Hongwei. Fractal Tortuosity Model and Permeability Characterization of Rock Salt [J]. Journal of Liaoning Technical University (Natural Science), 2018, 37(06): 893-898.
[22] Wang Shengcheng. Temperature Effect of External Nitrogen Flow in Low-Permeability Coal Seams and Gas Stimulation Mechanism [D]. Beijing: China University of Mining and Technology (Beijing), 2015.
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