Production decline law and influencing factors of high-rank coal CBM wells

Authors

JIA Huimin, PetroChina Huabei Oilfield Company, Changzhi 046000, China
HU Qiujia, PetroChina Huabei Oilfield Company, Changzhi 046000, China
MAO Jianwei,, PetroChina Huabei Oilfield Company, Changzhi 046000, China
MAO Chonghao, PetroChina Huabei Oilfield Company, Changzhi 046000, China
LIU Chunchun, PetroChina Huabei Oilfield Company, Changzhi 046000, China
ZHANG Qing, PetroChina Huabei Oilfield Company, Changzhi 046000, China
LIU Changping, PetroChina Huabei Oilfield Company, Changzhi 046000, China

Abstract

In order to reveal the production decline law of high-rank coal CBM wells, based on the development data of Fanzhuang block in southern Qinshui basin for more than 10 years, this paper studies the decline point, decline type and influencing factors of high-rank coal CBM wells by means of numerical simulation and statistical analysis. The results show that the decline point of the Fanzhuang block is 25% and the average decline point of the single well is 21%. Most wells begin to decline after drainage of 4 years. The decline point of CBM well is determined by matrix permeability and half length of fracture. The higher the matrix permeability is, the larger the effective control radius of single well is, the more effective control reserves are, and the larger the decline point is. The higher the matrix permeability, the greater the growth of decrease point caused by the increase of half length of fracture. Permeability is the main controlling factor of CBM well decline type. The higher the permeability is, the smaller the decline index is, and the slower the decline rate is. With the increase of permeability, the decline types are linear decline, exponential decline and hyperbolic decline successively. The reason is that for formation with high permeability, the average pore radius is large, which results in much weaker stress sensitivity and much greater permeability by shrinkage of the coal and rock, leading to much higher dynamic permeability and much slower decline rate.

Keywords

high-rank coal, coalbed methane production, decline law, decline point, main controlling factors, Fanzhuang block, Qinshui basin

DOI

10.3969/j.issn.1001-1986.2020.03.009

Recommended Citation

JIA Huimin, HU Qiujia, MAO Jianwei,, et al. (2020) "Production decline law and influencing factors of high-rank coal CBM wells," Coal Geology & Exploration: Vol. 48: Iss. 3, Article 10.
DOI: 10.3969/j.issn.1001-1986.2020.03.009
Available at: https://cge.researchcommons.org/journal/vol48/iss3/10

Reference

[1] 赵贤正,朱庆忠,孙粉锦,等. 沁水盆地高阶煤层气勘探开发实践与思考[J]. 煤炭学报,2015,40(9):2131-2136. ZHAO Xianzheng,ZHU Qingzhong,SUN Fenjin,et al.Practice and thought of coalbed methane exploration and development in Qinshui basin[J]. Journal of China Coal Society,2015,40(9):2131-2136.

[2] FETKOVICH M J. Decline curve analysis using type curves[J]. Journal of Petroleum Technology,1980,32(6):1065-1077.

[3] JORDAN C L,JACKSON R A,SMITH C R. Making the most of conventional decline analysis[C]//SPE114953. Presented at the CIPC/SPE Gas Technology Symposium 2008 Joint Conference. Calgary,Alberta,Canada:2008-06-1.

[4] 苗耀,牛绪海,左银卿. 沁水盆地樊庄区块煤层气高产井递减特征及采收率预测[J]. 煤炭技术,2014,33(9):318-320. MIAO Yao,NIU Xuhai,ZUO Yinqing. Production decline characteristics and recovery rate forcasting for coalbed methane well of high production in Fanzhuang block Qinshui basin[J]. Coal Technology,2014,33(9):318-320.

[5] 刘刚. 樊庄区块煤层气地质特征及产能分析[D]. 徐州:中国矿业大学,2017. LIU Gang. The geological characteristics and productivity analysis of CBM in Fanzhuang block[D]. Xuzhou:China University of Mining and Technology,2017.

[6] 王彩凤,邵先杰,孙玉波,等. 中高煤阶煤层气井产量递减类型及控制因素:以晋城和韩城矿区为例[J]. 煤田地质与勘探,2013,41(3):23-28. WANG Caifeng,SHAO Xianjie,SUN Yubo,et al. Production decline types and their control factors in coalbed methane wells:A case from Jincheng and Hancheng mining areas[J]. Coal Geology & Exploration,2013,41(3):23-28.

[7] OKUSZKO K E,GAULT B W,MATTAR L. Production decline performance of CBM wells[J]. The Journal of Canadian Petroleum Technology,2008,47(7):57-61.

[8] MORAD K,TAVALLALI M. The benefits of reworking declining CBM wells[C]//SPE148952. Presented at the Canadian Unconventional Resources Conference. Calgary,Alberta,Canada:2011-15-17.

[9] AMINIAN K,AMERI S,SANCHEZ M,et al. Type curves for coalbed methane production prediction[C]//SPE 91482. Presented at SPE Eastern Regional Meeting. Charleston,W V,U S A:2004-15-17.

[10] 肖翠. 现代产量递减分析法在鄂尔多斯盆地延川南煤层气田中的应用[J]. 天然气工业,2018,38(增刊1):102-106. XIAO Cui. Application of modern production decline analysis method in coal seam gas field of south Yanchuan,Ordos basin[J]. Natural Gas Industry,2018,38(S1):102-106.

[11] 王江顺,张远凯. 基于现代产量递减分析法的煤层气井应用研究[J]. 煤炭技术,2018,37(9):64-66. WANG Jiangshun,ZHANG Yuankai. Research on application of CBM wells based on modern production decreasing analysis[J]. Coal Technology,2018,37(9):64-66.

[12] 贾慧敏,孙世轩,毛崇昊,等. 基于煤岩应力敏感性的煤层气井单相流产水规律研究[J]. 煤炭科学技术,2017,45(12):189-193. JIA Huimin,SUN Shixuan,MAO Chonghao,et al.Study on single-phase flow water production law of coalbed methane well based on coal and rock stress sensitivity[J]. Coal Science and Technology,2017,45(12):189-193.

[13] 刘世奇,赵贤正,桑树勋,等. 煤层气井排采液面-套压协同管控:以沁水盆地樊庄区块为例[J]. 石油学报,2015,36(增刊1):97-108. LIU Shiqi,ZHAO Xianzheng,SANG Shuxun,et al. Cooperative control of working fluid level and casing pressure for coalbed methane production:A case study of Fanzhuang block in Qinshui basin[J]. Acta Petrolei Sinica,2015,36(S1):97-108.

[14] 胡秋嘉,李梦溪,贾慧敏,等. 沁水盆地南部高煤阶煤层气水平井地质适应性探讨[J]. 煤炭学报,2019,44(4):1178-1187. HU Qiujia,LI Mengxi,JIA Huimin,et al. Discussion of the geological adaptability of coal-bed methane horizontal wells of high-rank coal formation in southern Qinshui basin[J]. Journal of China Coal Society,2019,44(4):1178-1187.

[15] 胡秋嘉,贾慧敏,祁空军,等. 高煤阶煤层气井单相流段流压精细控制方法:以沁水盆地樊庄-郑庄区块为例[J]. 天然气工业,2018,38(9):76-81. HU Qiujia,JIA Huimin,QI Kongjun,et al. A fne control method of flowing pressure in single-phase flow section of high-rank CBM gas development wells:A case study from the Fanzhuang-Zhengzhuang block in the Qinshui basin[J]. Natural Gas Industry,2018,38(9):76-81.

[16] ARPS J J. Analysis of decline curves[R]. SPE 945228,1945.

[17] 陈元千,唐玮. 广义递减模型的建立及应用[J]. 石油学报,2016,37(11):1410-1413. CHEN Yuanqian,TANG Wei. Establishment and application of generalized decline model[J]. Acta Petrolei Sinica,2016,37(11):1410-1413.

[18] 陈元千,周翠. 线性递减类型的建立、对比与应用[J]. 石油学报,2015,36(8):983-987. CHEN Yuanqian,ZHOU Cui. Establishment,comparison and application of the linear decline type[J]. Acta Petrolei Sinica,2015,36(8):983-987.

[19] 贾慧敏,胡秋嘉,祁空军,等. 高阶煤煤层气直井低产原因分析及增产措施[J]. 煤田地质与勘探,2019,47(5):104-110. JIA Huimin,HU Qiujia,QI Kongjun,et al. Reasons of low yield and stimulation measures for vertical CBM wells in high-rank coal[J]. Coal Geology & Exploration,2019,47(5):104-110.

[20] 贾慧敏,胡秋嘉,祁空军,等. 煤层气流压回升型不正常井储层伤害机理与治理[J]. 煤田地质与勘探,2019,47(4):69-75. JIA Huimin,HU Qiujia,QI Kongjun,et al. Damage mechanism and countermeasures of reservoir with abnormal pickup of CBM flow pressure in well[J]. Coal Geology & Exploration,2019,47(4):69-75.