Numerical simulation of gas production for multilayer drainage coalbed methane vertical wells in southern Qinshui Basin

Authors

LIU Shiqi, Jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization, Carbon Neutrality Institute, China University of Mining and Technology, Xuzhou 221008, ChinaFollow
FANG Huihuang, School of Earth and Environment, Anhui University of Science and Technology, Huainan 232001, China
SANG Shuxun, Jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization, Carbon Neutrality Institute, China University of Mining and Technology, Xuzhou 221008, China
HU Qiujia, Shanxi CBM Branch of PetroChina Co. Ltd., Changzhi 046000, China
DUAN Weiying, Huabei Oilfield Company of PetroChina Co. Ltd., Renqiu 062552, China
JIA Huimin, Shanxi CBM Branch of PetroChina Co. Ltd., Changzhi 046000, China
MAO Chonghao, Shanxi CBM Branch of PetroChina Co. Ltd., Changzhi 046000, China

Abstract

With the development of CBM (coalbed methane) exploitation, multilayer drainage of the CBM well has received wide attention. The production control technology is the key to ensure high and stable gas production of CBM well multilayer drainage. However, the complex geological conditions of multiple coal seams increase the difficulty of production control of multilayer drainage. Numerical simulation technology is an effective method to study the production control technology of CBM well multilayer drainage. The scientific and reliable simulation results can provide a basis for production control. In this study, considering the influence of temperature effect, shrinkage effect of coal matrix, and effective stress on the fluid migration law in the coal seam, permeability and other coal seam physical parameters, the multi-physical field coupling mathematical model for the dynamic process of CBM vertical well multilayer drainage was established. The coupled solution of the multiple physical fields was obtained by using the finite element method. Then, the gas production effect of CBM vertical well multilayer drainage at different drainage rates and the dynamic evolution characteristics of permeability and other coal seam physical parameters were discussed by simulating a multilayer drainage CBM well group in Zhengzhuang block, Qinshui Basin, and corresponding engineering proposals were also put forward. The simulation results show that the gas contents of No.3 and No.15 coal seams in Zhengzhuang block are relatively high, and the CBM well group has a great potential to increase production, causing an insignificant effect of increasing the drainage rate on improving CBM recovery. In the production process, the effect of coal matrix shrinkage on permeability is stronger than that of effective stress, which is the guarantee to improve the drainage rate of CBM wells. On this basis, an appropriate increase in the drainage rate can increase the production of CBM wells when the drainage rate does not exceed the upper limit of the seepage capacity of the coal seam. Based on the simulation results, it is suggested to adjust the drainage rate mainly by controlling the working fluid level or fluid column pressure. To increase gas production of multilayer drainage CBM wells in No.3 and No.15 coal seams, the drainage rate of vertical well multilayer drainage in Zhengzhuang block is decreased by 0.12− 0.20 MPa/d in the fluid column pressure or by 12− 20 m/d in the working fluid level in the water production stage and pressure holding stage, which can not only increase production but also avoid reservoir damage.

Keywords

gas production for multilayer drainage, coalbed methane vertical well, drainage rate, working fluid level, multilayer drainage well, daily gas production, permeability, Zhengzhuang block of Qinshui Basin

DOI

10.12363/issn.1001-1986.22.01.0008

Recommended Citation

LIU Shiqi, FANG Huihuang, SANG Shuxun, et al. (2022) "Numerical simulation of gas production for multilayer drainage coalbed methane vertical wells in southern Qinshui Basin," Coal Geology & Exploration: Vol. 50: Iss. 6, Article 4.
DOI: 10.12363/issn.1001-1986.22.01.0008
Available at: https://cge.researchcommons.org/journal/vol50/iss6/4

Reference

[1] QIN Yong,MOORE T A,SHEN Jian,et al. Resources and geology of coalbed methane in China:A review[J]. International Geology Review,2018,60(5/6):777−812.

[2] 吴建光. 沁南地区煤层气生产潜力研究[J]. 中国煤田地质,2003,15(1):27−28. WU Jianguang. Research on productive potentiality of coalbed gas in region of southern Qinshui Basin[J]. Coal Geology of China,2003,15(1):27−28.

[3] KANG Junqiang,FU Xuehai,GAO Lin,et al. Production profile characteristics of large dip angle coal reservoir and its impact on coalbed methane production:A case study on the Fukang west block,southern Junggar Basin,China[J]. Journal of Petroleum Science and Engineering,2018,171:99−114.

[4] 魏迎春,张傲翔,姚征,等. 韩城区块煤层气排采中煤粉产出规律研究[J]. 煤炭科学技术,2014,42(2):85−89. WEI Yingchun,ZHANG Aoxiang,YAO Zheng,et al. Research on output laws of pulverized coal during coalbed methane drainage in Hancheng block[J]. Coal Science and Technology,2014,42(2):85−89.

[5] REN Jianhua,ZHANG Liang,REN Shaoran,et al. Multi–branched horizontal wells for coalbed methane production:Field performance and well structure analysis[J]. International Journal of Coal Geology,2014,131:52−64.

[6] CHEN Shida,TANG Dazhen,TAO Shu,et al. Current status and key factors for coalbed methane development with multibranched horizontal wells in the southern Qinshui Basin of China[J]. Energy Science & Engineering,2019,7(5):1572−1587.

[7] 易同生,周效志,金军. 黔西松河井田龙潭煤系煤层气–致密气成藏特征及共探共采技术[J]. 煤炭学报,2016,41(1):212−220. YI Tongsheng,ZHOU Xiaozhi,JIN Jun. Reservoir formation characteristics and co−exploration and concurrent production technology of Longtan coal measure coalbed methane and tight gas in Songhe field,western Guizhou[J]. Journal of China Coal Society,2016,41(1):212−220.

[8] 黄华州,桑树勋,苗耀,等. 煤层气井合层排采控制方法[J]. 煤炭学报,2014,39(增刊2):422−431. HUANG Huazhou,SANG Shuxun,MIAO Yao,et al. Drainage control of single vertical well with multi−hydraulic fracturing layers for coalbed methane development[J]. Journal of China Coal Society,2014,39(Sup.2):422−431.

[9] 周效志,桑树勋,易同生,等. 煤层气合层开发上部产层暴露的伤害机理[J]. 天然气工业,2016,36(6):52−59. ZHOU Xiaozhi,SANG Shuxun,YI Tongsheng,et al. Damage mechanism of upper exposed producing layers during CBM multi−coal seam development[J]. Natural Gas Industry,2016,36(6):52−59.

[10] 刘江,桑树勋,周效志,等. 六盘水地区煤层气井合层排采实践与认识[J]. 煤田地质与勘探,2020,48(3):93−99. LIU Jiang,SANG Shuxun,ZHOU Xiaozhi,et al. Practice and understanding of multi−layer drainage of CBM wells in Liupanshui area[J]. Coal Geology & Exploration,2020,48(3):93−99.

[11] 姜杉钰,康永尚,杨通保,等. 云南恩洪煤层气区块单井多煤层合采方式探讨[J]. 煤田地质与勘探,2018,46(2):80−89. JIANG Shanyu,KANG Yongshang,YANG Tongbao,et al. Combined CBM drainage of multiple seams by single well in Enhong block,Yunnan Province[J]. Coal Geology & Exploration,2018,46(2):80−89.

[12] 秦勇,张政,白建平,等. 沁水盆地南部煤层气井产出水源解析及合层排采可行性判识[J]. 煤炭学报,2014,39(9):1892−1898. QIN Yong,ZHANG Zheng,BAI Jianping,et al. Source apportionment of produced−water and feasibility discrimination of commingling CBM production from wells in southern Qinshui Basin[J]. Journal of China Coal Society,2014,39(9):1892−1898.

[13] 杨建超,李贵红,刘钰辉,等. 晋城地区煤层气井多层合采效果评价[J]. 煤田地质与勘探,2019,47(6):26−31. YANG Jianchao,LI Guihong,LIU Yuhui,et al. Evaluation of coalbed methane drainage effect for multi−target seams in Jincheng region[J]. Coal Geology & Exploration,2019,47(6):26−31.

[14] 孟尚志. 煤层气单支U型水平井合采多层技术研究：以柳林示范区为例[D]. 北京：中国地质大学(北京)，2014.

MENG Shangzhi. The technology design for single U–type horizontal well exploiting coalbed methane adjacent formation in Liulin[D]. Beijing：China University of Geosciences (Beijing)，2014.

[15] WANG Ziwei,QIN Yong. Physical experiments of CBM coproduction:A case study in Laochang district,Yunnan Province,China[J]. Fuel,2019,239:964−981.

[16] WU Caifang,ZHANG Xiaoyang,WANG Meng,et al. Physical simulation study on the hydraulic fracture propagation of coalbed methane well[J]. Journal of Applied Geophysics,2018,150:244−253.

[17] 李鑫,傅雪海. 不同层间距条件下煤层气井递进排采气、水产能研究[J]. 煤炭技术,2015,34(10):44−47. LI Xin,FU Xuehai. Research on gas and water capacity of CBM well during process of progressive drainage with different coal seam interval[J]. Coal Technology,2015,34(10):44−47.

[18] 姚帅,吴财芳,李腾. 潘庄区块煤层气井层间干扰数值模拟研究[J]. 煤炭工程,2014,46(3):80−83. YAO Shuai,WU Caifang,LI Teng. Study on numerical simulation of interferences between stratum interfaces of coal bed methane well in Panzhuang block[J]. Coal Engineering,2014,46(3):80−83.

[19] 张二超,吴财芳,党广兴,等. 滇东老厂区块多煤层煤层气合采层间干扰分析[J]. 河南理工大学学报(自然科学版),2020,39(1):10−17. ZHANG Erchao,WU Caifang,DANG Guangxing,et al. Interlayer interference analysis of the multi–layer drainage for multiple seams CBM in Laochang mining area of eastern Yunnan Province[J]. Journal of Henan Polytechnic University(Natural Science),2020,39(1):10−17.

[20] 王成. 铜川焦坪矿区煤层气储层数值模拟与排采制度研究[J]. 中国煤炭地质,2013,25(4):18−22. WANG Cheng. A study on CBM reservoir numerical simulation and drainage system in Jiaoping mining area,Tongchuan[J]. Coal Geology of China,2013,25(4):18−22.

[21] 吴艳婷. 多煤层区煤层气合层开发产能及经济性研究[D]. 北京：中国矿业大学(北京)，2018.

WU Yanting. Research on well productivity and economic feasibility of commingled coalbed methane production in multi–seam zone[D]. Beijing：China University of Mining and Technology(Beijing)，2018.

[22] 张政. 沁水盆地南部太原组含煤层气系统及其排采优化[D]. 徐州：中国矿业大学，2016.

ZHANG Zheng. Coalbed methane system and drainage optimization of Taiyuan Formation in southern Qinshui Basin[D]. Xuzhou：China University of Mining and Technology，2016.

[23] 张先敏,同登科. 考虑基质收缩影响的煤层气流动模型及应用[J]. 中国科学E辑:技术科学,2008,38(5):790−796. ZHANG Xianmin,TONG Dengke. Coalbed methane flow model considering matrix shrinkage and its application[J]. Scientia Sinica:Technologica,2008,38(5):790−796.

[24] 张先敏,同登科. 沁水盆地产层组合对煤层气井产能的影响[J]. 煤炭学报,2007,32(3):272−275. ZHANG Xianmin,TONG Dengke. The effects of pay formation combination on productivity of coalbed methane well in Qinshui Basin[J]. Journal of China Coal Society,2007,32(3):272−275.

[25] HU Qiujia,LIU Shiqi,SANG Shuxun,et al. Numerical analysis of drainage rate for multilayer drainage coalbed methane well group in southern Qinshui Basin[J]. Energy Exploration & Exploitation,2020,38(9):1535−1558.

[26] 刘世奇,方辉煌,桑树勋,等. 基于多物理场耦合求解的煤层CO₂–ECBM数值模拟研究[J]. 煤炭科学技术,2019,47(9):51−59. LIU Shiqi,FANG Huihuang,SANG Shuxun,et al. Numerical simulation study on coal seam CO₂–ECBM based on multi–physics fields coupling solution[J]. Coal Science and Technology,2019,47(9):51−59.

[27] LI Sheng,FAN Chaojun,HAN Jun,et al. A fully coupled thermal−hydraulic−mechanical model with two−phase flow for coalbed methane extraction[J]. Journal of Natural Gas Science and Engineering,2016,33:324−336.

[28] LIU Shiqi,FANG Huihuang,SANG Shuxun,et al. CO₂ injectability and CH₄ recovery of the engineering test in Qinshui Basin,China,based on numerical simulation[J]. International Journal of Greenhouse Gas Control,2020,95:102980.

[29] ZHAO Junlong,TANG Dazhen,XU Hao,et al. A dynamic prediction model for gas–water effective permeability in unsaturated coalbed methane reservoirs based on production data[J]. Journal of Natural Gas Science and Engineering,2014,21:496−506.

[30] FAN Yongpeng,DENG Cunbao,ZHANG Xun,et al. Numerical study of CO₂–enhanced coalbed methane recovery[J]. International Journal of Greenhouse Gas Control,2018,76:12−23.

[31] WANG Gang,WANG Ke,JIANG Yujing,et al. Reservoir permeability evolution during the process of CO₂–enhanced coalbed methane recovery[J]. Energies,2018,11(11):1−21.

[32] WANG Gang,WANG Ke,WANG Shugang,et al. An improved permeability evolution model and its application in fractured sorbing media[J]. Journal of Natural Gas Science and Engineering,2018,56:222−232.